Combes et al. Page 2954

Oropharyngeal cancer (OPC) is more frequent in men than women due to heavier and longer smoking rates in men. To determine if there is a difference in the proportion of human papillomavirus (HPV)–attributable OPC between men and women, Combes and colleagues retrieved HPV prevalence data from 63 OPC studies with gender data. The authors report that the U.S. had the highest M/F ratios of HPV prevalence in OPC, and the lowest M/F ratios were found in Asia. This work confirmed that HPV prevalence in OPC differs by gender and country, most likely as a consequence of male smoking habits.

Hou et al. Page 2748

Although physical activity (PA) is modifiable and linked to decreased breast cancer risk, its impact has not been investigated among indigenous African populations. Hou and colleagues recruited 558 breast cancer patients to complete a PA questionnaire. PA was significantly associated with reduced breast cancer risk in both pre- and postmenopausal women, with a dose–responsive relationship. The inverse association was present among lean women and overweight women, but not among obese women. PA of African women mainly consists of housework and work-related activities but this preliminary study suggests that modest PA may be significantly associated with reduced breast cancer risk.

Söderlund-Strand et al. Page 2757

Organized human papillomavirus (HPV) vaccination was introduced in Sweden in 2012 and on-demand vaccination has been in effect from 2006–2011. Söderlund-Strand and colleagues followed HPV prevalences in Sweden from 2008 to 2013. The authors report that among 13- to 22-year-old women, HPV6, 16, and 18 decreased from 2008 to 2013. HPV vaccination rates among 23- to 40-year-old women were lower compared to the younger population and HPV18 decreased only marginally. Major reductions of HPV6, 16, and 18 were found in age groups with concomitant increases in HPV vaccination coverage.

Khodr et al. Page 2765

Lesser degrees of terminal duct lobular unit (TDLU) involution have been associated with increased breast cancer risk, but factors that influence involution are largely unknown. Khodr and colleagues assessed whether circulating hormones are associated with levels of TDLU involution. Among premenopausal women, higher prolactin levels were associated with higher TDLU counts but higher progesterone was associated with lower TDLU counts. Among postmenopausal women, higher levels of estradiol and testosterone were associated with higher TDLU counts. These data suggest that select hormones may influence breast cancer risk, potentially through delaying TDLU involution.