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e15596 Background: We have previously shown in a Phase I trial that administration of immediate adjuvant chemotherapy (IAC) at the time of surgical resection and immediately postoperatively is safe and feasible in colon cancer (CC) patients. IAC avoids delays in adjuvant treatment and has the potential to improve survival and quality of life. However, two fundamental questions must be answered: will patients be willing to accept the possibility of more severe side effects in exchange for earlier treatment (Tx) completion and theoretically better survival? And will physicians depart from established CC treatment practices?. Methods: A web-based survey was administered to newly diagnosed CC patients (within 1 year of surgery) and survivors (> 1 year post op). A similar web-based survey was administered to surgeons and medical oncologists in academic and community settings across the country. Surveys assessed patients’ and providers’ treatment preferences, attitudes towards care, and perceived barriers to IAC. Descriptive statistics were conducted including chi-square tests to compare differences between patients’ and providers’ responses. Results: Responses were collected from 35 patients and 40 providers. Patient respondents were 48% survivors and 52% newly diagnosed CC patients. Among the providers, 60% of the medical oncologists and 75% of the surgeons worked at academic medical centers. Compared to providers, patients were more willing to: 1) proceed with IAC to finish treatment earlier thereby improving quality of life (p = 0.002); 2) proceed with IAC to finish treatment earlier, despite potential side effects (p < 0.001); and 3) proceed with a single dose of intraoperative chemotherapy that, based on final pathologic stage, may not be needed (p = 0.002). Patients were also more likely than providers to indicate that there are no barriers to collaborative care (p = 0.001) while providers were more likely to cite that collaborative care is time consuming (p = 0.001), comes with scheduling challenges (p = 0.001), and that physicians are not readily available to participate in it (p = 0.003). Conclusions: We observed a disconnect between what providers and patients value in the perioperative and adjuvant colon cancer treatment course. Colon cancer patients are willing to accept intraoperative chemotherapy and early adjuvant chemotherapy via this novel multidisciplinary approach even if this treatment were associated with additional side effects, and without promise of a survival benefit.[Table: see text]

e16045 Background: The penetration of chemotherapeutic drugs into metastatic peritoneal nodules remains at levels well below 1 mm, thus significantly limiting the antitumor effect of intraperitoneal chemotherapy (IPC). Recently, high-Intensity ultrasound (HIUS) has been discovered as a potential tool to improve peritoneal diffusion rates. Despite promising preliminary data, basic aspects regarding its technical feasibility, safety and possible limitations remain unclear. This study aims to enhance our current understanding of HIUS and test its applicability using an ex-vivo swine model. Methods: Three postmortem swine were subject to laparotomy with consecutive lavage with 0.9%NaCl saline and HIUS application. For this purpose, a large HIUS radiating pen was introduced into the abdominal cavity and HIUS was applied on two of the four abdominal quadrants for 300 seconds each at an output power of 70 W, 50 % amplitude and 20 kHz frequency. Following the procedure, small intestinal tissue samples were removed for further analyses. Results: In all specimen, peritoneal and subperitoneal layers showed structural changes only visible on a microscopic level. The peritoneal layer was transformed into a mash-like structure while the subperitoneal layer (depth of 142 +/- 28 µm) exhibited microcavities and vascular detachment from surrounding tissues. No bowel rupture or vascular perforations were observed. Conclusions: Our data indicate that HIUS is a technically feasible add-on procedure for IPC with measurable microscopic changes on the peritoneal surface and no apparent bowel toxicity. Pretreatment of the abdominal cavity with HIUS could significantly improve IPC efficacy. Further studies are required to optimize and evaluate this novel approach.

