Intervention: Sulfasalazine
Trial phase: Phase 3
ATC code: A07EC01 | G01AE10
SMILES: O=C(O)c1cc(/N=N/c2ccc(S(=O)(=O)Nc3ccccn3)cc2)ccc1O
Sex: All
Age groups: Adult | Older Adult
Healthy volunteers: No
Participants at risk: 43
Group description: Patients receive two 500 mg oral sulfasalazine tablets twice daily during radiotherapy and for 4 weeks after completion of radiotherapy.
Eligibility criteria:
DISEASE CHARACTERISTICS:

Diagnosis of cancer that supports the use of radiotherapy to the pelvis
No current or prior metastases beyond pelvic regional lymph nodes
Planning to receive a course of continuous definitive or adjuvant external-beam radiotherapy to a minimum dose of 4500 cGy with or without fluorouracil, capecitabine, or oxaliplatin

Planned course of pelvic radiotherapy must fall within the following parameters:

Pelvis must be encompassed by the planned radiotherapy fields

Superior border may not lie superior to the L4-5 interspace and may not be inferior to the most inferior aspect of the sacroiliac joints
Portions of the rectum may have special blocking, depending upon disease site

Total planned dose to the central axis midplane (for AP-PA parallel opposed fields) or isocenter (for 3- or 4-field techniques) for the pelvic field must lie between 4500-5300 cGy (inclusive)*

Subsequent to completion of treatment to the pelvic field, 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

Daily dose (specified at central axis midplane or at isocenter for multi-field techniques) must lie between 170-210 cGy (inclusive) per day*
NOTE: *For institutions that do not use midplane or isocenter as the point for specification of dose, it will be necessary to determine the dose according to the methods specified above in order to determine patient eligibility.
No perineal irradiation planned (e.g., anal cancer patients, patients who have had an abdominal-perineal resection)
No brachytherapy planned before the completion of all external-beam radiotherapy
No planned split-course radiotherapy

PATIENT CHARACTERISTICS:

ECOG performance status 0-2
Life expectancy ≥ 6 months
Hemoglobin ≥ 10.0 g/dL
Leukocytes ≥ 3,500/mm^3
ANC ≥ 1,500/mm^3
Platelet count ≥ 100,000/mm^3
Creatinine ≤ 1.5 times upper limit of normal (ULN)
AST ≤ 1.5 times ULN
Not pregnant or nursing
Negative pregnancy test
Fertile patients must use effective contraception
Willing to provide blood specimens as required by the study (Mayo Clinic Rochester patients only)
Able to complete questionnaires alone or with assistance
No history of inflammatory bowel disease
No history of gastrointestinal or genitourinary obstruction or porphyria
No history of G6PD deficiency
No history of irritable bowel syndrome
No history of blood dyscrasia
No history of severe allergies or asthma
No history of hepatic or renal disease
No diarrhea ≥ grade 3, rectal bleeding, abdominal cramping, or incontinence of stool within the past week
No medical condition that may interfere with the ability to receive study treatment
No known allergy to sulfasalazine, sulfa medications, salicylates, or any known component of drug formulation

PRIOR CONCURRENT THERAPY:

See Disease Characteristics
No prior pelvic radiotherapy
No prior abdominal-perineal resection, Hartmann procedure, or other surgical procedure leaving the patient without a functioning rectum
No planned use of leucovorin or cytotoxic chemotherapeutic agents concurrent with radiotherapy (except for fluorouracil, capecitabine, or oxaliplatin)
No other concurrent sulfasalazine
No concurrent digoxin