How to Read Your Cancer Pathology Report

By Dr. Lena Suhaila, ND, FABNO

A pathology report is the document that drives almost every decision about your cancer treatment, and most people are handed it with no instructions and no time to absorb it. You get the diagnosis in a rushed appointment, then go home and stare at a page of unfamiliar words about your own body. This guide walks through it in plain language so you can read the report yourself and ask sharper questions about it.

You can ignore most of the page. A handful of lines carry the decisions, and those are the ones to find, in the order they usually appear. Most of the examples here lean toward breast cancer, since the markers are most detailed there, and the structure applies to almost any solid tumor report.

Start at the top: who, what, where

The first section is identifying information. Your name, date of birth, the date the sample was taken, and a specimen number. Check that your name and date of birth are correct. Errors are rare, and this is the one line you're fully qualified to catch with no training at all.

Then it tells you what was sampled and from where. For example, "Left breast, 2 o'clock, ultrasound-guided core biopsy," or "Sigmoid colon, polypectomy." This is just describing where the tissue came from and how it was taken.

The diagnosis line

Somewhere there's a line labeled "Diagnosis" or "Final Diagnosis" that names what they found. That line is the headline, and the rest of the report is the detail behind it.

It might read "Invasive ductal carcinoma," "Adenocarcinoma," or "No malignancy identified."

Carcinoma means a cancer that started in the cells lining an organ or surface. Most common cancers, including breast, colon, lung, and prostate, are carcinomas.

In situ versus invasive. This distinction drives how the cancer is treated, so read it carefully. In situ means the abnormal cells are still contained where they started and have not broken through into surrounding tissue. Invasive, sometimes written infiltrating, means they have. As an example, "ductal carcinoma in situ" describes cells confined to the breast duct, while "invasive ductal carcinoma" describes cells that have moved beyond it.

Grade: how abnormal the cells look

Grade describes how much the cancer cells resemble the normal cells they came from. It reflects appearance and behavior. Size and spread are separate, and they come later in the report.

Low grade, grade 1, means the cells still look fairly normal and tend to grow slowly. High grade, grade 3, means they look very abnormal and tend to grow and spread faster. Grade 2 sits in between.

Breast pathology usually uses the Nottingham score, which adds three features into the final grade: how much the cells form normal duct structures, how abnormal the nuclei look, and how often the cells are dividing. If you see three small scores added into a total, that's what you're looking at.

If your report gives only a grade with no breakdown, ask for the three sub-scores behind it. The number to push for is which feature is driving the grade, because a grade 2 built mostly on a high dividing rate behaves differently from a grade 2 built on appearance alone. The sub-scores tell you that, and the single grade doesn't.

Grade and stage get confused all the time, so hold the difference clearly: grade is how the cells look, and stage is how far the cancer has spread.

Stage: how far it has spread

Stage describes the extent of cancer in your body. Many cancers use the TNM system, which has three parts.

T, for tumor, describes the size of the main tumor or how deeply it has grown. Higher numbers mean larger or deeper, so T1 is generally smaller than T3.

N, for nodes, describes whether cancer is found in nearby lymph nodes, and how many. N0 means none found in the nodes examined. N1, N2, and so on mean increasing node involvement.

M, for metastasis, describes spread to distant parts of the body. M0 means none found. M1 means distant spread was found.

So a stage written as "pT2 N0 M0" means a moderate-sized tumor, no cancer in the examined nodes, and no distant spread detected. The small "p" stands for pathologic, based on tissue actually examined, as opposed to "c" for clinical, based on imaging and exam before surgery. Pathologic staging is generally more precise because it comes from the real specimen.

If your early report gives an incomplete stage, ask whether this is the final stage or whether it will change after surgery. A biopsy is a small sample and usually can't stage fully; the surgical specimen plus imaging completes the picture. Knowing whether you're looking at a provisional or final number keeps you from drawing hard conclusions from something that's about to change.

Margins: Did they get it all

If your sample came from surgery rather than a needle biopsy, the report describes the margins, the edge of the tissue that was removed.

A negative, clear, or R0 margin means no cancer cells were seen at the cut edge, which suggests the cancer was removed with a rim of normal tissue around it. A positive margin means cancer cells reach the edge, which can mean some was left behind and more treatment may be discussed. Reports often give a distance, such as "tumor present 2 mm from the nearest margin."

If a margin is called positive or close, ask for the specific distance and which margin. "Close" means different things to different surgeons, and the actual number, for example tumor 1 mm from the posterior margin, is what drives the decision about whether more tissue needs to come out. Ask which edge and how many millimeters, not just whether it was clear.

The markers that guide treatment

Your oncologist relies on this section heavily, and it's often the hardest part for patients to follow. After identifying the cancer, the pathologist runs extra tests on the tissue to find features that predict how it behaves and what it responds to. Which markers appear depends on your cancer type. The ones below are the core breast panel, with notes for other cancers where relevant.

Hormone receptors, ER and PR. In breast cancer, the report says whether the cells carry estrogen receptors (ER) and progesterone receptors (PR), usually as a percentage with a positive or negative call. Receptor-positive cancers can be driven by those hormones, which also means they can respond to treatments that block them. A high percentage isn't bad news in itself; it points to treatments that can work against the cancer.

