KEY POINTS
- This retrospective study included 943 patients with locally advanced breast cancer treated with comprehensive nodal irradiation across a multicenter academic network from 2016–2023. 60 patients (6.4%) lived in zip codes where ≥18% of residents were classified as food insecure.
- Tumor characteristics were broadly comparable between food-insecure and non-food-insecure areas, including histology, clinical stage, ER, PR, HER2 and triple-negative status. Surgery and receipt of neoadjuvant, adjuvant or concurrent chemotherapy also did not significantly differ, reducing the likelihood that treatment omission alone explained the survival gap.
- Despite this, five-year overall survival was 74.9% versus 90.2% (p=0.005). On multivariable analysis, residence in a food-insecure area remained independently associated with mortality (HR 5.52, 95% CI 1.76–17.27; p=0.003).
- The survival difference was not accompanied by a detectable recurrence difference: median freedom from recurrence was 18.7 versus 21.1 months (p=0.339). Cause of death was unavailable in many patients, so the study cannot establish whether the excess mortality was cardiovascular, metabolic, cancer-related or due to another mechanism.
- Food-insecure-area residents carried substantially more baseline comorbidity: diabetes occurred in 28.3% versus 12.7%, hypertension in 63.3% versus 35.2%, and current smoking in 25.0% versus 5.4%. Diabetes independently predicted mortality (HR 2.96), while development of a new pulmonary condition was associated with an even higher risk (HR 9.57).
- An important nutritional pattern emerged over time. Obesity prevalence was not significantly different at consultation (57.4% vs 42.3%; p=0.153) but diverged at follow-up to 65.5% versus 40.9% (p<0.001); median follow-up BMI was 31.96 versus 28.80 kg/m². BMI itself did not remain independently associated with survival.
- Endocrine treatment was protective: receipt of endocrine therapy was associated with markedly lower mortality (HR 0.12, 95% CI 0.02–0.95; p=0.045) and longer duration was also favorable (HR 0.96 per month; p<0.001). Interestingly, food-insecure-area patients actually had longer median endocrine exposure—43 versus 23 months—and were more likely to receive proton therapy, arguing against straightforward undertreatment as the explanation.
CLINICAL TAKEAWAY
Patients living in highly food-insecure areas had a striking survival disadvantage despite similar breast cancer biology and broadly comparable treatment delivery. That makes nutritional and metabolic vulnerability a potentially important component of survivorship care, but this study cannot prove causality because food insecurity was assigned from zip code rather than measured individually and important socioeconomic confounding may remain.