P42.01 Tumor Size is an Independent Prognostic Factor after Pulmonary Metastasectomy

Abstract

Patients selection for lung metastasectomy is mainly based on several prognostic factors such as disease-free interval (DFI), number of nodules, nodal involvement and radicality of the resection. The dimension of resected metastases is an indirect indicator of tumour burden and probably increases the risk of local recurrence but its impact on survival remains to be confirmed. The aim of this study was to test the hypothesis that larger metastases have a worse long-term outcome. Data from a cohort of patients who underwent pulmonary metastasectomy in the period 1998-2018 was analysed to test the impact on survival of the number and size (diameter of the largest resected metastases < vs > 2 cm) of resected lesions, nodal involvement and R0 resection. Patients with a follow-up time inferior to 3 years were excluded. Overall survival was measured according to Kaplan Meier method and groups were compared by the log-rank test. Clinical relevance of prognostic factors was tested by univariate analysis and significant variables (p<0.05) were inserted into a Cox multivariate model. The study group was composed of 314 patients (median age 58 years, males 44%) with different histology (epithelial 80%, sarcoma 13.7%, melanoma 4.5%, germ-cell tumors 1.9%) and a median disease-free interval of 50 months. A single metastasis was present in 289 cases (62.1%) and nodal involvement in 21 (6.7%). The largest resected lesion had a diameter less than 2 cm in 110 patients (41.4%). A radical resection was obtained in the majority of cases (293, 93.3%). Median survival in patients who had smaller metastases (<2 cm) was 63 months as compared to 55 months in those with larger lesions (figure 1, p 0.05). Multivariate analysis pointed out a more favourable outcome for patients having smaller (OR 0.54, CI 0.39-0.74) and single lesion (OR 0.58, CI 0.42-0.79), no nodal involvement (OR 0.5, CI 0.31-0.82) and who had an R0 resection (0.31, CI 0.16-0.58). Size of resected lesions is an independent prognostic factor after pulmonary metastasectomy. Whether this effect is due to a higher rate of local recurrence or the expression of a biologically more aggressive disease remains unclear. In any case, a very accurate evaluation of resection margins should be performed when large (> 2cm) metastases are removed.