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Background: Octogenarians and nonagenarians diagnosed with breast cancer have a competing risk of death from other causes and their management is frequently found to be discordant with guidelines in comparison to the younger patients, particularly with low-risk disease. There is limited information about the disease trajectory and outcomes of patients with high-risk disease. Thus, this study was conducted. Methods: This is a retrospective, population-based observational study. Women aged 80 years of age or older and diagnosed with non-metastatic, high-risk breast cancer in Alberta, Canada between January 2004 and December 2017 were identified from the Alberta Cancer Registry. High-risk disease was defined as having any of the following; T3/4, any N positive, triple negative, or Her-2 positive disease. A risk scoring system was generated based on the presence of two anatomical and one biological high-risk features to generate 3 risk levels. Patients’ characteristics (age, Charlson comorbidity index, residence, education-, and income- quintiles), disease characteristics (stage, grade, receptor status,) treatment patterns (treatment delivered, facility) and survival were determined from linkage with administrative databases (Discharge Abstract Data, National Ambulatory Care Reporting System, and Vital statistics). Treatments were stratified into; none, hormonal treatment only (HT), surgery only (S), and surgery with any adjuvant treatment (S+A). Statistical methods included chi-square and Cox regression models. Association between patient, tumor and treatment variables and survival were assessed with uni- and multivariable analysis. Primary outcome was breast cancer specific survival (BCSS) in patients stratified by different risk levels in relation to the treatment delivered. Results: 1369 patients met the inclusion criteria. The median age was 84 years (interquartile range [IQR] 82-88). After a median follow-up of 35 months (m), 873 (64%) patients had died; 405 (46%) of deaths were due to breast cancer. On multivariable analysis, patients had a lower hazard of death from cancer if they were treated with S (HR = 0.51, 95%CI: 0.34, 0.77, p = 0.001) or S+A (HR = 0.41, 95%CI: 0.28, 0.6, p < 0.001) in comparison to HT alone. Patients who did not receive any form of treatment were more likely to die from breast cancer (HR 2.14 95%CI: 1.38, 3.31, p = 0.0006). Patients who had 1 or 2 risk features had higher cancer specific and overall survival if they had S or S+A (49/31m, 92/66m median differences respectively p < .0001). Those with 3 risk features showed longer survival if they received S+A (29/25m median differences p < .0001). Conclusions and Relevance: Our findings suggest that a significant proportion of older patients with breast cancer patients with high-risk features may have increased disease-specific mortality risk. Based on a priori risk levels, and in properly selected patients, treatment options including surgery and adjuvant treatment may be associated in longer survival. Table 1 - Population and Treatment CharacteristicsVariablesCategoryTotal (N=1369)Age group80-85817 (59.7 %)86-90388 (28.3 %)91-95146 (10.7 %)>9518 (1.3 %)Charlson Comorbidity Index0453 (33.1 %)1361 (26.4 %)>=2555 (40.5 %)TNM stageI239 (17.5 %)II663 (48.4 %)III422 (30.8 %)T stageT1416 (30.4 %)T2601 (43.9 %)T3163 (11.9 %)T4169 (12.3 %)Unknown20 (1.5 %)N stageN0526 (38.4 %)N1548 (40 %)N2159 (11.6 %)N385 (6.2 %)Unknown51 (3.7 %)Receptor statusER+orPR+andHer2-1071 (78.2 %)Her2+130 (9.5 %)ER-andPR-andHer2-123 (9 %)Unknown45 (3.3 %)Risk levels1922 (67.3 %)2371 (27.1 %)376 (5.6 %)Surgery typeNo surgery215 (15.7 %)BCS364 (26.6 %)Mastectomy790 (57.7 %)Sentinel surgeryno938 (68.5 %)yes431 (31.5 %)Chemotherapyno1337 (97.7 %)yes32 (2.3 %)Radiotherapyno991 (72.4 %)yes378 (27.6 %)Hormonotherapyno659 (48.1 %)yes710 (51.9 %) Citation Format: Abdulla Al-Rashdan, Yuan Xu, Lisa Barbera, Jeffrey Cao, Winson Cheung, Antoine Bouchard-Fortier, MayLynn Quan. High-risk breast cancer in oldest old: Exploring the effect of different treatments on outcomes [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS1-06.

Background The majority of women in Nigeria present with advanced-stage breast cancer. To address the role of geospatial access, we constructed a geographic information-system-based model to evaluate the relationship between modeled travel time, stage at presentation, and overall survival among patients with breast cancer in Nigeria. Methods Consecutive patients were identified from a single-institution, prospective breast cancer database (May 2009-January 2019). Patients were geographically located, and travel time to the hospital was generated using a cost-distance model that utilized open-source data. The relationships between travel time, stage at presentation, and overall survival were evaluated with logistic regression and survival analyses. Models were adjusted for age, level of education, and socioeconomic status. Results From 635 patients, 609 were successfully geographically located. The median age of the cohort was 49 years (interquartile range [IQR], 40-58 years); 84% presented with ≥stage III disease. Overall, 46.5% underwent surgery; 70.8% received systemic chemotherapy. The median estimated travel time for the cohort was 45 minutes (IQR, 7.9-79.3 minutes). Patients in the highest travel-time quintile had a 2.8-fold increase in the odds of presenting with stage III or IV disease relative to patients in the lowest travel-time quintile (P = .006). Travel time ≥30 minutes was associated with an increased risk of death (HR, 1.65; P = .004). Conclusions Geospatial access to a tertiary care facility is independently associated with stage at presentation and overall survival among patients with breast cancer in Nigeria. Addressing disparities in access will be essential to ensure the development of an equitable health policy.

Introduction Atypical lipomatous tumors or well-differentiated liposarcomas (ALT/WDLS) are low-grade soft tissue tumors that are commonly located on the trunk and extremities. There is no consensus on the best surgical approach for ALT/WDLS. Methods A systematic literature review of PubMed, Medline, Embase, Scopus, and google scholar was performed. All published studies on trunk or extremities ALT/WDLS with reported outcome data were considered and independently screened for inclusion by at least two of the authors. Results A total of eighteen studies comprising 793 patients with ALT/WDLS were included. 580 patients underwent marginal excision, with local recurrence observed in 69 (11.9%). 213 patients underwent wide excision with local recurrence in 7(3.3%). Recurrent tumors were successfully re-resected with marginal or wide excision. Dedifferentiation was confirmed in 9 patients (1.1%), and a distant pulmonary metastasis in 1 patient (0.1%). Discussion Marginal excision of truncal or extremities ALT/WDLS results in a slightly higher local recurrence rate. However, recurrences are almost always amenable to re-resection. The findings support the use of marginal excision for truncal or extremities ALT/WDLS.

