Prognostic factors after pulmonary metastasectomy of colorectal cancers: a single-center experience

Background: Surgical resection has been widely admitted as the treatment of choice for pulmonary metastases of colorectal cancer (CRC). Nevertheless, this practice is not supported by high level of evidence and patients' eligibility remains controversial. Aim of this study was to evaluate long terms results and factors influencing survival after lung metastasectomy of CRC. Methods: A single-center retrospective analysis of patients with pathologically proven colorectal metastasis, operated from 2004 to 2013, was performed. Patients were treated with a multidisciplinary approach and selected for surgery if complete resection was considered feasible. Results: Three hundred and six patients were considered for analysis. Mean number of lesions at CT scan was 2.6 +/- 2.3. Ratios of each largest resection type at first side surgery were: segmentectomy 20.6%, lobectomy 12.9%, bilobectomy 1.2%, pneumonectomy 1.2% and sub-lobar resection 64.1%, respectively. No in-hospital death occurred. At pathology, mean number of resected metastasis was 2.6 +/- 2.3, ranging from 1 to 12. Resection was complete in 92.5% of patients. Nodal involvement was proven in 40 (12.9%) patients. The initially planned complete resection could not be achieved in 23 (7.5%) cases. Mean follow-up was 3.06 +/- 2.36 years. Kaplan-Meier analysis revealed that recurrence-free survival (RFS) was 76.3% [ 95% confidence interval (95% CI), 71-80.7%], 38.9% (95% CI, 33-44.7%), 28.3% (95% CI, 22.5-34.4%) and 22.7% (95% CI, 16.5-29.5%) at 1, 3, 5 and 7 years, respectively. Overall survival (OS) estimates were 77.8% (95% CI, 72.7-82.7%), 59.0 % (95% CI, 51.2-66.4%), and 56.9% (95% CI, 48.4-65.0%) at 3, 5 and 7 years, respectively. Multivariate analysis, including pT parameter of the primary tumor, number of lesions, one-sided versus bilateral lung disease, and body mass index (BMI) (all significant at univariate analysis), showed that bilateral disease (P<0.001) and pT4 primary (P=0.005) were independent pejorative predictors of OS, whereas BMI >= 25 was protective (P=0.028). Conclusions: Bilateralism and primary tumor local extension influence the prognosis of patients surgically treated for pulmonary colorectal metastases. Specifically designed randomized trials are necessary.