Testosterone and Prostate Cancer
The Evidence as it Now Stands
For over sixty-five years, there has been a fear that T therapy will cause new prostate cancers to arise or hidden ones to grow. Although no large-scale studies have have yet been performed to provide a definitive verdict on the safety of T therapy, it is quite remarkable to discover that the long-standing fear about testosterone and prostate cancer has little scientific support. The old concepts, taken as gospel, do not stand up to critical examination. The best summary about the risk of prostate cancer from T therapy, based on published evidence, is as follows:
- Low blood levels of testosterone do not protect against prostate cancer.
- Low testosterone levels may increase the risk of prostate cancer.
- High blood levels of testosterone do not increase the risk of prostate cancer.
- Treatment with testosterone does not increase the risk of prostate cancer, even among men who are already at high risk for it.
In men who do have metastatic prostate cancer and who have been given treatment that drops their blood levels of testosterone to near zero, starting treatment with testosterone (or stopping treatment that has lowered their testosterone to near zero) might increase the risk that residual cancer will again start to grow.
One of the most important and reassuring studies regarding testosterone and prostate cancer was an article published in the Journal of National Cancer Institute in 2008, in which the authors of eighteen separate studies from around the world pooled their data regarding the likelihood of developing prostate cancer based on concentrations of various hormones, including testosterone. This enormous study included more than 3,000 men with prostate cancer and more than 6,000 men without prostate cancer, who served as controls in the study. No relationship was found between prostate cancer and any of the hormones studied, including total testosterone, free testosterone, or other minor androgens. In an accompanying editorial, Dr. Carpenter and colleagues from the University of North Carolina School of Public Health suggest scientists finally move beyond the long-believed but unsupported view that high T is a risk for prostate cancer.
Q. I’m fifty-three years old and I’ve been on testosterone therapy for two years, with good results. However, my father was diagnosed with prostate cancer at age seventy-five. Does this mean I need to stop testosterone?
A. There is a familial form of prostate cancer, but only in families in which prostate cancer occurs at age sixty-five years or younger. Even in those families where a family member develops cancer at a young age, this does not necessarily mean that every other male in the family will develop cancer. Men with a family history of prostate cancer should be sure to have a yearly PSA and prostate exam. There is no need to discontinue testosterone treatment.
Q. My physician started me on testosterone, but I never had a prostate biopsy. I am sixty-four years old. Was this a mistake?
A. Because there is no evidence that testosterone treatment increases the risk of prostate cancer, it is fine to begin therapy as long as your PSA and DRE are normal. Doctors Age Managment recommends prostate biopsy in men with low T because published data indicate there is an increased risk that cancer is already present in men with low T, but this is by no means a standard recommendation yet among physicians.
Q. Why do you perform prostate biopsies on men with low T if you don’t feel that testosterone treatment will make a hidden cancer grow.
A. Because so many men with prostate cancer will not die from it, even without treatment, there is a fair amount of controversy over how aggressive to be in making the diagnosis. It is worth knowing the diagnosis, whethere or not one chooses to be treated immediately. And because low T seems to represent a small but definite increased risk, biopsy in men over fifty with low T is worthwhile.
Q. A man in my bowling league was started on testosterone treatment and then developed prostate cancer one year later. Doesn’t that show that testosterone is risky for prostate cancer?
A. If the wide of this mad had switched to a new type of laundry detergent before the cancer was diagnosed, would we assume the cancer was caused by the detergent? Of course not. But we are predisposed to believe that T therapy causes prostate cancer, so it is easy to hear a story like this and assume that T therapy caused the cancer. Prostate cancer and T thereapy are both common in the United States, and both tend to occur in the same age range, so there will always be stories of men developing cancer some time after beginning T therapy. If testosterone really made prostate cancers grow, then we should see high rates of cancer among men who start testosterone therapy. But we don’t. It’s false logic.
Q. Isn’t it true that all men would eventually get prostate cancer if they lived long enough? If so, why does it even matter if testosterone were to increase the risk of something that is inevitable anyway?
A. Men do get prostate cancer at an increasingly high rate as they age. And it is true that most men diagnosed with prostate cancer would never have a moment’s trouble from it, even if it were left untreated, because most of these cancers grow so slowly that other medical conditions eventually become more troublesome. Yet for those with more aggressive forms of prostate cancer, the danger is very real. The challenge is to identify men at risk, because even high-grade prostate cancer is curable when caught early.
Q. It took more than thirty years for scientists to learn that hormones were dangerous for women and caused breast cancer. Isn’t it possible we’ll eventually find out the same is true for testosterone and prostate cancer?
A. The fear that hormone therapy is dangerous in women is currently being reevaluated, and it appears to not be as dangerous as was originally proclaimed. More to the point, it is critical to understand that men are not women and that testosterone is not estrogen. Anyone, particularly a scientist, must always allow for the possibility that new information will one day change current views. But after so much research over so many decades, there is little reason to believe that T therapy poses a major risk for prostate cancer. As a medical student once said to me, “If testosterone is really so dangerous for prostate cancer, why is it so hard to show it?”
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