Prospective evaluation of skin toxicities in patients receiving post-mastectomy irradiation of chest wall, supra/infraclavicular and internal mammary nodes delivered by conventional versus intensity-modulated radiotherapy technique.

Background: To determine whether IMRT could decrease skin toxicities in patients undergoing PMRT of chest wall, supra/infraclavicular (SCV), and internal mammary nodes (IMN) as compared to conventional technique.

Materials and Methods: Between 2009 and 2013, 106 patients treated with IMRT and 138 treated with conventional technique were followed up regularly. The skin toxicities were graded according to the CTCAE v4.0 issued by the NCI, and compared between groups.

Results: Grade 3 radiation dermatitis occurred in 49 patients (35.5%) in the conventional group and 14 (13.2%) in the IMRT group, and the difference was statistically significant ( p < 0.001), favoring IMRT. Moist desquamation at the area associated with adjacent fields' junctions or overlaps was observed in 35 patients (71.4%) in the conventional group and none in the IMRT group ( p = 0.023). Grade 2 telangiectasia occurred in 32 patients (23.1%) in the conventional group and 9 (8.5%) in the IMRT group; this difference was statistically significant ( p = 0.002), in favor of IMRT as well. Telangiectasias at the sub-sites associated with adjacent fields' junctions or overlaps were observed in 26 patients (81.2%) in the conventional group and none in the IMRT group ( p < 0.001). Further, 21 in the conventional group, who had initial moist desquamation at the sub-sites associated with adjacent fields' overlaps or junctions, subsequently developed skin telangiectasias at the identical sub-sites.

Conclusions: IMRT-based post-mastectomy irradiation of chest wall, SCV and IMN might decrease the occurrence of initial moist desquamation as well as subsequent telangiectasia at the subsites associated with adjacent fields' junctions or overlaps as compared to conventional technique.