Could eating only during daylight hours improve cancer treatment?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Male or female * Self-identify as Alaska Native or American Indian person and eligible for care at the ANMC * Age≥21 years * Histologically confirmed rectal cancer stage II, III, or IV (if curative) per AJCC criteria (neoadjuvant) * Histologically confirmed HER2+ or triple negative breast cancer stage I, II, or III, per AJCC criteria (neoadjuvant) * Histologically or cytologically confirmed solid tumor (adjuvant) * BMI≥18.5 kg/m2 * Plan to receive neoadjuvant or adjuvant therapy * Planned duration of neoadjuvant or systemic adjuvant therapy for \>3 months to allow sufficient time to assess impact of intervention * Must have capacity to give informed consent * Willing and able to adhere to the assessments, visit schedules, prohibitions, and restrictions * Has completed ≤ 4 weeks of neoadjuvant or adjuvant treatment prior to study enrollment * Score of \< 4 on U.S. Household Food Security Survey Module: Six-Item Short Form OR if score \>5, have clearance from dietitian Exclusion Criteria: * History of cytotoxic chemotherapy ≤12 months prior to rectal or breast cancer diagnosis (neoadjuvant) * Allergic reaction to any of the treatment agents * Any prior pelvic radiotherapy * Active second malignancy (exceptions: non-melanoma skin cancers or cervical carcinoma in situ adequately treated) requiring systemic therapy * History of GI perforation ≤12 months prior to enrollment * History of predisposing colonic or small bowel disorders with severe or rapidly worsening symptoms (not related to current cancer symptoms) * Receiving any parenteral nutrition or enteral (tube) feeding or using similar nutritional supplement during the study period * History of uncontrolled CHF defined as NYHA Class III or greater * Pre-existing grade ≥3 neuropathy * Currently participating in or has participated in a study of an investigational agent or investigational device ≤4 weeks of the first dose of treatment * Unstable psychiatric, sleep, or circadian conditions (common conditions such as sleep apnea and depression are acceptable as long as they are stabilized and not rapidly worsening) * Pregnant or breastfeeding * Currently perform overnight shift work \>1 day/week * Strictly adhering to a \<10-hour eating window on most days * Severe psychiatric, cognitive, or substance misuse disorders or social conditions that would interfere with adherence to study procedures.