Ian M. Thompson Jr., M.D., director of the Cancer Therapy & Research Center, is a researcher and urologist who has seen the results of one important study turn into another equally important set of findings. When results of his 10-year Prostate Cancer Prevention Trial (PCPT) were first published in the New England Journal of Medicine in 2003, they showed that men who took the drug finasteride were 25 percent less likely to develop prostate cancer.
However, of the men who developed prostate cancer, 18 percent had a more aggressive form of the disease. This finding caused concern and debate in the medical community that the drug might actually cause aggressive cancer. Many doctors decided not to prescribe it.
The puzzling data challenged Dr. Thompson to find out why. He continued following the nearly 19,000 men in the national trial and conducted dozens of follow-up studies to discover what caused this unusual finding.
What kept him going?
“I felt we owed the effort to The National Cancer Institute and the public, which funded the study; the participants, who took a pill every day for seven years and had a prostate biopsy because they thought cancer prevention was important; and our patients, who may suffer so much from this cancer. If indeed finasteride reduced cancer risk so much, we simply had to find out whether it increased the risk of aggressive cancer,” Dr. Thompson said.
Concentrating the cancer
Concerns that finasteride caused aggressive prostate cancer were finally calmed in 2007, when Dr. Thompson discovered the reason more aggressive cancers were found is because finasteride shrinks the prostate gland, making it easier to find the cancer through screening tests and prostate biopsy.
Significant study of 2013
Then, in 2013, the American Society of Clinical Oncology designated Dr. Thompson’s PCPT follow-up study, published in the New England Journal of Medicine, as one of the most significant practice-changing studies of the year.
“Now we know that the overall survival rate is precisely the same for men who take finasteride or who don’t, but the difference is, men who take finasteride are 30 percent less likely to get prostate cancer instead of 25 percent, as we originally thought,” Dr. Thompson said. The drug also decreased the chance of low-grade (less serious) prostate cancer by 43 percent.
Sparing men from unnecessary treatment
“If you look at the number of men diagnosed with prostate cancer annually and multiply that by 30 percent, that is the number of cancers we might be able to prevent each year,” he said. “That’s more than 71,000 men.
“That’s more than 175 jumbo jets full of men who won’t get cancer, who won’t face treatments with side effects like sexual dysfunction,” he said. “There’s nothing like disease prevention. Nothing comes close.”
Today, many men with even low-grade tumors are treated unnecessarily and the treatments they endure often carry significant side effects, such as sexual dysfunction and impotence. “If we can free thousands of men each year from that unnecessary burden,” Dr. Thompson said, “we could use those resources for other important medical interventions, reducing death and suffering from other diseases.”