e16037 Background: Due to limited efficiency of current intravenous and intraperitoneal chemotherapeutic approaches, treating advanced peritoneal metastases (PM) remains an ongoing oncologic challenge. As the peritoneum is an optimal biological compartment for metastatic growth, stopping progressive tumor extension at more advanced stages is currently unachievable. With this study, we aim to investigate whether changing the intraperitoneal environment using dehydration might halt tumor progression. Methods: Commercially available human colon cancer cells (HT-29) were dehydrated for 15 minutes at 90% humidity and compared to cells treated with only oxaliplatin. Cell vitality was measured and structural cell changes following dehydration were analyzed via scanning electron microscopy. Additionally, staining with hematoxylin and eosin was performed on peritoneal tissue to assess dehydration effects using an ex vivo model. Finally, a mathematical model was established to measure dehydration of the abdominal compartment for feasibility evaluation. Results: Partial dehydration has a significant cytotoxic effect on colon cancer cells ( p< 0.05) even if only shortly applied. The addition of oxaliplatin treatment following dehydration results in highly reduced cell vitality ( p< 0.01). Sole dehydration vs. sole oxaliplatin application have similar effects. SEM revealed a cellular collapse of HT-29 cells caused by dehydration. Histopathological examination of peritoneal tissue demonstrated that the dehydration effect is superficial with penetration depths of < 200 µm. Conclusions: Our data indicate that dehydration is a potentially feasible technique with measurable cytotoxic effects on colorectal cancer cells. While changing the physiological milieu of the peritoneal cavity by means of dehydration could significantly reduce PM extent, the consequences of volume fluid loss must be equally considered. Thus, further studies are required to find a sustainable extent of dehydration while maintaining circulatory stability.

150 Background: The optimal timing of adjuvant chemotherapy (AC) in nmCC is poorly defined. Delays in AC result in decreased survivalbut fear of postoperative complications often causes long intervals between surgery and AC initiation. Given the transient immune suppression, inflammatory changes and increase in circulating tumor cells occurring in the perioperative period, effective cytotoxic treatments should be considered at this time to limit metastatic spread. The immediate adjuvant chemotherapy concept intends to capitalize on the therapeutic benefits that can be achieved in the perioperative period (intraoperative and early postoperative). We aim to demonstrate that IAC is safe and tolerable for patients with nmCC. Methods: Patients with nmCC microsatellite stable invasive adenocarcinomas were treated with intravenous Leucovorin 20mg/m2 followed by a single dose of 5-Flurouracil 400mg/m2 at the time of minimally invasive surgical resection. High risk stage II and stage III received the first dose of standard AC at 14 days after surgery. Serial measurements of blood-based biomarkers (circulating tumor cells, cell free DNA, and neutrophil lymphocyte ratio were measured. Quality of life (QOL) was measured using EORTC QLQ-C30. Results: Of the 20 patients recruited, 40% had final pathology of stage III, 40% stage II and 20% stage I. All patients received intra-operative chemotherapy with no associated morbidity. Median length of stay was 2 days (range of 2-4). Grade 1 complications were reported in 2 (10%) of patients. No grade 2 or higher adverse events were reported. There was no mortality. Early postoperative AC was administered to 65% of patients. The median time to AC was 14 days (range 14-36). Overall quality of life and health scores were similar before surgery and at 30-day postoperatively (p < 0.05). Conclusions: A protocol based on immediate adjuvant chemotherapy starting at the time of surgical resection was found to be safe and feasible in nmCC with no adverse effects on surgical morbidity or quality of life. Further prospective studies are needed to explore the oncologic benefit of this novel systemic treatment approach.

200 Background: Appendiceal cancer (AC) is a rare disease process with complex treatment strategies. The objective of this study was to identify mutation-based genetic subtypes that may differ from the current histological classification, compare genetic make-up of primaries and metastases, and to find novel targetable alterations. Methods: The analysis involved the curation and normalization of mutation panels from adenocarcinoma and mucinous adenocarcinoma (n = 196) stored in the AACR GENIE Database v6.0. Genes mutated in less than two patients and tumors profiled with incomplete mutation panels were excluded from the study. The optimal number of AC subtypes was established using the Non-negative Matrix Factorization algorithm. Statistical comparisons of mutation frequencies were performed by using the Pearson’s χ2 test. Results: AC patients were stratified into five mutation subtypes. AC0 had no mutations in the 41 genes in the study. The most frequently mutated genes varied between the subtypes. AC1: KRAS (91.9%) and GNAS (77.4%); AC2: KRAS (52.5%), APC (32.5%), and GNAS (30%); AC3: KMT2D (38.7%), TP53 (38.7%), KRAS (35.5%), EP300 (22.6%); and AC4: TP53 (97.2%), KRAS (77.8%), and SMAD4 (36.1%). Additionally, AC3 was less likely to be mucinous (22.6% v 50.0-74.2%, p < 0.001) and had a higher mutation frequency (3.6 v 0-3.1, p < 0.001). There were no differences between primaries and metastases (p = 0.35). Conclusions: Characterization of these subtypes suggest a need for molecular rather than anatomic staging for AC. Histone regulation by KMT2D and EP300 may be considered for targeted therapy for patients with AC3. A prospective comparison of subtype prognosis and response to surgery and adjuvant treatment is needed.

