Is primary tumor resection associated with a longer survival in colon cancer and unresectable synchronous metastases? A 4-year multicentre experience.

Aim: To explore the survival impact of primary tumor resection (PTR) in patients with metastatic colon cancer (mCC) and unresectable metastases.

Methods: We retrospectively studied a multicenter cohort of consecutive mCC patients with unresectable metastases receiving first-line chemotherapy. A weighted Cox proportional regression model was used to balance for clinical variables associated with the probability of undergoing PTR, using inverse probability of treatment weighting (IPTW) based on a propensity score.

Results: Ninety-six patients were included. PTR was performed in 69 (72%). The rates of secondary resection of metastases (p = 0.02) and bevacizumab administration (p = 0.02) were higher in the PTR group. Raw median overall survival (OS) was 23.1 months (95%CI[14.6-27.8]) in the PTR group and 22.1 months (95%CI[12.3-23.7]) in the non-PTR group (p = 0.11). After adjustment on IPTW, OS was 23.1 months (95%CI[17.0-28.7]) in the PTR group and 17.2 months (95%CI[13.5-22.2]) in the non-PTR group (HR 0.68; 95%CI[0.50-0.93]; p = 0.016). This result remained significant on multivariate analysis (HR 0.71; 95%CI[0.50-1.00]; p = 0.05).

Conclusion: In mCC patients with unresectable metastases receiving chemotherapy, up-front PTR was independently associated with prolonged OS. Patients eligible for secondary metastases resection and/or bevacizumab may benefit the most from PTR. Randomized controlled trials are mandatory.