Poster Session, Saturday 28 January 2017 Abstracts S51 435 POSTER SPOTLIGHT Comparison of expectations between medical oncologists (MO) and hepatobiliary surgeons (HS) regarding the indications for liver metastatectomy D. Yusuf 1 , M. Ho 1 , S. Cleary 2 , M. Mazurek 3 , S. Ghosh 4 , W. Cheung 5 . 1 Cross Cancer Institute - University of Alberta, Medical Oncology, Edmonton- Alberta, Canada; 2 Princess Margaret Cancer Centre, Surgical Oncology, Toronto, Canada; 3 University of Alberta, Medicine, Edmonton, Canada; 4 Cross Cancer Institute - University of Alberta, Experimental Oncology, Edmonton- Alberta, Canada; 5 BC Cancer Agency Vancouver, Medical Oncology, Vancouver, Canada Background: Resection of liver metastases is curative for specific patients with advanced cancers. There is increasing aggressiveness in the use of metastatic resections, but guidelines describing appropriate indications for metastatectomy are lacking or obsolete in the era of novel systemic therapies and advanced surgical techniques. We compared expectations of MO vs HS in the management of liver metastases from colorectal cancer (CRC). Methods: MO and HS across Canada were surveyed to evaluate their criteria to determine resectability of liver metastases, their current access to and availability of multidisciplinary care, and their views regarding imaging in guiding management of these complex patients. Results: Of 220 experts surveyed, 145 (66%) responded of whom 137 (95%) had received specialized training in oncology. Among them, 109 (75%) reported the lack of institutional criteria to determine resectability of liver metastases while only 37 (26%) indicated that they had access to multidisciplinary tumor boards and clinics. MO and HS disagreed in terms of absolute contraindications (CI) for liver metastatectomy. For example, MO were more likely to consider significant liver parenchymal involvement, proximity to major vessels, and poor performance status as absolute CI when compared to HS (all p < 0.05). All physicians viewed CT scans as the preferred first-line imaging modality for evaluating CRC liver metastases, but significantly more HS indicated the value of also ordering MRI scans (p < 0.01). Likewise, there were notable discrepancies between physicians with respect to the types of clinical or radiographic findings that would modify their perspectives on resectability (Table). Likelihood to affect resectability MO (%) HS (%) P Bilobar involvement L 26 34 <0.01 H 28 0 No extrahepatic site L 1 6 <0.01 H 90 27 Node positive 1º L 50 37 <0.01 H 18 2 >1 lesion L 57 40 <0.01 H 12 0 Lesion >5 cm L 45 40 <0.01 H 17 0 CEA L 51 37 <0.01 H 16 1 Age and ECOG L 2 3 0.02 H 89 32 Short interval from 1º to metastasis L 25 32 <0.01 H 31 2 L, low; H, high. May not add to 100% if item skipped. Conclusions: Criteria used by MO and HS to determine resectability of CRC liver metastases are highly discordant and may compromise care. No conflict of interest. 436 POSTER Preoperative hyperfractionated concurent radiochemotherapy for locally advanced rectal cancers: a phase II clinical study A. Idasiak 1 , K. Galwas-Kliber 1 , K. Behrendt 1 , I. Wzie ˛tek 2 , M. Kryj 3 , E. Stobiecka 4 , E. Chmielik 4 , R. Suwi´ nski 1 . 1 Maria Skłodowska-Curie Memorial Cancer Center and Institute of Oncology- Gliwice Branch- Gliwice- Poland, Radiotherapy and Chemotherapy Clinic and Teaching Hospital, Gliwice, Poland; 2 Maria Skłodowska-Curie Memorial Cancer Center and Institute of Oncology- Gliwice Branch- Gliwice- Poland, Radiotherapy Department, Gliwice, Poland; 3 Maria Skłodowska-Curie Memorial Cancer Center and Institute of Oncology- Gliwice Branch- Gliwice- Poland, Department of Surgery, Gliwice, Poland; 4 Maria Skłodowska-Curie Memorial Cancer Center and Institute of Oncology- Gliwice Branch- Gliwice- Poland, Department of Pathology, Gliwice, Poland Background: The clinical experience in locally advanced rectal cancer suggest that accelerated hyperfractionated preoperative radiotherapy (HART) may provide the low rate of loco-regional recurrences after adequate preoperative radiotherapy and surgery. Unfortunately, the rate of distant metastases remains high, so there is apparent need for further improvement in local control, particularly in high-risk patients. The study was prospectively designed as a single-arm, single institution prospective trial of preoperative concomitant hyperfractionated radiotherapy with co-administration of two cycles of chemotherapy based on 5FU in patients with T2/N+ or T3/any N resectable mid-low primary rectal cancer. The aim