• Oncology Clinical Trials
• Reproductive Cancers
• Radiology
• Radiation Therapy

• Oncology Clinical Trials
• Oncology
• Reproductive Cancers
• Radiology
• Radiation Therapy

Long-term androgen deprivation therapy (LTAD) was found to be more effective in patients with intermediate and high-risk localized prostate cancer than short-term androgen deprivation (STAD) therapy, according to Almudena Zapatero, MD, Hospital Universitario de La Princesa, Madrid, Spain, who presented the findings of a phase 3 trial that compared LTAD with STAD in patients with intermediate and high-risk localized prostate cancer treated with high-dose radiotherapy to determine superiority.

Previous study findings support that overall survival is improved with hormone therapy and conventional-dose radiotherapy in patients with intermediate and high-risk prostate cancer and that biochemical outcomes as well as clinical outcomes were improved with dose-escalated radiotherapy. In the present multicenter, randomized, phase 3 trial, 355 patients were separated into 2 treatment groups and stratified into 2 risk groups. The STAD treatment arm included 4 months of neoadjuvant and concomitant androgen deprivation with 3-dimensional conformal radiotherapy ≥ 76 Gy, and the LTAD treatment arm included an additional 24 months of adjuvant androgen deprivation. Risk groups were separated into intermediate risk, defined as T1-T2 with a Gleason score of 7 and/or a prostate-specific antigen (PSA) score of 10 to 20, and high risk, defined as T3 and/or a Gleason score of 8 to 10 and/or PSA > 20.

Patients who received previous surgical treatment, neoadjuvant hormonal treatment > 3 months, and concomitant chemotherapy were excluded from study. Baseline characteristics were similar in both treatment groups. Median radiotherapy prostate dose was 78 Gy, and median follow-up was 63 months.

Using intent-to-treat analysis, researchers found the biochemical disease-free survival rate at 5 years to be higher in patients receiving LTAD than in those receiving STAD (89.8% vs 81.3%; P = .019). Stratification analysis found biochemical disease-free survival rates to be significantly higher with LTAD in the high-risk group (88.0% vs 75.9%; P = .058).

As with biochemical disease-free survival, 5-year overall survival rate was also higher in the LTAD arm compared with the STAD arm (94.8% vs 86.1%; P = .009), and the LTAD arm had significantly higher rates in the high-risk group with stratification analysis (96.1% vs 81.5%; P = .01).

Unlike previous results, significant differences for 5-year metastasis-free survival were only found in overall analysis and not during the stratification analysis. For overall analysis, the 5-year metastasis-free survival rate was 93.6% for the LTAD arm compared with 83.4% for the STAD arm (P = .009).

Multivariate analysis identified 4 independent factors associated with biochemical failure: patient age, treatment arm, radiation dose, and PSA nadir. Biochemical failure was twice as likely in patients treated with STAD than in those treated with LTAD.

A total of 38 deaths occurred during the study, with 5 deaths attributed to prostate cancer. All 5 deaths were in the STAD arm, and they resulted in a significant cause-specific survival outcome (P = .021). Toxicity rates were similar in both groups and reported as low by investigators. The most common adverse event was rectal bleeding, which occurred in 17 patients receiving LTAD and 13 patients receiving STAD.

Researchers noted that the 5-year follow-up was short in duration, and studies with longer follow-up are necessary to validate findings. Other limitations mentioned included the limited number of events and the absence of a control arm, but overall study results suggest that LTAD has superior benefit compared with STAD in patients with prostate cancer treated with high-dose radiotherapy, specifically in those with high-risk prostate cancer.

• © 2014 MD Conference Express®