Understanding Breast Cancer Pathology
The Key To Your Diagnosis: Insights From Dr. Hannah Gilmore
At Learn Look Locate, we’re committed to providing comprehensive, expert-backed information about breast cancer. We’re proud to present insights from Dr. Hannah Gilmore, a renowned anatomic pathologist specializing in breast pathology and LLL medical advisor. Dr. Gilmore’s expertise offers a unique perspective on the crucial role of pathology in breast cancer diagnosis and treatment.
Dr. Hannah Gilmore on Breast Cancer Pathology
Anatomic Pathologist and LLL Medical Advisor
“I would like patients to understand what pathology is and what we do. We look at your tissue, we interpret it, and we make the best diagnosis that we can for a patient. I want patients to know how much we care about them and value getting, making the right diagnosis.”
1. Unlocking Secrets about Breast Cancer Pathology
Before there’s a treatment plan, there’s a pathologist.
When tissue is removed during a biopsy or surgery, it goes to an anatomic pathologist like Dr. Gilmore the doctor most patients never meet, but whose diagnosis shapes everything that comes next.
“I’m the doctor that gets the tissue after your surgeon or your radiologist removes it, looks at it under the microscope, and says whether it’s malignant or benign.”
— Dr. Hannah Gilmore
That single determination benign or malignant is the foundation your entire care plan is built on.
2. The Hidden Role of Cell Pathology in Chemotherapy
Removing the tumor is often only part of the story.
Invasive breast cancer is considered a systemic disease — meaning a few microscopic cells may exist beyond the breast, which is why some patients need treatment that reaches the whole body.
“We consider cancer a systemic disease. Some patients need chemotherapy to get rid of all those tiny cells floating in the body. For a lot of patients with ER-positive, HER2-negative disease, chemotherapy won’t help — but hormonal therapy will. We treat locally to get the biggest areas out, but it requires treatment of the whole body.”
— Dr. Hannah Gilmore
What decides which path is right for you? Your tumor’s biology — the receptors and features the pathologist reads under the microscope. Our genomic testing page breaks down how those details guide treatment, and for hormone-positive cancers, our tamoxifen guide explains how hormonal therapy works.
3. The Importance of Pathology Reports
Behind every pathology report is a real person at a microscope who understands exactly what their words will mean to you.
“There’s someone in the lab behind the microscope, really looking at the tissue, making the best diagnosis — knowing there are patients behind there. We take our jobs really, really seriously.”
— Dr. Hannah Gilmore
Your report is one of the most important documents you’ll receive. You have every right to a copy, and to have your team walk you through it. As Dr. Gilmore puts it, it matters that you “know what all the medical terminology means and have a really trustworthy place to find this information” — which is exactly why this page exists.
4. The Risk of Benign Breast Disease Developing into Breast Cancer
Not every breast finding is cancer — but some benign findings still matter.
Dr. Gilmore divides benign breast disease into two groups: those without atypical cells, and those with them. The ones with atypical cells — atypical ductal hyperplasia (ADH) and atypical lobular hyperplasia (ALH) — are the ones to pay attention to.
“Women who have atypical ductal hyperplasia have about a four to five times risk of developing breast cancer. That automatically puts women into a high-risk category.”
— Dr. Hannah Gilmore
ADH is often found alongside calcifications on a mammogram. When it turns up on a core needle biopsy, the standard of care is to have the area surgically excised — to make sure nothing more serious is hiding nearby. It isn’t cancer, but it’s a signal worth acting on.
5. Early Diagnosis of Breast Cancer: Key to Receiving Quality Care
There’s a human being behind every diagnosis — including the one making it.
“It feels really good to be part of such important patient care. But it’s emotionally exhausting too. Even though I don’t see patients in front of me in clinic, I know what that diagnosis means for them.”
— Dr. Hannah Gilmore
That’s the quiet truth of pathology. The specialist reading your slide may never shake your hand, yet carries the weight of what your result means. Their commitment to getting it exactly right is a core part of the quality care you receive — and one more reason early detection, which hands you the most options, matters so much.
6. Why Pathology is Key in Breast Cancer Diagnosis
A pathology report doesn’t appear by magic. A team of people produces it.
