Patterns of Postmastectomy Radiotherapy in Immediate Breast Reconstruction-Results From the iBRA-2 Cohort Study

Long-term data indicate that postmastectomy radiotherapy (PMRT) is associated with improved overall survival in node-positive breast cancer patients. Immediate breast reconstruction (IBR) remains controversial in the context of planned PMRT, but rates of IBR are increasing. The aim of this study was to examine patterns of PMRT in patients undergoing mastectomy with or without IBR.

Data were collected from 2526 patients enrolled in the iBRA-2 prospective cohort study undergoing 2606 mastectomies with and without IBR between 1 July 2016 and 31 December 2016. Patients were recruited consecutively at 71 centres across the United Kingdom (UK) and Ireland and at five international centres. Univariable and multivariable logistic regression models were used to explore associations between recommendation for PMRT and patient- and procedure-related factors.

Of 2590 breast procedures included in the analysis, 696 were implant-based, 105 pedicled-flap and 230 free-flap reconstructions, and 32.5% of implant-based, 34.3% of pedicled-flap and 35.7% of free-flap reconstructions were recommended for PMRT. PMRT recommendation by cancer stage was 21% for T1-2 N0, 65% for T1-2 N1 and 89% for T_any N2 and T3 N_any. In multivariable analyses, patients with invasive disease undergoing implant-only reconstruction, but not pedicled-flap or free-flap reconstruction, were less likely to be recommended for PMRT than those undergoing mastectomy alone. The likelihood of being recommended for PMRT differed by region.

Although IBR was more likely to be performed for lower-stage cancers and in younger patients with fewer comorbidities, a third of patients undergoing IBR were recommended for PMRT. This adds to a growing body of evidence that IBR is becoming an acceptable option for women requiring PMRT. The study also highlighted regional variation in PMRT practice within the UK and Ireland, which merits further investigation.