e14211 Background: In the treatment of Peritoneal Metastasis, the delivery of pressurized chemo-aerosols into the capnoperitoneum has been reported to show superior qualities to the application of conventional liquid chemotherapy. However, there is little basic knowledge on how aerosol particle motion within the abdominal cavity may be influenced and directed by means of an electrostatic field. This study aims to investigate aerosol motion within the abdominal cavity using an ex-vivo model. Material and Methods: All experiments were performed in an ex-vivo box as well as on postmortem swine abdomen, both established ex-vivo PIPAC models previously introduced by our research team. Extra-abdominally created, unipolar charged aerosols are introduced to the abdominal cavity. A modulated electrostatic field within the abdominal cavity is established to examine aerosol particle collision via fluorescence microscopy and photography. Results: Aerosol particle collision was observed on the peritoneum in the varying electric field. Preliminary data suggests that tissue penetration rates change with a varying electric field (p < 0.05). Drug distribution pattern showed a significant improvement with a varying electric field vs. without (p < 0.05). Conclusions: Our data suggest that extra-abdominally created, highly drug concentrated aerosol particles have the capacity to achieve high drug penetration rates in the peritoneum. The addition of a varying electric field enhances particle collision as well as significantly improves drug distribution patterns. Further studies are required to investigate the in-vivo safety and efficacy of a varying electric field and the significance of extra-abdominally created chemo-aerosols with regards to possible clinical applications.

e14231 Background: Pressurized Intraperitoneal Aerosol Chemotherapy (PIPAC) is becoming an increasingly widespread approach for delivering intra-peritoneal chemotherapy (IPC) by means of a chemoaerosol. In current studies, a flexible and easy-to-handle endoscopic microcatheter (MC) approach has been introduced to replace the conventional micropump used in PIPAC. While this new method has many advantages such as wide availability, cost effectiveness and improved drug distribution, its possible occupational health risks remain unknown. Methods: PIPAC was performed on three post mortem swine using the MC device. According to standard protocol in patients, solutions of doxorubicin and oxaliplatin were aerosolized in a standardized procedure room with laminar flow. Multiple probes of all surgical material including instruments and sutures, surrounding area surfaces and the operating personals’ items such as gloves and gowns were collected. Moreover, the air filter of the operating room was examined for doxorubicin and oxaliplatin concentrations. Results: The majority of probes showed no measurable doxorubicin or oxaliplatin concentrations. No exposure was detected on the operating personals’ gowns as well as the surrounding area surfaces. While a few of the surgical materials as well as the personals’ gloves and the main part of the application system showed low drug exposure, no drug exposure was measurable in the room filter. Conclusions: Our ex-vivo data suggest that PIPAC delivered via MC is safe and does not exhibit any major occupational hazards if the safety protocol is followed. MC offers an improved, easy-to-handle and cost-effective alternative to the micropump used in conventional PIPAC. Furthermore, the MC offers the great advantage of flexibility which allows access even in anatomically difficult situations and reduces the surgical point of entry to only one abdominal trocar placement.

