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This study is aimed to correlate apparent diffusion coefficient (ADC) values and clinical T-stage, serum PSA, pathology Gleason scores. We also further analyzed whether ADC values could be used to appropriately define the risk groups. 135 biopsy-proven, radiotherapy-(RT)-treated, prostate cancer patients who underwent pre-RT DW-MRI and standard T2W pelvic MRI were included. ADC and normalized ADC (nADC) values were calculated from DW-MRI delivered a median 8.1 weeks after prostate biopsy. ADC values were correlated with clinical risk factor values by using Pearson correlation test. ADCs in low-, intermediate-, and high-risk patients were 0.873 +/- 0.122X10(-3) mm(2)/s, 0.763 +/- 0.124X10(-3) mm(2)/s, and 0.701 +/- 0.132X10(-3) mm(2)/s (p = 0.001), respectively. Patients with preRT PSA 20 ng/mL (p < 0.001). Mean ADC for patients with Gleason score 7 (p < 0.001). Clinical stage

The aim of this study into evaluate the treatment results of three dimensional conformal radiotherapy (3DCRT) and androgen deprivation therapy (ADT) in patients with clinically localized prostate cancer (CLPC). Between June 1998 and December 2011, 577 patients with the diagnosis of CLPC were treated. ADT was started 3 months prior to radiotherapy (RT). 3DCRT was delivered to prostate and the seminal vesicles (SV) to a total dose of 70Gy. Additionally, patients with lymph node (LN) positivity received 50.4Gy RT to pelvic LN's. Median follow up time was 65 months. Five-ten years overall survival (OS), cause specific survival (CSS), PSA relapse-free survival (PSA-RFS) and distant metastasis-free survival (DMFS) rates were 92-74%, 97-91%, 77-55% and 94-88%, respectively. OS was negatively affected from LN positivity (p < 0.001). In the subgroup of patients With GS 8, there was no significant difference between < 1 years and 1 years of ADT in terms of CSS, PSA-RFS and DMFS. OS was better in patients with < 1 years of ADT (p = 0.01). Five year OS (p = 0.02), CSS (p = 0.05), PSA-RFS (p = 0.01) and DMFS (p = 0.07) rates were inferior in the high risk group patients that used ADT 1 year. Acute and late RTOG grade III/IV gastrointestinal system toxicity rates were 1.7% and 5% and acute and chronic RTOG grade III/IV genitourinary system toxicity rates were 1.4% and 5%, respectively. 3DCRT and ADT combination is an effective treatment modality with acceptable toxicities in patients with clinically localized prostate cancer.

The aim of the study was to review the current clinical practices of radiation oncologists involved in the treatment of oropharyngeal cancer.The daily practices of radiation oncology centers for patients diagnosed with oropharyngeal cancer in 2010 were evaluated by a two-part questionnaire that separately assessed the information of the participating center and the charts of the treated patients.A total of 22 centers participated in the study, and 105 oropharyngeal cancer patients reported for our review. The use of positron emission tomography was a common practice in staging and radiotherapy planning. Multidisciplinary head and neck cancer clinics were available in 14 (64%) centers and were absent in 8 centers. Thirty-six of the 105 patients were not evaluated by a multidisciplinary clinic before the initiation of therapy, and adjuvant radiotherapy administration was found to be higher in this group. Percutaneous endoscopic gastrostomy tube placement was not a routine practice in any of the centers. Seventy-five patients received chemotherapy - 46 concurrently with radiotherapy and 29 as induction chemotherapy. Two centers administered conventional radiotherapy alone, 20 centers conformal radiotherapy, and 7 centers were able to provide intensity-modulated radiotherapy.Across all the centers there were small differences in the pretreatment evaluation of patients with oropharyngeal cancer. The greatest difference was in the technical delivery of radiation, with most of the centers using conformal radiotherapy despite the increasing availability of intensity-modulated radiotherapy. The use of chemotherapy has more readily adopted the current international standards in the treatment of oropharyngeal cancer.

