Repeated centralized MDT resectability assessment during first-line treatment in 1086 Finnish metastatic colorectal cancer (mCRC) patients nationwide (prospective RAXO study)

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Background: Resection of oligometastatic mCRC is curable in up to half and is probably underused in real-life oncology practice. In 2011, a prospective nationwide centralized evaluation of resectability was initiated to assess upfront and conversion to resectability. Methods: The RAXO-study included 1086 mCRCs referred for oncological treatments at all 21 Finnish oncology units (40% of eligible mCRCs in Finland). The MDT at Helsinki tertiary referral center (TRC) assessed resectability of liver, lung and other metastases upfront and twice during first-line therapy. Resectability evaluation was provided online and resections were performed according to clinical praxis, with major resections at TRCs. Results: Median age was 66.5 (range 24-90) yrs, 60% males, ECOG was 0 in 295 (27%), 1 in 600 (55%) and 2-3 in 191 (18%). Tumor was right-sided in 310 (29%), left in 769 (72%) and multiple in 7 (.6%). In the MDT assessment, 435 (40%) were considered resectable, 28% upfront and 12% after conversion. Resections or local ablative therapy were performed in 396 (91% of resectable, R0-1 in 74% and R2 in 17%), with 368 liver-, 91 lung- and 96 other operations. One metastatic site (n = 407), 2 (n = 369) and 3-6 (n = 310) were or became resectable in 65, 33 and 15%, respectively, and R0-1 resected in 54, 30 and 6%, respectively (P < 0.001). In multivariate analysis age < 66.5 (OR 1.51), ECOG 0 (OR 2.40); left-sided primary (OR 1.55), metachronous metastases (OR 1.49), 1-2 metastatic sites (OR 1.86) increased R0-1 resection rates; whereas primary/relapse in situ (OR 0.49), metastases in lung (OR 0.22), peritoneum (OR 0.30) or lymph nodes (OR 0.23) decreased R0-1 rates (P < 0.05). In univariate analyses BRAF wt (OR 0.34), normal CEA (OR 0.31) or normal Ca19-9 (OR 0.45) associated with R0-1 rates. Median OS was 2.4 yrs (CI95% 2.3-2.6) in all, 6.7 yrs in R0-1 (HR 0.15; CI95% 0.11-0.19), 2.8 yrs in R2 (0.50; 0.36-0.68) and 1.7 yrs in non-resected (reference group). Median PFS was 1.1 yrs (1.0-1.1) in all patients, 2.4 yrs in R0-1 (0.24; 0.20-0.28), 1.4 yrs in R2 (0.55; 0.42-0.71) and 0.8 yrs in non-resected patients. P < 0.001 for all comparisons. Conclusions: Repeated centralized MDTs in real-life mCRC patients show high resectability (40%) and resection rates (36%), even if multiple metastatic sites are present. Curative resection associates with good survival. Clinical trial information: NCT01531621.