A statistical formula based on the risk factors for melanoma may help define an individual’s risk of developing the skin cancer, according to researchers.

Melanoma is the least common, but deadliest, form of skin cancer. Studies have uncovered a number of risk factors - including family history of the disease, light skin and a history of bad sunburns - but that does fairly little to define any one person’s risk of developing the disease.

In contrast, building a statistical model that incorporates an individual’s risk factors for melanoma may zero in on that person’s odds of developing the disease, according to Dr. Eunyoung Cho of Brigham and Women’s Hospital and Harvard Medical School in Boston, the lead author on the new study.

She and her colleagues found that among 535 white adults who developed melanoma over 14 years, older age, family history, a high number of moles, history of severe sunburn and light hair were each associated with an increased risk of the skin cancer. In addition, men were at greater risk than women.

The researchers used these risk factors to develop a statistical model that predicted, with fair accuracy, a person’s odds of developing melanoma.

For example, a 50-year-old woman with no family of melanoma, one or two severe sunburns in her life, a few moles and blond hair was given a higher “risk score” than a woman the same age who had no moles, no history of bad sunburns and light brown hair. The former, according to the statistical model, was four to five times more likely than the latter to develop melanoma.

No statistical formula is perfect told Cho, but she explained, “This type of statistical model can summarize the impact of multiple risk factors and could be useful for clinicians to counsel their patients.”

Cho and her colleagues report their findings in the Journal of Clinical Oncology.

Overall, the “profile” of a person with the lowest risk of developing melanoma over the next 10 years was a 40-year-old woman with black hair, no moles, no history of severe sunburns and no melanoma in her family.

On the other hand, a redhead with multiple moles, a family history of melanoma and past episodes of serious sunburn would have a much higher risk of the skin cancer.

Eventually, the researchers note, a reliable statistical model could allow doctors to more precisely define an individual’s risk of melanoma, and possibly avoid removing skin lesions that are unlikely to become cancerous.

SOURCE: Journal of Clinical Oncology, April 2005.