Surgical Resection of Pulmonary Metastases from Melanoma in Oligometastatic Patients: Results from a Multicentric Study in the Era of Immunoncology and Targeted Therapy

In the last decade, the emergence of effective systemic therapies (ESTs) in the form of both targeted and immuno-based therapies has revolutionized the treatment of patients with advanced stage III and stage IV melanoma. Even though lungs represent the most frequent site of melanoma metastases, only limited data are available on the role of surgery in isolated pulmonary metastases from malignant melanoma (PmMM) in the era of ESTs. The aim of this study is to describe the outcomes of patients who underwent metastasectomy of PmMM in the era of ESTs, in order to identify prognostic factors affecting survival and to provide a framework for more informed patient selection of treatmeant with lung surgery in the future. Clinical data of 183 patients who underwent metastasectomy of PmMM between June 2008 and June 2021 were collected among four Italian Thoracic Centers. The main clinical, surgical and oncological variables reviewed were: sex, comorbidities, previous oncological history, melanoma histotypes and primary site, date of primary cancer surgical treatment, melanoma growth phase, Breslow thickness, mutation pattern disease, stage at diagnosis, metastatic sites, DFI (Disease Free Interval), characteristics of lung metastases (number, side, dimension, type of resection), adjuvant therapy after lung metastasectomy, site of recurrence, disease-free survival (DFS) and cancer-specific survival (CSS; defined as the time interval between the first melanoma resection or lung metastasectomy and death from cancer). All patients underwent surgical resection of the primary melanoma before lung metastasectomy. Twenty-six (14.2%) patients already had a synchronous lung metastasis at the time of primary melanoma diagnosis. A wedge resection was performed in 95.6% of cases to radically remove the pulmonary localizations, while an anatomical resection was necessary in the remaining cases. The incidence of major post-operative complications was null, while only 21 patients (11.5%) developed minor complications (mainly air leakage followed by atrial fibrillation). The mean in-hospital stay was 4.46 ± 2.8 days. Thirty- and sixty-day mortality were null. After lung surgery, 89.6% of the population underwent adjuvant treatments (47.0% immunotherapy, 42.6% targeted therapy). During a mean FUP of 107.2 ± 82.3 months, 69 (37.7%) patients died from melanoma disease, 11 (6.0%) from other causes. Seventy-three patients (39.9%) developed a recurrence of disease. Twenty-four (13.1%) patients developed extrapulmonary metastases after pulmonary metastasectomy. The CSS from melanoma resection was: 85% at 5 years, 71% at 10 years, 54% at 15 years, 42% at 20 years and 2% at 25 years. The 5- and 10-year CSS from lung metastasectomy were 71% and 26%, respectively. Prognostic factors negatively affecting CSS from lung metastasectomy at multivariable analysis were: melanoma vertical growth (p = 0.018), previous metastatic sites other than lung (p < 0.001) and DFI < 24 months (p = 0.007). Our results support the evidence that surgical indication confirms its important role in stage IV melanoma with resectable pulmonary metastases, and selected patients can still benefit from pulmonary metastasectomy in terms of overall cancer specific survival. Furthermore, the novel systemic therapies may contribute to prolonged survival after systemic recurrence following pulmonary metastasectomy. Patients with long DFI, radial growth melanoma phase and no site of metastatization other than lung seem to be the best candidate cases for lung metastasectomy; however, to drive stronger conclusions, further studies evaluating the role of metastasectomy in patients with iPmMM are needed.