Detection of melanoma by dermatologists linked with earlier tumor stage, higher survival rates
(17 April 2007: VIDYYA MEDICAL NEWS SERVICE) -- Individuals whose melanoma is diagnosed by a dermatologist may be more likely to have early-stage cancer and to survive five years than those with melanoma diagnosed by a non-dermatologist, according to a report in the April issue of Archives of Dermatology, one of the JAMA/Archives journals.
Estimates suggest that melanoma will affect 1 in 52 men and 1 in 77 women in the United States during their lifetimes, according to background information in the article. If melanoma is removed at an early stage, when the tumor is still relatively thin (less than 1 millimeter thick), patients have a 90 percent cure rate. However, metastastic melanoma that has spread to other areas usually requires both surgery and chemotherapy and five-year survival rates are less than 20 percent. "From a health policy perspective, whether a difference in melanoma outcome is associated with a patient’s physician type (specifically, dermatologists vs. non-dermatologists) is of particular interest to this discussion," the authors write.
Michelle L. Pennie, M.D., Emory University School of Medicine, Atlanta, and colleagues attempted to determine whether such a difference exists using data from two sources: Medicare enrollment and claims files from the government and a National Cancer Institute (NCI) database that includes information about patients’ demographics, date of diagnosis, stage of cancer at diagnosis and date of death. The researchers linked records from the two databases for 2,020 patients, comparing codes for different kinds of physician visits in the Medicare database to cancer diagnoses and outcomes in the NCI database.
Of the 2,020 patients, 1,467 (73 percent) were diagnosed with melanoma by a dermatologist and 553 (27 percent) were diagnosed by a non-dermatologist. Tumors diagnosed by dermatologists were thinner on average than those diagnosed by non-dermatologists (.86 millimeters vs. 1 millimeter). "We also looked at melanoma stage at diagnosis and observed significant differences between provider types, with a preponderance of thin melanoma (stage zero, or stage I or II) in the dermatologist group and a preponderance of thick melanoma (stage III or stage IV) in the non-dermatologist group," the authors write.
After six months, two years and five years, patients whose cancer was diagnosed by a dermatologist had a higher survival rate than those diagnosed by a non-dermatologist. "The two-year and five-year survival rates were 86.5 percent and 73.9 percent for the dermatologist group compared with 78.8 percent and 68.7 percent for the non-dermatologist group," the authors write. "When looking at the mortality rates by cause of death, both groups had similar non-cancer–related mortality rates. However, the dermatologist group had lower cancer-related mortality rates and a lower overall mortality rate."
Patients who visited dermatologists most likely had higher survival rates because their tumors were thinner and detected earlier, the authors note. "Although the difference between a melanoma that is .86 millimeters thick and one that is 1 millimeter thick does not correlate with different clinical stages, tumor thickness is a powerful predictor of patient survival and a likely driver of the outcomes we observed," the authors write.
"These results suggest that increasing access to dermatologists, particularly for older patients who have higher rates of melanoma, may represent one approach to improving melanoma-related health outcomes from a health policy perspective," the authors conclude.
Arch Dermatol. 2007;143:488-494.
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