1 January 2018
The American Joint Committee on Cancer (AJCC) has recently updated the staging system used for breast cancer. Cancer stage refers to the amount of cancer (size of the main tumor, spread to lymph nodes or other areas). The definitions of each stage vary depending on cancer type. Cancer stage often correlates with outcomes, and treatment recommendations usually take into account stage of disease.
As our knowledge of tumor biology increases, it has become clear that stage is not the only factor that impacts prognosis. Tumor biology and behavior are very important, and in some cases may be more important than stage. A small tumor with aggressive behavior characteristics may may result in worse outcomes compared to a larger, but slower growing cancer. The 8th version of the AJCC staging system for breast cancer now takes into account tumor biology. Factors such as cell grade, ER/PR and Her2/neu status, and even the results of tumor genomic tests will be incorporated into the clinical and pathological prognostic stage. Taking into account these biologic factors means that the stage will have more meaningful prognostic information. Some larger tumors will now be considered stage I, and some smaller lesions will be upstaged based on their biology. In a large validation study performed by researchers at the University of Texas MD Anderson Cancer Center, 31% of patients were upstaged, and 20% of patients were downstaged. The updated prognostic stage performed better (in terms of predicting patient outcomes) than the standard anatomic stage.
The new staging system will take some getting used to. The tables used to help determine clinical and pathologic prognostic stage are 5-6 pages long. However, this new system will give us more meaningful information in terms of prognosis and outcomes. Just please be patient with your physician when you ask “what is my stage?” – it is no longer a simple question!
American Cancer Society CA Cancer Journal: Breast Cancer – Major Changes in the AJCC 8th Edition