Double primary recurrent human epidermal growth factor receptor 2-positive breast cancer and esophageal cancer that responded well to chemotherapy.

Double primary breast and esophageal cancer have been no reported cases in which treatment methods other than surgery were selected because of multiple metastasis or advanced cancer. The patient was a 52-year-old woman who had received left pectoral muscle-preserving mastectomy and axillary lymph node dissection (level 2) 7 years prior, following the diagnosis of left breast cancer. The postoperative diagnosis was pT2 N3a M0 stage IIIC and luminal human epidermal growth factor receptor 2 (HER2) phenotype. After the surgery, six courses of triple chemotherapy with 5-fluorouracil (5-FU), epirubicin, and cyclophosphamide and four courses of docetaxel (DTX) were administered, and letrozole was administered for 5 years. Seven years after the surgery, swelling of her left axillary, supra-, and subclavicular lymph nodes, and sternum osteolysis were observed on computed tomography (CT). Radioisotope uptake was observed in the esophagus on positron emission tomography. An esophageal cancer was observed in the upper thoracic esophagus on esophagogastroscopy. The patient was administered a local treatment for esophageal cancer and systemic chemotherapy for both cancers. As a primary therapy, double chemotherapy with 5-FU and cisplatin (FP) (two courses) + radiotherapy on the esophagus and left supraclavicular lymph nodes (total target dose of radiotherapy was 60 Gy /30 fractions) was performed with the concomitant use of trastuzumab and zoledronate. Marked shrinkage [complete response (CR)] of the esophageal cancer was observed on esophagogastroscopy and shrinkage (partial response) of the left axillary and supra- and subclavicular lymph nodes were observed on CT. The secondary treatment included pertuzumab + trastuzumab + DTX. Bilateral pleural effusions were observed in the eighth course; therefore, DTX was withdrawn and the treatment was continued with only the molecularly targeted drugs. Two years have passed since the initiation of treatment. The individual lymph node metastatic foci have disappeared or markedly shrunk (CR) on CT scans and the sternal metastases have remained hard without change. In addition, CR for esophageal cancer has been maintained. We report a case of double primary recurrent HER2-positive breast cancer and esophageal cancer that responded well to radiotherapy and chemotherapy.