The incidence of breast biopsy following treatment for breast cancer is not well-characterized. We sought to determine the frequency and outcomes of breast biopsy and the need for subsequent surgery in patients treated with breast-conserving surgery (BCS). Using a prospective database, we identified patients in Alberta, Canada, treated with BCS for screen-detected breast cancer or ductal carcinoma in situ (DCIS) from 2010 to 2014. Post-treatment breast procedures were identified from physician claims data. Multivariable analysis was performed to identify factors associated with biopsy. We included 2065 patients with a median of 6.4 years of follow-up; most had DCIS (n = 426, 20.6%) or stage I disease (n = 1385, 67.1%). Post-treatment core biopsy was performed in 389 (18.8%, 95% confidence interval [CI] 17.2–20.6%) patients, and excisional biopsy was performed in 19 (0.9%, 95% CI 0.6–1.4%) patients. The per-patient benign-to-malignant biopsy ratio was 3.2 to 1, and the overall malignancy rate was 6.1% (95% CI 5.1–7.2%). Younger age, proximity to a cancer center, positive margins, and the use of magnetic resonance imaging were associated with biopsy (p

Retroperitoneal sarcoma (rps) encompasses a heterogeneous group of malignancies with a high recurrence rate after resection. Neoadjuvant radiotherapy (nrt) is often used in the hope of sterilizing margins and decreasing local recurrence after excision. We set out to compare local recurrence-free survival (lrfs) and overall survival (os) in patients treated with or without nrt before resection. Patients diagnosed with rps from February 1990 to October 2014 were identified in the Alberta Cancer Registry. Patients with complete gross resection of rps and no distant disease were included. Patient, tumour, treatment, and outcomes data were abstracted in a primary chart review. Baseline characteristics were compared using the Wilcoxon nonparametric test for continuous data and the Fisher exact test for dichotomous and categorical data. Survival was analyzed using Kaplan&ndash, Meier curves with log-rank test. Cox regression was performed to control for age, sex, tumour size, tumour grade, date of diagnosis, multivisceral resection, and intraoperative rupture. Resection alone was performed in 62 patients, and resection after nrt, in 40. Use of nrt was associated with multivisceral resection and negative microscopic margins. On univariate analysis, nrt was associated with superior median lrfs (89.3 months vs. 28.4 months, p = 0.04) and os (119.4 months vs. 75.9 months, p = 0.04). On multivariate analysis, nrt, younger age, and lower tumour grade predicted improved lrfs and os, sex, tumour size, date of diagnosis, multivisceral resection, and tumour rupture did not. In this population-based study, nrt was associated with superior lrfs and os on both univariate and multivariate analysis. When feasible, nrt should be considered until a randomized controlled trial is completed.

Well-differentiated liposarcomas (WDLS) are low-grade lipomatous tumors with low malignant potential. Previous review identified controversy on whether upfront wide resection is necessary when they occur on the trunk or the extremities. MDM2 amplification is a genetic mutation typically present in WDLS and absent in benign lipomas (BL). We aimed to study the influence of MDM2 status on the management/recurrences of lipomatous tumors in the trunk or the extremities.All patients with lipomatous tumors with MDM2 testing in the Province of Alberta between 2015 and 2020 were identified from the Cancer Cytogenetics Laboratory dataset. High grade sarcomas, retroperitoneal, head/neck, or groin tumors were excluded. Primary outcome measures including MDM2 status, surgical margin, local recurrence, reoperation rate, dedifferentiation, and metastasis were abstracted from chart review. Descriptive statistics were used to analyse treatment patterns and recurrence rates according to MDM2 status.Total of 764 charts were retrieved, and 282 were included for analysis. 33 showed MDM2 amplification (11.7%), and 2 of them had local recurrence (6.1%). Two patients with recurrent tumors underwent limb-salvaging reoperation (6.1%), but no dedifferentiation or metastasis was seen.Findings in this study confirmed the benign behaviour of truncal/extremities lipomas with no MDM2 amplification. Given we found a 6.1% recurrence rate in MDM2 amplified tumors, a prolong follow up of this subset of patients is warranted. Overall, regardless of the MDM2 status, we believe an initial marginal excision is a reasonable surgical approach as recurrences are rare, and they can be managed with re-excision when they occur.

Background Cytoreductive surgery and heated intraperitoneal chemotherapy (CRS/HIPEC) are commonly used in the treatment of peritoneal carcinomatosis (PC) originating from colorectal, appendiceal and ovarian cancers. It is unclear what benefit CRS/HIPEC might have for PC from uncommon etiologies, therefore we sought to describe local practice patterns and evaluate overall survival (OS). Methods All patients who had CRS/HIPEC between 2000 and 2016 were identified using our institutional cancer database. Patients with appendiceal, colorectal, and ovarian pathologies were excluded. Kaplan-Meier curves were used to estimate and demonstrate 5-year OS. Cox regression analysis was performed to determine factors associated with OS. Results Of all patients treated with CRS/HIPEC at our institution, 38 were treated for PC of rare origin. Etiologies included 23 patients with mesothelioma, 8 with primary peritoneal carcinoma, 4 with small bowel tumours and 3 with gastric cancer. Median OS of 35.4, 20.8, 25.4, and 20.2 months were obtained for each group respectively. 5-year OS for each pathology was 8.7%, 0.0%, 25.0%, and 33.3% respectively with corresponding mean PCI of 31.3, 23.6, 21.5, and 12.7. No independent prognostic factors were significant on Cox regression analysis. Median length of stay was 19 days. Readmission rate within 30 days of discharge was 7.9%. Rate of Grade III/IV complications was 34.2%. No thirty-day mortality. Conclusion Survivals beyond 20 months can be obtained with the use of CRS/HIPEC for rare PC etiologies aligning with results of other groups. CRS/HIPEC in well-selected patients demonstrates a clinical benefit and this could be confirmed with a multi-institutional study.

e12578 Background: The optimal local regional management of the positive axilla in patients who convert to clinical negative nodal status after neoadjuvant chemotherapy (NAC) remains unclear. Specifically, the benefit of completion axillary node dissection (cALND) remains in question, particularly given the associated morbidity. With results of the A11202 trial pending, we noted regional variation in the management of the axilla in this population. We therefore aimed to describe the current management of women with positive SNB after NAC, describe recurrence patterns and identify predictors of cALND in a large, population-based, real-world setting. Methods: We identified all patients who had biopsy-proven nodal disease on presentation, underwent NAC and were then clinically downstaged allowing SNB as part of their index surgery from our Synoptec provincial operative database, from January 2016 to September 2021. Pre and post NAC tumour characteristics, patient demographics, treatments and final pathology were abstracted and conveyed using descriptive statistics. Primary outcome measures were treatment with cALND and recurrence. A Cox regression model was utilized to determine predictors of both outcomes. Results: A total of 850 patients had biopsy-proven axillary disease at presentation and subsequently underwent NAC. Of these, 364 patients converted to clinically-negative node status and had a SNB, of which 175 (48%) had persistent nodal disease. Median age of this group was 50 (IQR 43-60) and 143 patients (81.7%) were treated by a high-volume breast surgeon. Most patients had clinical T1/2 tumours (73.1%) before NAC, of which 21.1% were HER2 positive, and 12.6% were triple-negative. Post NAC, 95 patients (54.3%) underwent mastectomy. A total of 39/175 patients (22.3%) underwent a cALND. Median number of sentinel nodes was 4 (IQR 3, 5); the proportion of positive sentinel nodes did not differ in those who had cALND (0.59 vs. 0.59, p = 0.95). Almost all patients (96.6%) had regional radiation. After a median of 17 months of follow-up, 33 (18.8%) SNB positive patients recurred; the majority (29 (87.9%)) had a distant recurrence, 3 (9.1%) had an isolated local breast/chest wall recurrence, and only 1 (3.0%) had an isolated regional recurrence. As far as local control, in patients with any regional recurrence, 4/7 (57.1%) had undergone cALND. Treatment site was the only significant predictor of cALND on multivariable analysis. Predictors of recurrence were low BMI, triple-negative status and clinical T3/4 disease before NAC. Conclusions: The lack of definitive data for patients with persistent pathologic nodal disease after NAC has led to variable practice patterns, with lower than expected rates of cALND. Within our cohort, there was not a significant association between omission of cALND and regional recurrence.

