Risk factors for lymph node metastases and prognosticators of survival in patients undergoing pulmonary metastasectomy for colorectal cancer.

BACKGROUND Systematic lymph node dissection is not routinely performed in patients undergoing pulmonary metastasectomy (PM) of colorectal cancer. The aim of the study was to identify risk factors for lymph node metastases (LNM) and to determine prognosticators for survival in colorectal cancer patients with pulmonary metastases. METHODS We retrospectively reviewed our prospective database of 165 patients with colorectal cancer undergoing PM and systematic lymph node dissection with curative intent from 1999 to 2009. The χ(2) test, regression analyses, Kaplan-Meier analyses, log rank tests, and Cox regression analyses were used to determine prognosticators for LNM and survival. RESULTS The prevalence of LNM was 22.4%. Lymph node metastases were more often detected in case of rectal cancer and if anatomic resections in term of segmentectomy or lobectomy had to be performed for PM. The number of pulmonary metastases showed a nonlinear association with the risk of positive postoperative LNM. For 1 to 10 pulmonary metastases, each additional pulmonary metastasis conferred a 16% increase in risk for LNM. Rectal cancer, M-status of the primary tumor, number of pulmonary metastases, and disease progression during pre-PM chemotherapy were independent prognosticators for survival. Lymph node metastases were not an independent prognosticator. CONCLUSIONS Rectal cancer, required anatomic resections, and multiple metastases were risk factors for LNM. Rectal cancer, M-status of the primary tumor, number of pulmonary metastasis, and disease progression during pre-PM chemotherapy were independent negative predictors of survival, stratifying patients with poor prognosis who may benefit from chemotherapy before or after PM.