Ashlee Williams (Host): Getting a breast cancer diagnosis can be overwhelming and scary. And then, the pathology report comes filled with unfamiliar terms, numbers, and abbreviations that can leave you wondering, what does all of this actually mean?

Welcome to the Healthier You Podcast. I'm Dr. Ashlee Williams. And today, I'm talking with Dr. Eun Oh, a board-certified pathologist here at Kaiser Permanente, about how to understand the information in a breast cancer pathology report. What terms like ER positive, HER2, grade and margin mean, and what they tell your care team about determining the next steps in treatment. Dr. Oh, thanks so much for being here today.

Eun Oh, MD: So glad to be here. It's a very exciting topic to discuss.

Host: It's such a great topic to discuss. Okay, let's start with the basics. What exactly is a breast cancer pathology report, and what role does a pathologist play?

Eun Oh, MD: So, you know as you know, pathologists are a type of physician who looks at tissue under a microscope to determine whether there's a cancer or not. And if there's a cancer, we want to provide all the information that's relevant for your cancer treatment so that your oncologist or surgeons can give you a treatment that are most effective.

And so, typically, you will get a pathology report right after a biopsy procedure or excision surgery. And it will contain informations, such as: is a cancer there identified? If cancer is there, what kind of cancer is it? Is it invasive or in situ? What grade is it, how big is the tumor, et cetera.

So, all this information will be provided to you in a pathology report so that the patients and physicians can take the next step for your cancer journey.

Host: Yes. You know, we doctors like to refer to pathologists as the doctor's doctor. You really take these biopsies and figure out what is going on in the actual pathology. Now, when the patient gets the report, there's so many words, it's so much language. When someone opens up their pathology report, what are the most important sections? Like, what should they look for in that report?

Eun Oh, MD: So, one of the best places to start in the pathology report is final diagnosis section, and that's the section where the most important information about your diagnosis will be. And so, if a cancer is diagnosed, then it will have terms like DCIS, which means ductal carcinoma in situ, which is a cancer that's confined to the milk duct, which has not invaded to your surrounding tissue yet. You may also see terms like invasive ductal or lobular carcinoma, which is an infiltrating type of cancer, meaning the tumor has sort of escaped from the normal duct and start growing into the normal tissue. In the report, you may also see things like estrogen receptor, progesterone receptor, HER2/neu, Ki67, which I will explain a little bit more detail in a little bit. But you will have information like that.

The report will also contain information like histologic grade, which tells information about how closely does a cancer cell resemble your normal breast tissue. Grade 1 typically means the tumor cells look close to your normal breast ducts and glands, and Grade 3 means the tumor cells do not look much like your normal breast tumor cells. And anything that's kind of between a grade 1 and grade 3 are assigned Grade 2. And you'll also find information like estrogen receptor, progesterone receptor,  Ki67, HER2, and all these biomarker information are very important for your treatments.

And if there were a lymph node biopsy done, we'll also tell you information whether tumor cells, have spreaded to the lymph nodes as well as if you receive a lumpectomy or mastectomy, they will tell you whether the tumor cells are far away, you know, from the edges of your resected sample as well.

Host: Wow. IThere's so much information contained in that report. And you mentioned about these terms that patients do hear about very often, which is the ER and PR and the HER2. What do these results tell us?

Eun Oh, MD: Yeah. So, ER stands for estrogen receptor, and some cancer cells have these estrogen receptor markers around their tumors, and this marker helps them grow. And so if a cancer cell has an estrogen receptor on a special test called immunohistochemical study, then we call that cancer ER positive or estrogen receptor positive. Likewise, progesterone receptor is a type of hormonal marker that can be expressed on a breast cancer cell as well. And so if that is expressed, we call that PR positive or progesterone receptor positive cancer.

HER2 is a biomarker that can be expressed on the tumor surface, which means that the tumor has this increased activity of a HER2 gene that helps tumor cells grow fast. And likewise, Ki67 is a marker of how fast tumor cells are growing. So, together with ER, PR, HER2, Ki67 information, your oncologist and surgeons can figure out, "Hey, what is the best way to treat this cancer?"

Host: Interesting. And you also mentioned in the report, it talks about tumor size and margins and lymph node status. Tell us why those findings are important.

Eun Oh, MD: These information are not included in the biopsy report typically, but more after you received a lumpectomy or mastectomy. It is because the pathologist has to examine the entire tumor to determine how large is the tumor and how close is it to the edge of the tissue that was cut out from your body. And depending all this information, we give something called pathologic staging, which tells you how large the tumor is. The number ranges from I to IV. Four means your tumor is very large, and one means that your tumor cells are very small. This information can help surgeons determine whether the patient needs to have more surgery versus whether the patient can proceed with radiation treatment or chemotherapy. And the margin status is also important because sometimes a tumor can be very far away from the edges of the tissue that was taken or sometimes a tumor can be very close, very, very close, or it could be sort of like right at the margin or at the edge of tissue. In that case, the patient may have to go back to the surgery to get more tissue taken out so that the chance of tumor recurring or developing again is reduced.

Host: Got it. Okay. So, you have this new diagnosis of breast cancer, and you've gotten all this additional information. How does it all come together, and when should patients ask their doctors if they have additional questions?

Eun Oh, MD: Yeah, I think that's a really good question because pathology report can be difficult to, you know, digest. There's just so much information, and there's so many technical terms and numbers which may not be very intuitive when you read through the report. So, I think it's important for you to list a number of questions you might have during your visit to your surgeon or oncologist and ask them, "Hey, what do these numbers mean? What do these abbreviations mean? What does this mean?" Like, the histologic type, grade, you know, what do they mean? And so, your surgeon and oncologist, together with how it looked on your imaging studies, what your medical history is, and what the lymph node status and, you know, baseline health status is, they can determine what is the best treatment to offer to this patient to defeat this cancer.

Host: Wow. Thank you so much, Dr. Oh, for helping us make sense of something that can feel incredibly overwhelming after a breast cancer diagnosis. Here are a few takeaways:

A breast cancer pathology report describes the cancer's characteristics, including its type, grade, and receptor status, and it gives your team important information that can guide treatment decisions. ER, PR, and HER2 results provide important information about the biology of the cancer and can help doctors determine which treatments may be appropriate. After surgery, the pathology report may provide information such as tumor size, surgical margins, and lymph node status that helps doctors understand how extensive the cancer is. Grade and stage are not the same thing. Grade describes what the cancer cells look like, while stage describes how extensive the cancer is and whether it has spread. You don't have to interpret your pathology report alone. Bring your questions to your care team and ask them to explain any terms or results you don't understand.

For more expert insights, visit kp.org/doctor and explore more episodes of Healthier You wherever you get your podcasts. If you found this episode helpful, be sure to subscribe so you don't miss what's next. And leave a comment with topics you'd like for us to cover in a future episode. Thank you. And from all of us at Kaiser Permanente, be well.