Late effects of combined modality treatment with adjuvant neutron therapy for locally advanced breast cancer

Late effects of combined-modality treatment with adjuvant neutron therapy for reducing risk of local and regional recurrences in patients with locally advanced breast cancer are considered in the article. Treatment of breast cancer with photon beam therapy that uses low linear energy transfer (low LET) radiation can cause development of recalcitrant radioresistant recurrences. In such a case the use of neutrons, the type of high LET radiation, are more effective for treatment of some radiorestant tumors due to radiobiological properties of neutrons. Multimodal treatment (T2-4N0-3M0) that combined neo-adjuvant and adjuvant chemotherapies, radical mastectomy and postoperative external beam radiation therapy (EBRT) was delivered to 128 breast cancer patients. Patients under study (n=68) received adjuvant neutron therapy and those in the control group (n=60) received electron therapy. Late effects of the combined modality treatment were estimated by 8-year disease-free and overall survivals in the two groups of patients. Disease-free survival was significantly higher in patients received adjuvant neutron therapy delivered to the anterior chest wall as compared with the survival in the group received electron therapy: 94.3±4.2% and 81.4±5.9%, (p=0.055) respectively. The overall survival was reliably higher in the study group - 76.6±7.6%, as compared with the survival in the control group - 47.6±9.1%, (p=0.426). Neutron therapy was well tolerated, and I-II grade local radiation-induced skin reactions were the most common. The presented results allow making conclusion that adjuvant neutron therapy following radical mastectomy is evidence-based, effective and safe treatment for locally advanced breast cancer T2-4N0-3M0. Delivery of the systemic chemotherapy to the patients prolongs their overall survival and improve quality of life.