Long-Term Survival and Toxicity in Patients Treated With Radiotherapy for Neuroendocrine Breast Cancer: A Single-Center Experience.

Abstract

PURPOSE/OBJECTIVE(S)\nNeuroendocrine breast cancer (NEBC) is an uncommon histotype of breast carcinoma. Due to their rarity, no recommendation has been made for their management; in daily practice, the same guidelines as for ductal invasive carcinoma apply for NEBC. However, the place of radiotherapy in the management of resectable NEBC is still debated since multiple epidemiological studies failed to demonstrate any clinical benefit, probably due to a lack of statistical power. We aimed to report the long-term survival and toxicity in patients treated with radiotherapy for NEBC at our institute.\n\n\nMATERIALS/METHODS\nAll NEBC patients referred between 1995 and 2005 to the Department of Radiation Oncology at our institute for local or locoregional breast radiotherapy, as a complement to surgery, were identified. The whole breast or the chest wall was irradiated to 50 Gy in 25 fractions. For patients treated with breast-conserving surgery, a 16 Gy tumor bed boost could be delivered for those younger than 50 years at the time of diagnosis, narrow surgical margins or pathological criteria of aggressiveness. Regional lymph nodes were irradiated to 46 Gy in 23 fractions depending on the clinical and pathological findings, according to local guidelines. Adjuvant chemotherapy was delivered based on clinical and histological considerations and relied on anthracyclines and taxanes. A five-year hormone-therapy by tamoxifen or aromatase inhibitor was indicated in the case of hormone receptor positivity. Patients were followed every 6 months to 5 years and annually thereafter.\n\n\nRESULTS\n18 patients were treated with normofractionated breast radiotherapy for locoregional management of NEBC. With a median follow-up of 5.7 years, three patients died of their cancers, two patients had local recurrences and three patients developed distant metastases. There was no regional relapse, contralateral breast cancer or second non-breast cancer. Five-year overall and metastasis-free survivals were both 88% [73%-100%], whereas 5-year locoregional and local controls were both 100%. In univariate analysis only, pathological tumor size was significantly associated with overall survival and metastasis-free survival (HR\u202f=\u202f1.26 [95% CI: 1.00-1.58], P\u202f=\u202f0.04 and HR\u202f=\u202f1.13 [95% CI: 1.00-1.28], P\u202f=\u202f0.04, respectively). No patients developed grade ≥2 toxicity. Two patients experienced a grade 1 fibrosis, 2 patients had a grade 1 breast pain on the last clinical evaluation and 1 patient had a persistent grade 1 breast oedema.\n\n\nCONCLUSION\nRadiotherapy appears effective and well-tolerated for locoregional management of resectable neuroendocrine breast cancers, as a complement to surgery.