Pulmonary metastasis in rectal cancer: a retrospective study of clinicopathological characteristics of 404 patients in Chinese cohort

OBJECTIVES: This study aim to investigate the incidence, timing and risk factors of metachronous pulmonary recurrence after curative resection in patients with rectal cancer. DESIGN: A retrospective cohort study. SETTING: This study was conducted at a tertiary referral cancer hospital. PARTICIPANTS: A total of 404 patients with rectal cancer who underwent curative resection from 2007 to 2012 at Beijing Hospital were enrolled in this study. INTERVENTIONS: The pattern of recurrence was observed and evaluated. PRIMARY AND SECONDARY OUTCOME MEASURES: The incidence and timing of recurrences by site were calculated, and the risk factors of pulmonary recurrence were analysed. RESULTS: The 5-year disease-free survival for the entire cohort was 77.0%. The most common site of recurrence was the lungs, with an incidence of 11.4%, followed by liver. Median interval from rectal surgery to diagnosis of pulmonary recurrence was much longer than that of hepatic recurrence (20 months vs 10 months, P=0.022). Tumour location, pathological tumor-node-metastasis (TNM) stage and positive circumferential resection margin were identified as independent risk factors for pulmonary recurrence. A predictive model based on the number of risk factors identified on multivariate analysis was developed, 5-year pulmonary recurrence-free survival for patients with 0, 1, 2 and 3 risk factors was 100%, 90.4%, 77.3% and 70.0%, respectively (P<0.001). CONCLUSIONS: This study emphasised that the lung was the most common site of metachronous metastasis in patients with rectal cancer who underwent curative surgery. For patients with unfavourable risk profiles, a more intensive surveillance programme that could lead to the early detection of recurrence is strongly needed.