Benefit of primary tumor resection in stage IV colorectal cancer with unresectable metastasis: a multicenter retrospective study using a propensity score analysis.

PURPOSE

Retrospective studies have shown that primary tumor resection improves the prognosis of patients with colorectal cancer (CRC) with unresectable metastasis (mCRC). The aim of this study was to investigate the prognostic impact of primary tumor resection in various subgroups of mCRC patients.

METHODS

A total of 1982 patients with mCRC from January 1997 to December 2007 were retrospectively evaluated. The impact of primary tumor resection on cancer-specific survival (CSS) was analyzed using propensity score analysis to mitigate selection bias. Covariates in the models for propensity scores included treatment period, age, gender, tumor location, depth, lymph node metastasis, number of metastatic organs, and carcinoembryonic antigen (CEA) levels.

RESULTS

Among the whole patient population, primary tumor resection significantly improved CSS [hazard ratio (HR) 0.46, 95% confidence interval (CI) 0.32-0.66, p < 0.01]. However, primary tumor resection did not significantly improve CSS in the following subgroups: patients treated in the first 5 years of the study (HR 0.56, 95% CI 0.28-1.13, p = 0.08), patients aged >65 years (HR 0.72, 95% CI 0.36-1.42, p = 0.31), female patients (HR 0.60, 95% CI 0.31-1.17, p = 0.13), patients with right-sided colon cancer (HR 0.68, 95% CI 0.39-1.20, p = 0.17), and patients without nodal involvement (HR 0.54, 95% CI 0.25-1.17, p = 0.09).

CONCLUSIONS

Our study suggests that primary tumor resection improves the survival of patients with mCRC. However, the prognostic benefit is different among patient subpopulations.