Background/Aim: Women with breast cancer are at increased risk of subsequent primary malignancies, specifically lung cancer. The aim of this study was to report the frequency of lung cancer in patients with breast cancer, and patients' characteristics and surgical outcomes. Patients and Methods: We investigated 1,066 consecutive female patients undergoing surgical resection for breast cancer and 666 undergoing surgical resection for lung cancer. Results: Lung cancer with breast cancer was observed in 14 patients (1.3% of breast cancer and 2.1% of lung cancer cases; mean age=65 years), and 3/14 (21.4%) patients were smokers. Sixteen lung cancer lesions in 14 patients were adenocarcinomas and one was squamous cell carcinoma. All 14 patients were alive at the time of this report; 4/14 (28.6%) patients had recurrent breast cancer and 1/14 (7.1%) had recurrent lung cancer. In synchronous cases, 5/6 (83.3%) patients received concomitant surgery for both breast cancer and lung cancer. Patients' postoperative courses were uneventful. In metachronous cases, eight patients had lung cancer a mean of 33 months after breast cancer surgery. All eight patients received adjuvant therapies and 4/8 (50%) patients received adjuvant therapies for recurrent breast cancer, including chemotherapy, radiotherapy, hormonal therapy, and anti-HER2 therapy. All patients had early-stage lung adenocarcinoma and underwent surgical resection. Conclusion: Concomitant surgery for synchronous lung and breast cancer was feasible and safe. In metachronous cases, lung cancers tended to be detected within 3 years after surgery for breast cancer. Careful follow-up for postoperative breast cancer may contribute to the detection of early-stage lung cancer.
