Group revises staging system for melanoma
January 1, 2002
Group revises staging system for melanoma
Evidence-based study shifts several priorities
A committee of the American Joint Committee on Cancer (AJCC) has significantly revised the staging system for cutaneous melanoma, which can be crucial in helping physicians determine the best treatment and helping patients understand the extent of their disease. What was most significant about the findings of the committee is that they were based, for the first time, on an in-depth statistical analysis.
"Often the cancer staging systems that are developed are based on a review of the literature, or on very sketchy data from institutions, so we never really had one staging system that fully utilized a database that looks at it in-depth," explains Seng-jaw Soong, PhD, a biostatistician at the University of Alabama at Birmingham’s (UAB) Comprehensive Cancer Center, on whose work the revisions were based. "For melanoma, this is the first time we have been able to compare data from different institutions around the world to provide a universal database, and I believe we have been quite successful in developing what we feel is a very accurate staging system for melanoma," Soong says.
In addition to UAB’s 25-year database, the statistical analysis used data from 13 other institutions around the world, incorporating information from 17,600 patients, he explains. Evidence-based staging is far superior to staging derived solely from the literature, Soong says. "The literature can be incorporated, too, but the most important component is data. In a review of literature, you see reports from here and there, so the data set may not be uniform. Ours, on the other hand, is both large and uniform," he says.
The AJCC staging system classified melanoma in four stages:
- Stage I or Stage II melanoma is localized disease.
- Stage III is regional disease.
- Stage IV means the cancer has spread to distant parts of the body.
As a result of the statistical study, several significant changes were made in melanoma staging. For example, tumor ulceration, which is not included in the current staging system, has been prioritized in the new system.
Microscopic examination of ulceration, Soong explains, can be an indication of tumor aggression. "Much of the research shows ulceration to be an important prognosis factor, but it had never been used in current or in previous staging. Because we now had a data set, we could see its importance. In fact, in our medical model, it shows ulceration to be the second most important factor; this was a very important finding." Other significant changes were made, including a shift in focus to the number of positive nodes, as opposed to the size of nodes, which again was borne out by the data. And the level of tumor invasion as a predictor was minimized, except in select cases.
Having the most accurate data possible is critically important, Soong notes, because "a staging system has important implications in quality control of patient care." Soong says this approach has implications far beyond melanoma. "The major implication of this work is not just a much improved melanoma staging system for the AJCC, but also creating a model for developing evidence-based staging systems for other cancers." In fact, he adds, this type of staging system could be used for all types of cancers.
There might be components that would be common to all evidence-based staging systems, says Soong, but that is not really the critical issue. "There would clearly be different factors, because we would be dealing with a different set of cancers, such as in breast cancer," he says. "But if we could pull all of the data sets together in a more uniform fashion, then we could develop a very good staging system."
Need more information?
For more information, contact: Seng-jaw Soong, PhD, Tumor Institute, University of Alabama at Birmingham, Birmingham, AL 35242. Telephone: (205) 934-3679.
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