Triple-negative breast cancer (TNBC) is more common among young women, although it frequently presents in older patients. Despite an aging population, there remains a paucity of data on the treatment of TNBC in elderly women. We conducted a systematic review of the peer-reviewed and unpublished literature that captures the management and breast-cancer-specific survival (BCSS) of women ≥70 years old with TNBC. Out of 739 papers, five studies met our inclusion criteria. In total, 2037 patients with TNBC treated between 1973 and 2014 were captured in the analysis. Women ≥70 years old were less likely to undergo surgical resection compared to those

Modern management of colorectal cancer (CRC) with peritoneal metastasis (PM) is based on a combination of cytoreductive surgery (CRS), systemic chemotherapy, and hyperthermic intraperitoneal chemotherapy (HIPEC). Although the role of hipec has recently been questioned with respect to results from the PRODIGE 7 trial, the role and benefit of a complete CRS were confirmed, as observed with a 41-month gain in median survival in that study, and 15% of patients remaining disease-free at 5 years. Still, CRC with PM is associated with a poor prognosis, and good patient selection is essential. Many questions about the optimal management approach for such patients remain, but all patients with PM from CRC should be referred to, or discussed with, a PM surgical oncologist, because cure is possible. The objective of the present guideline is to offer a practical approach to the management of PM from CRC and to reflect on the new practice standards set by recent publications on the topic.

Background: The COVID-19 pandemic has put enormous pressure on hospital resources, and has affected all aspects of patient care. As operative volumes decrease, cancer surgeries must be triaged and prioritized with careful thought and attention to ensure maximal benefit for the maximum number of patients. Peritoneal malignancies present a unique challenge, as surgical management can be resource intensive, but patients have limited non-surgical treatment options. This review summarizes current data on outcomes and resource utilization to help inform decision-making and case prioritization in times of constrained health care resources. Methods: A rapid literature review was performed, examining surgical and non-surgical outcomes data for peritoneal malignancies. Narrative data synthesis was cross-referenced with relevant societal guidelines. Peritoneal malignancy surgeons and medical oncologists reviewed recommendations to establish a national perspective on case triage and mitigating treatment strategies. Results and Conclusions: Triage of peritoneal malignancies during this time of restricted health care resource is nuanced and requires multidisciplinary discussion with consideration of individual patient factors. Prioritization should be given to patients where delay may compromise resectability of disease, and where alternative treatment options are lacking. Mitigating strategies such as systemic chemotherapy and/or surgical deferral may be utilized with close surveillance for disease stability or progression, which may affect surgical urgency. Unique hospital capacity, and ability to manage the complex post-operative course for these patients must also be considered to ensure patient and system needs are aligned.

Low grade appendiceal mucinous neoplasm (LAMN) is the primary source of pseudomyxoma peritonei (PMP). PMP may develop after seemingly complete resection of primary tumor by appendectomy, which is unpredictable due to lack of reliable prognostic indicators. We retrospectively reviewed 154 surgically resected LAMNs to explore if any of the macroscopic and microscopic characteristics may be associated with increasing risk of PMP development. Our major findings include: (1) As compared to those without PMP, the cases that developed PMP were more frequent to have (a) smaller luminal diameter (1 cm) and thicker wall, separate mucin aggregations, and microscopic perforation/rupture, all suggestive of luminal mucin leakage; (b) microscopic acellular mucin presenting on serosal surface and not being confined to mucosa; and (c) neoplastic epithelium dissecting outward beyond mucosa, however, with similar frequency of neoplastic cells being present in muscularis propria. (2) Involvement of neoplastic cells or/and acellular mucin at surgical margin did not necessarily lead to tumor recurrence or subsequent PMP, and clear margin did not absolutely prevent PMP development. (3) Coexisting diverticulum, resulted from neoplastic or non-neoplastic mucosa being herniated through muscle-lacking vascular hiatus of appendiceal wall, was seen in a quarter of LAMN cases, regardless of PMP. The diverticular portion of tumor involvement was often the weakest point where rupture occurred. In conclusion, proper evaluation of surgical specimens with search for mucin and neoplastic cells on serosa and for microscopic perforation, which are of prognostic significance, should be emphasized.

Objectives Heated intraperitoneal chemotherapy (HIPEC) has not been universally adopted at the time of interval cytoreductive surgery for primary epithelial ovarian cancer (EOC) despite evidence of a 12-month overall survival (OS) benefit in a recent landmark randomized trial. We performed a systematic review and meta-analysis to assess oncologic outcomes and perioperative morbidity following HIPEC among primary EOC patients. Methods We searched MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials, and the Cochrane Database of Systematic Reviews, from inception to August 2019, for observational and randomized studies of primary EOC patients undergoing HIPEC. We assessed risk of bias using the Institute of Health Economics Quality Appraisal Checklist for single-arm cohort studies, Newcastle-Ottawa Scale for comparative cohort studies, and Cochrane Collaboration's Tool for randomized trials. We qualitatively summarized survival outcomes and calculated the pooled proportion of 30-day grade III-IV morbidity and postoperative death. Results: We identified 35 articles including 2252 primary EOC patients; one study was a randomized trial, and only six studies included a comparator group of surgery alone. The timing, temperature, and chemotherapeutic agents used for HIPEC differed across studies. Reported OS was highly variable (3-year OS range: 46–77%); three comparative cohort studies and the sole randomized trial reported statistically significant survival benefits for HIPEC over surgery alone, while two comparative cohort studies did not. The pooled proportions for grade III-IV morbidity and postoperative death at 30 days were 34% (95% CI 20–52) and 0% (95% CI 0–5) respectively. Conclusion One randomized trial suggests that HIPEC at time of interval cytoreductive surgery should be considered in patients with primary EOC. However, there is significant heterogeneity in literature with respect to an appropriate HIPEC regimen, short- and long-term outcomes. High-quality prospective randomized trials are urgently needed to clarify the role of HIPEC in the first-line treatment of primary EOC.