If the percentages aren't given, ask for them. A report sometimes says "ER positive" with no number, and the number carries information a yes-or-no doesn't. Strongly positive behaves differently from weakly positive, and that shapes how much benefit is expected from hormone-blocking treatment. Getting the actual percentages moves the conversation from "you're positive" to "you're this positive," which is more useful to plan around.

HER2. A breast and sometimes stomach marker, reported as 0, 1+, 2+, or 3+ on a test called IHC, then translated into negative, positive, or equivocal. A 2+ equivocal result usually triggers a follow-up test called FISH for a clear answer. HER2 status decides whether a whole category of targeted treatments is an option.

If your result came back equivocal, ask whether FISH was done and what it showed. Equivocal means the result is unclear and needs a closer look, which is what the FISH test provides. Don't walk away treating equivocal as your final answer, since a definite HER2 result can change your options and an unresolved one leaves a real decision hanging.

Ki-67. A measure of how many cancer cells are actively dividing, given as a percentage. A higher Ki-67 generally indicates a faster-dividing, more proliferative cancer, and a lower one a slower pace. What counts as "high" varies by cancer type and lab, so use the report's own interpretation rather than comparing your number to one you found online.

If Ki-67 isn't on your report, ask for it. Not every lab runs it by default, and not every report includes it even when it was tested. Ask your surgeon, oncologist, or whoever ordered the pathology to tell you the number, and if it wasn't tested, ask whether it can be. Ki-67 captures something neither grade nor stage does: how fast the cancer is dividing right now. That pace can inform how closely you're monitored and the urgency behind treatment timing, and it points at the metabolic and inflammatory conditions driving proliferation, which are things you can begin working on. It won't decide your whole plan on its own, and it's a piece of the picture you have every right to see.

Microsatellite instability (MSI) and mismatch repair (MMR). Less common in breast cancer and central in colorectal and endometrial cancers. You'll see terms like MSI-high, MSS (stable), dMMR (deficient), or pMMR (proficient). These describe a specific genetic feature of the tumor that can affect both treatment options and whether genetic counseling is recommended for your family.

If you have a colorectal or endometrial cancer and this testing isn't on your report, ask whether it was done, what it showed, and what it means for you. Its value reaches beyond the tumor itself. An MSI-high or dMMR result can open certain immunotherapy options, and it can flag a hereditary syndrome running in a family, which your relatives may need to know about.

If a marker on your report isn't covered here, that's expected. There are many, and they're cancer-specific. Write the term down and ask directly: "What is this, and how does it change my options?"

The parts you can skip on a first read

Reports contain a "gross description," what the tissue looked like to the naked eye including measurements, and a "microscopic description," technical detail about what the pathologist saw under the lens. They're written for other clinicians, and you can set them aside. The diagnosis, grade, stage, margins, and markers are the lines that carry the decisions.

A working example

Say a breast report reads: "Invasive ductal carcinoma, Nottingham grade 2, pT2 N0 M0, margins negative, ER positive 90%, PR positive 80%, HER2 negative, Ki-67 15%."

Translated: a cancer that began in the breast duct and grew beyond it, moderately abnormal-looking cells, a moderate-sized tumor with no cancer in the examined lymph nodes and no distant spread detected, removed with clear edges, strongly hormone-receptor-positive, HER2-negative, with a moderate rate of dividing cells. That one line tells the treating team a great deal about what comes next. Once you can read it, you can follow the conversation about your own care instead of nodding through it.

What helps now that you have the report

The pathology report tells you what the cancer is. The next questions are what's driving it at the molecular level, and whether anything in it can be targeted by a specific treatment. Two kinds of testing go past the standard report, and both can usually be run from your tumor sample.

Comprehensive genomic profiling for therapy selection. This sequences the tumor across hundreds of clinically important genes, often with RNA sequencing to catch fusions and structural changes, and reports the alterations inside your tumor along with the targeted therapies and immunotherapies they point to and any clinical trials your profile qualifies for. It also reads markers like microsatellite instability and tumor mutational burden, which inform whether immunotherapy is an option. Tempus and Natera's Altera are two widely used examples, with results back in roughly two weeks. This profiling pays off when a targetable alteration the standard report never checked for turns out to be present, because that can open a treatment no one would otherwise have considered.

Circulating tumor DNA monitoring for surveillance. A test like Natera's Signatera does a different job. It's built from your own tumor tissue to identify your cancer's unique mutation fingerprint, after which a simple blood draw checks whether fragments of that DNA are circulating. It detects residual disease after treatment and catches recurrence early, and repeated over time it shows whether a treatment is holding. In a long-term breast cancer study, serial testing flagged recurrence with high sensitivity and a median of around ten months before it appeared on imaging. Tempus offers ctDNA monitoring as well, so depending on the lab your oncologist uses, both jobs can sometimes run under one roof. With Natera, Altera and Signatera can be ordered together off a single tumor sample, so you get therapy selection and recurrence monitoring without giving up more tissue than necessary.

