Testing Diet Intervention Versus Non-Diet Intervention for Management of Bowel Symptoms in Rectal Cancer Survivors

PRIMARY OBJECTIVES: I. To compare total bowel function score, as measured by the Memorial Sloan-Kettering Cancer Center Bowel Function Instrument (BFI), at 18 weeks post-randomization between the intervention and attention control arms. EXPLORATORY OBJECTIVES: I. To compare total bowel function score at 26 weeks post-randomization between the intervention and attention control arms. II. To compare bowel function subscale scores (dietary, urgency, frequency), as measured by the BFI at both 18- and 26- weeks post-randomization between the intervention and attention control arms. III. To compare lower anterior resection syndrome (LARS) scores (for anastomosis participants only), quality of life, and dietary quality at both 18- and 26- weeks post-randomization between the intervention and attention control arms. IV. To compare motivation, self-efficacy, and positive/negative affect at both 18- and 26- weeks post-randomization between the intervention and attention control arms. V. To assess study feasibility, adherence, retention, and acceptability at both 18 and 26 weeks post-randomization. VI. To explore variation in primary and exploratory study outcomes according to sex, and to investigate whether intervention effects on the primary outcome differ across subgroups defined by sex. OUTLINE: Patients are randomized to 1 of 2 arms. ARM I: Patients receive diet modification coaching via telephone for 10 sessions over 30-60 minutes over 17 weeks. Patients also receive 3 motivational messages per week via email and/or text message beginning after session 6. ARM II: Patients receive general healthy living education via telephone for 10 sessions over 30-60 minutes over 17 weeks. Patients also receive 3 motivational messages per week via email and/or text message beginning after session 6. After completion of study, patients are followed up at 26 weeks.