Probiotic Therapy in Preventing Gastrointestinal Complications in Patients Undergoing Chemotherapy and Pelvic Radiation Therapy

DISEASE CHARACTERISTICS: * Current diagnosis of cancer that supports the use of continuous definitive or adjuvant external-beam radiotherapy (RT) to the pelvis to a minimum dose of 4,500 cGy with the following parameters: * The pelvis must be encompassed by the planned RT fields * The superior border may not lie inferior to the most inferior aspect of the sacroiliac joints * Portions of the rectum may have special blocking, depending upon disease site * The total prescription dose must lie between 4,500-5,350 cGy (inclusive) * A boost to primary tumor or tumor bed may be planned * Planned treatment is to be given 4-5 times per week on a one- treatment-per-day basis * The daily prescribed dose must lie between 170-210 cGy (inclusive) per day * No planned split-course RT * No proton RT * Will receive concurrent administration of chemotherapy (fluorouracil, capecitabine, cisplatin, oxaliplatin, carboplatin, and/or mitomycin C) during pelvic RT * No current or prior metastases beyond regional lymph nodes PATIENT CHARACTERISTICS: * ECOG performance status (PS) of 0, 1, or 2 * Life expectancy ≥ 6 months * Able to complete questionnaire(s) by themselves or with assistance * Not pregnant or nursing * Negative pregnancy test done ≤ 7 days prior to registration, for women of childbearing potential only * Fertile patients must use effective contraception * Hemoglobin \> 10.0 g/dL * White blood cells (WBC) \> 3,500/mm³ * Absolute neutrophil count (ANC) \>…