Patterns of post-mastectomy radiotherapy in immediate breast reconstruction – Results from the iBRA-2 cohort study

Purpose:

Long-term data indicates that post-mastectomy 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.

Methods:

Data were collected from 2,526 patients enrolled in the iBRA-2 prospective cohort study undergoing 2,606 mastectomies with and without IBR between 1 July 2016 and 31 December 2016.  Patients were recruited consecutively at 71 centres across the United Kingdom and Ireland, and at five international centres. Univariable and multivariable logistic regression was used to explore associations between recommendation for PMRT with patient and procedure-related factors.

Results:

Of 2,590 breast procedures included in the analysis, 696 were implant-based, 105 pedicled flap and 230 free-flap reconstructions.  32.5% of implant-based, 34.3% of pedicled, 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 Tany N2 and T3 Nany.  In multivariable analyses, patients with invasive disease undergoing implant-based reconstruction were less likely than those undergoing mastectomy only to be recommended for PMRT, which was not the case for those undergoing pedicled or free-flap reconstruction.  The likelihood of being recommended for PMRT differed by region.

Conclusion:

Although IBR was more likely to be performed for lower stage cancers and in younger patients with fewer co-morbidities, 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.