Using a unique, long-term data set from their country's military, Swedish investigators report that acne in late adolescence is associated with a statistically significant increased risk for prostate cancer compared with not having acne in the latter teen years. The analysis is the first prospective, large-scale, population-based study using clinically diagnosed acne to test the idea that the skin condition may be tied to prostate cancer. The study was published online December 4 in the International Journal of Cancer. The Swedish team reviewed long-term health data on 243,187 young men, almost all of whom were born in the mid-1950s and conscripted into the country's military as 18- and 19-year olds, during the 1970s. At the time, military service was mandatory in Sweden, but this requirement was dropped in the 1980s. Acne was one of many conditions evaluated and recorded at the time of conscription. During a median follow-up of 36.7 years, 1633 men were diagnosed with prostate cancer, report the authors, led by Henrik Ugge, MD, a urologist at Örebro University. Most of the men with prostate cancer did not have acne (n = 1586). Of those with acne (n = 47), only 2 had severe disease. A prostate cancer risk was present for acne in general (hazard ratio [HR], 1.43; 95% confidence interval [CI], 1.06 - 1.92) but was more dramatic and nearly sixfold for severe acne (HR, 5.70; 95% CI, 1.42 - 22.85). An epidemiologist not involved with the study pointed out that the severe acne finding is less exact. "The hazard ratio of 6 is based on only 2 men with severe acne developing prostate cancer. That estimate is not very precise as it has a very wide confidence interval. The association for acne vs no acne of 1.4 is much more precise," said Elizabeth Platz, ScD, MPH, professor of epidemiology at Johns Hopkins Bloomberg School of Public Health in Baltimore, Maryland. The recorded 2% prevalence of acne in the military cohort, say the study authors, is much lower than that of the general adolescent population in Western countries. However, they point out that 2% is in keeping with other findings on acne in similar settings. In short, they suggest that the acne had to be extensive to be recorded at all and very severe to recorded as severe. When looking at disease stage, the researchers found a statistically significant association between acne and advanced cancer (HR, 2.37; 95% CI, 1.19 - 4.73). However, the tie with localized disease was of "borderline" significance (HR, 1.39; 95% CI, 1.00 - 1.94). The new findings add to "accumulating evidence" that suggest Propionibacterium acnes, which is commonly associated with acne vulgaris, may play a role in prostate carcinogenesis, say Dr Ugge and his coauthors. P acnes is part of the normal flora of the skin, large intestine, and other organs but may become pathogenic. The bacterium has been identified as the most prevalent microorganism in prostate cancer specimens, the authors point out. These bacteria have also been tied to the presence of inflammatory foci in prostate cancer, they add. The Swedish team has been among many researchers worldwide investigating the possible association between acne and prostate cancer in the last decade. "We have, for example, previously observed that P acnes are more common in prostates from men with prostate cancer compared to cancer-free controls," Dr Ugge told Medscape Medical News. Other research has found a tie between acne and prostate cancer risk. For example, another cohort study that used prospectively collected data showed an increased prostate cancer risk for men who recalled earlier tetracycline treatment for more than 4 years; the drug is commonly prescribed for severe acne and was used as a marker thereof (Int J Cancer. 2007;121:2688-2692). The senior author of that 2007 paper was Dr Platz. She commented to Medscape Medical News that the possible link between acne and prostate cancer is "not common knowledge." Dr Platz said it is more recognized that the phenomenon of prostate tissue inflammation may be tied to the development of prostate cancer. "Bacterial infection [such as with P acnes] is one possible elicitor of inflammation," she explained. Asked to comment on the new from Sweden, Dr Platz said, "I am impressed by the scale of the study, the clever use of military conscription records circa late adolescence that included information on acne from the physical examination, and the ability to follow up these men for prostate cancer." I am impressed by the scale of the study [and] the clever use of military conscription records. Dr Elizabeth Platz The "few" other epidemiologic studies exploring the acne–prostate cancer tie have been "inconsistent," said Dr Ugge and coauthors. But that mixed bag may be the result of self-reported acne and retrospective data collection, they observe. The extensive record-keeping at a federal level in Sweden was a big help in examining the possible tie between acne and prostate cancer. "The possibility to assess the large cohort available in the Swedish Military Conscription Register presented a great opportunity to address the question — albeit indirectly — from an epidemiological perspective," said Dr Ugge. Prostate Cancer Was Mostly Detected Earlier Than Is Typical Dr Ugge and coauthors point out that their efforts might be described as having examined the association between acne and early prostate cancer diagnosis because the median follow-up was about 37 years and the men were originally 18 and 19 years old. It is unknown whether the associations found will remain for prostate cancer at later ages. But Dr Ugge suspects that the ties will continue over time. "It is possible that this finding only holds for prostate cancer at a younger age," he said, but he pointed out that "a previous epidemiological study [the one conducted by Dr Platz and colleagues] with follow-up to a higher age, which used long-time tetracycline treatment as a marker for severe acne, observed similar results. This suggests that the association may be generalizable also to later ages." Nevertheless, more research is needed into this possible link between acne and prostate cancer. For now, says Dr Ugge, "the result of the study is of more theoretical interest, in the general discussion on the role of inflammation and possible implication of P acnes in prostate carcinogenesis." The study was supported by grants from the UK Economic and Social Research Council. The authors and Dr Platz have disclosed no relevant financial relationships. Int J Cancer. Published online December 4, 2017. Abstract Source
