Beyond the first cut: Impact of repeat surgery versus boost on breast induration-A post hoc analysis from the DBCG...

Following breast-conserving surgery (BCS), patients with narrow surgical margins frequently undergo repeat surgery (RS) or receive a tumour-bed boost to reduce the risk of local recurrence. Both interventions may increase the risk of late toxicity, including breast induration and adverse cosmetic outcomes. Comparative long-term data on these outcomes remain limited. This post hoc analysis assessed the impact of RS and tumour-bed boost on grade 2-3 breast induration and cosmetic outcomes in patients receiving whole-breast irradiation (WBI) for early-stage breast cancer or ductal carcinoma in situ (DCIS).

The analysis included 1919 patients from two multicentre randomised phase III trials within the Danish Breast Cancer Group (DBCG): DBCG HYPO (WBI 50Gy/25fr versus 40Gy/15fr) and DBCG PBI (40Gy/15fr, WBI versus partial breast irradiation (PBI)). Of these, 303 patients (16 %) underwent RS and 220 patients (11 %) received a boost. Patients were categorised into four groups: 'RS and boost', 'boost only', 'RS only', and 'No RS, no boost'. At 5 years, the cumulative incidence of grade 2-3 breast induration was highest in the 'RS and boost' group (30.7 %), followed by 'boost only' (25.7 %), 'RS only' (18.1 %), and 'No RS, no boost' (13.5 %). Adjusted hazard ratios confirmed this pattern. No significant differences in cosmetic outcomes were observed between the 'RS only' and 'boost only' groups at 3 or 5 years.

A tumour-bed boost was associated with a higher risk of breast induration compared to RS, with no difference in cosmetic outcome.