Peritoneal recurrences after cytoreductive surgery (CRS) and heated intraperitoneal chemotherapy (HIPEC) for appendiceal and colorectal cancers are frequent. This study aimed to evaluate the safety, technical feasibility and perioperative and long-term outcomes of repeat CRS/HIPEC in patients with recurrent peritoneal carcinomatosis of colorectal and appendiceal origin.Data were collected from patients treated from 2000 to 2016 for recurrent peritoneal carcinomatosis from appendiceal or colorectal cancer with CRS/HIPEC at 2 specialist centres. Data on demographics, procedure details, morbidity and survival were recorded. Analyses compared the iterations of CRS/HIPEC to assess the safety and effectiveness of repeat surgery.Of all patients who underwent CRS/HIPEC in the 2 centres, 37 patients underwent a repeat procedure. Operative time was similar for the first and second surgeries (412.1 v. 412.5 min, p = 0.74) but patients had a significantly lower peritoneal carcinoma index score with the second surgery (21.8 in the first iteration v. 9.53 in the second iteration, p0.001) and significantly less blood loss (1762 mL in the first iteration v. 790 mL in the second iteration, p = 0.001). There was a nonsignificant decrease in grade III–IV complications and there was no 30-day mortality associated with repeat procedures. For patients with colorectal cancer, median disease-free survival was 9.6 months and median overall survival was 40 months. For patients with appendiceal cancer, median disease-free survival was 15 months and overall survival was 64.4 months.Repeat CRS/HIPEC procedures for recurrent appendiceal and colorectal peritoneal carcinomatosis are safe in well-selected patients, without increased morbidity or mortality, and they are associated with significant long-term survival, particularly for patients with appendiceal cancers. These results support the use of repeat CRS/HIPEC in these patients.Les récurrences péritonéales après une chirurgie cytoréductrice (CCR) et une chimiothérapie hyperthermique intrapéritonéale (CHIP) pour les cancers de l’appendice et colorectaux sont fréquentes. Cette étude visait à évaluer l’innocuité, la faisabilité technique et les résultats périopératoires et à long terme d’une reprise de CCR/CHIP chez les patients qui présentent une récurrence de carcinomatose péritonéale ayant son origine au niveau colorectal ou de l’appendice.Des données ont été recueillies sur des patients traités entre 2000 et 2016 pour une récurrence de carcinomatose péritonéale ayant son origine au niveau colorectal ou de l’appendice par CCR/CHIP dans 2 centres spécialisés. On a tenu compte des données démographiques, des détails des interventions, ainsi que de la morbidité et de la survie. Des analyses ont permis de comparer les premières et deuxièmes CCR/CHIP pour évaluer l’innocuité et l’efficacité des chirurgies répétées.De tous les patients soumis à des CCR/CHIP dans les 2 centres, 37 ont subi l’intervention de nouveau. Le temps opératoire a été similaire pour les premières et les deuxièmes chirurgies (412,1 c. 412,5 min, p = 0,74), mais les patients présentaient un score de carcinomatose péritonéale beaucoup plus bas lors de la deuxième chirurgie (21,8 pour la première intervention c. 9,53 pour la seconde, p0,001) et des pertes sanguines significativement moindres (1762 mL pour la première intervention c. 790 mL pour la seconde, p = 0,001). On a noté une diminution non significative des complications de grades III–IV et on n’a déploré aucune mortalité à 30 jours en lien avec la reprise de l’intervention. Pour les patients atteints d’un cancer colorectal, la survie médiane sans maladie a été de 9,6 mois et la survie médiane globale a été de 40 mois. Pour les patients atteints d’un cancer de l’appendice, la survie médiane sans maladie a été de 15 mois et la survie médiane globale a été de 64,4 mois.La reprise des CCR/CHIP pour les récurrences de carcinomatose péritonéale ayant leur origine au niveau colorectal ou de l’appendice est sécuritaire chez les patients soigneusement sélectionnés, sans accroissement de la morbidité ou de la mortalité, et elles sont associées à une survie à long terme significative, particulièrement chez les patients ayant un cancer de l’appendice. Ces résultats appuient la reprise des CCR/CHIP chez ces patients.

Two new cancer centers providing radiation therapy opened in Alberta, Canada, in 2010 and 2013, respectively. We aimed to assess whether opening the new RT centers influenced mastectomy rates for breast cancer. Breast cancer patients who underwent surgery from 2004 through 2015 were identified from the Alberta Cancer Registry. Mastectomy rates for 64 predefined health status areas (HSAs) were calculated after adjusting for patient and system factors. Variations in mastectomy rates among the HSAs were quantified using weighted coefficient of variation (CV). Multivariable logistic regressions were performed to determine associations between driving time and mastectomy use in the entire cohort and in subgroups. Of the 21,872 patients, the proportion of patients who lived a ≤ 60 min drive from the nearest RT center significantly increased from 68.8% (95% CI 67.7–69.9%) to 80.7% (95% CI 79.5–81.9%) during the study period. Concurrently, the crude provincial mastectomy rate decreased from 56.2% (95% CI 55.3–57.1%) to 45.3% (95% CI 44.1–46.5%). However, variation in adjusted mastectomy rates (weighted CV) across the 64 HSAs increased from 9.5 to 14.6. Factors associated with mastectomy included age, larger tumor size, lymph node involvement, higher tumor grade, molecular subtype, lobular histology type, more comorbidities, academic institution, region, earlier period of diagnosis, and longer driving time to the nearest RT center. Opening new RT centers in previously underserved regions reduced driving times to the nearest center, and was associated with a reduction in mastectomy rates; however, these reductions among regions across the province were not uniform.

Background As Canada’s population ages, incidence of gastric cancer in elderly patients is increasing. There is little data on treatment and outcomes of gastric cancer in patients older than age 75. This study aimed to assess treatment patterns and outcomes of non-metastatic elderly gastric cancer patients in Alberta, Canada. Methods Records of elderly patients (age 75 or older) diagnosed with localized gastric or gastroesophageal junction cancer between 2007 and 2012 who received curative intent surgery were retrospectively collected from the Alberta Cancer Registry. A chart review was completed to gather demographics; treatment details of surgery, chemotherapy, and radiotherapy; and outcomes. Descriptive analyses were undertaken, and variables were compared with parametric and nonparametric tests where appropriate. Results 130 predominantly male (69%) patients, median age 80 (range 75–96) were included. 17 patients (13%) received multimodality therapy. 115 (88.5%) had negative margins on final pathology. Mean lymph nodes retrieved were 16 (range 0–43). 46 surgical patients (35.4%) had grade II or higher complications. 13 patients had a perioperative death (Clavien grade V). Four (3.1%) patients completed perioperative chemotherapy, and 13 (10%) patients had adjuvant chemo/radiotherapy. 50 (38.5%) recurred at median 13 months, while 80 (61.5%) did not have a recurrence of their cancer at any time during follow up. The 5 year DFS for the surgery only group was 67.3% and multimodality group was 52.9% (p = 0.25). The 5 year OS for the surgery only group was 38.9% and multimodality group was 47.1% (p = 0.52). Conclusions Our findings suggest that even with surgery alone, selected elderly patients with non-metastatic gastric cancer can obtain apparent prolonged survival, despite not receiving standard of care multimodality therapy. More studies are needed to optimise elderly patients’ treatment selection.

