Pathology Report Decoder

What a pathology report is

A pathology report is written by a pathologist, a doctor who examines the tissue removed at a biopsy or operation under the microscope and with special stains. It states what the cancer is (its type), how abnormal the cells look (grade), how far it has grown (the pT and pN categories), whether it was fully removed (margins) and which receptors or markers the cells carry. Treatment decisions rest on it more than on any scan.

You have the right to a copy in every EU country. Reports use a fixed vocabulary, which is why the same words appear on reports from Lisbon to Vilnius, and why decoding them line by line is possible.

Grade versus stage

Grade and stage are different measures that are easily confused. Stage describes how far the cancer has spread (size, nodes, distant sites). Grade describes how the cells look and behave: a low grade means cells still resemble normal tissue and tend to grow slowly, a high grade means they look very abnormal and tend to grow fast. A small, early-stage tumour can be high grade, and a large one low grade.

Most cancers use grades 1 to 3 or 1 to 4. Breast cancer uses the Nottingham score (3 to 9) to reach grades 1 to 3; prostate cancer uses Gleason patterns summed to a score of 6 to 10, now reported as Grade Groups 1 to 5 so that a 3+4 and a 4+3 are no longer both just a 7.

Receptors and markers that guide treatment

In breast cancer three results decide the shape of treatment: the oestrogen receptor (ER), the progesterone receptor (PR) and HER2. ER or PR positive cancers usually receive hormone therapy; HER2-positive cancers receive HER2-targeted drugs; cancers negative for all three (triple negative) are treated mainly with chemotherapy and, in some settings, immunotherapy. Since 2022 the HER2-low category has gained its own treatments, which is why a 1+ is no longer simply negative.

Ki-67 measures the share of cells that are dividing. Laboratories draw the line in different places, so guidelines treat only values of 5 percent or under and 30 percent or more as clearly low or high. Other tumour types have their own decisive markers: PD-L1 in lung cancer, MSI or mismatch repair status in bowel and womb cancer, BRAF in melanoma.

Margins and vessels: what the surgeon looks for

When a tumour is removed, the pathologist inks the outside of the specimen and checks whether cancer cells reach the edge. Clear margins (R0) mean the tumour came out with a rim of healthy tissue. Positive margins (R1) mean cells at the edge, and often lead to further surgery or radiotherapy. What counts as close varies by cancer type: 1 mm is standard for invasive breast cancer, 2 mm for DCIS, and several millimetres for some skin cancers.

Lymphovascular invasion means cancer cells were seen inside tiny lymph or blood vessels within the tumour. It is a marker of a slightly higher risk of spread, not proof of it, and it is weighed together with grade, size and node status.

Getting a copy and a second opinion

Ask for a printed or electronic copy of every pathology report, including addenda that arrive later with receptor or genetic results. Keep them together; they are the documents a second-opinion centre or a clinical trial team will ask for first.

A second pathological opinion is routine, not an insult: many cancer centres review outside slides before treating a new patient, and studies show grade and margin readings change in a meaningful minority of cases. In most EU countries your treating doctor can request it, and cross-border second opinions are covered by the EU directive on patients’ rights in cross-border healthcare.

Questions to ask

Bring the result with you and ask:

• Can I have a copy of the full report, including any addenda?
• What is my grade, and how does it change the treatment plan?
• Which receptor or marker results matter most in my case, and are any still pending?
• Were the margins clear, and if not, what happens next?
• Would a second pathology review be useful, and how do we arrange it?