Localized hormone receptor-positive breast cancer disease-free 5 years after endocrine therapy switch

What happened, in summary

This 40-year-old lawyer was otherwise in excellent health apart from migraines when she was diagnosed with a 2 cm right breast cancer. The tumor was moderately differentiated, strongly estrogen receptor-positive and progesterone receptor-positive, HER2-negative, and had low Ki-67. Lumpectomy with axillary sentinel node biopsy showed no lymph-node involvement. Her Oncotype DX score was 12, so her adjuvant treatment focused on endocrine therapy rather than chemotherapy. Because she was premenopausal, she started tamoxifen together with Lupron-induced ovarian suppression. After 8 months of monthly Lupron, she developed supraventricular tachycardia and an urticarial rash. Two episodes of rapid heart rhythm required emergency hospital visits, and 24-hour Holter monitoring documented additional brief episodes, each lasting less than 5 minutes. Her doctors suspected the rash reflected an allergic reaction to Lupron and changed ovarian suppression to goserelin. Soon after the switch, both the rash and the rapid-heart episodes stopped. She remained free of those symptoms for the rest of adjuvant hormonal treatment. Her hemoglobin, chemistry tests, liver function, and echocardiogram remained normal during therapy. She completed 36 months of combined tamoxifen and goserelin. After treatment stopped, her menstrual periods resumed within a few months. Additional years of endocrine therapy were not pursued because she was considering pregnancy. At her last examination in March 2013, 5 years after diagnosis, she remained disease-free. The treatment decision balanced recurrence prevention, medication safety, and future pregnancy plans. Once the ovarian-suppression drug was changed, she was able to complete planned endocrine therapy without further heart-rhythm or rash problems. Her later disease-free visit shows successful completion despite the early endocrine-therapy complication.