Only surgical resection can identify the second primary lung cancer out of the metastasis after gastric cancer surgery.

Objective: Solitary pulmonary lesions (SPLs) in patients with a history of malignancy require not only the distinction between benign and malignant, but also that between metastatic and primary lesions. We aim to establish the clinical strategy for the treatment of a solitary pulmonary lesion that is detected during the postoperative surveillance for gastric cancer.

Methods: We retrospectively examined the clinical records of the patients who underwent curative resection for gastric cancer between January 1999 and December 2009. Patients who were diagnosed with solitary pulmonary lesion during the postoperative surveillance underwent pulmonary resection, and were reviewed with regard to their histological diagnosis and prognosis.

Results: Out of a total of 1017 patients who underwent gastric resections during this period, 13 patients with solitary pulmonary lesion underwent pulmonary resection. These tumors were shown to be eight primary lung cancers, four metastatic tumors (three from gastric cancer) and one benign nodule. Of the eight patients with primary lung cancer, seven remained alive after pulmonary resection, including one liver metastasis case, and the other died without recurrence. In contrast, the other three patients with metastasis from gastric cancer died with distant metastasis, despite undergoing curative pulmonary resection. One of these three metastatic patients was misdiagnosed as primary lung cancer by transbronchial biopsy before surgery.

Conclusions: Solitary pulmonary lesions detected during postoperative gastric cancer surveillance should undergo surgical resection to distinguish between primary and metastatic disease because of the quite different prognosis of these two entities.