For men with low-risk prostate cancer, low levels of testosterone may indicate a worsening of their disease. That’s the conclusion of a new study published in BJU International. The findings may help physicians identify patients with low-risk prostate cancer who should receive aggressive anticancer treatment.
Men with prostate cancer that is not life threatening and is only slowly progressing, can often forego treatment and instead undergo active surveillance. This involves close monitoring to ensure that their disease does not become serious and jeopardize their health. Unfortunately, doctors currently have no reliable way of predicting which men will develop evidence of worsening or more aggressive disease during active surveillance.
Ignacio San Francisco, MD, of the Pontificia Universidad Católica de Chile, and his colleagues looked to see if testosterone levels might provide any indication. After following 154 men with low-risk prostate cancer for 38 months, the investigators found that low levels of free testosterone were significantly linked with an increased risk of developing more aggressive disease.
They found no significant association with total testosterone concentrations, although there was a general trend towards increased risk with lower levels. Free testosterone comprises one to two percent of total testosterone and is considered a useful surrogate for the biologically active portion of circulating testosterone.
“These results suggest low levels of testosterone are associated with more aggressive prostate cancer. This contradicts long-held beliefs that high testosterone is risky for prostate cancer, and low testosterone is protective,” said Dr. San Francisco.
Hormone therapy and prostate cancer
Hormones occur naturally in your body. They control the growth and activity of normal cells. Cancer of the prostate gland depends on the male hormone testosterone to grow. So lowering the amount of testosterone in the body can reduce the chance of an early prostate cancer coming back after treatment. Or it can shrink an advanced prostate tumour down or slow its growth.
Sometimes hormone therapy can make advanced prostate cancer symptoms disappear completely. This kind of treatment usually works well for a few years. After that, the cancer often stops responding to the hormone treatment and starts to grow again. There are various treatment options when that happens.
The results of this study provide valuable information to clinicians and their patients concerning risk factors for prostate cancer progression in men undergoing active surveillance. “In borderline cases, the presence of low values of free testosterone may help determine whether it is more prudent to initiate treatment rather than continue observation,” said Dr. San Francisco.
Testosterone is the most potent androgen, and it does make the man. It’s responsible for the deep voice, increased muscle mass, and strong bones that characterize the gender, and it also stimulates the production of red blood cells by the bone marrow. In addition, testosterone has crucial, if incompletely understood, effects on male behavior. It contributes to aggression, and it’s essential for the libido or sex drive, as well as for normal erections and sexual performance. Testosterone stimulates the growth of the genitals at puberty, and it is one of the factors required for sperm production throughout adult life. Finally, testosterone also acts on the liver. Normal amounts are harmless, but high doses can cause liver disease and boost the production of LDL (“bad”) cholesterol while lowering the amount of HDL (“good”) cholesterol.
Although testosterone acts directly on many tissues, some of its least desirable effects do not occur until it is converted into another androgen, dihydrotestosterone (DHT). DHT acts on the skin, sometimes producing acne, and on the hair follicles, putting hair on the chest but often taking it off the scalp. Male-pattern baldness (androgenic alopecia) is one thing, prostate disease quite another – but DHT also stimulates the growth of prostate cells, producing normal growth in adolescence but contributing to benign prostatic hyperplasia (BPH) in many older men.
Scientists have taken advantage of the link between male pattern baldness and BPH to develop a single medication for both conditions. Finasteride blocks the conversion of testosterone to DHT; when taken in a 5-mg dose (Proscar), it helps some men with BPH, and in a 1-mg dose (Propecia), it helps some men with androgenic alopecia. A newer drug, dutasteride (Avodart), has a similar effect on BPH but is not yet approved for baldness.