Impact of Primary Tumor Location on Postoperative Recurrence and Subsequent Prognosis in Nonmetastatic Colon Cancers: A Multicenter Retrospective Study Using a Propensity Score Analysis.

Objective: We aimed to clarify the prognostic impact of primary tumor location on recurrence after curative surgery and subsequent survival in patients with nonmetastatic colon cancer. Summary of background data: Right and left colon cancers are suggested to be oncologically different; however, their prognostic differences have been conflictingly reported.

Methods: A total of 5664 patients with curatively resected stage II-III colon cancer were reviewed, retrospectively. Relapse-free survival (RFS) after primary surgery and cancer-specific survival (CSS) after recurrence were compared between patients with right and left colon cancer. Patients' backgrounds were matched using propensity scores.

Results: Although patients with right colon cancer had more advanced disease, their 5-year RFS rate was significantly superior compared with that in those with left colon cancer (83.9% vs 81.1%, P = 0.019). However, the 5-year CSS after recurrence rate was significantly inferior in patients with right colon cancer compared with that in those with left colon cancer (30.6% vs 43.6%, P = 0.016).

Conclusions: The primary tumor location of nonmetastatic colon cancer might have different prognostic implications for the rates of recurrence after curative resection and cancer-specific mortality after recurrence.