Dr. Ian Thompson
Dr. Ian Thompson, president of CHRISTUS Santa Rosa Hospital Medical Center and vice president of oncology. Credit: Scott Ball / San Antonio Report

After 25 years, Dr. Ian Thompson feels like he’s closed the book on the safety and effectiveness of an inexpensive prescription drug in preventing prostate cancer.

Thompson, president of CHRISTUS Santa Rosa Hospital Medical Center and vice president of oncology, led one of the largest cancer prevention trials ever mounted, a randomized study involving nearly 19,000 men that began in 1993. The long-term study recently determined that finasteride, a common hormone-blocking drug used to treat prostate enlargement and male-pattern baldness, significantly reduced the risk of prostate cancer for men over 55.

The study’s results, coupled with finasteride’s low cost, are expected to transform treatment for prostate cancer, the most common cancer diagnosed in American men.

“This discovery could benefit tens of thousands of men each year in the United States by identifying a drug that can safely and effectively prevent prostate cancer,” Thompson said. “Treatment for the disease is costly and can have serious side effects, such as impotence and urinary incontinence.”

An internationally recognized urologic oncologist, Thompson serves as the genitourinary cancer chair for SWOG, an organization supported by the National Cancer Institute that conducts clinical trials in adult cancers. He previously directed the Cancer Therapy and Research Center, now UT Health San Antonio MD Anderson.

In an interview with the Rivard Report, Thompson discussed prostate cancer treatment and prevention, and access to health care in San Antonio. The interview has been edited for length and clarity.

Rivard Report: What are some of the common symptoms and risk factors for prostate cancer? 

Ian Thompson: Most prostate cancers do not cause symptoms and would not otherwise be found if not for prostate-specific antigen (PSA) testing or biopsies. The principal risk factor is age – affecting men over the age of 50 – followed by family history, which can increase a person’s risk twofold. Other risk factors include race and ethnicity: Black men have double the risk of dying from prostate cancer compared to their non-Hispanic white counterparts, and Asians have the lowest risk overall, but there is not a single gene that causes the disease.

RR: You recently published study results showing that Finasteride significantly reduces a man’s risk of getting prostate cancer – the same drug that in 2003 was found to increase risk. How did you come to the final result?

IT: When the study began in 1993, there had been a five-fold increase in the number of prostate cancer diagnoses since PSA testing, which screens for cancerous proteins in blood, had become widespread. There were very serious concerns regarding over-detection and over-treatment, since all prostate cancer diagnoses at the time were treated immediately, either surgically or with radiation.

The National Cancer Institute began looking into finasteride, and it became one of the most complicated trials ever created, because in addition to reducing the risk of prostate cancer by up to 30 percent, the drug also helps the PSA test better detect high-grade prostate cancer and improves the likelihood of detecting cancer in a biopsy because the prostate is smaller. Because of the uptick in high-risk prostate cancer diagnoses as a result of improved testing, initial results of the study published in 2003 indicated that finasteride may increase the risk of an aggressive cancer diagnosis and should not be used for prevention.

The link between finasteride use and lethal prostate cancer became a “sticky fact” that we worked to dispel over the next several years through follow-up studies, including an 18-year analysis of prostate cancer survival rates among participants to determine cause of death. In 2013, we were able to successfully conclude that finasteride reduces the risk of cancer by about one third, and there is no greater risk of prostate cancer death.

RR: Were there any other notable results from the trial?

IT: Yes. In the 1990s, antioxidant supplements including vitamin E and selenium were promoted and regularly used by more than 75 percent of men 50 years or older in the U.S. to stave off and minimize the risk of prostate cancer. A 10-year study on the effects of these supplements found that selenium had no impact on diagnosis or outcome, while vitamin E, considered the best potential prevention option at the time, actually increased the risk of prostate cancer by 17 percent. If you are taking vitamin E [to prevent] prostate cancer, stop immediately.

RR: Has prostate cancer research been impacted by changes in government funding and availability?

IT: The total number of dollars received this year for cancer research is higher than we have ever seen. The challenge we face is that the population is larger so the need is greater. Scientific opportunities have expanded exponentially so it can be harder to secure funding for new research opportunities. The National Cancer Institute can fund maybe 10 percent of the grant requests they receive per year, and within the remaining 90 percent of unfunded projects there may be a Nobel Prize winner. Health care and education should get the bulk of our national investment, and they don’t.

RR: What kind of advancements in cancer research and treatment do we have to look forward to in the next five to 10 years?

IT: The number of things in cancer and medicine is exploding so quickly that perhaps the most important new field is in data management. Computer scientists and mathematicians are the most recruited people in the medical field right now and are helping us make sense of large volume of big data we have available to help improve treatment. Another thing to watch for is the rise in immunotherapies, which we are seeing take over for conventional treatment of cancer now that we have a better understanding of how to roll them out. If you can train your body’s immune system to reject cancer cells, the thought process is that you do not just cure the cancer; it will never come back because the body is immune – but the complexity of it is astonishing.

RR: How does the access to health care in San Antonio compare to similar cities in the U.S.?

IT: We are blessed. We have great universities, great hospitals, great doctors, and in the cancer field we have some of the best in the nation. There is generally great access to health care across the city from good physicians. I always get a kick when someone leaves San Antonio to get a second opinion, but it’s written in the Bible: “A prophet is never acknowledged in his own country.” So at least it goes back a couple thousand years. Can San Antonio continue to aspire to improve care? Absolutely. Are there things that are going on in San Antonio to do just that? Absolutely.

RR: How can healthcare availability and access in San Antonio be improved? 

IT: We need to spend more time talking about health care in San Antonio and how it’s presented. If you look at other cities like Houston or Dallas, medical centers in those areas have hotels that are built for patients coming in. As we get the word out about the great medical care happening in San Antonio, we will need to develop infrastructure to support that.

RR: How did we come to have a physician shortage in the U.S., and what are the current and future impacts?  

IT: We have a maldistribution of doctors across the field of medicine because our system of making physicians is not as responsive as it needs to be, and it is difficult to adjust production in provider type because it would need to be retooled a decade in advance. In San Antonio, we have many urologists, but if you go to Laredo, there are only two, and our population here is only four times larger. With the number of practicing neurologists in the U.S. currently, we would not have the ability to take care of an infectious disease outbreak if one occurred.

Roseanna Garza reports on health and bioscience for the San Antonio Report.