Adding chemotherapy to hormone therapy improves survival of men with prostate cancer, according to results from the STAMPEDE trial presented at the American Society of Clinical Oncology Annual Meeting on 31 May 2015.
The presentation reported results from 2,962 men who were assigned to four of STAMPEDE’s nine treatment arms:
- Standard treatment arm (at least three years of hormone therapy, with or without radiotherapy)
- Standard treatment plus docetaxel (a chemotherapy drug) for six 3-week cycles
- Standard treatment plus zoledronic acid (a drug used to treat bone cancers) for two years
- Standard treatment plus both docetaxel and zoledronic acid.
These men were followed up for an average of 3.5 years. Six in 10 of these men had cancer that had distant spread beyond their prostate when joining the trial, and the rest had high-risk, locally advanced prostate cancer. The average age of men in the trial was 65.
Men in the group allocated the standard treatment plus docetaxel lived on average for 10 months longer than men who had the standard treatment alone. Docetaxel seemed to be particularly good for men whose disease had spread to other parts of their body, increasing average survival by 22 months.
Men in the group allocated the standard treatment plus zoledronic acid did not live longer than men who had the standard treatment alone.
Men in the group allocated the standard treatment plus docetaxel plus zoledronic acid as well as the standard treatment lived longer on average than those who had the standard treatment alone. However, adding zoledronic acid to docetaxel did not seem to add any benefits beyond just docetaxel and the standard treatment.
While docetaxel was associated with some additional side effects compared to the standard treatment alone, as expected, the side effects were manageable. The most common extra side effects men on docetaxel reported were blood problems (having a low number of white blood cells, which increases the risk of infections). Very few patients stopped docetaxel due to side effects. The side effects were generally short term. After one year, there was no difference in the numbers of severe side effects reported by men in any of the trial arms.
Matt Sydes, senior trial statistician at MRC CTU at UCL, said “The data clearly show that docetaxel has a positive impact for men with high-risk hormone-naïve prostate cancer. We expect docetaxel will become part of a new standard-of-care for suitable men.”
The researchers say that docetaxel should be routine practice in suitable men with newly diagnosed prostate cancer that has spread to other parts of the body. Doctors should also consider it for men with high-risk prostate cancer that has not spread to other parts of the body, as it substantially delays the disease getting worse, spreading or causing death.
STAMPEDE (Systemic Therapy in Advancing or Metastatic Prostate Cancer: Evaluation of Drug Efficacy) is the largest randomized clinical trial of treatment for men with prostate cancer ever conducted, with nearly 7,000 patients enrolled since 2005. The trial, which continues to recruit new men, has an innovative multi-arm, multi-stage design.
The multi-arm multi-stage or “MAMS” design, which was developed by MRC CTU, allows several treatments to be assessed against a single control arm. Recruitment can be stopped early to treatments that are not sufficiently promising after interim analyses. New treatments that become available after the trial has started can also be added. Matt Sydes said “We have shown in STAMPEDE that we can put this innovative design into practice.”
These results will be published in full in a peer-reviewed journal later this year. Sites will continue to follow-up these men to look at longer-term outcomes. The STAMPEDE trial is also looking at a number of other approaches to treating men with prostate cancer.
This study received funding and support from Cancer Research UK, UK Medical Research Council, the UK National Cancer Research Institute, the UK Department of Health, Sanofi-Aventis, Novartis, Pfizer, Janssen, and Astellas, with the Chief Investigator supported by University of Birmingham and University of Warwick.