Treatments for advanced prostate cancer that’s metastasizing, or spreading in the body, are getting better, and men with the disease are living longer because of them, new research has found.
For years, the only available treatments for these aggressive tumors were androgen-deprivation therapies (ADT) that block testosterone, the male sex hormone that makes prostate cancer cells grow faster. Giving ADT slows cancer progression, but tumors typically develop resistance against it within three years and start growing again.
But then newer treatments for metastatic prostate cancer started showing up. A drug called docetaxel was approved by the FDA in 2004, followed by cabazitaxel in 2010, sipuleucel-T in 2011, abiraterone in 2011, and enzalutamide in 2012. Each of these drugs targets metastatic prostate cancer in different ways, and men who took any one of them in clinical trials lived longer than men who took ADT by itself.
For the current study, researchers set out to answer a unique question. They wanted to know if the combined market availability of these drugs was making a survival difference for men being treated for metastatic prostate cancer in the general population.
To find out, they divided men tracked by a national cancer registry into two groups. One group of 4,298 men had been diagnosed with metastatic prostate cancer between 2004 and 2008, and another equally sized group was diagnosed with the disease between 2009 and 2014. All the men in both groups were matched in terms of age, race, cancer stage at diagnosis, treatment, and other factors.
Results showed that the duration of survival before men died specifically from prostate cancer lasted approximately 32 months among those diagnosed during the earlier time frame, and 36 months among those diagnosed during the later one. Similarly, the duration of survival before men died from any cause after a metastatic prostate cancer diagnosis was 26 months between 2004 and 2008, and 29 months during the 2009–2014 time frame.
The authors acknowledge that the survival improvements are modest, but add they may not fully account for longer survival improvements from abiraterone and enzalutamide, which only came into widespread use at the end of the study period. Furthermore, men who respond extraordinarily well to the new treatments may live far longer than those who don’t. In general, the evidence provides “valid evidence in support of [newer] novel treatments,” the authors wrote.
Dr. Mark Garnick, the Gorman Brothers Professor of Medicine at Harvard Medical School and Beth Israel Deaconess Medical Center, and editor in chief of HarvardProstateKnowledge.org, says, “This study provides important information that men with advanced forms of prostate cancer are now living longer than they once did, sometimes years longer. Those of us who have been treating prostate cancer for decades appreciate this study’s fundamental finding that the improved longevity from newer cancer drugs is considerable.”