Women have long been overrepresented in incidences of anal cancer and a new Tasmanian study may give some clue as to why.

Researchers from the Menzies Institute for Medical Research and University of Tasmania School of Medicine have found that front-to-back wiping may be linked with HPV-associated anal outcomes, including presence of cancer or pre-cancer, and of cancer-causing HPV carriage in the anus.

Compared to other women, women who wiped front-to-back were up to 1.9 times more likely to have abnormal anal cytology, up to 3.6 times more likely to have abnormal anal histology, and up to 2 times more likely to have anal carriage of cancer-associated HPV. 

At the same time, women who dabbed post-toilet had significantly lower frequencies of these anal outcomes, from one-quarter to more than three-quarter reduction in anal outcomes compared with women who did not dab.

Women who wiped back to front – less than 10 per cent of participating women – showed no significant impact on anal outcomes.

"It is a potential explanatory factor and something we want to explore further," research team member Dr Steve Simpson Jr said.

"It's been a long-standing medical mystery why women make up a large proportion of anal cancer."

Researchers were unable to make recommendations from the study and cannot ascribe causality, but Dr Simpson had some advice: "If one were to make recommendations, it would be that dabbing might be the safest thing to do," he said.

More than 160 Tasmanian women with human papillomavirus-mediated gynaecologic cancer or high-grade dysplasia were recruited for the The Tasmanian Gynaecological and Anal Neoplasia Study.

Researchers aimed to evaluate the prevalence and determinants of comorbid anal dysplasia and oncogenic human papillomavirus anal carriage. 

The study was printed in the journal Cancer Epidemiology.