A Case of Breast Cancer Treated for Late Recurrence and Iatrogenic Contralateral Cancer

Abstract

We report the case of a late recurrence of breast cancer and an iatrogenic contralateral cancer in a 73-year-old woman. She was first diagnosed with right breast cancer (ER:+, PgR:+, HER2:1+) at the age of 35 years. After right mastectomy, she began tamoxifen therapy but discontinued treatment. At the age of 55 years, she developed a recurrence in the chest wall of the affected side, and at the age of 58 years, she had metastasis to the contralateral left axillary lymph node (ER:+, PgR:+, HER2:1+). She underwent radiotherapy thereafter (clinical complete remission, hereafter cCR). At the age of 65 years, a contralateral left supraclavicular lymph node metastasis was detected, and cyclophosphamide was administered but discontinued. She began exemestane therapy, and the metastatic lesion disappeared after 1 year. At the age of 70 years, she developed left breast cancer (ER:-, PgR:-, HER2:3+). After left mastectomy and axillary lymph node dissection (pT1cN1(1/4) ER-PgR-HER2: 3+), postoperative adjuvant antibody therapy (Pertuzumab+Trastuzumab) was administered for 1 year. At the age of 73 years, two masses were noted at the outer aspect of the left latissimus dorsi. A pathological diagnosis of adenocarcinoma (ER:+, PgR:+, HER2:0) was made. Re-recurrence of a radio-treated site of contralateral axillary metastasis of the right breast cancer and distant metastasis within the latissimus dorsi were diagnosed. Radiotherapy was administered to the lateral border of the latissimus dorsi (40 Gy). Thereafter, she was treated with a CDK4/6 inhibitor and a selective estrogen down regulator.