OPTIMIZING RADIOTHERAPY OF THE INTERNAL MAMMARY CHAIN IN BREAST-CARCINOMA BY SCINTIGRAPHY

Background and purpose: The reduction in breast cancer death, as repor ted in recent trials, was found to be significant and techniques of mi nimizing cardiac dose were found to be important. The purpose of our s tudy was to investigate the location of the internal mammary chain (IM C) both in the lateral and dorsal direction, in primary breast cancer patients. Material and methods: In 320 female breast cancer patients a scintigram of the IMC (IMC-s) was performed. Lateralisation and depth were determined. Special attention was paid to the consequences of th e use of fixed target volumes. Results: Lateralisation was determined in 281 patients, with a mean of 33.9 mm. Depth was determined in 266 p atients, with a mean of 31.0 mm. We showed, that the location of the I MC lymph nodes varies considerably, both in the lateral and in the dor sal direction. The maximum values of the lateralisation and the corres ponding depth did not correlate. Using electron beam therapy, a fixed target volume defined by a(ipsi)lateralisation of 50 mm and a dose spe cification on a depth of 30 mm was demonstrated to include the IMC ade quately, in 12% of all cases. Conclusions: The use of fixed target vol umes in the radiotherapy of the IMC in breast cancer patients is inapp ropriate. We recommend performing an IMC-s, in treatment position, wit h appropriate adjustment of the target volume.