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750 Background: Optimal sequencing of therapies in synchronous metastatic rectal cancer (SMRC) remains unknown. Aim: To compare sequencing of treatment modality and outcomes in SMRC. Methods: Retrospective audit of patients with SMRC registered on the multi-centre Treatment of Recurrent and Advanced Colorectal Cancer database between 1/1/2009 and 30/6/2015. Patients were grouped according to initial treatment mode: chemotherapy (C), chemoradiation (CRT), surgery (S) and best supportive care (BSC). Results: 247 patients were identified: median age was 62yrs, ECOG 0-1 87%, male 64%, 1-2 metastatic sites 86% (liver 56%) and treatment intent was curative in 14%. Median follow-up was 19m. Primary tumour resection occurred in 95 patients (38%). Compared to no resection, these patients had improved median OS (41 vs 16 months; p < 0.0001) and PFS (15 vs 10 months; p < 0.0001). There was no difference in outcome with varying treatment combinations and sequences of S with CRT/C (p > 0.05). For unresected patients, the most common initial treatment was C (30%). Any active treatment was associated with better OS compared to BSC (6.4m): C (16.1m, p < 0.0001), CRT (20.6m, p = 0.001) and C&CRT (21.8m, p < 0.0001). Most active treatments were associated with better PFS compared to BSC (6.4m): C (10.8m, p = 0.015) and C&CRT (10.6m, p = 0.012). There was no significant PFS difference comparing BSC to CRT (p = 0.25). There were no OS nor PFS differences between: comparisons of C, CRT and C&CRT (p > 0.05). Initial treatment strategies were compared for 129 patients receiving multimodal therapy, where 22 (17%) had initial treatment with C (60% subsequent resection) compared to 85 (66%) commencing with CRT (70% subsequent resection). Commencing with CRT was associated with a longer OS compared to C (31 vs 21 months; p = 0.014). Conclusions: For patients undergoing primary tumour resection, no difference in outcomes were demonstrated with the addition of C and/or CRT. For unresected patients, there was a survival benefit associated with active therapy, with no significant difference between C, CRT or C&CRT. This supports the current practice of using these modalities at clinicians’ discretion. Review of patient factors potentially influencing treatment choice is ongoing.

e14518 Background: Variation in outcomes for rectal (RC) and colon (CC) cancer have been reported, particularly in the advanced disease setting. Established differences in patterns of metastatic sp...

572 Background: At initial diagnosis of mCRC, accurate assessment of patient prognosis is critical to defining the optimal initial treatment strategy. While performance status (PS) and number of metastatic sites are presumed surrogates of TB, to date TB assessment has not been formally examined as a potential prognostic marker in mCRC, despite supportive evidence in other malignancies. Methods: We developed a CT-based scoring system for TB on mCRC patients from the TRACC (Treatment of Recurrent and Advanced Colon Cancer) database. Objective (size and number of metastases) and subjective (clinical judgment) scoring systems were used to separate patients into high, moderate, or low TB subsets. Subjective scoring was repeated by a blinded second assessor on a subset of cases. Clinicopathologic correlates with TB were then assessed, along with survival outcomes for each subset. Results: 151 patients were assessed, median age was 68 years and 51% were male. Using subjective scoring, 55 (36%), 33 (22%), and 63 (42%) were categorized to high, moderate, and low TB subsets. Concordance between assessors using subjective scoring for 30 selected cases was 80% (high), 60% (moderate), and 90% (low). Factors correlating with increasing TB (high vs. low) on objective scoring were PS (31 vs 5% ≥ 2, p = 0.0002), number of disease sites (57 vs 9% ≥2, p < 0.0001) and for patients with mCRC at presentation, reduced likelihood of primary CRC resection. Median overall survival was superior in low compared to high TB subsets for subjective (not reached vs. 15.9mths, p < 0.0001) and objective (not reached vs. 14.7mths, p < 0.0001) scores. Survival difference for low vs high TB were maintained on objective scoring even when patients with resectable metastases were excluded (22.7 vs. 11.9mths, p = 0.0017). Conclusions: TB measured subjectively or objectively is associated with overall survival in mCRC, and is a potential novel prognostic marker. Multi-variate analyses will be performed, and an independent validation cohort is being examined. As TB inversely correlated with primary resection for patients with mCRC at presentation, including TB assessment in further analyses of the survival impact of primary CRC resection is one potential application of this measure.