“I’d like patients to understand what we do. We look at your tissue, we interpret it, and we make the best diagnosis we can. People think tissue goes into a lab and a result comes out — but there are people behind there, and I want patients to know how much we care about getting the diagnosis right.”
— Dr. Hannah Gilmore
Because so much rides on this one result, you’re always allowed to seek a second opinion on your pathology — especially from a breast specialist. It’s common, reasonable, and never something to feel awkward asking for.
7. Pro Tips for Understanding Your Pathology Report
You don’t need a medical degree to read your report. You need to know what to look for.
“Every patient should have a copy of their pathology report and be able to go over it with their doctor — and understand what it means for them now and in the future.”
— Dr. Hannah Gilmore
Here are the five things worth finding and asking about:
- Cancer type — DCIS, invasive ductal, or invasive lobular carcinoma
- Grade — how abnormal the cells look (1 = slower-growing, 3 = more aggressive)
- Hormone receptor status — ER, PR, and HER2, which guide hormone and targeted therapy
- Tumor size and lymph nodes — key details used to determine stage
- Your questions — what type, what grade, what the receptors mean, whether nodes are involved, and how it all affects treatment
Write your questions down before your appointment. A report that once looked like a foreign language becomes a map you can follow.
8. Decoding Breast Cancer Terminology: Pathologist Explains
Stage. Grade. Histology. The words on your report have precise meanings — and knowing them takes away some of their power to frighten.
Dr. Gilmore separates the terms clearly:
“Clinical staging — 1A, 1B, 2A — describes how big the cancer is and whether it’s spread to lymph nodes. Histology means what type of cancer it is; most are invasive ductal carcinomas, but there are others like invasive lobular. And grade — we grade breast cancers one, two, or three. Grade one looks most like normal breast cells. Grade three is the highest and tends to be the most aggressive, because the cells don’t look much like the normal cells they came from.”
— Dr. Hannah Gilmore
The short version: grade is how the cells look, stage is how far the cancer has spread — two different questions, both important. For more on how these numbers shape your plan, see our genomic testing page. Grade and margins also help answer one of the biggest DCIS questions — whether you’ll need radiation.
9. Vital Tips for Coping with a Breast Cancer Diagnosis
The information arrives faster than the heart can process it. That’s normal.
“A breast cancer diagnosis is so overwhelming, and patients are often in such shock that they have a hard time understanding what everything on their reports means. But when you take the time to understand it — and ask questions of your clinicians and navigators — you start to develop more control over your situation, and you can really be part of your planning.”
— Dr. Hannah Gilmore
You don’t have to understand everything in one appointment. Bring someone with you. Write questions down as they come. Understanding your diagnosis at a human pace is how you move from passenger to partner in your own care.
10. What is DCIS or Ductal Carcinoma In Situ?
Breast cancer isn’t one disease — it’s many. And one of the most important distinctions is invasive versus non-invasive.
“DCIS stands for ductal carcinoma in situ. These are cancer cells, but they’re still inside the ducts of the breast — they haven’t been able to get out and invade the tissue. DCIS is most commonly found on screening mammography, because the cells inside the ducts become necrotic, die, and calcify. When invasive cancer cells invade, they have the ability to metastasize — to go to lymph nodes or other sites in the body.”
— Dr. Hannah Gilmore
That’s what makes DCIS (stage 0) so different: it’s contained, and outcomes are generally very favorable. Our full guide to Stage 0 ductal carcinoma in situ walks you through what it means and what comes next — including whether you’ll need radiation. And when DCIS involves the nipple, it can appear as Paget’s disease, which Dr. Gilmore notes is far less common now thanks to screening.
11. The Science Behind Pathology
Ever wonder what actually happens to your tissue after it leaves the room?
“In pathology, our way of looking at the world is our glass slide. When we make a glass slide of tissue, the stain we use is called an H&E — and an H&E turns our world into pink and purple. Those colors are what we see under the microscope, so we can look at what’s normal, what’s not, and identify cancer cells invading outside the ducts.” — Dr. Hannah Gilmore
That pink-and-purple landscape is where diagnosis happens. And because breast cancer “can look like a whole lot of different diseases,” it takes a trained eye — and often extra tests like immunohistochemistry — to read it correctly.
