Adjuvant postmastectomy radiotherapy might be associated with better survival in women with heart failure receiving total mastectomy.

<bold>Background: </bold>To date, no data on the effect of adjuvant postmastectomy radiotherapy (PMRT) on oncologic outcomes, such as all-cause death, locoregional recurrence (LRR), and distant metastasis (DM), are available in women with left-side breast invasive ductal carcinoma (IDC) and heart failure with reduced ejection fraction (HFrEF).<bold>Patients and Methods: </bold>We enrolled 646 women with left-breast IDC at clinical stages I-IIIC and HFrEF receiving radical total mastectomy (TM) followed by adjuvant PMRT or non-adjuvant PMRT. We categorized them into two groups based on their adjuvant PMRT status and compared their overall survival (OS), LRR, and DM outcomes. We calculated the propensity score and applied inverse probability of treatment weighting (IPTW) to create a pseudo-study cohort. Furthermore, we performed a multivariate analysis of the propensity score-weighted population to obtain hazard ratios (HRs).<bold>Results: </bold>In the IPTW-adjusted model, adjuvant PMRT (adjusted HR [aHR]: 0.52; 95% confidence interval [CI]: 0.37-0.74) was a significant independent prognostic factor for all-cause death (P = 0.0003), and the aHR (95% CI) of LRR and DM for adjuvant PMRT was 0.90 (0.79-0.96; P = 0.0356) and 0.89 (0.54-1.50; P = 0.6854), respectively, compared with the nonadjuvant PMRT group.<bold>Conclusion: </bold>Adjuvant PMRT was associated with a decrease in all-cause death, and LRR in women with left IDC and HFrEF compared with nonadjuvant PMRT. [ABSTRACT FROM AUTHOR]