Richard J. Bleicher, MD, FACS, Fox Chase Cancer Center/Temple Health offers anyone facing cancer a look into the positive, negatives… and history and potential changes… of the breast cancer staging system.
“Doctor, what stage is my tumor?”
It’s a question that I, as a breast cancer surgeon, hear every day, multiple times a day. It’s a question that is attributed more weight than nearly any other question I hear, and it unfortunately has, for many women, become a euphemistic way of asking “Doctor, will I live or die from this disease?”
It’s a question that causes me dread as a surgeon, and one that I don’t like to answer, because despite how patients place all their hopes on what stage they’re “given,” it’s merely a way of indicating a general odds of what will happen. But it doesn’t tell a woman that she will live or die from the disease, nor tell her that she will or won’t have a recurrence, nor tell her how fast the tumor will grow, nor where it will spread, if it does. And yet everyone wants to know “what stage is my tumor?” and takes this as the final word about their future.
So what is a tumor’s stage, anyway? (And first, let me digress by saying that a patient isn’t stage 0, I, II, III, or IV; her tumor is.) A tumor’s stage is the group or category that describes its extent. Most staging systems, and specifically staging of breast cancer, have three components: the Tumor size and characteristic component, designated by T, the lymph Node involvement component (meaning whether the cancer has spread to the nodes, and how extensively), designated by N, and the Metastatic component (meaning whether it has gone to distant organs), designated by M. These make up staging, or what we call the TNM classification of a cancer.
Within T, N, and M, there are subcategories with their own definitions; so for instance breast cancers between 0.1 and 2.0 cm are classified as T1. Those ranging from 2.1 cm to 5.0 cm are classified as T2, and those above 5.0 cm are T3. There are groupings of N stage based on the number and extent of nodal involvement, and the M component designates that either distant metastases do or do not exist. The T, N, and M classifications are then grouped together to create the overall tumor stage, which is 0 through IV. Stage 0 is the earliest stage, and IV is the most advanced. So for instance, T1N1M0 and T2N0M0 are both stage II, and are grouped together because tumors classified this way have prognoses that are similar. Many people confuse stage with grade, but they are not the same. Stage is the extent of disease. Grade is how much the tumor cells look like normal vs abnormal cells.
So why do we do bother with this abstruse system?
Staging was first developed over sixty years ago and codified decades later to provide three benefits to patients and physicians. The first was to provide uniform groupings of tumors, to easily and precisely describe the extent of disease and to determine a patient’s prognosis. The second was to allow better assessment of treatment for the disease, and the third was to allow more productive research, by grouping tumors together that should behave similarly.
Staging has served us well since it was first proposed, and it is standard to stage every tumor and discuss tumors in the context of their stage. The problem has been that while staging groups tumors that are thought to have similar prognoses, we still find variation in how those tumors behave within each stage. Sometimes the patients do far better than we expect, and sometimes they don’t do as well as we predict. Moreover, we continue to find ways to refine staging and improve the classifications, which is why, every few years, the staging system is updated with a new edition to more accurately reclassify tumors and group those with similar prognoses together.
So have we made any big strides in staging recently? Yes, we have.
One of the rules of the staging system dictates that when a breast cancer involves or grows significantly into skin, it is automatically classified as a stage III tumor. This detail currently overrides the usual T or N classification. This rule has been around since the beginning of staging because decades ago, most tumors that involved skin were large and locally advanced, and so their prognosis was poor. These women were therefore told that their tumor was stage III, and chance of survival was only fair. But at Fox Chase Cancer Center, we have noticed that there are tumors that involve skin, but that are not large locally advanced cancers; these are small and just happen to arise near skin. Most importantly though, these patients seem to do as well as women having similarly-sized early breast cancers, and frequently did better that those with tumors that were stage III.
So we set out investigate whether these small skin-involved tumors’ classification as stage III was warranted.
And guess what: It’s not.
When we evaluated nearly a thousand women with such small skin-involved tumors (the largest series ever published of this type), classifying the tumors by just their tumor size (T) and nodal status (N), it turns out that these women don’t all have survival similar to women of stage III tumors. If you ignore the skin involvement, many have a prognosis as good as whatever the T and N stage suggests. This means that for some women (those with small skin-involved tumors), the stage and prognosis they have been given was excessively grave and likely inaccurate. Thus, we should change the staging system from relying first on the skin involvement as the overriding factor to determine stage, to instead always look at the TNM stage first, and using skin involvement as a secondary subordinate detail. It is our hope that the committee that decides changes to the next version of the staging system, considers these findings when they update the staging system again this year.
So yes, we continue to get better, and more accurately classify and predict how tumors should be staged, and what that portends for the patient. Staging isn’t perfect, but it’s not going anywhere anytime soon, because it’s the best classification system we’ve got. And no matter how good we get, I will always dread those words. “Doctor, what stage is my tumor?” because it’s merely a set of odds, and doesn’t seal your fate in stone.
As I always tell patients: “You may have breast cancer. But your breast cancer doesn’t have you.”