Treatment of the axilla by tangential breast radiotherapy in women with invasive breast cancer

Background The objective of this study was to determine if standard tangential breast radiation covered the sentinel lymph node in women with invasive breast cancer. Methods Women with invasive breast cancer treated by lumpectomy, radiotherapy and sentinel node biopsy at our institution were included in this study if the sentinel lymph node site had been marked with a clip. Plain films were used to determine if the clip fell within the tangential fields. Results: Between April 1999 and May 2001, 36 women with invasive breast cancer treated by lumpectomy, sentinel lymph node biopsy and breast radiation were identified. Median age was 56 years (range 34 to 80) with a median tumor size of 1.1 cm (range 0.3 to 2.9 cm). The clip marking the sentinel lymph node fell within the tangential fields in 34 of 36 (94%) of the patients. The radiation dose to the clip area was greater than 4,400 cGy in 50% of those calculated by three-dimensional techniques. Conclusions: The sentinel lymph node is located within classic tangential fields in the overwhelming majority of women with invasive breast cancer. The extent of the radiation fields, and ultimately the final dose, may need to be modified if the intent is for prophylactic treatment.