What's the Score? Understanding Your Pathology Report's Key Numbers

Patient Expert

So, you've just received a copy of your pathology report from the oncologist, and you're totally mystified by the "medicalese" it contains. Where to turn?

If you're up for studying and interpreting the entire report, check out our Guide to Understanding Your Pathology Report.

But if you want a quick, "down and dirty" explanation of the key numbers in the report; or if you don't have your pathology report, but only a few scattered parts your oncologist has shared, read the following guide for a fast explanation of your pathology report's key numbers.

This is a detailed examination of your cancer cells: what they look like, and how fast they're growing. It all boils down to behavior: the more quickly the cells are growing and the farther they stray from normal cell behavior, the more aggressive your cancer.

Different pathologists use different scales to determine grade, but here's the simple explanation: grades go from 1 to 3, with 1 the lowest (least aggressive), and 3 the highest (most aggressive).

Occasionally, the report will state grade a different way, giving it as a Scarff-Bloom-Richardson (SBR) grade of 1 to 9. In that case, 1 to 3 is low (grade 1); 4-6 is medium (grade 2); and 7-9 is high (grade 3).

Your cancer's stage is based heavily on three things: information about your tumor; information about your lymph nodes; and whether or not the cancer has metastasized to other parts of your body. The American Joint Committee on Cancer has developed shorthand for determining these three aspects of your breast cancer, called TNM. Here's how it works:

T = tumor size, the tumor diameter measured in centimeters; 1 centimeter = approx. 1/3 inch. Your T score can be any of the following:** TX: the tumor couldn't be accessed;**** T0: no tumor;**** Tis: in situ; tumor hasn't moved beyond its original ducts or lobules;**** T1: less than 2cm;**** T2: 2-5cm;**** T3: more than 5cm;**** T4: any size, but attached to the chest wall and spread to the chest lymph nodes.**** N = palpable nodes, which indicates whether cancer has spread to the lymph nodes.**** NX: the nodes couldn't be accessed;**** N0: no spread;**** N1: cancer has spread to the "movable" nodes in your armpit (axillary nodes) on the same side as your breast cancer;**** N2: cancer has spread to the "attached" lymph nodes on the same side as your breast cancer; these nodes are attached to one another, or to other structures in your armpit;**** N3: cancer has spread to the lymph nodes in your breast.**** M = metastasis; whether the cancer has spread to other parts of your body beyond the breast and lymph nodes (distant metastasis).**** MX: metastasis can't be assessed;**** M0: no distant metastasis;**** M1: distant metastasis.**

So, here's how to interpret the jumble of numbers and letters you may see in your pathology report, that look something like this: pT2, pN1, M0. Or this: T2N1M0.

The interpretation of either of these is as follows:
-Your tumor is 2-5cm;

-Cancer has spread to the movable lymph nodes under your arm;

-There's no distant metastasis.

Your doctor will take this TNM information, combine your scores, and come up with your cancer stage.

Here's a simplified rundown of breast cancer stages:

Stage 0: In situ cancer. No invasion/infiltration; no lymph node involvement; no metastasis. Often called "pre-cancer," because the cancer is entirely contained in the milk ducts or lobules where it started.

Stage 1: Your tumor is less than 2cm; there's no lymph node involvement; and no metastasis.

Stage 2: Your tumor is less than 2cm, but you have one or more lymph nodes involved; OR it's 2-5cm, either with or without lymph node involvement. There's no distant metastasis.

Stage 3: Your tumor is up to 5cm, with involvement in one or more "fixed" nodes; OR it's less than 5cm, but has invaded your skin or chest wall (nodes involved or not). There's no distant metastasis.

Stage 4: Any size tumor; lymph node involvement or not; but distant metastasis has been identified. In other words, the cancer has spread from your breast to your bones, brain, liver, or lungs.

**Hormone receptor status  **
If your cancer is hormone-receptive (as about 70% of breast cancers are), it opens up an additional way to guard against a recurrence: hormone drug therapy, which has been proven to reduce recurrence in women with hormone-receptive cancer.

Your report will indicate whether your cancer is estrogen and/or progesterone positive (ER/PR+). It may simply say "positive," or it may give a percentage (5%, 15%, etc.) If it indicates any kind of positive result, you'll take hormone therapy drugs; if it says "0%," or "negative," you won't.

-HER2 status
You might see the term "HER2 over-expression" in your report. This refers to the HER2 gene. If this gene produces too much protein (too many receptors), the cells grow too quickly, which means cancer cells become overly aggressive and grow extra-fast.

There are currently two common ways to test for HER2 status:

-IHC (immunohistochemistry): This test is scored from 0 to 3; 0-1 are considered negative, while 2-3 are positive.

-FISH (fluorescent in situ hybridization): This is reported simply as a positive, or negative.

A positive result means your HER2 gene is indeed making too much protein, and your cancer is more aggressive; about 25% to 30% of breast cancers are HER2 positive. A positive HER2 result means you'll probably take the drug Herceptin for a year, either after or concurrent with chemotherapy. Herceptin isn't a hormone drug, but rather a "targeted therapy," an antibody that prevents cancer cells from growing.

A Ki-67 result may be mentioned in your pathology report, given as a score from 0% to 100%. It had been thought in the past that the higher the score, the more aggressive your cancer.

But increasingly, oncologists are dropping their requests for the Ki-67 test. Institutions such as Memorial Sloan-Kettering in New York now call the test "unreliable" for a number of reasons, including large score variations within the tumor itself, as well as wide swings over time.

So if you don't see a Ki-67 score, don't worry. And if you do - understand that it may not be a super-reliable indicator of how serious your cancer might be.