A prospective cohort study enrolling 100 women with histologically confirmed breast cancer in Tehran, Iran, will capture nine repeated dietary records across early, mid, and late chemotherapy phases. The primary endpoint is a composite cardiometabolic risk score assessed pre- and post-chemotherapy, with secondary analyses targeting biochemical markers and psychological outcomes via validated questionnaires. Exploratory analyses will examine end-of-treatment serum vitamin D as a concurrent biomarker, with results reported as multivariable-adjusted beta coefficients.
This is a study protocol, not a results paper — no clinical findings exist yet — and it is a preprint posted on medRxiv, not yet peer-reviewed, meaning the methodology itself could still be revised. That said, the design addresses a genuine evidence gap: most existing data on nutrition during chemotherapy rely on single dietary snapshots rather than repeated assessments across treatment phases. Nine dietary records represent meaningful temporal resolution. The cohort size of 100, however, is modest, limiting statistical power for subgroup analyses and reducing generalizability across cancer stages and chemotherapy regimens. The observational design also cannot establish causation; confounding by socioeconomic status, symptom burden affecting appetite, and unmeasured supplementation remains a real concern. Still, for a field dominated by small cross-sectional studies, a prospectively designed, multi-timepoint dietary assessment protocol is a methodological step forward. Clinically, if completed and peer-reviewed, this work could inform evidence-based dietary guidance during chemotherapy — a domain where oncology nutrition remains underspecified.
