Dermatologist skin examinations detect more, thinner skin cancers than patients identify themselves

Most melanomas detected in a general-practice dermatology clinic were found by dermatologists during full-body skin examinations of patients who had come to the clinic for different complaints, according to a report in the August issue of Archives of Dermatology, one of the JAMA/Archives journals. In addition, cancers detected by dermatologists were thinner and more likely to be in situ (only on the outer layer of skin) than were cancers detected by patients.

"Early melanoma detection is the cornerstone of effective treatment, but guidelines remain sparse regarding appropriate screening procedures for both the general population as well as high-risk patients," the authors write as background information in the article. "While it is known that screening identifies melanomas at an earlier stage than would be found otherwise and that physicians detect melanomas with less tumour thickness, the US Preventive Services Task Force states that current evidence is insufficient to recommend for or against routine screening. The population seen in skin cancer screenings differs markedly from that seen in a dermatology practice with a high-risk patient population."

Jonathan Kantor, MD, MSCE, and Deborah E. Kantor, MSN, CRNP, of North Florida Dermatology Associates, Jacksonville, analysed 126 cases of melanoma diagnosed at the practice between July 2005 and October 2008. Of these, 51 cases were invasive (had spread to deeper layers of the skin) and 75 were in situ.

Overall, 56.3 percent of all melanomas and 60 percent of melanomas in situ were detected by the dermatologists and were not among the reasons the patient had visited the clinic. "A greater proportion of melanomas in the physician-detected group (mean [average], 63.4 percent) than in the patient-detected group (mean, 54.5 percent) were in situ," the authors write.

Dermatologist detection was also associated with thinner melanomas. "Including only invasive melanomas, the median [midpoint] melanoma depth for the physician-detected group was 0.33 millimetres, and for the patient-detected group the median depth was 0.55 millimetres," they continue. Patients whose melanoma was detected by a clinician were significantly more likely to have cancers thinner than 1 millimetre.

"These data suggest that minimising the substantial public health and financial impact of melanoma may be aided by a full-body skin examination. While self-examination plays a critical role in early detection, prior studies have suggested that physicians, and dermatologists in particular, may be better able to detect melanomas with lesser tumour thickness. Because increasing tumour thickness is closely correlated with decreasing survival, it follows that complete examination plays an important role, particularly in high-risk populations," the authors write.

"Further research in this area, and in the cost-effectiveness of screening, may lead to important changes in practice that could potentially reduce melanoma mortality and improve patient outcomes," they conclude.

(Source: JAMA/Archives: Archives of Dermatology: August 2009)