Moderate hypofractionation for chest wall irradiation is under-represented within randomised trials. Mastectomy was not included in the Ontario trial and represented less than 10% of patients in the START B trial. Although it has been established as standard of care in some countries for many years, the overall uptake of moderate hypofractionation for chest wall irradiation is still low in Europe. There is no biological reason to assume that the efficacy and toxicity profile observed after breast conserving surgery does not apply to postmastectomy irradiation. Wang and colleagues reported the results of a single-centre trial of postmastectomy radiotherapy in 810 women with primary T3–4 tumours or at least four positive axillary nodes randomised to 43.5 Gy in 15 fractions or 50 Gy in 25 fractions, both to the chest wall and level 3–4 axillary nodal regions. At around 5 years of median follow-up, the risk of locoregional recurrence was similar between treatment groups, and no significant increase in late normal tissue effects was observed. The only significant difference described was the reduced severity of acute skin toxicity in patients treated with hypofractionation, which is reassuringly consistent with recent observations from the past decade. Further evidence is awaited from other groups, which are conducting clinical trials to investigate this clinical setting across Europe.
Mastectomies are increasing worldwide, due to genetic testing, women’s choice, and the improvements in modern reconstruction techniques. Indeed, breast reconstruction has transformed a mastectomy in a much less demolitive procedure. It is possible either as a delayed step (delayed breast reconstruction) or simultaneously to the oncological procedure (immediate breast reconstruction). Thanks to modern “conservative mastectomies” (skin-sparing, nipple-sparing, and skin-reducing), immediate breast reconstruction has become a very common option and it is preferred to both delayed breast reconstruction and no reconstruction at all. Implants have been by far preferred in Europe for many years and lately this is frequent in the US as well. An immediate implant-based breast reconstruction (IBBR) can be either performed in two stages, using tissue expanders (TE), to be exchanged with permanent implants, or in one stage, with an immediate permanent implant positioning (direct-to-implant, DTI). The choice of TE or DTI is based on oncological, anthropometric, and comorbidity factors. More recently, a paradigm shift has been introduced in the IBBR scenario, namely the prepectoral approach.
There are no large, randomized trials testing moderate hypofractionation after mastectomy radiotherapy in the setting of breast reconstruction. Small, non-randomised series suggest that late normal tissue effects and capsular contracture rates are like those obtained with 2 Gy daily fractionation. The lower equivalent dose in 2 Gy fractions with 40 Gy in 15 fractions compared with 50 Gy in 25 fractions would, in fact, favour moderately hypofractionated radiotherapy because it results in less side-effects. This dose and fractionation have been a standard of care for all types of breast reconstruction for several years in many countries.
Relative mastectomy proportions within the FAST-Forward trial were as follows: 6.7% in the 40 Gy group, 6.5% in the 27 Gy group, and 6.1% in the 26 Gy group. One local recurrence was observed in the 40 Gy group and none in the 173 patients in the five fraction groups. The 2021 UK Royal College of Radiologists’ Consensus Statements Programme reached a consensus on offering 26 Gy in five fractions over 1 week for chest wall irradiation without reconstruction. Immediate reconstruction rates within the FAST-Forward trial were less than 1% across all groups with only ten patients receiving immediate implant-based reconstruction.
An overview on recent advances on fractionation for external beam radiation therapy chest wall irradiation with or without breast reconstruction, including the recently published ESTRO-ACROP consensus recommendations on patient selection and dose and fractionation for external beam radiotherapy in early breast cancer, is hereby presented.