Health Literacy, Nutritional Knowledge, and Weight Trajectories During Endocrine Therapy in Breast Cancer Survivors: Educational Implications for Oncology Practice

Purpose Weight gain during endocrine therapy is common among breast cancer survivors and may adversely affect long-term metabolic and oncologic outcomes. While obesity is a recognized prognostic factor, limited research has examined how nutritional knowledge and health literacy translate into real-world weight trajectories during endocrine therapy. This study evaluated the association between perceived nutritional knowledge, information sources, and weight trajectories, including exploratory analysis of patients receiving CDK4/6 inhibitors. Methods This single-center cross-sectional observational study was conducted in January 2023 at a tertiary oncology center (AOU Sassari, Italy). Consecutive women aged 35–85 years with luminal breast cancer receiving endocrine therapy for ≥ 4 months were invited to participate during routine follow-up visits. Of 112 eligible patients, 100 were included in the final analysis. Participants completed a structured questionnaire assessing anthropometric data, dietary habits, perceived nutritional knowledge, and communication patterns. Weight trajectories were categorized as gain, loss, or stable. Pearson’s chi-square test was used for categorical comparisons. Odds ratios (OR) with 95% confidence intervals (CI) were calculated. Statistical significance was set at p < 0.05. Results Sixty percent of participants were overweight or obese during therapy, compared with approximately 30% in the general female Italian population. Fifty-two percent gained weight (+ 7.2 kg), 32% lost weight (− 3 kg), and 16% remained stable. Forty-eight percent of patients in the weight-loss group mentioned fiber/vegetables in an open-ended dietary question compared to 8% in the weight-gain group. Fiber-oriented dietary awareness was strongly associated with weight loss (OR = 10.59; 95% CI 3.08–36.38; p < 0.001). Patients receiving CDK4/6 inhibitors (28%) were predominantly overweight but showed attenuated weight-gain patterns (exploratory observation). Conclusions Breast cancer survivors exhibit increased metabolic vulnerability during endocrine therapy. Applied nutritional literacy—rather than perceived knowledge alone—is strongly associated with favorable weight trajectories. Structured nutritional counseling may improve survivorship outcomes. Implications for Cancer Survivors Interactive health literacy represents a modifiable target for metabolic risk reduction in breast cancer survivorship.