Preliminary data suggest that severe acne, as measured by tetracycline use for four or more years, may be associated with an increased risk of prostate cancer, according to a recent report.


Researchers at the Johns Hopkins Bloomberg School of Public Health in Baltimore and the Har-

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vard School of Public Health in Boston based the finding on a study of participants in the Health Professionals Follow-up Study, which in 1986 enrolled 51,529 male health professionals aged 40 to 75 years.


A 1992 follow-up questionnaire asked subjects whether they had ever used tetracycline for at least two months at a time, for example, as a treatment for acne or some other condition, and for how long (two to 11 months; one to two years; two to three years; or four or more years). Tetracycline has long been used as a treatment for severe acne.


Only 0.5% of the 34,629 men eligible for the 1992 follow-up had used the antibiotic for four years or longer. The men who used tetracycline for at least four years had an adjusted 70% higher risk of prostate cancer compared with men who did not use tetracycline, the investigators reported in the International Journal of Cancer (2007;121:2688-2692).


These men were more likely than the those who never used tetracycline to report a history of young-onset prostatitis and other prostatitis, more regular use of non-steroidal anti-inflammatory drugs, less vertex baldness, a greater number of blistering facial sunburns, greater alcohol intake, and less milk and calcium intake. Therefore, these and other factors were taken into account in the analysis. The re-searchers observed no association between prostate cancer and use of tetracycline for less than four years.


In 2006, 100 randomly selected men who reported tetracycline use on the 1992 survey were mailed a supplemental questionnaire on indications for tetracycline; the group included 50 men who reported using the antibiotic for less than four years and 50 who reported using it for four or more years.


Of the 41 patients who used tetracycline for less than four years, 41.5% reported that it was used to treat acne, 14.6% for rosacea, and 21.9% for various other conditions. Twenty-two percent denied or could not recall using the drug for at least two months. Most of these men originally reported using the antibiotic for only two to 11 months.


Of the 42 subjects who reported four or more years of tetracycline use, 61.9% reported taking for

acne, 23.8% for rosacea, 4.8% for folliculitis, and 7.1% for other conditions or reason that they had since forgotten, the authors noted. One man (2.4%) denied using the antibiotic for at least two months.


The researchers noted that two other prospective studies yielded similar results, with one study uncovering a nonsignificant association between prostate cancer mortality and self-reported acne history, and the other finding a nonsignificant link between prostate cancer and the presence of Propionibacterium acnes—a bacterium believed to have a role in acne pathogenesis—in specimens of transurethral resection of the prostate.


The investigators say their results should be viewed cautiously because of the small number of subjects exposed to tetracycline, the use of a surrogate measure of severe acne, and the complex etiology of acne, which can have causes other than Propionibacterium acnes infection.