Older men should visit their doctors to check for melanoma because they are less likely to find it themselves in time, U.S. researchers said on Monday.

Many men over 40 are not aware of their skin cancer risks, or the need for regular exams to check for early signs skin cancer, when it is easiest to treat, they said.

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Trained doctors are more likely to spot a dangerous skin cancer early, Dr. Susan Swetter of Stanford University Medical Center in California and colleagues wrote in the Archives of Dermatology.

"For men 40 years or older, who constitute more than half of all melanoma deaths in the United States, we have identified at least two key variables (physician exams and education) as major targets for new interventions to promote earlier melanoma detection," the researchers wrote.

Melanoma, the rarest and deadliest form of skin cancer, is becoming more common and death rates are climbing, especially among men over 50.

Swetter and colleagues surveyed 227 melanoma patients age 40 and older between 2004 and 2006 within three months of being diagnosed. Fewer than 20 percent of the men were aware of melanoma warning signs and fewer than half practiced skin self-examinations.

A quarter of the men had thick, harder-to-treat tumors. Those whose tumors were smaller and thus more treatable were more likely to have been aware of skin cancer risks and the importance of skin cancer exams by doctors.

Another analysis of the data by Alan Geller of Harvard found more than half of patients whose melanomas were detected by a doctor were 65 or older.

Americans over 65 have health coverage under Medicare, the federal insurance program for the elderly, and tend to make more frequent visits to their doctors.

Most of the melanomas were on the patient's back, and Geller and colleagues said the findings suggest the need for "Watch your back" education campaigns that stress the need for physician screening programs, particularly for this high-risk group.

Melanoma accounts for less than 5 percent of skin cancer cases but causes most skin cancer deaths. The American Cancer Society estimates that about 62,480 new melanomas were diagnosed in the United States during 2008.