According to Ms Dobrea, Manager of the Oncology Research and Biospecimen Program at St. Joseph Hospital/Center for Cancer Prevention and Treatment in Orange, CA, cancer staging is vital to the medical community because it provides a common language for physicians around the world to talk about a cancer with no ambiguity or misunderstanding, and to thereby further medical advancements.
AJCC staging is a formalized process of determining how much cancer is in the body by classifying the location and size of the primary tumor, as well as its lymph node involvement and the extent to which it has spread. “By understanding the staging, we can determine what we’re dealing with, including the prognosis and treatment options,” she said. “And that includes treatment options on clinical trials.”
AJCC Staging Overview
Internationally, the TNM staging system in the AJCC Cancer Staging Manual is the most widely used system of cancer staging. This system categorizes cancer using 3 categories: The “T” category describes the original primary tumor, the “N” category describes whether the cancer has reached nearby lymph nodes, and the “M” category tells whether the cancer has spread to other parts of the body.
“Think of it as the category representing dollar bills and the subcategory representing the change. Add that together to get the final stage,” she explained. “It’s really important to know what stage the patient is so you know their prognosis and treatment options.”
There are 5 types of staging: clinical, which establishes how much cancer is present based on physical exams and imaging (nomenclature is cTNM); pathologic (pTNM); recurrence (rTNM); autopsy (aTNM); and posttherapy, which refers to a patient who has already had neoadjuvant therapy and is staged again at a later time (ycTNM). “But it’s important to remember that in cancer, restaging doesn’t really exist,” she clarified. “If a patient with stage 2A breast cancer later becomes metastatic, you still refer to them as having stage 2A disease that has progressed or metastasized. As far as treatment options and prognosis, that’s very different than the case of someone who walks in with late-stage cancer.”
Molecular profiling also serves to provide a snapshot of the unique combination of elements that characterize a tumor. According to Ms Dobrea, tumor markers/biomarkers can help to guide and monitor treatment and predict recovery and recurrence, although they are not technically part of the staging process.
8th Edition Main Changes
Some of the high-level changes to the 8th edition include a more rigorous level of evidence and scientific review, and a transition from a “population-based” to a more “personalized” approach. The old AJCC staging editions used population-based survival data to predict clinical outcomes with TNM staging alone. It now incorporates nonanatomical factors in finding population survival outcomes (Gleason Score in prostate cancer; ER, PR, and HER2 in breast cancer; and LDH in melanoma).
Imaging is now included in every chapter in the staging manual. Each disease site has a dedicated chapter, and the imaging component in each chapter guides physicians on what to order, gives clear reporting guidelines to radiologists, and aids in communication so that the managing physician can stage accurately. “The involvement of the radiologist is new, and it’s huge in the 8th edition,” she said. “This is probably the biggest change for most oncology teams, but it truly promotes timely communication between the various specialists.”
The main lung-specific changes include new T size, prognostic relevance of qualified nodal disease, new criteria for single extrathoracic metastasis, and new stage groupings. In colorectal cancer, the presence of tumor deposits changes the “N” category, and the “M” category is expanded.
The entire breast chapter was rewritten, and the 2 most significant updates are to the anatomic stage and the prognostic group. Now, a final prognostic stage in breast cancer is reached by using a combination of anatomic TNM plus biomarker information—which includes tumor grade and hormone receptor status—as well as multigene panels/genomic profile assays. Additionally, lobular carcinoma in situ is now treated as a benign entity and was removed from the 8th edition. It is no longer considered a malignancy and is instead considered a risk factor.
Is the 8th Edition Better?
Last year, MD Anderson published a paper comparing the prognostic state with the anatomic state in 2 different cohorts: their own breast cohort, and a large population cohort from the California cancer registry, all of whom had breast cancer and were treated with surgery as their initial intervention. They evaluated TNM stage, tumor grade, and ER and PR status.
In the MD Anderson database there were just over 3300 patients with stage 1 to 3C breast cancer. Using the 8th edition staging, almost 30% of the patients were upstaged, and about 28% were downstaged. “It provided a more accurate stratification with respect to disease-specific survival than the old staging,” said Ms Dobrea. And in the almost 55,000 patients with stage 1 to 4 breast cancer from the California cancer registry, prognostic staging used in the 8th edition upstaged about 31% and downstaged 21%, performing better than the old system that used only anatomic TNM staging.