Radiotherapy dosimetry and complications in modified radical mastectomy with first-stage breast reconstruction: target coverage and lung protection.

OBJECTIVES: To compare the radiotherapy dosimetry and complications in patients undergoing modified radical mastectomy (MRM) with first-stage breast reconstruction (FSBR) versus MRM alone. The study aimed to investigate the effect of radiotherapy on breast reconstruction aesthetics and provide evidence for personalized treatment plans. METHODS: A total of 82 female patients who underwent MRM between 2016 and 2019 were included. They were first divided into two groups: 51 patients received FSBR (FSBR group) and 31 did not (MRM group). Among the 59 patients who subsequently underwent radiotherapy, 28 were from the FSBR group and 31 were from the MRM group; the remaining 23 FSBR patients received no radiotherapy. Both groups received intensity modulated radiation therapy (IMRT) with the parameters that Planning target volume 1 (PTV1, regional lymph nodes) and planning target volume 2 (PTV2, chest wall) were both prescribed as 50 Gy in 25 fractions over 5 weeks. The homogeneity index (HI), conformity index (CI), target coverage, and dose/volume of organs at risk (OARs) were compared between these two groups. Radiotherapy-related complications were also analyzed. Additionally, the FSBR group was further subdivided into a radiotherapy subgroup (n = 28) and a non-radiotherapy subgroup (n = 23) to evaluate the effect of radiotherapy on breast aesthetics. RESULTS: For OARs, the FSBR group showed better lung protection compared to the MRM group in terms of Dmean, Dmax, V5, V20, V30, and V40 (all P < 0.05). There were no significant differences in target coverage, HI, or CI between the groups (both P > 0.05). The incidence of radiodermatitis was similar (P > 0.05). The aesthetic outcomes of reconstructed breasts were significantly lower in the radiotherapy group compared to the non-radiotherapy group (P < 0.05). Despite reduced aesthetic outcomes, FSBR did not compromise radiotherapy dosimetry and provided better lung protection compared to MRM alone. CONCLUSION: FSBR may be a viable option for patients requiring postoperative radiotherapy, as it offers comparable dosimetry and enhanced lung protection.