Influence of primary tumor location and resection on survival in metastatic colorectal cancer

BACKGROUND: Patients with right sided colorectal cancer are known to have a poorer prognosis than patients with left sided colorectal cancer, whatever the cancer stage. To this day, primary tumor resection (PTR) is still controversial in a metastatic, non resectable setting. AIM: To explore the survival impact of PTR in patients with metastatic colorectal cancer (mCRC) depending on PTL. METHODS: We retrospectively collected data from all consecutive patients treated for mCRC at the Centre Georges Francois Leclerc Hospital. Univariate and multivariate Cox proportional hazard regression models were used to assess the influence of PTR on survival. We then evaluated the association between PTL and overall survival among patients who previously underwent or did not undergo PTR. A propensity score was performed to match cohorts. RESULTS: Four hundred and sixty-six patients were included. A total of 153 (32.8%) patients had unresected synchronous mCRC and 313 (67.2%) patients had resected synchronous mCRC. The number of patients with right colic cancer, left colic cancer and rectal cancer was respectively 174 (37.3%), 203 (43.6%) and 89 (19.1%). In the multivariate analysis only PTL, PTR, resection of hepatic and or pulmonary metastases and the use of oxaliplatin, EGFR inhibitors or bevacizumab throughout treatment were associated to higher overall survival rates. Survival evaluation depending on PTR and PTL found that PTR improved the prognosis of both left and right sided mCRC. Results were confirmed by using a weighted propensity score. CONCLUSION: In mCRC, PTR seems to confer a higher survival rate to patients whatever the PTL.