Effect of Androgen Blockade Therapy on Thymus Function in Older Patients Who Have Undergone Radical Prostatectomy for Localized Prostate Cancer

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)