12. The Nature of Cancer Cells
Cancer begins when a single cell forgets how to stop.
“Cancer occurs when there’s a mutation in a cell — one that means the cell can’t keep itself in check. Most normal cells in our body know how to stop growing, but a cancer cell doesn’t. It keeps growing and growing until it causes problems. In the breast, that might be a big lump.” — Dr. Hannah Gilmore
Healthy cells grow, divide, and die on a schedule. Cancer cells ignore those signals — and that loss of control is exactly what the pathologist recognizes on the slide. Understanding why cancer cells behave this way is what makes the rest of your report finally make sense. Knowledge is power in your breast cancer journey, and understanding your diagnosis is where that power begins.
Frequently Asked Questions
Why is my breast cancer pathology report so long?
Pathology reports are detailed because they include all the microscopic features of your tissue, including tumor type, grade, margins, lymph node involvement, and hormone receptor status. Each detail helps your doctors create the most effective treatment plan.
What is the difference between pathology and genomics?
Pathology focuses on diagnosing disease by examining tissue and cells, while genomic testing looks at gene activity within the tumor to predict how it may behave and respond to treatment. Both are critical to personalized breast cancer care.
Who actually writes my pathology report?
Your report is written by a board-certified pathologist—an expert doctor trained to examine tissue under a microscope and interpret the findings. At Learn Look Locate, Dr. Hannah Gilmore is one such expert guiding patients like you.
Can I get a second opinion on my pathology report?
Yes, you absolutely can—and many patients do. Getting a second review from another pathologist, especially one who specializes in breast cancer, can help confirm the diagnosis or offer additional insight.
Is DCIS considered cancer in a pathology report?
DCIS (Ductal Carcinoma In Situ) is a non-invasive form of breast cancer. It means the cancerous cells are confined to the milk ducts and haven’t spread. It is usually noted clearly in the pathology report.
If your report shows DCIS, one of the biggest next questions is whether you’ll need radiation. Do I Need Radiation If I Have DCIS? walks you through how your pathology guides that decision.
What does ER+, PR+, or HER2+ mean on my pathology report?
These refer to hormone receptors. ER+ and PR+ mean your tumor responds to estrogen or progesterone, while HER2+ means the tumor makes too much of the HER2 protein. These factors affect your treatment options.
What does it mean if my margins are clear or not clear?
“Clear margins” mean no cancer cells were found at the edge of the tissue removed. “Positive” or “close margins” may indicate that some cancer cells were left behind, which could require further treatment or surgery.
How long does it take to get my pathology report after surgery or biopsy?
Most reports are ready within 3–5 business days, but complex cases may take longer. Your surgeon or oncologist will review the findings with you once available.
Can a pathology report predict if my cancer will return?
Not directly, but it provides important clues. Factors like tumor grade, size, lymph node involvement, and receptor status are used to estimate recurrence risk, especially when combined with genomic testing.
How can I learn more about what's in my pathology report?
Ask your doctor to walk through it with you. You can also request a copy and compare terms using resources like Learn Look Locate’s breast cancer education pages or reputable sources like BreastCancer.org or Mayo Clinic.
About the Expert
Meet Hannah Gilmore, MD
Dr. Hannah Gilmore is a board-certified anatomic pathologist specializing in breast pathology at University Hospitals Cleveland Medical Center and Associate Professor of Pathology at Case Western Reserve University in Cleveland, Ohio. As the Division Chief of Anatomic Pathology, she has made innovative changes to the practice of the discipline with emphasis on subspecialization, multidisciplinary care, molecular diagnostics, and digital pathology. Dr. Gilmore has published widely on the pathogenesis of breast tumors and the identification of their diagnostic, predictive, and prognostic markers. Her expertise and dedication to patient care make her an invaluable member of the Learn Look Locate Medical Advisory team.
Understanding breast cancer pathology is crucial for patients navigating their diagnosis and treatment. At Learn Look Locate, we’re grateful for Dr. Hannah Gilmore’s expertise in helping demystify this complex aspect of breast cancer care. Her insights empower patients to better understand their diagnosis and actively participate in their treatment decisions. Remember, knowledge is power in your breast cancer journey, and Learn Look Locate is here to support you every step of the way.