The incidence of breast biopsy following treatment for breast cancer is not well-characterized. We sought to determine the frequency and outcomes of breast biopsy and the need for subsequent surgery in patients treated with breast-conserving surgery (BCS).Using a prospective database, we identified patients in Alberta, Canada, treated with BCS for screen-detected breast cancer or ductal carcinoma in situ (DCIS) from 2010 to 2014. Post-treatment breast procedures were identified from physician claims data. Multivariable analysis was performed to identify factors associated with biopsy.We included 2065 patients with a median of 6.4 years of follow-up; most had DCIS (n = 426, 20.6%) or stage I disease (n = 1385, 67.1%). Post-treatment core biopsy was performed in 389 (18.8%, 95% confidence interval [CI] 17.2-20.6%) patients, and excisional biopsy was performed in 19 (0.9%, 95% CI 0.6-1.4%) patients. The per-patient benign-to-malignant biopsy ratio was 3.2 to 1, and the overall malignancy rate was 6.1% (95% CI 5.1-7.2%). Younger age, proximity to a cancer center, positive margins, and the use of magnetic resonance imaging were associated with biopsy (p 0.05). Additional surgery was performed in 150 (7.3%, 95% CI 6.2-8.5%) patients; 93 (4.5%, 95% CI 3.6-5.4%) patients underwent mastectomy. Surgery was performed for local recurrence/ipsilateral cancer in 62 (3.0%) patients, contralateral breast cancer in 60 (2.9%) patients, bilateral breast cancer in 3 (0.1%) patients, and benign indications/prophylaxis in 25 (1.2%) patients.One in five patients required breast biopsy during post-treatment surveillance following BCS and most revealed benign findings. Rates of additional surgery, especially subsequent mastectomy due to ipsilateral or contralateral malignancy, were low. Patients can be reassured of these findings during pre-treatment counseling and post-treatment surveillance.

Contralateral prophylactic mastectomy (cpm) has been increasingly common among women with unilateral invasive breast cancer (ibca) even though the data that support it are limited. Using a population-based cohort, the objectives of the present study were to describe factors predictive of cpm in young women (&le, 35 years) with ibca and to evaluate the impact of the procedure on mortality. All women diagnosed during 1994&ndash, 2003 and treated with cpm were identified from the Ontario Cancer Registry. Logistic regression was used to identify patient and tumour factors associated with the use of cpm. Multivariate analyses were used to assess the effect of cpm on recurrence and mortality. Of 614 women identified, 81 underwent cpm (13.2%). On multivariable analysis, factors associated with cpm included negative lymph node status, negative estrogen receptor status, and initial breast-conserving surgery with re-excision. At follow-up, breast cancer&ndash, specific mortality was similar for women who did and did not undergo cpm. Use of cpm in young women with ibca (compared with non-use) was not associated improved breast cancer&ndash, specific mortality. Factors found to be predictive of cpm were negative lymph node status, negative estrogen receptor status, and initial breast-conserving surgery followed by re-excision.

Various intraoperative margin assessment techniques have been shown to improve margin status in breast-conserving surgery (BCS) for cancer. Our study sought to evaluate multiple margin assessment techniques on a population level and determine their effects on margin status.Patients undergoing wire-localized BCS for invasive cancer in Alberta, Canada, were assessed using a prospectively entered database of patient and tumor characteristics. Margin status was obtained from chart review. Four margin assessment techniques were studied: specimen mammography (SM), intraoperative ultrasound (US), gross assessment by pathologist (GP), and frozen section analysis (FS). Multivariable logistic regression adjusting for confounders was used to assess effect of any technique on margin status, with secondary analysis evaluating effects of individual techniques.Margin assessment was performed in 1165 of 1649 patients (71 %). The overall positive margin rate was 20.8 %. Adjusting for confounders, we found no difference in the odds of a positive margin with any margin assessment technique versus wire localization alone (OR 0.79, p = 0.22, 95 % CI 0.54-1.16). Individually, both GP and FS reduced the risk of a positive margin (GP-OR 0.56, p = 0.002, 95 % CI 0.39-0.81; FS-OR 0.43, p = 0.046, 95 % CI 0.19-0.98), whereas SM and US showed no effect (SM-OR 1.23, p = 0.29, 95 % CI 0.84-1.81; US-OR 1.09, p = 0.83, 95 % CI 0.50-2.37).Use of any margin assessment technique did not improve margin status compared to wire localization alone. Gross assessment by pathologist and frozen section analysis improved margin status compared to imaging-alone techniques. Further exploration is required to refine optimal margin assessment methods.

The aim of this study was to characterize treatment trends and outcomes of women who have preexisting cardiovascular disease (CVD) prior to the diagnosis of breast cancer.This represented a retrospective, population-based cohort study that analyzed pooled data from the provincial cancer registry, physician billing claims, hospital discharge abstracts, ambulatory care, and the 2011 census in a large Canadian province. Multivariable logistic regression was performed to identify the associations of CVD with breast cancer treatment and outcomes. Kaplan-Meier analyses were conducted and survival was compared between CVD and non-CVD groups. Cox regression models were constructed to determine the effect of CVD on overall and cancer-specific survival.A total of 25,594 women with breast cancer were eligible and included in the current analysis. Preexisting CVD was associated with a lower likelihood of receiving chemotherapy (odds ratio [OR], 0.56; 95% confidence interval [CI], 0.48-0.66; P .0001) and radiotherapy (OR, 0.75; 95% CI, 0.67-0.83; P .0001), but a higher probability of undergoing mastectomy (OR, 1.13; 95% CI, 1.03-1.25; P = .011). Unadjusted Kaplan-Meier analyses showed that individuals with preexisting CVD experienced worse median overall and cancer-specific survival when compared with those without CVD (87 vs. 150 months and 106 vs. 131 months, respectively; both P .0001). Adjusting for measured confounders, the presence of preexisting CVD continued to predict for worse overall survival (hazard ratio, 1.55; 95% CI, 1.43-1.67; P .0001), but not cancer-specific survival (hazard ratio, 1.11; 95% CI, 0.98-1.27; P = .099).Patients with breast cancer with preexisting CVD are less likely to receive recommended treatment for their cancer and more likely to exhibit worse overall survival.

