Oncologic outcomes after poly-4-hydroxybutyrate scaffold in post-mastectomy breast reconstruction: a retrospective, multi-center cohort study

BACKGROUND: Poly-4-hydroxybutyrate (P4HB) scaffolds are increasingly used in post-mastectomy implant-based breast reconstruction. Clinical adoption has outpaced evidence regarding oncologic outcomes and recurrence detection in reconstructed breasts. METHODS: We conducted a real-world cohort study via the Guardian Research Network database (2016-2023). Female patients with breast cancer undergoing mastectomy and reconstruction were identified; 269 P4HB cases were compared with 269 stratified, randomly sampled non-P4HB controls. Primary endpoints were LRR and LRRFS; secondary endpoints included disease-specific and overall survival. Cumulative incidence functions accounted for competing risk of non-breast cancer death. Administrative censoring at 3 years (as well as time aligned cohorts) was used to mitigate temporal imbalance. RESULTS: Over a median follow-up of 2.2 years in P4HB and 5.5 years in controls, LRR was uncommon (4/269 (1.5%) vs. 6/269 (2.2%)). The 3-year cumulative incidence of LRR was 1.6% in both groups. Disease-specific mortality was rare (0.7% vs. 2.6%). No early signal of differences in locoregional recurrence was observed between groups within the observed follow‑up period. CONCLUSIONS: In this real-world, multi-center analysis, no detectable signal of increased locoregional recurrence was observed between cohorts. These findings do not establish evidence of oncologic equivalence, but rather an absence of a detectable early signal of increased risk within the observed follow-up. Larger, time-aligned datasets with plane-stratified surveillance and analyses are warranted to further evaluate oncologic outcomes given the comparator cohort included a greater proportion of earlier-era reconstructions than the P4HB cohort, reflecting more recent clinical adoption of P4HB.