RATIONALE: Gabapentin may be effective in relieving hot flashes in men who have prostate cancer. It is not yet known which regimen of gabapentin is most effective in treating hot flashes.

PURPOSE: Randomized phase III trial to compare different regimens of gabapentin in treating men who have prostate cancer.

OBJECTIVES:

• Determine the effectiveness of gabapentin in managing hot flashes in men with prostate cancer.
• Determine the response of patients to this drug.
• Determine the toxicity of this drug in these patients.
• Determine the quality of life of patients treated with this drug.

OUTLINE: This is a randomized, double-blind, placebo-controlled, multicenter study. Patients are stratified according to the number of hot flashes per day (2-3 vs 4-9 vs 10 or more) and duration of hot flash symptoms (less than 9 months vs 9 months or more). Patients are randomized to one of four treatment arms.

All patients are observed for 7 days prior to drug administration in order to collect baseline hot flash information.

• Arm I: Patients receive oral gabapentin once daily on days 1-28.
• Arm II: Patients receive oral gabapentin once daily on days 1-7 and twice daily on days 8-28.
• Arm III: Patients receive oral gabapentin once daily on days 1-7, twice daily on days 8-14, and three times daily on days 15-28.
• Arm IV: Patients receive oral placebo on one of three schedules corresponding to arms I-III.

Patients in all arms may continue therapy with gabapentin for an additional 8 weeks.

Quality of life is assessed at baseline, day 28, and at the end of the additional 8 weeks.

Patients are followed at 6, 12, and 24 months.

PROJECTED ACCRUAL: A total of 220 patients (55 per treatment arm) will be accrued for this study within 1 year.

Required characteristics:

1. Men with a history of prostate cancer who have received or are receiving androgen ablation therapy.
2. Must be on a stable dose of hormone therapy for the past 4 weeks and must not be planning on discontinuing hormone therapy throughout the duration of the randomized phase (5 weeks).
3. Presence of hot flashes for ≥1 month prior to study entry.
4. Bothersome hot flashes (defined by their occurrence ≥14 times per week and of sufficient severity to make the patient desire therapeutic intervention).
5. Life expectancy ≥ 6 months.
6. ECOG Performance Status (PS) 0 or 1.
7. ≥18 years of age

Contraindications:

1. History of renal insufficiency (defined as a creatinine ≥1.5 x UNL in the last two years).

2. Any of the following current (≤ 4 weeks) or planned therapies:

   • Antineoplastic chemotherapy
   • Androgens
   • Estrogens
   • Progestational agents

3. History of allergic or other adverse reaction to gabapentin.

4. Prior use of gabapentin.

5. Antidepressants (use is allowed if patient has been on a stable dose for ≥1 month and does not plan to modify this treatment during the next 5 weeks).