BACKGROUND AND OBJECTIVES Using a 2 mm margin criteria, we evaluated the effect of intra-operative margin assessment on margin status and re-excisions following breast-conserving surgery (BCS) for ductal carcinoma in situ (DCIS). METHODS We identified patients undergoing BCS for DCIS from a prospective, population-based database. Multivariable logistic regression was used to determine the effect of specimen mammography, ultrasound and macroscopic assessment by a pathologist on margins and re-excision rates. RESULTS In 588 patients, 52% (95% confidence interval [CI], 48%-56%) had positive margins (

Synopsis Desmoid tumors can be safely managed with watchful waiting, including either observation alone or tamoxifen/NSAIDs. Surgery at first presentation can be associated with significant treatment burden. Background Immediate surgery was historically recommended for desmoid tumors. Recently, watchful waiting, (tamoxifen/NSAIDs or observation alone), has been advocated. Methods All diagnoses of desmoid tumor within the Alberta Cancer Registry from August 2004 to September 2015 were identified. Patients with FAP were excluded. Demographics, tumor characteristics and treatment and outcome data were collected. Outcomes were compared between immediate surgery and watchful waiting. The effect of abdominal wall site on progression and recurrence and the effect of microscopic margin on recurrence were assessed with Fisher's exact test. Results We identified 111 non-FAP patients. Median follow-up was 35 months from diagnosis. 74% were female. Mean age was 42. Fifty (45%) underwent watchful waiting, of whom 21(42%) progressed, with median PFS of 10 months. Fifty-three (48%) underwent resection at presentation, of whom 8 (15%) recurred, with median disease-free survival of 22 months. Abdominal wall lesions were equally represented in both groups, and equally likely to progress on watchful waiting (50% vs 39%, p = 0.53), but there was a trend toward decreased recurrence after surgery. (5% vs 23%, p = 0.08). Microscopic margin had no effect on recurrence (14% of margin negative vs 20% of margin positive, p = 1.0). Conclusions Watchful waiting was successful in 58% of patients, and a further 28% only required one aggressive treatment thereafter, for a total of 86%. Surgery had a favorable recurrence rate (15%), but some recurrences were associated with significant treatment burden. Treatment should be tailored to individual patients in a multidisciplinary setting. A trial of observation appears warranted in most patients. Recurrence rate was not affected by positive margins.

Current guidelines recommending wide local excision (≥ 1 cm margin) for all breast phyllodes tumours regardless of classification are based on retrospective data. Benign phyllodes tumours of the breast are not aggressive. They are often indistinguishable from fibroadenomas on core biopsy and are diagnosed only after excisions without attention to margins. Once the diagnosis is made, the decision to operate and obtain further margins versus wait-and-watch is the dilemma breast surgeons face on a regular basis.

Anti-hormonal therapy (tamoxifen) is recommended for estrogen receptor (er)&ndash, positive breast cancer (bca), however, its effect on low-receptor cancers is unclear. We retrospectively evaluated the effect of adjuvant tamoxifen in patients with weakly er-positive bca. We identified 2221 bca patients who had been er-tested by ligand-based assay (lba) during 1976&ndash, 1995 and who had been treated and followed until 2008. Cox proportional hazards models adjusted for age, body mass index, tumour size, nodal status, surgery, and chemotherapy were used to assess the effect of er level on bca survival in patients who received tamoxifen. Overall, 17% (383) of patients were within 0&ndash, 3 fmol/mg cytosol protein, and 12% (266) were within 4&ndash, 9 fmol/mg cytosol protein. Patients with er levels of 0&ndash, 3, 4&ndash, 9, 10&ndash, 19, 20&ndash, 49, and 50 fmol/mg or more cytosol protein had 20-year bca survival rates of 56%, 56%, 63%, 71%, and 60% respectively. Of the 2221 patients studied, 661 (29.8%) received anti-hormonal therapy. Within the latter group, er levels of 0&ndash, 49, and 50 fmol/mg or more cytosol protein were associated with a hazard ratio for lower bca mortality: respectively, 1.00 (reference), 0.59 (p = 0.09), 0.19 (p < 0.0001), 0.26 (p < 0.0001), and 0.31 (p < 0.0001)&mdash, the risk reduction being significant only for er levels of 10 fmol/mg or more cytosol protein. Tamoxifen use in bca patients with a weakly positive er status (4&ndash, 9 fmol/mg cytosol protein), compared with those having higher er levels (&ge, 10 fmol/mg cytosol protein), is not associated with a significantly lower bca-specific mortality. Our results do not support treatment with anti-hormonal therapy for bca patients with a weakly positive er status as identified by lba.

e17093 Background: Heated intraperitoneal chemotherapy (HIPEC) following cytoreductive surgery in the treatment of primary epithelial ovarian cancer (EOC) after neoadjuvant chemotherapy was associated with a significant 12 months improved overall survival (OS) in a well-designed randomized controlled trial. Nonetheless, there remains uncertainty about the benefit and safety of HIPEC in ovarian cancer. The aim of this review was to assess efficacy and safety of HIPEC in primary EOC. Methods: We conducted a systematic search in Medline, Embase, the Cochrane Central Register of Controlled Trials, and the Cochrane Database of Systematic Reviews, from inception to February 22nd 2018 for observational and randomized studies of patients with primary EOC undergoing HIPEC at cytoreductive surgery with no language restrictions . We assessed risk of bias with the Institute of Health Economics Quality Appraisal Checklist for single-arm studies, and Newcastle-Ottawa Quality Scale for double-arm studies. We determined the pooled proportion of 30-day grade 3-4 morbidity, reoperation, and postoperative death. Results: Thirty-five articles including 1937 patients with primary EOC met inclusion criteria. Timing of HIPEC and type of chemotherapy regimens were not consistent between studies. There was significant variation in the reported OS of patients treated with HIPEC at cytoreductive surgery for primary EOC (3-year OS:48-77%; 5-year OS:17-72%). Thirteen articles were including in a meta-analysis to determine to the safety of HIPEC. The pooled proportions for 30-day Grade 3-4 morbidity, 30-day reoperation, and 30-day postoperative death were 33.0% (95% CI 23.0-45.0), 9.0% (95% CI 5.0-17.0) and 3.0% (95% CI 1.0-5.0) respectively. Conclusions: The use of HIPEC in primary EOC is associated with significant morbidity. There is significant heterogeneity in current literature. Higher quality, large prospective randomized control trials are needed to further support the benefit of HIPEC at cytoreductive surgery in the first-line treatment of primary EOC.

