2.2. Main outcomes and definitions

Main outcomes were survival and freedom from the first recurrence of metastasis after surgery (disease‐free survival [DFS]).

Disease‐free interval (DFI) was defined as the time lapse between resection of the primary tumor and first diagnosis of pulmonary metastases whereas DFS was the period after PM without evidence of tumor re‐recurrence.

Neoadjuvant treatment was defined as the administration of chemotherapy or irradiation of a tumor before definitive surgical treatment, in this case, referred to the primary neoplasm whereas an adjuvant treatment was a systemic treatment administered after surgical resection.

Tumorectomy was defined as the removal of a nodule along with minimal surrounding normal pulmonary tissues. An “open approach” was a surgical procedure through thoracotomy or sternotomy.