Optimal radiotherapy technique selection for left-sided breast cancer remains challenging. This study compared volumetric-modulated arc therapy (VMAT), VMAT+IMRT (VMAT+IMRT) and IMRT+VMAT (IMRT+VMAT) using an innovative integrated scoring system and risk factor (RF) assessment.

Retrospectively analysed 41 patients with left-sided breast cancer. Treatment plans were evaluated using an integrated scoring system considering tumour coverage and organs at risk (OARs) sparing. RF analysis assessed potential adverse effects on the heart and lungs. Correlation analysis explored relationships between integrated scores and risk factors.

VMAT showed the best overall integrated score (1·0931 ± 0·1707), followed by IMRT+VMAT (1·2011 ± 0·2440) and VMAT+IMRT (1·2264 ± 0·2499). VMAT had the highest percentage of Excellent OAR plans (14·6%), while VMAT+IMRT and IMRT+VMAT showed better PTV coverage (53·7% and 51·2% Excellent, respectively). RF analysis revealed: VMAT (heart RF: 0·341, lung RF: 0·671), VMAT+IMRT (heart RF: 0·294, lung RF: 0·750) and IMRT+VMAT (heart RF: 0·533, lung RF: 0·546). Correlation analysis showed strong positive correlations between integrated scores and lung RF for VMAT (r = 0·671) and VMAT+IMRT (r = 0·750), with IMRT+VMAT showing moderate correlations for lung (r = 0·546) and heart (r = 0·533) RFs.

VMAT demonstrated the best balance between PTV coverage and OAR sparing, hybrid techniques improved target coverage but increased risk to OAR. The RF analysis highlighted varying impacts on heart and lung across techniques. This analysis provides valuable insights for technique selection, potentially improving treatment outcomes and reducing complications in left-sided breast cancer radiotherapy.