The Eastern experience has reported the safety of laparoscopic assisted gastrectomy (LAG) for gastric cancer. Its use in Western countries is still debated owing to concerns about its oncologic equivalence to open gastrectomy (OG). We sought to review and compare their operative outcomes and oncologic specimen quality (number of harvested lymph nodes and surgical margins) for gastric adenocarcinoma (GA).We reviewed the charts of all patients undergoing LAG (2007-2010) and OG (2000-2010) for GA in a single institution. Several surgeons performed the OGs, whereas 1 fellowship-trained laparoscopic surgeon performed LAGs. The primary outcome was quality of the surgical specimen, assessed by the number of harvested lymph nodes (LNs) and margin status. Secondary outcomes were perioperative events. Data were analyzed as intention to treat.We retrieved 60 cases (47 OGs, 13 LAGs). The conversion rate was 23%. Mean operative time was 115 minutes longer and blood loss was 425 mL less (both p0.001) for LAGs. A mean of 14.4 (standard deviation [SD] 9.8) and 11.2 (SD 8.2) LNs were harvested for OGs and LAGs, respectively (p = 0.29). Negative margins were achieved for all patients. Mean length of stay was similar (LAG: 19 d v. OG: 18.9 d; p = 0.91). The groups did not differ on major postoperative complications (12.7% v. 23.1%; p = 0.39) or operative mortality (2.1% v. 7.7%; p = 0.32).Laparoscopic assisted gastrectomy is a challenging but safe and feasible procedure in experienced hands. It offers the same radical resection as OG regarding negative margins and LN retrieval. Long-term follow-up is warranted.La gastrectomie assistée par laparoscopie (GAL) a été démontrée dans des études orientales comme sécuritaire dans le traitement de l'adénocarcinome gastrique (AG). En occident, l'équivalence oncologique de la GAL avec la gastrectomie ouverte (GO) demeure cependant controversée. Cette étude vise à comparer le devenir postopératoire et la qualité des spécimens oncologiques de ces interventions, dans le traitement de l'AG.Tous les dossiers de patients opérés par GAL (2007–2010) ou GO (2000–2010) pour AG dans un seul centre hospitalier ont été revus. Différents chirurgiens ont réalisé les GO. Toutes les GAL ont été réalisées par un seul chirurgien sur-spécialisé en chirurgie laparoscopique. Le critère d'évaluation principal était la qualité du spécimen chirurgical évaluée par le nombre de ganglions lymphatiques (GL) prélevés et le statut des marges de résection. Le critère d'évaluation secondaire était la morbidité postopératoire. Les données ont été analysées en fonction de l'intention de traiter.Soixante cas ont été inclus (47 GO, 13 GAL). Le taux de conversion s'est établi à 23 %. Le temps opératoire moyen était plus long de 115 minutes, et les pertes sanguines moyennes moindres de 425 mL (La gastrectomie assistée par laparoscopie est une intervention complexe, mais peut être réalisée de manière sécuritaire en des mains expertes. Elle offre un spécimen oncologique comparable à la gastrectomie ouverte, en termes de lymphadénectomie et de marges de résection. Un suivi à long terme demeure nécessaire.

Purpose: To evaluate the utility of multidisciplinary case conferences (MCCs) on physician decision making in benign and malignant breast disease management. Methods: Patients with interesting or challenging diagnostic or management issues were discussed at biweekly diagnostic breast MCCs. Prior to discussion, a clinical summary and intended management plan prior to the MCC was presented. For each case, diagnostic images/histopathology were centrally reviewed after which group discussion achieved a management consensus which was documented prospectively. Initial management plans were compared to the post-MCC consensus. A change in a management plan was defined as a consensus plan different from the pre-MCC plan or no definite plan prior to the MCC. Results: From November 2014 to December 2015, 76 patients (43 malignant and 33 benign diagnoses) were discussed in 19 MCCs. All cases presented resulted in a consensus management recommendation. Thirty-one case discussions (41%) resulted in a changed management plan (20 malignant and 11 benign diagnoses). Management changes included avoidance of immediate surgery (9% of cases), change in the type of surgery (5%), non-invasive investigation to invasive/surgical intervention (7%), and detection of a new suspicious lesion (1%). Conclusion: MCCs had a substantial impact on physician decision making. Management plans changed in 41% of cases presented, the majority due to new/clarified diagnostic information. Presentation of cases at MCCs should be encouraged, especially for challenging diagnostic or management issues regarding malignant or benign breast diagnoses.

Background. Transcatheter arterial lipiodol chemoembolization (TACE) can be used in cirrhotic patients with hepatocellular carcinoma to avoid tumor progression before transplantation.Objective. To evaluate the efficacy and safety of TACE used as a bridge to liver transplantation.Methods. TACE was performed in 30 cirrhotic patients with hepatocellular carcinoma. Milan criteria were used to select patients for transplant. Patients had a good or moderately impaired liver function, no arterioportal fistulae, and a good portal perfusion.Results. 48 TACE were performed in 30 patients. Before transplantation, 4 patients were dropped off the list due to tumor extension or liver failure. Complete necrosis of the tumor was observed in 11 patients and partial necrosis in 15 patients. After transplantation, 6 patients died and tumor recurrence was observed in 5 patients with a tumor beyond Milan criteria or no response to TACE.Conclusion. TACE is useful as a bridge to liver transplantation in a selected group of cirrhotic patients with hepatocellular carcinoma. A combined therapeutic approach before surgery might improve the prognosis in these patients.

e18723Background: Cancer and CVD are the two leading causes of death. As the population ages, more patients will be affected with both conditions. Cardio-oncology research has largely focused on ch...

e18616Background: Clinical trials are the gold standard for evaluating novel interventions, but only a small proportion of patients participate. Strict eligibility criteria can contribute to low ac...

Background Pemetrexed is a systemic chemotherapeutic agent used in the treatment of malignant mesothelioma. This drug represents a potentially promising intraperitoneal (IP) agent to use for hyperthermic intraperitoneal chemotherapy (HIPEC) in the treatment of peritoneal mesothelioma. However, this has yet to be supported by preclinical studies. Therefore, we aimed to study the effect of pemetrexed dose and perfusion temperature on the resultant pemetrexed concentration in 3 different compartments (systemic circulation, portal circulation and peritoneal tissues) using a murine model. Methods Under general anesthesia, 29 Sprague-Dawley rats were submitted to 3 different doses of IP pemetrexed (500, 1000 and 1500 mg/m 2 ) combined with 3 different perfusion temperatures (37, 40 and 43 °C) for a total duration of 25 min. At the end of perfusion, samples in different compartments (systemic circulation, portal circulation and peritoneum) were harvested and concentrations of pemetrexed were measured using high performance liquid chromatography. Results With increasing dose of IP pemetrexed, higher concentrations were measured in the 3 compartments tested. In peritoneal cells, the difference between IP doses of 500 and 1000 mg/m 2 (2.03 vs. 19.17 μg/g, p 2 (19.17 vs. 22.80 μg/g, p = 0.027). When the perfusion temperature increased, we observed a proportional rise of pemetrexed concentration in both the portal and systemic compartments; while in the peritoneal cells, the pemetrexed concentration increased up to 40 °C, after which it plateaued. Conclusion Both heat and increasing doses of IP pemetrexed enhance peritoneal cell concentration of pemetrexed. However, for temperatures above 40 °C, pemetrexed concentration reached a plateau in peritoneal cells. Systemic and portal concentrations increased proportionally with both increasing temperatures and IP doses. We believe these results should be taken into consideration for the design of an eventual clinical study in humans.

