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3600 Background: Even though the implementation of multimodal treatment strategies including neoadjuvant radiochemotherapy (RCT) has led to improved survival distant metastases are still limiting the prognosis of rectal cancer patients. In this context, we investigated the HER-2 status in rectal cancer patients, UICC stages II and III. Our aim was to assess the HER-2 positivity rate in primary tumors and metachronous metastases. Methods: In this study 264 rectal cancer patients (192 male, 72 female; median age 64 years) from phase-II/-III-trials of the German Rectal Cancer Study Group (CAO/ARO/AIO-94 and 04) were included. HER-2 status was determined pretherapeutically in tumor biopsies as well as resection specimens and metachronous metastases (n=27) using immunohistochemistry (IHC0 to IHC3+) scoring and S-ISH-amplification detection. Tumors with IHC3+ or S-ISH ratio ?2.0 were classified as HER-2 positive; results were correlated with clinicopathological parameters and long-term survival. Results: A positive HER-2 status was found in 12.4% of pre-treatment biopsies, in 29.3% of the resection specimens and 22.2% (n=6) of metastases. With a median follow-up of 46.5 months patients with HER-2-positivity showed better disease free survival (p=0.06) and cancer-specific survival (CSS, p=0.05). The 5-years survival rate was 96.4% (HER-2-positive) versus 79.5% (HER-2-negative). In multivariate analyses HER-2 status was as an independent (p=0.0053) predictor for CSS along with (y)pN-status (p

e14167 Background: Multidisciplinary treatment in patients with colorectal liver metastases (CRLM) is standard in modern oncology. However, for interdisciplinary discussion assessing complimentary disciplines' potential and changes in personal views is crucial. We evaluated experienced medical oncologists' (MO) and surgeons' (SG) assessment of resectability and indication for chemotherapy (CTx) in patients with CRLM. Methods: Thirty patients who underwent R0-resection of CRLM between 2001 and 2011 at our department were selected. Medical history and staging data were presented to MO (n=10) and SG (n=11) in a virtual tumor board (TB1). Standardized blinded TED-voting answers (9 options) included assessment of resectability and the indication for pre- and/or postoperative CTx. The virtual tumor board was followed by training in terms of state-of-the-art lectures on potential of CTx and surgery. Assessment was then repeated in a second virtual tumor board (TB2). Results: 630 (21x30) answers were obtained per tumor board. In TB1 resectability, borderline resectability and definite unresectability were expected in 433, 161 and 36 answers, respectively. Resectability was significantly more often expected by SG (p

644 Background: Surgical resection is the standard of care for resectable colorectal metastases (CRM). Preoperative chemotherapy allows assessment of tumorbiology and has been shown to convert approximately 30% of unresectable patients into secondary resectability. In patients with second metastatic recurrence (SMR), complete (R0) resection of all metastases seems to be accompanied with a survival benefit. The role of chemotherapy is unclear. Methods: Between 01/2001 and 31/08/2011 R0-resection could be achieved in 178 patients with liver only CRM at our institution. 103 patients developed SMR 10.4 ± 8.9 months after R0-resection of hepatic CRM. Of these, 79 patients had perioperative 5FU-based chemotherapy for treatment of the primary tumor and/or first liver metastases. Median follow-up from diagnosis of SMR was 21 (range 1-80) months. Results: SMR occurred in 80 patients at a single site (48x liver, 18x lung, 14x other) and in 23 patients at multiple sites (11x liver and lung, 7x including lung, 4x including liver, 1x other). 9 patients refused therapy and received best supportive care. 42 patients with single site recurrence were scheduled for primary surgery. R0-resection could be achieved in 26 patients (62%). 52 patients were treated with 8.1 ± 8 cycles of 5FU-based chemotherapy (5x 5FU/FS, 21x FOLFOX, 26x FOLFIRI) extended by the EGFR-antibody cetuximab (n=9) or the VEGF-antibody bevacizumab (n=18). 9 of these patients were scheduled for surgical exploration. R0-resection could be achieved in 5 patients with single site and 2 patients with multiple site recurrence. Morbidity and mortality rates for all operated patients were 16% and 0%, respectively. 5-years DFS rate for R0-resected patients was 20%. 5-years OS rate were 43% for R0-resected patients versus 11% for patients with R1/2 resection and palliative therapy (p Conclusions: Surgical resection of SMR offers a survival benefit and became possible even in 7 of 52 patients (13%) initially treated by chemotherapy. Therefore, all therapeutic options should be used in patients with SMR to achieve R0-resection of CRM.

435 Background: Fluorouracil (5FU) remains the backbone of neoadjuvant radiochemotherapy (RCT) as well as adjuvant therapeutic strategies in multimodal treatment of rectal cancer patients. Due to its central role as the major target of 5FU thymidylate synthase (TS) is a promising biomarker in rectal cancer. We assessed TS in 208 patients with regard to its predictive/prognostic capacity for disease free DFS and overall cancer specific survival (CSS). Methods: 167 patients cUICC stages II (28%) and III (72%) received preoperative 5FU based RCT followed by total mesorectal excision (TME) A comparison group n = 41 received postoperative RCT after primary TME. All patients were treated after standardized protocols within phase-II/-III trials of the German Rectal Cancer Study Group. TS levels from pretreatment biopsies and corresponding resection specimens were assessed by immunohistochemical staining for their impact on DFS and CSS. Additionally, a TS gene polymorphism (28 bp repeat) was analysed in respect to intracellular protein expression levels and prognostic significance. Results: Patients with low TS expression in pre-treatment biopsies showed a correlation with impaired CSS (p = 0.015). After neoadjuvant RCT there was evidence of lymph node metastases ypUICC stage III in 32.6%. Complete histopathologically confirmed tumor regression TRG 4 was achieved in 16 patients (9.5%). During follow-up (median 57 months) patients with low intratumoral TS expression and positive nodal status were at high risk for local and/or distant metastatic recurrence (p = 0.040). Analysis of the 28bp repeat revealed a correlation of *3/*3 genotype with high TS expression in pretherapeutical biopsies (p = 0.05). Conclusions: TS represents a prognostic biomarker in locally advanced rectal cancer indicating an unfavourable outcome for patients with low TS expression and might help to adapt adjuvant therapy regimens by stratifying patients according to their risk for cancer recurrence. No significant financial relationships to disclose.