The difference between the two. Comprehensive genomic profiling, like Tempus or Altera, looks at the tumor itself and asks what it's made of and what might treat it. It's usually done once, around diagnosis, to help choose therapy. Circulating tumor DNA monitoring, like Signatera, looks at your blood over time and asks whether cancer is still there or coming back. It's done repeatedly, often for months or years after treatment. One is a detailed map of the tumor for picking a treatment. The other is an early-warning system for tracking whether that treatment is working and whether the cancer returns. You may use both, since they answer different questions at different stages.

Neither kind of testing is guaranteed to be part of your standard workup. Sometimes an oncologist orders it routinely, sometimes not, and what makes sense depends on your cancer type and where you are in treatment. Ask your oncologist directly whether comprehensive genomic profiling and ctDNA monitoring are appropriate for you, and what each result would change. If they aren't already in motion, these tests can also be ordered through an integrative oncology practice, including mine, and read alongside the rest of your terrain rather than in isolation.

One caution, so the enthusiasm stays grounded. More data isn't automatically better. A test is useful when its result would change a decision, so the goal is turning the right numbers into a clearer plan rather than collecting all of them.

What an integrative oncologist also reads

A conventional oncologist reads the report to choose treatment, which is exactly their job. There's a second layer of reading that asks a different question: what does this report suggest about the conditions that allowed this cancer to develop, and what can be done to change those conditions alongside treatment.

A high Ki-67 or a high grade, for instance, raises the question of what's feeding rapid cell division, which is where metabolic and inflammatory markers like fasting insulin, fasting glucose, and inflammatory signaling become relevant. Hormone-receptor status opens a conversation about how the body produces and clears those hormones, not only how to block them with medication. None of this replaces oncology treatment. It runs alongside it, and it starts from the same report you're now able to read.

Questions to bring to your next appointment

Take the report with you and ask: What exactly is my diagnosis, in plain words? What is my grade, and what does it mean for how this behaves? What is my stage, and is this final or will it change after surgery? Were the margins clear, and if not, by how much and which one? Which markers were tested, what did each show, and how does each change my options? Should I have comprehensive genomic profiling or ctDNA monitoring? Is there anything here that suggests genetic counseling for my family?

You don't have to understand everything on the day you're diagnosed. Find the few lines that carry the decisions, and ask good questions about the rest. It's your report, about your body. Read it, and ask about anything on it you don't understand.

If you want help reading your own report and deciding which next steps fit your situation, that's part of what I do. Work With Me.

Frequently asked questions

What's the difference between cancer grade and stage? Grade describes how abnormal the cancer cells look under the microscope and how fast they tend to grow. Stage describes how far the cancer has spread in the body. A cancer can be high grade but early stage, or low grade but later stage. They answer different questions and are set by different parts of the report.

What does ER positive or PR positive mean on a breast pathology report? It means the cancer cells carry estrogen or progesterone receptors, so those hormones can drive the cancer's growth. That also makes the cancer likely to respond to treatments that block those hormones. The percentage tells you how strongly positive the cancer is, which is why it helps to ask for the actual number rather than just "positive."

What does HER2 positive mean?

HER2 is a protein that, when overexpressed, can make a breast or stomach cancer grow more aggressively, and it also makes the cancer a candidate for HER2-targeted treatments. It's reported from 0 to 3+. A 3+ is positive, 0 and 1+ are negative, and 2+ is equivocal and needs a follow-up FISH test to settle the answer.

What does Ki-67 mean, and what number counts as high?

Ki-67 is the percentage of cancer cells actively dividing, a measure of how fast the cancer is growing. There's no single universal cutoff for "high," because it varies by cancer type and by lab, so use your report's own interpretation. If Ki-67 isn't on your report, ask whether it was tested and request the number.

What does it mean if my surgical margins are positive?

A positive margin means cancer cells reach the cut edge of the removed tissue, which can mean some cancer was left behind and more surgery or treatment may be discussed. A negative or clear margin means a rim of normal tissue surrounded the cancer. Ask for the specific distance and which margin, since "close" is interpreted differently by different surgeons.

Should I get genomic testing like Tempus or Altera, or ctDNA monitoring like Signatera?

They do different jobs. Comprehensive genomic profiling, such as Tempus or Natera's Altera, reads the tumor once to find targetable mutations and guide treatment selection. ctDNA monitoring, such as Natera's Signatera, reads your blood repeatedly over time to detect residual disease and catch recurrence early. Many people use both. Whether either is right for you depends on your cancer type and situation, so ask your oncologist, or work with an integrative oncologist who can order and interpret them alongside the rest of your picture.

Sources and further reading

• Tempus, Genomic Profiling for Oncology and Oncology Patient Resources. tempus.com

• Natera, Altera comprehensive genomic profiling. natera.com/oncology/altera

• Natera, Signatera molecular residual disease testing. natera.com/oncology/signatera-advanced-cancer-detection

• The breast cancer ctDNA lead-time figure is from the long-term EBLIS study reported in Natera's breast cancer clinical materials. Confirm the primary citation (Garcia-Murillas et al.) before publishing.