Background: Reconstructive surgeons have shifted from correcting contour irregularities using autologous fat transfer (AFT) toward reconstructing full breasts. Although several studies have researched the volumetric aspects of AFT, some outcomes such as volume retention, viability, and possible confounders for graft survival, remain unclear. This study aimed to answer these questions.

Methods: Post-mastectomy women of the multicenter prospective BREAST-trial were randomized to either AFT breast reconstruction or implant-based reconstruction (IBR). Volumes were assessed using the Vectra 3D imaging system and compared at 12 months post-operative. Volume retention was defined as the augmented volume divided by the lipofilling volume. Significant confounders for graft survival were identified using multivariable regression analysis.

Results: A total of 148 patients (75 AFT, 73 IBR) were included in the final analyses. Post-operative volumes differed significantly at 12 months in favor of the IBR group (83.8 ml, p < 0.001). For AFT patients, graft survival did not decrease between 6 and 12 months, with a mean graft survival of 37.1% at 12 months. Significant confounders for graft survival included chest circumference (β = 1.107, p = 0.001), comorbidities (β = 28.567, p = 0.002), age (β = -0.514, p = 0.007), and total lipofilling (β = -0.028, p < 0.001).

Conclusion: Plastic surgeons can reconstruct voluminous breasts post-mastectomy using only AFT, and these breast volumes stabilize at 6 months and VECTRA 3D is reliable for breast volume measurement. Approximately a third of the grafted fat was calculated to survive post-operatively and reconstructive surgeons should be aware not to transfer too much fat in one session.