e16516 Background: Cure is potentially achievable in select patients with mCRC with limited metastatic disease to liver and/or lung. To date the peri-operative strategies undertaken by oncologists in routine practice for such pts have not been well documented. Methods: A clinical database recording information on all pts diagnosed with mCRC since July 2009 from 5 hospitals was analysed. Management strategies where a curative-intent resection had occurred; was planned; or was a potential option were compared with those managed with palliative intent. Results: Status at the time of first review regarding systemic chemotherapy (CT) was documented for 354 pts. 15 (4.2%) had undergone curative-intent resection; 37 (10.5%) had a resection planned; 36 (10.2%) were considered potentially resectable if response to treatment was good; and 266 (75.1%) were treated with palliative intent. Only one patient (1.9%) already resected or planned for resection was >ECOG1, compared with 8% (3/36) potentially resectable and 20% (53/266) palliative pts. CT was delivered in 12 (80%) already-resected, 29 (78%) planned for resection, 33 (92%) potentially-resectable and 202 (76%) palliative-intent pts. Combination CT was the dominant strategy, although 5 of 12 (42%) resected pts received single agent treatment. 17% (n=2) resected pts received bevacizumab with CT, compared with 29% (n=18) of planned or potentially-curative pts and 55% (n=112) of those treated with palliative intent. At the time of analysis 17 pts (46%) with a planned resection and 7 (20%) considered potentially curative have had surgery, while 6 (2.3%) where treatment was initially considered palliative have had curative-intent surgery. Conclusions: Treatment strategies for pts with mCRC differ significantly based on the treatment intent, and may be affected by surgical preference and referral pattern. Bevacizumab was less likely to be used for already-resected pts and the use of single agent therapy in this group was also not uncommon. Many pts initially considered resectable do not ultimately undergo resection, whereas occasional ‘palliative’ pts may become resectable, confirming the importance of continued consideration of this option.

682 Background: Cure is potentially achievable in select patients (pts) with mCRC with limited metastatic disease to liver and/or lung. To date the peri-operative strategies undertaken by oncologists in routine practice for such pts have not been well documented. Methods: A clinical database recording information on all pts diagnosed with mCRC since July 2009 from 5 hospitals was analysed. Management strategies where a curative-intent resection had occurred; was planned; or was a potential option were compared with those managed with palliative intent. Results: Status at the time of first review regarding systemic chemotherapy (CT) was documented for 280 pts. 11 (4%) had already undergone curative-intent resection; 31 (11%) had a resection planned; 27 (10%) were considered potentially resectable if their response to treatment was good; and 207 (74%) were treated with palliative intent. No pts already resected or planned for resection were >ECOG 1, compared with 11% (3/27) potentially resectable and 17% (36/207) palliative pts. CT was delivered in 9 (82%) already-resected, 26 (84%) planned for resection, 26 (96%) potentially-resectable and 159 (77%) palliative-intent pts. Combination CT was the dominant strategy, although 7 of 11 (66%) already-resected pts received single agent treatment. No already-resected pts received bevacizumab with CT, compared with 27% (n=14) of planned or potentially-curative pts and 55% (n=88) of those treated with palliative intent. At the time of analysis 13 pts (42%) with a planned resection and 8 (30%) considered potentially curative have had surgery, while 3 (1.4%) where treatment was initially considered palliative have had curative-intent surgery. Conclusions: Treatment strategies for pts with mCRC differ significantly based on the treatment intent, and may be affected by surgical preference and referral pattern. Bevacizumab was less likely to be used for already-resected pts and the use of single agent therapy in this group was also not uncommon. Many pts initially considered resectable do not ultimately undergo resection, whereas occasional ‘palliative’ pts may become resectable, confirming the importance of continued consideration of this option.

665 Background: Clinical trials support the addition of bevacizumab (Bev) to first line chemotherapy for metastatic colorectal cancer (mCRC). However, given that there are alternate biological agents that can be used with chemotherapy; and rare but potentially serious toxicities with Bev, there has been variable use of the drug in routine care. The purpose of this study was to prospectively explore 1st line use of Bev in routine clinical care. Methods: A multi-site data collection was initiated in July 2009 when Bev became publicly available in Australia. A particular focus was capturing information regarding clinician decision-making that is not routinely recorded or is often poorly documented. Comprehensive comorbidity data was collected, along with specific factors, both patient (pt) and disease-related, that may impact on treatment decisions. Major adverse events that may be related to Bev were also recorded. Results: For the 2-year period from July 2009-June 2011, a database search identified 278 pts diagnosed with mCRC at five participating hospitals. 240 pts (86%) had received 1st line chemotherapy. 102 (43%) also received Bev, the majority in combination with oxaliplatin based chemotherapy (n = 81, 79%). Bev use increased significantly from 40.4% (34/84) of all pts receiving chemotherapy in July-December 2009, to 65.8% (25/38) in January-June 2011 (p=0.0114). Overall the most frequent reasons for clinicians advising against the use of Bev were a bleeding or asymptomatic primary in situ (n=28, 23%), known hypertension (n=14, 11%), clinical trial participation (n=14, 11%), poor performance status (n=9, 7%), and perceived risk of arterial ischemic event (n=8, 6.5%). There have been four episodes of gastro-intestinal perforation, 3 in pts receiving Bev (2.9% of Bev treated patients). Conclusions: Bev use in first line mCRC has significantly increased over time, presumably as further positive safety data emerges regarding safety in older and frailer pts, and clinician prescribing experience increases. The major grounds for not using Bev in the 1st line mCRC setting were specific clinical contexts where the risk of adverse events may be increased.