The results reported on four of the trial's nine treatment arms:
- The standard treatment group, in which men had at least 3 years of hormone therapy, with or without radiation therapy
- Standard treatment plus docetaxel chemotherapy for six 3-week cycles
- Standard treatment plus zoledronic acid for 2 years
- Standard treatment plus both docetaxel and zoledronic acid
Combined treatment improved survival
The researchers found that men who had standard treatment plus docetaxel lived an average of 10 months longer than men who had the standard treatment alone. Docetaxel also extended time to relapse by 38% in all patients. "We hope our findings will encourage doctors to offer docetaxel to men newly diagnosed with metastatic prostate cancer, if they are healthy enough for chemotherapy. Men with locally advanced, nonmetastatic prostate cancer may also consider docetaxel as part of upfront therapy, as it clearly delays relapse," said lead study author Nicholas David James, MD, PhD, Director of the Cancer Research Unit at the University of Warwick and Consultant in Clinical Oncology at Queen Elizabeth Hospital Birmingham.
Men in the group who had standard treatment plus zoledronic acid did not live longer than men who had the standard treatment alone. Men in the group who had standard treatment plus docetaxel and zoledronic acid did live longer than those who had standard treatment alone. However, adding zoledronic acid to docetaxel did not seem to add benefits beyond docetaxel and standard treatment combined.
As expected, the docetaxel treatment was associated with some side effects beyond the standard treatment. However, the researchers reported the side effects were manageable. Very few patients discontinued docetaxel due to side effects.
The subjects included 2,962 men who were followed up for an average of 3.5 years. Sixty percent of these men had cancer that had spread beyond the prostate when they joined the trial. The remaining 40% had high-risk, locally advanced prostate cancer.
Two smaller trials have previously reported results on using docetaxel in men with advanced prostate cancer. The CHAARTED study (see p.3 in the Quest Summer/Fall 2014 issue) found similar results as STAMPEDE. GETUGAFU 15 did not show a survival advantage. STAMPEDE included a larger and broader patient population than these two previous trials.
Nearly 7,000 men have enrolled in the UK-led STAMPEDE trial since 2005. Researchers continue to recruit men for the study, which uses an innovative multistage and multi-arm design. Lead author Nicholas James, MD, PhD, presented the recent results at the 2015 American Society of Clinical Oncology (ASCO) annual meeting in Chicago in June.