Neoadjuvant chemotherapy in breast cancer is used to downstage locally advanced and inoperable tumors. Expanded benefits of neoadjuvant chemotherapy include downstaging of tumors to allow breast-conserving surgery (BCS) and assessment of in vivo tumor response. We sought to identify patterns and predictors of neoadjuvant chemotherapy use to determine if this has translated into population-level clinical practice. All patients undergoing surgery for invasive breast cancer between January 2012 and June 2014 were identified from our provincial synoptic operating room database. Data regarding patient demographics, hospital, operating surgeon, preoperative tumor characteristics, neoadjuvant treatment, and type of surgery performed were collected. Descriptive statistics and multivariable analysis were used to identify predictors of neoadjuvant chemotherapy. A total of 4186 patients were identified, 363 (8.53 %) of whom underwent neoadjuvant chemotherapy. A significant increase was seen in the use of neoadjuvant chemotherapy over time. In multivariable analysis, neoadjuvant chemotherapy was associated with prechemotherapy tumor size, multicentricity, lymph node positivity, and decreasing patient age. In addition, there was significant variability in neoadjuvant chemotherapy use between operating surgeons. Of those patients who underwent neoadjuvant chemotherapy, 68.9 % were not pretreatment candidates for BCS. At the time of definitive surgery, 72.1 % had mastectomy, with 18.7 % opting for contralateral prophylactic mastectomy. As reported, this was due to the tumor being advanced/too large (50.4 %), patient preference (12.6 %), multicentricity (8.8 %) and margins, genetics, and previous radiotherapy (4 %). A significant increase in the use of neoadjuvant chemotherapy over time was identified, and treatment with mastectomy as definitive surgical management remained high. There was significant variability in neoadjuvant chemotherapy use by the operating surgeons, in addition to factors generally associated with more locally advanced/aggressive tumors.

Background: Participation in multidisciplinary case conferences (MCCs) continues to be highly variable, in spite of proven benefits. One contention is the lack of perceived utility on patient management. Purpose: To evaluate the utility of MCCs on physician decision making in benign and malignant breast disease management. Methods: At the Foothills Medical Centre, diagnostic breast MCCs occur biweekly. Patients with interesting or challenging diagnostic or management issues were discussed by attending surgeons, radiologists, pathologists, nurse coordinators and oncologists. Prior to case discussion, the presenting physician was asked to specify his/her management plan. Their response was recorded and compared to the management plan consensus after the MCC discussion. For each case a clinical summary and question was provided by the presenting physician, followed by a review of diagnostic images and/or pathology. After group discussion, a management consensus was achieved and documented. A management change was defined as a difference compared to the pre-MCC plan or if there was no definite management plan prior to MCC. Results: From November 5th, 2014 to May 6th, 2015, 52 patients were discussed in 11 MCCs (1 to 8 patients per MCC). No MCCs were cancelled due to insufficient patients. Of these, 23 (44%) had a change in the management plan compared to the pre-MCC intent including 7 cases where there was no clear plan prior to MCC. Among the 23 cases with a management change, 12 (52%) were due to new or clarified information from radiology review, 6 (26%) were due to new or clarified details from pathology review and 5 (22%) changes occurred from both radiology and pathology review. All cases presented resulted in a consensus management recommendation. Conclusion: The MCCs had a substantial impact on physician decision making. Nearly half of cases presented resulted in a change in clinical recommendation, the majority of which were based on new/clarified diagnostic imaging or pathology information. Presentation of cases at MCCs should be encouraged given their clinical impact on patient care, especially for challenging diagnostic or management issues. Citation Format: Foster T, Bouchard-Fortier A, Olivotto I, Quan ML. Effect of multidisciplinary case conferences on physician decision making: Breast diagnostic rounds. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P5-02-07.

82 Background: Contralateral mastectomy (CM) has recently been shown to be associated with survival benefit in women with breast cancer. The objectives of the present study were to describe factors predictive of CM in young women (≤35 years old) with invasive breast cancer and evaluate its impact on survival, in a large population based cohort. Methods: All women diagnosed with invasive breast cancer aged ≤35 from 1994 – 2003 treated with mastectomy were identified from the Ontario Cancer Registry. Patient demographics, complete tumour and treatment characteristics were abstracted from primary chart review. Cox proportional hazard regression was performed to assess factors associated with performance of CM and its effect on recurrence and overall survival, performance of CM was modeled as a time varying co-variate. The models were controlled for known predictors including age, tumor size, nodal status, ER/PR, LVI, histologic grade, systemic therapy and adjuvant radiation. Results: There were 628 women identified. Of these, 101 underwent a CM (16.1%). On multivariable analysis, factors predictive of CM were negative lymph node status (HR: 1.74, 95% CI [1.052-2.872]; p-value = 0.031) and negative estrogen receptor status (HR: 2.7, 95% CI [1.314-5.736]; p-value = 0.007). After a median follow up of 11 years, no significant survival benefit was observed in women undergoing CM compared to those who did not (HR: 0.95, 95% CI [0.61-1.46], p-value = 0.80). Conclusions: Performance of CM in young women with invasive breast cancer did not result in a significant survival benefit, compared to those without CM. Factors found to be predictive of performance of CM negative lymph node status and negative estrogen receptor status. Further studies are needed to determine if a subset of young women might benefit from CM.

6549 Background: The objective of this study was to evaluate characteristics associated with burnout in Canadian oncologists and oncology resident physicians (ORP). Methods: Canadian medical oncolo...

627 Background: Threshold of estrogen receptors positivity in breast cancer has been lowered to ≥1% of stained cells by immunohistochemistry testing. This change was based on experts’ recommendations from the 2009 St Gallen International Expert Consensus and from the 2010 guidelines of the American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP). However few studies support these guidelines and the benefit of treating weakly positive estrogen receptor tumors (1-9%) is unknown. Methods: We identified 2221 breast cancer patients with estrogen receptors tested by ligand-based assay, treated and followed in our institution between 1976 and 2008. Date and cause of death were identified through linkage to Quebec Mortality File. A multivariate Cox proportional-hazards model was used to assess the effect of estrogen receptor levels on breast cancer mortality in patients who received hormonal therapy (tamoxifen). Results: In patients with low estrogen receptors, 17% (383 patients) were within 0-3 fmol/mg of cytosol and 12% (266 patients) were within 4-9 fmol/mg of cytosol. Patients with estrogen receptor levels of 0-3, 4-9, 10-19, 20-49, and ≥50 fmol/mg of cytosol had a 20-year breast cancer survival rate of 56%, 56%, 63%, 71% and 60% respectively. From the 2221 patients, 661 (29.8%) received hormonal therapy. In these patients, estrogen receptor levels of 0-3, 4-9, 10-19, 20-49 and ≥50 fmol/mg of cytosol were associated with lower breast cancer mortality (HR (p-value) of 1.00 (reference), 0.59 (0.09), 0.19 (