How to read a cancer pathology report

A pathology report is a formal document from the pathologist who examined your biopsy or surgical specimen. It contains the most important single piece of information about your cancer — the exact diagnosis — plus the molecular and structural details that shape your treatment plan.

Pathology reports are dense and use specific language. Here’s what each section typically contains and what matters.

The header

Patient name, date of birth, medical record number, ordering physician, specimen type and date. Verify this information is yours. Mix-ups are rare but serious.

Gross description

What the pathologist saw with the naked eye — size, shape, color of the specimen. Usually technical. Not typically where treatment-relevant information lives.

Microscopic description and final diagnosis

This is the most important section. Look for:

Tumor type (histology)

The kind of cell the cancer started from. Examples:

• Adenocarcinoma — cancer of glandular tissue (common in colon, lung, prostate, pancreas, breast)
• Squamous cell carcinoma — cancer of flat surface cells (common in skin, lung, head and neck)
• Lobular carcinoma — a specific breast cancer subtype
• Ductal carcinoma — another breast cancer subtype
• Non-small cell vs small cell — major lung cancer division
• Glioblastoma / astrocytoma — brain cancer subtypes

The specific histology drives treatment options. Two “breast cancers” can behave and respond to therapy very differently.

Tumor grade

How abnormal the cells look under the microscope, usually 1 (most like normal tissue, slowest-growing) through 3 (most abnormal, faster-growing). Some cancers use their own grading systems (Gleason for prostate, Nottingham for breast, etc.).

Grade is different from stage. Grade is about the cells; stage is about the extent of spread.

Tumor size

The largest dimension of the invasive cancer, usually in centimeters. Size factors into stage.

Margins

If it was a surgical specimen, the pathologist measured the distance from the cancer to the edge of the removed tissue:

• Negative margin — no cancer at the edge (good)
• Positive margin — cancer extends to the edge (often requires more surgery or radiation)
• Close margin — cancer very near the edge (varies by cancer type whether this is concerning)

Lymph node involvement

If nodes were removed, the report will say how many were examined and how many contained cancer (e.g., “2 of 12 lymph nodes positive for metastatic carcinoma”). Node involvement is a major determinant of stage and systemic therapy recommendations.

Lymphovascular invasion, perineural invasion

Whether cancer cells were seen inside blood vessels, lymphatic channels, or around nerves. Presence suggests higher risk of spread.

Molecular / biomarker results

Increasingly, pathology reports include molecular tests. These are the critical drivers of targeted therapy and immunotherapy decisions.

Common markers by cancer type:

Breast cancer

• ER (estrogen receptor) / PR (progesterone receptor) — percent positive or negative
• HER2 — 0, 1+, 2+, or 3+ by IHC; FISH confirms 2+ cases. Positive HER2 is targetable.
• Ki-67 — proliferation index

Lung cancer (non-small cell)

• EGFR, ALK, ROS1, BRAF, MET, RET, KRAS, NTRK, HER2 — each has associated targeted therapies if positive
• PD-L1 — percent of tumor cells expressing (drives immunotherapy decisions)

Colorectal cancer

• KRAS, NRAS, BRAF — affect targeted therapy eligibility
• MSI (microsatellite instability) / MMR (mismatch repair) — MSI-H / dMMR tumors respond to certain immunotherapies
• HER2 — newer targeted therapy options

Many cancers

• Tumor mutational burden (TMB) — immunotherapy response predictor
• MSI / MMR — as above
• BRCA1/2, HRD — PARP inhibitor eligibility

If you don’t see molecular testing appropriate for your cancer type, ask your oncologist whether it should be ordered. Modern treatment hinges on these results; skipping them can mean missing a life-changing therapy option.

Staging information

Some reports include a pathologic stage (pT, pN, pM) based on the surgical specimen. This is different from clinical stage, which is based on imaging before surgery. Your oncologist will use the final stage to plan further treatment.

What to do with the report

1. Get a copy. You’re entitled to one. Request it at the appointment or via the patient portal.
2. Ask your oncologist to walk you through it. Bring the report to the next visit. Don’t try to decode everything alone.
3. Compare it to clinical-trial eligibility. If you’re considering trials (see our trial-finding guide), the specifics in the pathology report will determine qualification.
4. Consider a second pathology opinion. For rare cancers or unusual features, a second review at an academic center can change the diagnosis. See how to get a second opinion.

When to ask for re-review

• The diagnosis is uncommon or unusual
• Your cancer behaves differently from what the initial diagnosis would predict
• You’re considering aggressive treatment (major surgery, intensive chemo) and want to be sure
• Pathologists sometimes disagree — published data suggests diagnosis changes in about 10% of second reviews at academic centers

A second pathology opinion is inexpensive and routine at NCI-designated cancer centers.