Vitamin D and Soy Supplements in Treating Patients With Recurrent Prostate Cancer

Phase 2

Completed

Brief Summary: RATIONALE: Vitamin D and soy extract may be effective in lowering prostate-specific antigen (PSA) levels in patients with recurrent prostate cancer that has not responded to previous treatment.

PURPOSE: This phase II trial is studying how well giving vitamin D together with soy supplements works in treating patients with recurrent prostate cancer.

Detailed Description: OBJECTIVES:

* Test the response of biochemically recurrent prostate cancer to a combination of cholecalciferol (i.e., vitamin D) and soy isoflavones (i.e., soy extract) after failed definitive local therapy as determined by PSA response.

OUTLINE: Patients receive oral cholecalciferol twice daily and a soy supplement (i.e., soy bar or shake) once daily. Treatment continues for 3-12 months in the absence of disease progression or unacceptable toxicity.

Blood samples are obtained at baseline and periodically during study to measure serum PSA, serum calcium, plasma cholecalciferol, and plasma soy isoflavone levels. Blood samples are also analyzed for expression of cholecalciferol receptor, p21, and p27 in peripheral blood lymphocytes as surrogate markers of the actions of cholecalciferol and genistein. Protein expression is assessed by immunoblot analysis of cell lysates as well as quantitative polymerase chain reaction.

Patients complete a toxicity questionnaire once each month to assess for cholecalciferol and soy supplementation toxicities and symptoms of hypercalcemia.

After completion of study therapy, patients are followed every 3 months for 1 year.

Recruitment & Eligibility

Inclusion Criteria

Not provided

Exclusion Criteria

Not provided

Arm && Interventions

Group	Intervention	Description
Soy and Vitamin D	soy	Patients will receive oral supplementation with both 2,000 IU per day of vitamin D (cholecalciferol) and soy (160 mg per day soy isoflavones). Serum PSA and plasma levels of vitamin D will be assessed monthly. Soy isoflavones levels will be assessed every three months.
Soy and Vitamin D	Vitamin D	Patients will receive oral supplementation with both 2,000 IU per day of vitamin D (cholecalciferol) and soy (160 mg per day soy isoflavones). Serum PSA and plasma levels of vitamin D will be assessed monthly. Soy isoflavones levels will be assessed every three months.

Primary Outcome Measures

Name	Time	Method
Number of Participants Showing a 50% Reduction in Serum Prostate Specific Antigen(PSA) During Treatment	up to one year

Secondary Outcome Measures

Name	Time	Method
Changes in PSA Slope	up to one year
Time to Progression	up to three years	Progression will be defined as a 50% rise in serum PSA compared to the baseline value confirmed on at least two measurements at least two weeks apart.
Number of Adverse Events, Grades 1-5	up to one year	Toxicity will be graded according to the revised NCI Common Terminology Criteria for Adverse Events v 3.0, (CTCAE). Number of events with grade 1-5 will be reported.
Changes in PSA Doubling Time	up to one year