• Size of thymus as assessed by CT scan
• Fraction and absolute number of circulating peripheral blood CD4+ and CD8+ T cells with a "naive" phenotype
• Number of T-cell receptor excision circles in peripheral blood cells

RATIONALE: Studying changes in thymus function in patients who have been undergoing androgen blockade therapy for prostate cancer may help doctors learn more about how well patients will respond to treatment, may help in planning cancer treatment, and may help the study of cancer in the future.

PURPOSE: This clinical trial is studying the effect of androgen blockade therapy on thymus function in older patients who have undergone radical prostatectomy for localized prostate cancer.

OBJECTIVES:

• Determine if inhibition of sex steroid action is associated with increased thymic size in older patients who have undergone radical prostatectomy for localized adenocarcinoma of the prostate.
• Determine if inhibition of sex steroid action is associated with an increase in the absolute number or percentage of circulating "naive" phenotype T cells, and/or an increase in the frequency of T-cell receptor excision circles in peripheral blood cells.

OUTLINE: This is a nonrandomized, single-blind, cohort study. Patients are stratified according to hormonal therapy after surgery (yes vs no).

Patients undergo CT scan of the thymus. Blood samples are analyzed by flow cytometry to determine phenotype of T cells.

PROJECTED ACCRUAL: A total of 40 patients will be accrued for this study.

• Other: flow cytometry
• Other: laboratory biomarker analysis
• Other: physiologic testing
• Procedure: computed tomography

DISEASE CHARACTERISTICS:

• Histologically confirmed adenocarcinoma of the prostate
• Underwent prior radical prostatectomy as local definitive therapy for prostate cancer

• Meets criteria for 1 of the following strata:

  • Has received ≥ 9 months of androgen blockade therapy (either single-agent luteinizing hormone-releasing hormone or combined androgen blockade) for serologic progression after surgery

    • Serologic progression defined as a rising prostate-specific antigen, which has risen serially on two determinations (from baseline) ≥ 1 week apart, and no objective evidence of metastatic disease
    • Prior radiotherapy for serologic progression allowed
  • Did not receive any form of androgen blockade therapy within the past 9 months
• No metastatic disease by abdominal/pelvic CT scan and whole-body scan

PATIENT CHARACTERISTICS:

• Able to tolerate CT scanning in the supine position
• No prior medical condition known to have effects on the thymus, including myasthenia gravis, lymphoma, hyperthyroidism, or cachexia
• No autoimmune disorders
• No acute illness, including active infection requiring antibiotics

PRIOR CONCURRENT THERAPY:

• See Disease Characteristics
• No prior systemic chemotherapy
• No prior immunological therapy
• No prior single-agent antiandrogen (e.g., high-dose bicalutamide)
• No prior or concurrent 5-alpha reductase inhibitors (e.g., finasteride), PC-SPES, or estrogen-containing nutraceuticals
• No concurrent systemic steroid therapy (topical steroids allowed)