Why the report matters
Two women can both be told they have breast cancer and yet have completely different diseases that need completely different treatment. The pathology report is what tells your team exactly what kind of cancer you have and how it is likely to behave. It is the single most important document in planning your care — which is why it is worth understanding at least the headline features.
You will not be expected to interpret it alone. But knowing what the terms mean turns a frightening page of jargon into a set of facts you can discuss.
Invasive or in-situ
The report will first say whether the cancer is invasive or in-situ. In-situ disease (most commonly DCIS, ductal carcinoma in situ) means abnormal cells are contained within the ducts and have not spread into surrounding breast tissue. Invasive cancer has grown beyond the duct into the breast tissue and, in principle, has the ability to spread further. Most invasive breast cancers are of "no special type" (also called ductal); lobular is the next most common.
Tumour grade (1, 2 or 3)
Grade describes how abnormal the cancer cells look under the microscope and how quickly they appear to be dividing. It is not the same as stage.
- Grade 1 — cells look relatively normal and grow slowly (low grade)
- Grade 2 — intermediate appearance and growth rate
- Grade 3 — cells look very abnormal and grow quickly (high grade)
A higher grade suggests a more active cancer, which influences the choice of treatment. It does not, on its own, decide your outcome.
Size and stage
Stage describes how much cancer there is and whether it has spread. It is often summarised using the TNM system: T for the size of the tumour, N for whether lymph nodes are involved, and M for whether it has spread to distant parts of the body. These combine into an overall stage from 0 to 4. Early-stage disease (0, 1, and many stage 2 cancers) is confined to the breast and nearby nodes and is very treatable.
Lymph nodes
Breast cancer tends to spread first to the lymph nodes in the armpit. The report will say how many nodes were examined and how many contained cancer. Node-negative means none were involved; node-positive means one or more were. This is one of the strongest guides to the risk of the cancer returning and to whether additional treatment such as chemotherapy or radiotherapy is advised.
A sentinel lymph node biopsy is often used to check the nodes with the least possible surgery. If the sentinel nodes are clear, a full clearance of the armpit can usually be avoided — sparing you the arm swelling that can follow more extensive node surgery.
Hormone receptors: ER and PR
ER (oestrogen receptor) and PR (progesterone receptor) tell you whether the cancer is fuelled by these hormones. A cancer reported as ER-positive or PR-positive is one that hormones help to grow — which is actually useful, because it means hormone-blocking tablets (endocrine therapy) can be used to lower the risk of recurrence, often for several years. The report may give a percentage or a score; higher generally means more strongly hormone-driven.
HER2 status
HER2 is a protein that, when present in excess, drives a more aggressive cancer. A HER2-positive result used to be worrying news; today it is matched by highly effective targeted drugs that specifically block HER2, transforming outcomes for these cancers. HER2 is usually reported as negative, positive, or equivocal (borderline, needing a further test called ISH to confirm).
Ki-67
Ki-67 is a marker of how many cells are actively dividing — a measure of proliferation. A higher percentage suggests a faster-growing tumour. It is one of several factors, read alongside grade and receptor status, that help decide whether chemotherapy adds benefit.
Putting it together
No single line of the report decides everything. Your team reads them together to build a picture: the type and grade of the cancer, its size and node status, and its receptor profile (ER, PR, HER2). From this comes the plan — which surgery, and whether chemotherapy, radiotherapy, hormone therapy, or targeted therapy will help. Two people with the same tumour size can have very different plans because their receptor profiles differ.
Bring your report to every consultation. If you are seeking a second opinion, carry the full pathology report, your imaging, and any biopsy results. A specialist can only give you a meaningful opinion with the actual results in front of them — not a summary from memory.
If you have a report in hand and want it explained clearly, that is exactly what a consultation is for. Dr. Shruthi Neela reviews reports and imaging in detail and translates them into a plan you can understand.