Christopher R. Shea, MD
The eighth edition of the American Joint Committee on Cancer (AJCC) Cancer Staging System is going into effect January 1, 2018, with the goal to educate clinicians on 12 new staging systems and revised staging definitions—an area likely to help physicians treating patients with melanoma.
The updated AJCC edition, as well as other changes in the melanoma field, should be absorbed beyond researchers, experts say. Dermatologists and pathologists must also familiarize themselves with the evolving landscape, especially for their patients.
“It is important for dermatologists to know more than only about the skin aspects, because many patients will view their dermatologists as their primary care physician for their melanoma,” explained Christopher R. Shea, MD. “It is important to know something about the revolution in the molecular biology of melanoma. Obviously, we are not in a position to perform—in most cases—the sentinel lymph node surgeries or to prescribe and manage these checkpoint inhibitors and so forth. But, we need to know about them.”
Shea, the Eugene J. Van Scott Professor of Medicine, chief of the Section of Dermatology at The University of Chicago Medicine, discussed the pathology and dermatologic management of melanoma during the 2017 OncLive®
State of the Science Summit on Melanoma and Immuno-Oncology. In an interview during the meeting, he expressed the importance of expanding melanoma knowledge to more specialists as well as the advancements in pathology over the last several years.
OncLive: What did you discuss on your lecture on pathology in melanoma?
: Pathology is actually extremely important because that’s where it all begins; that is how we get the diagnosis. More importantly, we can also get a lot of information about prognosis. We get the diagnosis, which is what it is, and prognosis, which is what it may do.
Over the years, pathologists have developed a more refined understanding of what to look for under the microscope to get that information, which is used for staging. Clinical and pathologic staging dictates the treatment, and it’s also very important for predicting survival.
What advances have we seen in pathology over the last few years?
Most importantly, there’s going to be a new AJCC Cancer Staging System that’s actually being published now; it’s in a period now in which we’re learning about it and people can get ready for it. It will be in effect in January 2018. This incorporates some changes from the seventh edition. Again, it has to do with particulars of the pathologic changes, like the importance of the mitotic figures and the ulcerations in the tumors.
What are the biggest differences between the seventh and eighth editions?
Most importantly, it has to do with thin melanomas—which were thought to be 1 millimeter or less. They were thought to be stage Ia unless they had either mitotic figures or ulcerations. The presence of either or both would upgrade the disease to stage Ib, which means that it is a worse prognosis. It is still stage I, but it’s a worse subset of that.
It’s been discovered that the mitotic figures, although they’re still very important, are not the best way to classify the staging. Therefore, that’s actually been dropped as a criterion for stage Ia and stage Ib. After only being in the AJCC classification for one go around—the previous edition—it’s now been dropped. Instead, they are looking at 1-millimeter thickness but also 0.8 millimeters as a breakpoint. The point of this is that, previously, very thin melanomas that might have had 1 mitotic figure were automatically considered to be a higher risk and undergo sentinel lymph node biopsies. It was very rare that those were found to be metastatic melanomas. That is the rationale for that change.
What major questions still exist with staging melanoma?
As with all kinds of staging, staging is a general prediction for a population and not for a single individual patient. There is always an element of probability to it. The refinements we’re going to see going forward will likely be related to novel markers of the biology of the tumor that hopefully are going to be validated. However, right now, they are still not reflected in the official staging classifications.