Growth rate of chemotherapy-naïve lung metastasis from colorectal cancer could be a predictor of early relapse after lung resection.

PURPOSE: The aim of this study was to elucidate a potential risk factor for early relapse after pulmonary metastasectomy of colorectal cancer and to propose an optimal treatment strategy for lung metastasis with an aggressive nature. METHODS: Seventy patients who underwent pulmonary metastasectomy for diachronically measurable pulmonary lesions were retrospectively analyzed. We calculated the tumor doubling time (TDT) as the growth rate of lung metastasis and divided the study population into two groups: Rapid (TDT ≤ 100 days) and Slow (TDT > 100 days). RESULTS: The patients consisted of 47 males and 23 females, with a mean age of 63 years. Forty-two patients had a relapse after pulmonary metastasectomy with a median follow-up duration of 24 months. There was a significant difference in relapse-free survival between the Rapid and Slow groups (p = 0.047). Using a multivariate analysis, no preoperative chemotherapy and a high level of serum carcinoembryonic antigen were proven to be significant risk factors for relapse after metastasectomy. Meanwhile, multivariate analyses among 37 patients without preoperative chemotherapy indicated that TDT was the sole significant factor for relapse-free survival. In addition, eight of nine patients with relapse within 12 months were placed into the Rapid group. CONCLUSIONS: Although this was a preliminary study with a small number of patients, it suggested that lung metastases demonstrating a TDT of 100 days or less have a high risk of early relapse after metastasectomy.