Earwax and breast cancer might be genetically linked.© Photodisc.

Are you wet and sticky or dry and tan? A fingerful of earwax could reveal more than you think, say researchers homing in on the gene that makes ears gluey or flaky. They believe that the same gene could be linked to susceptibility to breast cancer.

Earwax, or cerumen, comes in two types: wet or dry. The consistency depends on secretions from glands in the outer ear, which combine with sloughed off skin and hair. The wet stuff is brown and sticky, the dry version grey or tan and brittle.

Norio Niikawa and his colleagues at the Nagasaki University School of Medicine in Japan were inspired to scrape out ears by the fact that breast cancer rates are higher in Japanese women with wet rather than dry wax.

The observation suggests that the earwax gene, or others close to it, affect incidence of the disease. "We thought it a good opportunity to study the genetics of earwax," Niikawa says. The researchers presented their results at May's International Congress on Human Genetics in Vienna.

Earwax and breast cancer might be genetically linked.© Photodisc.

The group sought out the gene by tracing earwax type in eight families - first interviewing them and then, if wax consistency was unclear, taking a swab. Like the shape of Mendel's peas, wax type has a classic pattern of inheritance, with the wet form 'dominant' over dry.

"It's an interesting story," says Nicholas Petrakis, who studies breast cancer at the University of California, San Francisco. The frequency of earwax types is known to vary in different ethnic groups. Wet predominates in European and African populations, whereas dry is more common in Asia.

Earwax glands are related to the apocrine glands that secrete fluid in the breast, he explains, so it is plausible that in some populations one gene could have a role in both wax type and breast-cancer risk. "It'll be a great one if it's true," says Petrakis - an earswab would be an easy test for this genetic risk factor.

"We expect the earwax gene to control the development and function of the apocrine glands," agrees Niikawa.