Prognosis of Lung Cancer Patients with a Past History of Colorectal Cancer

Objectives: The prognosis in lung cancer patients with a prior history of extrapulmonary cancer is controversial. In the current multicenter joint research in Japan, we focused on the relationship between a history of colorectal cancer and its prognostic impact in patients with subsequent lung cancer. Methods: Between 2000 and 2013, we designed a retrospective multicenter study at three institutes in Japan to evaluate the prognostic factors in lung cancer patients with a previous surgery for colorectal cancer. Results: The cohorts consisted of 123/4431 lung cancer patients with/without a previous history of surgery for colorectal cancer. The median follow-up period was 6.1 years after lung cancer surgery. The 5-year overall survival in lung cancer patients with/without colorectal cancer was not significantly different, regardless of the stage of lung cancer (overall: 71.3 versus 74.7%, P = 0.1426; Stage I lung cancer: 83.3 versus 84.8%, P = 0.3779; Stage II or more lung cancer: 47.7 versus 54.4%, P = 0.1445). Based on multivariate Cox regression analysis in 4554 lung cancer patients, a past history of colorectal cancer was not a significant prognostic factor (P = 0.5335). Among the 123 lung cancer patients with colorectal cancer, age and absence of adjuvant chemotherapy for colorectal cancer were significant prognostic factors based on multivariate analysis (P = 0.0001 and 0.0236). Furthermore, there was no difference in the overall survival of lung cancer patients according to the stage of colorectal cancer (Stage I: 74.7%; Stage II/III: 66.5%, P = 0.7239). Conclusions: A history of antecedent colorectal cancer did not contribute to the prognosis in patients with subsequent lung cancers.