of the study was to assess the safety and efficacy of accelerated hyperfractionated radiotherapy (HART) with concurrent 5FU- based chemotherapy in patients with locally advanced rectal cancer. Materials and Methods: Patients with resectable locally advanced (T3 or N+) rectal cancer were eligible. The patients received total dose 42 Gy in 28 fractions of 1.5 Gy, two times daily, with at least 8 hours interval, with concurrent chemotherapy: 5FU-325 mg/m 2 (bolus) on days 1-3 and days 16-18. The primary endpoint included tolerance, postoperative complication rate and pathological response rate. The secondary endpoints included loco-regional relapse free survival (LRCS), metastasis free survival (MFS) and overall survival (OS). Results: Out of 53 patients enrolled; two did not undergo surgery. Of the 51 patients evaluable for pathologic response there were 8 (15.6%), 20 (39.3%), 18 (35.3%), and 5 (9.8%) patients with TRG 0, 1, 2 and 3, respectively. Downstaging of the primary tumor and lymph nodes was observed in 22 (43%) and 25 (49%) patients, respectively. The primary tumor ypCR (ypT0) rate was 15% (8/51). The nodal ypCR rate for cN+ patients was 60% (21/35). The total ypCR (ypT0N0M0) rate was 11% (6/51). Toxicity included: Grade 3 diarrhea (8/51, 15.7%), Grade 2 diarrhea (22/51, 43.1%), Grade 2 leucopenia (7/51, 13.7%), Grade 2 neutropenia (6/51, 11.7%), Grade 1 thrombocytopenia (3/51, 5.9%). No Grade 4 toxicity was reported. Fourteen patients (27.5%) presented with postoperative complications (during 3 months after surgery). There were 6 loco-regional relapses (11.8%) and distant metastasis occurred in 11 patients (21.6%). The 2-year cumulative loco-regional relapse free survival, MFS and OS was 87%, 79% and 89%, respectively. Conclusion: The proposed preoperative HART with co-administration of two cycles of 5FU had acceptable toxicity profile and provided satisfactory rate of ypCR. This created rationale to initiate a phase III randomized study that was registered under ClinicalTrials.gov Identifier: NCT01814969. No conflict of interest. 437 POSTER The role of multidisciplinary team discussions in clinical practice: a population-based assessment of rectal cancer patients in Catalonia P. Manchon-Walsh 1 , J. Prades 1 , L. Aliste 1 , J.A. Espinas 1 , J.M. Borras 1 . 1 Department of Health- Government of Catalonia, Catalonian Cancer Strategy, L’Hospitalet Llobregat Barcel, Spain Background: Rectal cancer treatments usually require the involvement of a Multidisciplinary team (MDT) due to its multimodal treatment and, combined with its incidence, it could be a sentinel tumor to assess the role assigned by clinicians to the MDT discussions. The variables associated to the probability of neoadjuvant treatment were assessed in Catalonia (Spain). Methods: Clinical practice was assessed by means of a clinical audit (retrospective cohort study) of all rectal cancer patients who underwent elective surgery with a radical intent in public hospitals in Catalonia during 2011/12. Data on MDT, type of specialists attending the MDT (s) and timing of meetings related to surgery as well as on clinical management were retrieved from clinical documentation. Hospital volume was calculated on the basis of the yearly number of rectal cancer surgery performed over the study period (11, 12-19, 20-39, 40). A multivariate logistic regression model was carried out in order to assess the variables associated with the MDT evaluation and with neoadjuvant treatment. Results: Of the 1794 patients with a rectal cancer surgery during 2011/12, 74.1% were discussed at a MDT meeting (82.2% before initiation of neadjuvant surgery). After adjustment for sex and age, advanced TNM stage (stage III OR: 1.38, 95% CI 1.02–1.86; stage IV OR: 2.62, 95% CI 1.57–4.38), tumor in low rectum (OR: 1.46, 95% CI 1.09–1.97) and receiving treatment in an intermediate volume hospital (12-19 cases/year: OR: 3.28, 95% CI 2.04–5.27; 20-39 cases/y OR: 1.57, 95% CI 1.07–2.30) were found to be significantly associated to MDT discussion. Among stage II and III patients, having been discussed in a pre-surgical MDT meeting and the participation of the radiation oncologist increased the likelihood of neoadjuvant treatment as well as younger age, advanced stage and low rectal cancer. Conclusions: The percentage of patients discussed in an MDT could be increased, as it has been demonstrated in other countries. However, the great majority of patients were evaluated in the most relevant moment for clinical decision-making in rectal cancer, before first treatment. In our