68 Background: The aim was to assess the intensity of 68Ga-PSMA uptake in the primary tumour in patients locally advanced prostate cancer treated with definitive radiotherapy. Also correlation between the maximum standardized uptake value (SUVmax) of primary tumour and the Gleason score (GS) or prostate-specific antigen (PSA) level was assessed. Methods: The data of 201 biopsy-proven prostated cancer patients were retrospectively analysed. Median age of entire cohort was 68 years (range; 45 – 85 years). PET/CT images were analysed visually and semiquantitatively by measuring the SUVmax. The SUVmax of the primary tumour was assessed in relation to both PSA level and GS. Results: Median age of entire cohort was 68 years (ranged 45 – 85 years). Median PSA value at diagnosis was 20.3 ng/mL (ranged 2.1 – 301.0 ng/mL). Forty-two patients (23.9%) was in intermediate risk group, and 159 patients (79.1%) had high risk disease. Seventy two patients (36.8%) had regional lymph node metastasis. Median SUVmax of primary tumor and metastatic lymph nodes were 13.0 (ranged 1.3 - 84.3) and 12.6 (ranged 3.6 – 64.5), respectively. Patients with GS 7 or lower had significantly lower SUVmax compared to patients with GS > 7 (12.1±8.4 vs. 20.9±16.4; p < 0.001). However, there was no significant difference in SUVmax of tumors with GS of 3+4 and 4+3 (14.8±8.6 vs. 16.3±12.7; p = 0.6). Patients with PSA ≥10.0 ng/mL exhibited significantly higher uptake than those with PSA levels < 10.0 ng/mL (12.1±8.4 vs. 20.9±16.4; p < 0.001). SUVmax of intermediate risk patients was significantly lower than that of high risk patients (12.7±11.1 vs. 19.8±16.8; p = 0.01). In 72 patients with lymph node metastasis SUVmax was significantly higher compared to 129 patients without lymph node metastasis (24.9±21.3 vs. 14.7±10.6; p < 0.001). Conclusions: Tumours with GS 7 or lower, patients with PSAvalues ≤10 ng/mL, intermediate risk patients and patients without regional lymph node metastasis showed significantly lower 68Ga-PSMA uptake. 68Ga-PSMA-PET/CT should be preferentially applied for primary staging of prostate cancer in patients with GS > 7, PSA levels ≥10 ng/ml, high risk patients and patients with regional lymph node metastasis.

316 Background: To evaluate the potential benefit of curative radiotherapy (RT) to primary tumor in metastatic castration resistant prostate cancer (mCRPC) patients treated with abiraterone. Methods: The clinical parameters of 106 mCRPC patients treated with abiraterone in the either pre- or post-chemotherapy setting were retrospectively evaluated. All patients had PSA progression or radiographic progression suitable for metastasis according to the RECIST guidelines with or without PSA progression. Patients were either oligometastatic (≤5 metastases) at diagnosis or became oligometastatic after systemic treatment were analyzed. Local RT to primary tumor and pelvic lymphatics was delivered in 44 patients (41%), while 62 patients (59%) did not have RT to primary tumor. Results: Median follow-up times for patients overall and for those who survived were 14.2 months (range, 2.3–54.9 months) and median OS for entire cohort was 21.9 months. The median OS was significantly higher in patients treated with local RT to primary tumor compared to patients without local RT (p = 0.04). Local RT to prostate and pelvic lymphatics significantly diminished local recurrence rate ( p = 0.003). In univariate analysis, a decline in PSA levels ≥50% of baseline was significant prognostic factor for both OS and PFS in entire cohort and in patients receiving prostate RT. In multivariate analysis, PSA response ≥50 of baseline obtained ≥3 weeks after abiraterone therapy is the only significant prognostic factor for better OS and PFS. Additionally, local RT to prostate is nearly significant prognosticator for improved OS. Patients treated with primary RT to prostate had significantly less progression under abiraterone and longer abiraterone period compared to patients without local prostate RT. Conclusions: Local prostate RT significantly improves OS and local control but not PFS, in mCRPC treated with abiraterone. Patients treated with primary RT to prostate had significantly less progression under abiraterone and longer abiraterone period compared to patients without local prostate RT.

WOS: 000370169700013, PubMed ID: 26500735, To date, the Rare Cancer Network (RCN) has initiated more than 90 studies and 54 peer-reviewed publications were produced as a result. The Second International Symposium of the Rare Cancer Network recently took place in Istanbul, Turkey on April 17-18, 2015, and update was given on multiple currently ongoing projects, while also giving room for new proposals which will shape the direction of future studies for the group. This companion issue of the RCN Proceedings summarized the findings of this meeting, while also serving as a call for fresh projects and papers which will continue to energize the group and advance the oncologic science. A brief introduction to the principles, history, and vision of the RCN was also included. To review, the academic year of 2014-15 marked an enormous success for the international members of the RCN, with the generation of 8 fully published papers and more than 12 newly proposed topics. By the collective efforts of all RCN members, in the future, we look forward to the upcoming opportunities in continuing to advance the standard of chemo-and radiotherapeutic oncologic care for selected rare tumor topics. The studies of these rare cancers often do not allow the design and execution of prospectively enrolled trials; however, these uncommon malignancies do impact the humankind and add to its suffering globally in significant ways.

