Optimizing radiotherapy of the internal mammary chain in breast carcinoma by scintigraphy

Abstract

Background and purpose: The reduction in breast cancer death, as reported in recent trials, was found to be significant and techniques of minimizing cardiac dose were found to be important. The purpose of our study was to investigate the location of the internal mammary chain (IMC) 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 the use of fixed target volumes. Results: Lateralisation was determined in 281 patients, with a mean of 33.9 mm. Depth was determined in 266 patients, with a mean of 31.0 mm. We showed, that the location of the IMC lymph nodes varies considerably, both in the lateral and in the dorsal direction. The maximum values of the lateralisation and the corresponding depth did not correlate. Using electron beam therapy, a fixed target volume defined by a (ipsi)lateralisation of 50 mm and a dose specification on a depth of 30 mm was demonstrated to include the IMC adequately, in 12% of all cases. Conclusions: The use of fixed target volumes in the radiotherapy of the IMC in breast cancer patients is inappropriate. We recommend performing an IMC-s, in treatment position, with appropriate adjustment of the target volume.