A Multicentre Study of the Relationship between Abdominal Flap and Mastectomy Weights in Immediate Unilateral Free Flap Breast Reconstruction and the Effect of Adjuvant Radiotherapy

Abdominal free flaps are considered the gold standard for post-mastectomy autologous breast reconstruction. A key element of outcome assessment is breast symmetry often achieved by approximating the reconstructed breast dimensions such as weight (wt) to those of the mastectomy. However, the ideal relationship between these two entities remains unclear. 525 immediate unilateral abdominal free flap breast reconstruction (FFBR) patients were enrolled in a multicentre study (UK 141; Italy 384) and subdivided into Group A (flap wtmastectomy wt, n=260) and Group C (flap wt=mastectomy wt, n=102). Their rates of contralateral balancing and ipsilateral revision surgeries were compared using Chi-Square tests. Radiotherapy influence on these adjustment procedures was also assessed. More contralateral balancing procedures (17%) were performed than ipsilateral revisions (10%). Group A rates of contralateral balancing procedures were three times higher than Group B's with a ratio of 37 to 1 versus Group C (37% vs 11% vs 1% respectively, p<0.001). Similarly, the ipsilateral breast revision surgery rate in Group A was double that of Group B and almost three times that of Group C (17% vs 8% vs 6% respectively, p=0.01). Adjuvant radiotherapy disproportionately increased ipsilateral revisions versus contralateral balancing surgeries (p=0.028). A flap-to-mastectomy weight ratio of less than 1 (Group A) significantly increases subsequent adjustments on both contralateral and reconstructed breasts whilst irradiation predisposes to ipsilateral revisions. This is important in patient counselling and intraoperative flap contouring. Flap weight should ideally approximate or exceed mastectomy weight in unilateral FFBR.