Do you obsessively scrutinize your skin for unusual blemishes and visit your doc for an annual whole-body check for cancer? It may not do you any good, a panel of government experts says.

The U.S. Preventive Services Task Force (USPSTF) says there isn’t enough evidence for or against the checks, during which you or your doctor looks for changes in the color, size and texture of skin growths. The panel's position—which reinforces guidelines it published in 2001—appears tomorrow in the Annals of Internal Medicine. The guidelines apply to people without noticeable changes in the symmetry, border, color or diameter of their moles—not to people with those symptoms or with a cancer history, says Tracy Wolff, a medical officer with the USPSTF who co-authored the paper.

The task force makes recommendations about the effectiveness of medical treatments every five to seven years to U.S. primary-care doctors. When it reviewed the latest data on whole body exams, the panel didn’t find evidence that they reduced mortality from skin cancer or the disease's spread. And it found that there are few studies of how accurately docs identify suspicious moles in real patients, rather than in photos. The task force recommends better research.

"There isn’t consensus about whether screening is beneficial or not. And there isn’t consistency about how frequently or which populations" should get checked, Wolff tells "It points to the limited evidence in this area."

Nevertheless, Wolff believes that the checks have likely become more common following awareness campaigns about skin cancer and sunscreen use. The American Cancer Society (ACS) and American Academy of Dermatology recommend skin exams as part of periodic adult checkups that include exams of the mouth, thyroid, ovaries, testicles and lymph nodes for cancer. The academy also advocates that the general public "check their birthday suit on their birthday." The American College of Obstetricians and Gynecologists recommends exams for teens and women who have lots of sun exposure or a family or personal history of skin cancer or precancerous lesions. The Skin Cancer Foundation also suggests annual checks by a dermatologist. "We believe people should be screened once a year and are not changing our guidelines," says Erin Mulvey, a spokesperson for the foundation.

Skin cancer is the most commonly diagnosed tumor in the U.S., with more than one million cases found annually, according to the ACS. Most types of skin cancer are treatable, but one form, melanoma—the kind of cancer Arizona Sen. John McCain has battled four times—can be deadly if it's not caught early. Melanoma killed an estimated 8,420 people in the U.S. last year, according to the National Cancer Institute.

Image of melanoma by National Cancer Institute via Wikimedia Commons