e17019 Background: To report the role of combined chemotherapy in SGT. Methods: 251 patients with SGC treated in 2001-2011 were included in a collaborative IRB-approved retrospective RCN study. Chemotherapy is empirically administered based on extrapolation from conventional head and neck squamous cell carcinoma (Ca) (SCC) and data on systemic treatment in localized SGC are lacking. Results: Median age was 60 yo with 2/5 females/males. Tumor sites were the parotid 74.9%, submandibular 16%, sublingual 2.8% or minor gland 4%. Histologic findings were adenoid cystic (ACC) 17.3%, mucoepidermoid (MEC) 19.8%, adenoCa 15.6%, salivary duct (SDC) 10.3%, acinic cell (Aci) 6.2%, ex-pleomorphic 7.8%, undifferentiated 4.9%, myoepithelial 3.3%, epithelial myoepithelial 1.6%, basal cell 1.2%, lymphoepithelial 1.2%, others 4.0%. Surgery was performed in 95.1% (complete resection 38.1%). T stages 1, 2, 3 and 4 were 17.2%, 41.2%, 18.1% and 23.5% respectively. N stages were N0 61%, N1 13%, N2 24%, N3 2%. Perineural, vascular or lymphatic emboli were present in 47%, 24%, 27% respectively. Irradiation was performed postoperatively 96% or exclusively 4% (unilateral 84%, performed w/ photons only 78%, IMRT 41%). Chemotherapy was administered in 18%, dependent on grade, N stage, and emboli (p ≤ .05). None of 17 ex-pleomorphic, 25% of undifferentiated, 36% of SDC, and 66.7% of lymphoepithelial Ca received chemotherapy (p NS). With a median follow-up of 42 months for living patients, crude local, regional, metastatic relapse rates were 112% (in field 85%), 10%, 25%, respectively. Crude death rate was 28% including 77% from SGC. 5-year survival (5y OS) was 63%. The only prognostic factor was nodal involvement (p .002). However, 5y OS differed by histology: ACC 79%, MEC 84%, Aci 67%, SCC 43%, adenoCa NOS 40%, SDC 37%. Chemotherapy did not improve survival whatever histology. Conclusions: Further prospective studies are warranted to define the role of chemotherapy by histology in the setting of localized SGT. Also molecular profile-driven systemic treatments should be investigated.

22 Background: To evaluate the effect of neoadjuvant androgen deprivation treatment (ADT) on prostate specific membrane antigen (PSMA) tracer uptake demonstrated in 68Ga-PSMA-positron emission tomography (PET/CT) in non-metastatic hormone-naïve prostate cancer patients. Methods: The clinical data of 108 prostate cancer patients who received neoadjuvant ADT were retrospectively analyzed. All patients had a baseline 68Ga-PSMA-PET/CT scan and a second scan was delivered median of 2.9 months after initiation of ADT. Patients with clinical and radiological evidence of distant metastasis were excluded from the study. The maximum standardized uptake value (SUVmax) of primary tumor (SUVp) and metastatic lymph nodes (SUVln) as well as PSA response were assessed between pre- and post-ADT 68Ga-PSMA-PET/CT scans. Results: The median SUVp and SUVln were 14.0 (range, 4.9 – 78.4) and 13.2 (range, 3.6 – 64.5), respectively. There was a significant moderate correlation between baseline serum PSA and SUVp (Spearman = 0.513, pp, and SUVp. A decrease in SUVp was seen in 91 patients (84%) with a median value of 66% (range, 5% – 100%), while 17 patients (16%) had no change in or an increase in PSMA tracer uptake with a median value of 24% (range, 0% – 198%). Patients with Gleason score (GS) of 7 had significantly higher metabolic response rates compared to other patients. The disease progression was significantly higher only in patients with GS > 7 disease compared to GS 7 disease. The PSA response to ADT was lowest in patients with ISUP high-grade tumors. A total of 16 patients (15%) had progressive disease, and in 9 patients (8%), radiotherapy decisions were modified according to post-treatment 68Ga-PSMA-PET/CT scans. Conclusions: The current study includes the largest number of patients analyzed to date and demonstrates that ADT causes a significant decrease in serum PSA values and SUVp and SUVln. The authors demonstrate that 68Ga-PSMA-PET/CT may be used as a quantitative imaging modality after neoadjuvant ADT in hormone-naïve non-metastatic PC patients.

Positron emission tomography (PET) has the potential to improve staging and radiation treatment-planning (RTP) for tumors in various sites. We compared computed tomography (CT) with co-registered 18F-fluorodeoxyglucose (FDG)-PET-CT) as the basis for delineating gross tumor volume (GTV) in patients with rectal carcinoma undergoing preoperative three-dimensional conformal radiotherapy (3D-CRT).