Phase I study of extended field intensity modulated radiation therapy (EF-IMRT) and docetaxel in patients with node-positive prostate cancer

Abstract

e16154 Background: Treatment for patients with node positive prostate cancer remains challenging. With hormonal ablation therapy (HAT), conventional radiation doses to the lymph nodes produces few cures or long-term remissions, likely due to suboptimal doses and/or fields of radiation. Docetaxel has radiosensitizing properties. We conducted a phase I study combining HAT with EF-IMRT and concurrent docetaxel in men with biopsy-proven node positive prostate cancer. Methods: Eligible patients had biopsy proven N1M0 disease and adequate hematologic and hepatic function. All subjects received neoadjuvant HAT (bicalutamide 50 mg/d with an LHRH agonist) for at least 2 months but less than 13 months prior to EF-IMRT and continued for 2 years after completion of radiation (bicalutamide discontinued at the end of radiation). EF-IMRT target doses: prostate 81.0 Gy/45 fractions; intraprostatic target 81.0 - 84.6 Gy/45 fractions; pathologically involved lymph node 72 Gy/43 fractions; pelvic lymph nodes 54.0 Gy to 70.2 Gy/43 fractions. Ultrasound targeting and a water filled rectal catheter balloon were used daily to minimize movement and locate the prostate. Weekly docetaxel was administered during radiation at 5, 10 or 17 mg/m2. The primary endpoint was determining grade III/IV toxicity. Results: Nine patients have been treated. No grade III/IV toxicities occurred within the defined observation period. All subjects received their prescribed radiation and chemotherapy doses. One patient developed an anal fissure and one patient had tachyarrhythmias about 6 months after radiation. Seven of 9 patients are now beyond the 2 year post-radiation period; 4 patients remain in remission; one patient developed primary lung cancer; another was lost to follow up at 1 year post-radiation and 3 had relapsed disease within the 2 year post-radiation window. Conclusions: The addition of weekly docetaxel to EF-IMRT along with HAT is well tolerated in patients with node positive prostate cancer. Phase II studies are warranted based on these results. [Table: see text]