Background: Although systemic therapies have shown to result in survival benefit in patients with metastatic colorectal cancer (mCRC), outcomes in patients with peritoneal carcinomatosis (PC) are poor. No data are available on outcomes of current chemotherapy schedules plus targeted agents in mCRC patients with PC.
Methods: Previously untreated mCRC patients treated with chemotherapy in the CAIRO study and with chemotherapy and targeted therapy in the CAIRO2 study were included and retrospectively analysed according to presence or absence of PC at randomisation. Patient demographics, primary tumour characteristics, progression-free survival (PFS), overall survival (OS), and occurrence of toxicity were evaluated.
Results: Thirty-four patients with PC were identified in the CAIRO study and 47 patients in the CAIRO2 study. Median OS was decreased for patients with PC compared with patients without PC (CAIRO: 10.4 versus 17.3 months, respectively (p ≤ 0.001); CAIRO2: 15.2 versus 20.7 months, respectively (p < 0.001)). Median number of treatment cycles did not differ between patients with or without PC in both studies. Occurrence of major toxicity was more frequent in patients with PC treated with sequential chemotherapy in the CAIRO study as compared to patients without PC. This was not reflected in reasons to discontinue treatment. In the CAIRO2 study, no differences in major toxicity were observed.
Conclusion: Our data demonstrate decreased efficacy of current standard chemotherapy with and without targeted agents in mCRC patients with PC. This suggests that the poor outcome cannot be explained by undertreatment or increased susceptibility to toxicity, but rather by relative resistance to treatment.
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