Prophylactic HIPEC with oxaliplatin might be of benefit in T4 and perforated colon cancer: another possible interpretation of the COLOPEC results.

The COLOPEC trial failed to show evidence for improved relapse-free survival (RFS) between the two study groups: 80,9% (95% CI 73.3-88.5) in the experimental group and 76.2 % (68.0-84.4) in the control group (one-sided log-rank p = 0.28). Nevertheless only 87 patients received the adjuvant HIPEC treatment in the experimental arm (n = 100). This group had a peritoneal relapse of 19 %, but only 10 % had a truly peritoneal relapse as 9 of them had stablished peritoneal carcinomatosis and 1 case was a peritoneal recurrence but did not receive adjuvant HIPEC. We conducted a per-protocol analysis comparing the 87 patients which truly received the adjuvant HIPEC to the 102 patients in the control arm and obtained an OR 0.396 (95 % CI 0.17-0.91) with a (Pearson Chi-Square p = 0.026, two-tailed Fisher exact test p = 0.032). This contradicts the COLOPEC reported conclusions and shows that adjuvant HIPEC could have an important protective role against peritoneal recurrence.