Physicians take critical look at AJCC staging system, melanoma prognostication tool

Key Points

International report - The latest melanoma staging system from the American Joint Committee on Cancer (AJCC) and a tool developed for predicting the clinical outcome of individual patients with localized or regional cutaneous melanoma ( http://www.melanomaprognosis.org/) have stirred debate among dermatopathologists.

According to Clay J. Cockerell, M.D., the frequency with which new recommendations on melanoma pathology reporting and prognostication have been issued by the AJCC in the past few years has created frustration for clinicians trying to remain current. He also questions the process by which the recommendations are developed, noting that the responsible committee is composed predominantly of surgeons and oncologists, whereas dermatologists and dermatopathologists, who are on the front line of making the diagnosis, were minimally represented.

Furthermore, retrospective studies often are used as an information source for developing the recommendations, and there is no vetting of the recommendations by the specialty societies that are important stakeholders prior to finalization, says Dr. Cockerell, director, division of dermatopathology, University of Texas Southwestern Medical Center, Dallas.

Focusing on the tool for melanoma prognostication, Dr. Cockerell says he questions its heavy weighting on histology.

"The impetus for the most recent changes to the AJCC staging system reflects a desire to provide more accurate prognostication for individual patients diagnosed with melanoma. However, despite what the committee would like, the microscope is simply not a crystal ball," Dr. Cockerell says.

"There are several problems with using melanoma histologic variables for prognostication, and it is also important to keep in mind that disease course and patient outcome are influenced by the individual's immune response plus other factors that are not taken into account by looking under the microscope," he says.

Outlining the shortcomings of the AJCC criteria for prognostication, Dr. Cockerell says that one of the problems is that the histologic variables cannot be applied to partial biopsies in many cases. In addition, several of the variables used, including Breslow thickness, ulceration, regression, and vertical growth phase, are subjective.

The simplified reporting of ulceration as either present or absent is also problematic, as it poses the potential for overcalling ulceration, a feature that places patients in a worse prognostic category, he explains.

"Identifying ulceration as absent or present does not allow differentiation between an advanced lesion that is necrotic and infarcted and a thin lesion that appears ulcerated as a result of external trauma," he says. "At least one study performed by Googe et al. (J Cutan Pathol. 2011;38(1):112-113) has shown that ulceration in thin melanomas is rare, so dermatologists should be wary if ulceration is reported in a thin melanoma, especially those less than 1 mm in thickness."