Rare skin cancers of the hair, nails, sweat and mammary glands appear to be increasing in the United States, according to a study published in the Archives of Dermatology, and reported by AOL Health.

For the study, researchers from the National Cancer Institute looked at trends, incidence and survival rates from 16 cancer registries from 1978 to 2005.

Findings showed cancer of the sweat glands was the most commonly diagnosed form of these rare cancers. Cancer rates were greatest in non-Hispanic whites and least in Hispanic whites, blacks, Asians and Pacific Islanders.

Scientists also noted that men were more likely than women to get one of the cancers. And, in general, the cancer rates rose with age.

Although researchers don’t know why these rare skin cancers have increased, Jorge R. Toro, MD, the study’s author, said some reasons included changes in the way tumors are currently being classified, in the increase in sun and UV radiation exposure and the growing population of elderly Americans.

But researchers said there is hope. Scientists found patient survival rates were 99 percent if docs caught tumors early and confined them to one area. If the cancer spread, the survival rate was 43 percent.

Click here to learn why sun protection is vital to reducing your skin cancer risk.