The Radiotherapy Effectiveness Gap in Breast Cancer: Survival Impact and Preventable Mortality in India’s National PoCSS Registry
Priya Pathak, Gokul Sarveswaran, Jayasankar Sankarpillai, Thilagavathi RamamoorthyPURPOSE
Radiotherapy (RT) is a core component of curative breast cancer treatment, yet many patients who meet stage and surgery based criteria do not receive it. Using India’s national Patterns of Care and Survival Studies (PoCSS) registry, this study quantified survival differences between patients who received versus missed indicated RT and estimated the magnitude of preventable mortality associated with RT underuse.
METHODS
Breast cancer cases recorded in the PoCSS registry (2009-2020) were classified as RT indicated based on stage and surgery: locally-advanced disease (T3-T4 or N2-N3), early-stage disease treated with breast-conserving surgery (T1-T2, N0-N1), and post-mastectomy node positive disease (N1-N3). Patients with unknown T, N, or M stage or with stage IV disease were excluded. Overall survival at 36, 60, and 120 months was estimated for RT-indicated patients who received versus did not receive RT. Absolute survival differences, relative risk reduction (RRR), and preventable deaths per 1000 missed RT cases were calculated, with preventable mortality defined as Risk_NoRT × RRR × 1000. Adequate RT was defined as ≥40 Gy total dose.
RESULTS
Among 56,534 eligible patients, 62.1% (n=35,102) met RT indication criteria. Of indicated cases, 35.0% (n = 12,293) did not receive RT. Adequate RT was delivered to 46.2% (n = 16,235) of RT-indicated patients and was associated with a 21–35% RRR compared with inadequate or no RT. RT receipt produced the greatest RRR at 36 months (49%), decreasing to 43% at 60 months and 32% at 120 months. Absolute survival benefits were 12% at 36 months and 15% at 120 months. Estimated preventable deaths per 1000 RT indicated patients were 5, 44, and 111 for stage I, II, and III disease, respectively, and 149 when all RT-indicated patients were combined at 120 months. Over 10 years, an estimated 1,827 deaths were potentially preventable among RT-indicated patients who did not receive RT.
CONCLUSION
Missing RT corresponded to one preventable death for every 7–200 RT indicated patients. Improving access to timely, adequate RT may meaningfully reduce breast cancer mortality at the population level. These estimates reflect RT indication based on stage and surgery and may not fully capture all guideline based clinical factors.