This phase II trial studies how well time-restricted eating works in reducing side effects of radiation or chemoradiation side effects when compared to nutritional counseling among patients with prostate, cervical, and rectal cancers. Time-restricted eating, also called short term fasting or intermittent fasting, is an eating plan that alternates between not eating food (fasting) and non-fasting periods. Nutritional counseling involves being asked to follow a healthy, balanced diet that includes instructions on what kinds of food are better tolerated during radiation and chemoradiation therapy. This trial may help researchers determine if certain diets may improve the anti-cancer effects of radiation therapy and reduce the side-effects of this treatment. If successful, these diets may be integrated into the future treatment of prostate, cervical, and rectal cancers.

PRIMARY OBJECTIVES:

I. To test the hypothesis that time-restricted eating during radiation therapy (RT) or chemotherapy and radiation therapy (chemoRT) could reduce the level of accumulated double stranded deoxyribonucleic acid (dsDNA) damage in peripheral blood mononuclear cells (PBMCs) over the course of RT as measured by the gH2ax assay.

II. To examine if time-restricted eating during RT is associated with reduced toxicity as measured by clinician reported adverse events using Common Terminology Criteria for Adverse Events (CTCAE) version (v)5.0, improved patient quality of life as measured by European Organization for the Research and Treatment of Cancer Quality of Life (EORTC-PR25) (prostate cancer) and EORTC-CR29 (rectal cancer), reduced dsDNA damage as measured by assay for 8-oxo-dG and persistent DNA damage in shed epithelial cells from the urinary tract, reduced oxidative DNA damage as measured by reduced cumulative 8-oxoguanine DNA adducts, impacts the diversity of microbiome in relation and development of radiation induced microbiota dysbiosis and metabolic impact using liquid chromatography mass spectrometry (LC/MS) metabolomic analysis and correlative serological markers including IGF-1.0).

OUTLINE: Patients are randomized to 1 of 2 arms.

ARM I: Patients undergo time-restricted eating Monday through Friday only of each week on study during standard RT or chemoRT. Patients also undergo collection of blood throughout the trial.

ARM II: Patients receive nutritional counseling on study. Patients also undergo collection of blood throughout the trial.

Inclusion Criteria:

• Male and female patients aged 18 or older
• Localized high risk prostate cancer or node positive prostate cancer histologically confirmed by biopsy or recurrence after surgical resection planning to receive whole pelvis radiation therapy +/- androgen deprivation therapy or
• Locally advanced cervical cancer receiving whole pelvic/paraaortic radiation therapy + concurrent cisplatin-based chemotherapy or
• Locally advanced rectal cancer receiving whole pelvis radiation therapy + concurrent 5FU/capecitabine
• Eastern Cooperative Oncology Group (ECOG) Performance Status 0-2
• Able to provide a written consent for study participation

Exclusion Criteria:

• PROSTATE CANCER: Prior radiation therapy to the prostate gland or pelvis
• PROSTATE CANCER: Prior therapy with androgen deprivation therapy for longer than 6 months
• PROSTATE CANCER: Prior chemotherapy
• PROSTATE CANCER: Men with diabetes may enroll, provided they are on stable doses of antihyperglycemic medication for at least 6 months and provided the physician managing their diabetes feels they can safely hold antihyperglycemic medication during daily time-restricted eating
• PROSTATE CANCER: Must be eligible to receive neoadjuvant and concurrent androgen deprivation therapy, but androgen deprivation therapy is not required
• PROSTATE CANCER: Men whose treatment plan includes up-front docetaxel will be excluded due potential confounding
• PROSTATE CANCER: Patients whose body mass index (BMI) is less than 21 at time of screening
• PROSTATE CANCER: Men who are currently undergoing a strict macronutrient or time limited diet including ketogenic, low-carbohydrate (carb), paleolithic (paleo), or warrior diet are excluded
• GYNECOLOGIC CANCER: Prior radiation therapy to the cervix, uterus or pelvis
• GYNECOLOGIC CANCER: Prior chemotherapy
• GYNECOLOGIC CANCER: Women must not be pregnant, planning to become pregnant or lactating at the time of enrollment or during the course of the study
• GYNECOLOGIC CANCER: Women with diabetes may enroll, provided they are on stable doses of antihyperglycemic medication for at least 6 months and provided the physician managing their diabetes feels they can safely hold antihyperglycemic medication during daily time-restricted eating
• GYNECOLOGIC CANCER: Must be eligible to receive chemotherapy that is cisplatin based
• GYNECOLOGIC CANCER: Patients whose BMI is less than 21 at time of screening
• GYNECOLOGIC CANCER: Women who are currently undergoing a strict macronutrient or time limited diet including ketogenic, low-carb, paleo, or warrior diet are excluded
• RECTAL CANCER: Prior pelvic radiation therapy
• RECTAL CANCER: Prior chemotherapy
• RECTAL CANCER: Patients with diabetes may enroll, provided they are on stable doses of antihyperglycemic medication for at least 6 months and provided the physician managing their diabetes feels they can safely hold antihyperglycemic medication during daily time-restricted eating
• RECTAL CANCER: Patients whose BMI is less than 21at time of screening
• RECTAL CANCER: Women must not be pregnant, planning to become pregnant or lactating at the time of enrollment or during the course of the study
• RECTAL CANCER: Patients who are currently undergoing a strict macronutrient or time limited diet including ketogenic, low-carb, paleo, or warrior diet are excluded