e14215 Background: Pressurized Intraperitoneal Aerosol Chemotherapy (PIPAC) is becoming an increasingly widespread approach in which intra-peritoneal chemotherapy (IPC) is delivered in the shape of a chemoaerosol formed by an aerosol creating device. Disadvantages of current PIPAC applications include nearly instant liquid drug accumulation in the recto-uterine pouch. This study aims to investigate the feasibility of respraying the accumulated liquid to prevent local cytotoxicity and tissue trauma as well as to possibly adjust drug concentrations and improve both distribution patterns and penetration levels. Methods: A well-established, previously described postmortem swine model was used. 200ml of doxorubicin solution were aerosolized within the abdominal cavity at a pressure of 12 mm Hg C02 and 37° degrees Celsius. A suction tube was placed in the recto-uterine pouch and accumulating liquid doxorubicin solution following aerosol formation was collected and recycled in consecutive PIPAC repetitions. PIPAC repetitions were performed by using only the remaining liquid drug within the pouch. Consecutive residual volumes within the recto-uterine pouch were measured, as well as tissue penetration rates at different locations of the peritoneal wall. Results: Liquid formation was continuously reduced with each consecutive spray cycle. Tissue penetration rates were significantly higher following the recycling process (p < 0.05). Drug distribution pattern showed a significant improvement following the recycling process vs. after initial aerosol formation (p < 0.05). Conclusions: Respraying the accumulated liquid drug in the recto-uterine pouch is both feasible and important to eliminate liquid accumulation following PIPAC application. Preliminary data gathered in this study suggest that such a recycling process both improves drug distribution and increases penetration levels. However, recycling might also increase the technical complexity of the entire applicational procedure.

e14703 Background: Colorectal cancer (CRC) incidence is rising among patients under age 50. As such, we set out to determine the proportion of CRC-related hospital admissions and distribution of co...

614 Background: Though adjuvant chemotherapy is well-established for treating patients with AJCC Stage III colon cancer, there is growing interest in giving chemotherapy neoadjuvantly for these patients. Since clinical staging to determine eligibility requires accurate preoperative imaging, our objective was to determine whether computed tomography (CT) scans can be used to detect nodal disease in colon cancer patients. Methods: We identified patients with AJCC stage I-III colon cancer who underwent curative resection between 2006 and 2010 at our institution. Patient CT scans were obtained and final radiologic reports were recorded in a database. CT images underwent secondary prospective review by a blinded independent surgeon with the intent to identify mesenteric lymphadenopathy (N+). Clinical staging from the original radiologic report and secondary surgeon review of the CT images were then compared with pathologic staging. Results: Imaging and pathology were available for 67 colon cancer patients. Original radiologic review reported N+ disease in 10 of 67 patients (15%), but final pathology revealed 31 of 67 (46%) patients to be N+. Therefore, radiological review correctly predicted Stage III disease in 10 of 31 (32%) patients. On final pathology, 36 of 67 (54%) patients had no nodal disease (N0). Radiologic reports noted absence of lymphadenopathy in 29 of 67 (43%) patients, thus accurately predicting N0 disease in 29 of 36 (80%) patients. Of 67 studies, 14 (21%) had no mention of lymphadenopathy and were considered N0. Of these 14, 6 were N+ on final pathology. Surgeon review accurately identified N+ disease in 4 of these 6 patients. On surgeon review, sensitivity increased from 32% to 68% while specificity dropped from 80% to 61%, corresponding to a decrease in false negatives from 68% to 32% and an increase in false positives from 20% to 39%. Conclusions: Current clinical staging of colon cancer by CT has low accuracy. However, actively seeking nodal disease improves sensitivity but with minor loss of specificity. Improved radiologic criteria and technology may further increase accuracy in clinical staging of Stage III colon cancer patients who will receive neoadjuvant treatment.

3510 Background: LE alone is an effective treatment for selected T1 RCs, however, for T2 RCs it results in unacceptable local recurrence and survival. The Z6041 phase II trial investigates the efficacy of CRT and LE for treating T2N0 RC. Methods: Patients (pts) with ultrasound-staged T2N0 RC and ECOG PS ≤ 2 were treated with capecitabine (825 mg/m2 days 1-14 and 22-35) and oxaliplatin (50 mg/m2 weeks 1, 2, 4 and 5) during radiation (RT) (total dose 54 Gy) followed by LE. Due to toxicity, the dose of RT was reduced to 50.4 Gy and capecitabine to 725 mg/m2 (5 days/week/5 weeks). Pts were evaluated for clinical and pathologic response. pCR was defined as ypT0N0. The association between pCR rate and pre-treatment pt and tumor characteristics were assessed by logistic regression. The agreement between clinical and pathologic assessment of response was evaluated by sensitivity and specificity. Results: Of the 90 pts accrued (66% male; age [mean ± SD], 63 ± 11; 83% ECOG PS 0, and 89% white), 6 pts did not receiv...