Melanoma and testosterone
High testosterone levels in men are associated with an increased risk of melanoma
A new study shows that testosterone levels in the body are statistically associated with the risk of developing potentially fatal skin cancer, but the causal relationship between them remains unproven.
According to Cancer Research UK, which funded the study, one in 36 British men and one in 47 British women will be diagnosed with melanoma during their lifetime. The analysis shows that 86% of melanoma cases can be prevented by reducing the use of tanning beds or sun exposure, but other factors, including age and genetics, also determine the degree of risk. One of these factors turned out to be testosterone, at least for men.
"There has been indirect evidence of a link between testosterone and melanoma before, but this is the first time we have been able to look directly at hormones in the blood," says Eleanor Watts from Oxford University. "Although we've seen prostate, breast and endometrial cancers linked to testosterone before, this is the first time we've seen such an association with melanoma risk in men."
In an article published by the International Journal of Cancer (Watts et al., Prospective analyses of testosterone and sex hormone‐binding globulin with the risk of 19 types of cancer in men and postmenopausal women in UK Biobank), Watts and her colleagues report that they studied data on testosterone levels in blood samples, collected by the British Biobank from 182,600 men and 122,100 women aged 40 to 69 years. All participants did not have cancer for at least two years after taking samples and did not take hormonal drugs at the beginning of the study. The researchers took into account both the total level of testosterone in the blood and freely circulating testosterone – in other words, testosterone not bound to proteins. They then used National Health Service records to find out if the participants had melanoma.
The results show that by 2015-2016, 9519 men and 5632 women (5.2% and 4.6% of participants, respectively) had been diagnosed with cancer. Other types of skin cancer, except melanoma, were not taken into account. The analysis took into account many factors, including ethnicity, body mass index, smoking, alcohol consumption and physical activity, to find out if there is a correlation between testosterone levels and specific types of cancer. It turned out that in men, a higher level of testosterone, free or total, was associated with a greater risk of developing malignant melanoma. Thus, it was found that an increase in free testosterone for every 50 picomoles per liter increases the likelihood of developing melanoma by 35%. According to Watts, 90% of the men included in the study had a concentration of free testosterone from 130 to 310 pmol/L.
Among other results, higher levels of freely circulating testosterone were found to be associated with an increased risk of prostate cancer in men, while in postmenopausal women, high levels of testosterone, free or total, were associated with a greater likelihood of endometrial and breast cancer. However, it is not yet possible to talk about a direct connection of testosterone with these diseases. "It's hard to say for sure that these effects are caused by testosterone, and not by another biomarker associated with it," Watts says, adding that further research is needed. There is, for example, the possibility that a high level of testosterone is associated with behavioral patterns, including professional activities, which increase the dose of solar radiation received by a person. "For everyone, regardless of gender, the main way to reduce the risk of skin cancer, including melanoma, is to avoid the harmful effects of the sun," the scientists remind.
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