RATIONALE: Estrogen may cause the growth of ovarian cancer cells. Hormone therapy using tamoxifen may fight ovarian cancer by blocking the use of estrogen by the tumor cells. Measuring CA 125 levels may help doctors predict a patient's response to tamoxifen and help plan the best treatment.

PURPOSE: This phase II trial is studying CA 125 levels in treating patients with relapsed advanced ovarian cancer, fallopian tube cancer, or primary peritoneal cancer who are receiving tamoxifen.

OBJECTIVES:

• Determine the percentage of patients with relapsed advanced ovarian carcinoma, fallopian tube carcinoma, or primary peritoneal carcinoma who have a log linear rise in CA 125 levels.
• Determine whether the log linear part of the curve is consistent enough to allow comparison of the slope before and after introduction of a new therapy.
• Compare the serial doubling time before and after commencing tamoxifen citrate treatment.
• Determine the number of patients required to detect a significant difference in CA 125 doubling time before and after starting tamoxifen citrate treatment.

OUTLINE: Patients undergo blood collection once a month to measure CA 125 levels. Once the CA 125 level goes above the upper limit of normal (ULN) or has started to rise from its nadir level (if not previously normal), CA 125 levels are measured every 2 weeks. When CA 125 levels reach 4 times the ULN or 4 times the nadir level (if not previously normal), patients begin oral tamoxifen citrate once daily for 3-6 months in the absence of disease progression or unacceptable toxicity. CA 125 levels will continue to be measured every 2 weeks during treatment.

PROJECTED ACCRUAL: A total of 200 patients will be accrued for this study.

DISEASE CHARACTERISTICS:

• Histologically confirmed advanced ovarian carcinoma, fallopian tube carcinoma, or primary peritoneal carcinoma

• Completed therapy for first relapse

  • Had an elevated CA 125 level before starting relapse therapy with ≥ 50% fall by completion of that therapy or response according to RECIST criteria

• No significant cancer-related symptoms requiring urgent treatment

PATIENT CHARACTERISTICS:

• ECOG performance status 0-2
• Life expectancy > 3 months
• Hemoglobin > 10 g/dL
• WBC > 2,500/mm^3
• Platelet count > 100,000/mm^3
• Creatinine < 2 times upper limit of normal (ULN)
• AST/ALT < 2 times ULN
• Bilirubin < 1.5 times ULN
• No evidence of significant clinical disorder or laboratory finding that would preclude study participation
• No psychiatric disorder that would preclude informed consent
• Not pregnant or nursing

PRIOR CONCURRENT THERAPY:

• No other concurrent hormonal therapy, except hormone-replacement therapy
• Other concurrent medications allowed provided dose is stable