Reduced thoracic vertebrae metastases following post mastectomy parasternal irradiation

A retrospective study of 118 women with breast cancer metastatic to bone is presented. All had originally received post mastectomy adjuvant radiation therapy for Stage II (T2 N0, T2 N1, T1 N1) infiltrating duct carcinoma of breast. Sixty-two women (group A) received a parasternal portal and 56 women (group B) did not. There was significantly less metastatic involvement of the mid-dorsal vertebrae D5-6-7-8, 13% in group A compared to 60% in group B. The mean time to diagnosis of metastatic disease was 33 months (group A) and 36 months (group B). The dose of radiation to the vertebrae through which the parasternal beam exited was estimated at between 1000-1600 rad over three to four weeks. This observation may have significant implications for the management of high risk operable breast cancer.