Understanding Your Lung Cancer Pathology Report

A pathology report contains a description of your pathology results. This document, written by a pathologist, details the characteristics of cells and tissues obtained during a biopsy or surgery. The pathologist can determine if the cells are benign (not cancerous) or malignant (cancerous) by examining the sample with a microscope.

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If you have cancer, the pathology report will provide details about the size, shape, and appearance of the cancer cells. These characteristics help your doctors stage the disease, direct the appropriate treatment, and predict the likely outcome (prognosis). The report may also include genetic test results, which can help determine whether the cancer cells have mutations that respond to newer targeted therapies.

Pathology reports can be very detailed and may vary from one lab to the next, but they have similar parts and layouts.

Patient Information

The pathology report opens with basic information about you, as well as a list of your healthcare providers and relevant dates.

The report will typically list:

  • Your name
  • Date of birth
  • Age
  • Sex
  • Name of the referring doctor who ordered the test
  • Names of other doctors being copied on the report
  • Date and time when the specimen was collected
  • Date and time when the specimen was received by the lab
  • The address of the lab

The pathology report also contains a case number issued by the lab. It is important to note that this is not the same reference number used by your health insurance company.

Specimens Received

The word specimen refers to any tissue or fluid sample sent to the lab for evaluation.

In this section of the pathology report, the pathologist will outline what type of sample was received and from which part of the body the sample was taken. If lung cancer is suspected, the submitted specimens may include:

The specimen may be an entire mass or lymph node taken during open surgery. Or, it may only include a sample of tissues taken during a needle biopsy (in which a hollow-core needle is inserted through the chest into a tumor) or an endoscopic exam (in which a fiberoptic scope is inserted through the mouth into the airways).

A tumor's location can play an important role in differentiating lung cancer types. For instance, cancers that develop in the airways are more likely to be squamous cell carcinoma, while those that develop on the outer edges of the lung are more likely to be adenocarcinoma.

Along with the type of sample obtained, the pathologist will refer to its location with a combination of letters and numbers.

Examples include:

  • "R" for right
  • "L" for left
  • "A" for anterior (to the front)
  • "P" for posterior (to the back)
  • "ESS" for entire sample submitted

Diagnosis/Interpretation

Most pathology reports will clearly state whether cancer cells were detected or not. This is usually included under the heading "Diagnosis" or "Interpretation."

In some cases, the diagnosis may precede "Specimens Received." In others, the diagnosis and specimen information will be consolidated under the same heading.

If lung cancer is present in your sample, the pathologist will diagnose the type of cancer.

The most common types of lung cancer are:

These distinctions can help predict how quickly or slowly a tumor will grow and spread.

Not all lung cancers fit into one category. Some small cell carcinomas have areas with squamous cell carcinoma, adenocarcinoma, or large cell carcinoma mixed in. These tumors would be classified as mixed type or combined small cell carcinomas.

A tumor might also be described as "not otherwise specified (NOS)," meaning that the pathologist was not able to determine if the tumor was adenocarcinoma, squamous cell carcinoma, large cell carcinoma, or some of the other rarer type of carcinoma.

The pathologist who issued the findings will sign off the report, providing their name and the date.

Gross Examination

The gross examination, also known as the macroscopic examination, describes the pathologist's examination of the sample without any diagnostic tools.

With respect to lung cancer, gross examination describes:

  • Tumor size: The measurements include the largest dimension and the general dimension in centimeters (cm)
  • Tumor margins: This is the measurement of the healthy tissue surrounding the tumor in the specimen
  • Tumor extension: This details whether the tumor appears to have grown into surrounding tissues.
  • Lymph node involvement: This provides information about whether lymph nodes extracted during surgery have any abnormalities in size, shape, or texture

The information provided in the "Gross Examination" section is not diagnostic, but it outlines abnormalities that help support the diagnosis and characterize the disease. For example, sometimes cancer can produce an obviously irregular texture, but sometimes tumor cells might not result in changes that are visible without a microscope.

Microscopic Evaluation

After the gross examination, the pathologist will evaluate tissue samples under the microscope. The pathologist will cut small tissue blocks from the specimen, which are frozen, sliced paper-thin, and mounted on glass slides.

There are several important pieces of information that can be derived from a microscopic evaluation:

  • Tumor type: The microscopic exam can differentiate the types of lung cancer based on the size, structure, and organization of cells and whether certain proteins are revealed when the sample is stained. These include protein biomarkers known as TTF-1, p63, and chromogranin.
  • Tumor grade: Histological grading is used to describe how much the specimen cells look like normal cells. Cells that look more normal are described as "well-differentiated," while cells that do not look normal are described as "undifferentiated" or "poorly differentiated." In general, tumors are graded as grade 1, 2, 3, or 4, depending on the degree of abnormality.
  • Tumor margins: Tissues surrounding the tumor may be negative/"clean" (meaning there are no cancer cells) or positive/"involved" (meaning there are cancer cells).
  • Lymph node involvement: Cancer cells from the tumor can spread to nearby lymph nodes. Microscopic evaluation can define whether a lymph node is positive or negative for cancer and whether the cancer is localized (limited to the place it started) or regional (affecting nearby organs or tissues).

Molecular Test Results

If your pathology results show that you have lung cancer, your doctor might also order molecular testing, also known as genetic profiling, to identify genetic mutations in the cancer cells.

On your pathology report, the molecular testing results will be listed as either "positive" or "negative" for each treatable gene mutation. It may also include the specific genetic test used to make the diagnosis.

Some mutations cause certain receptors to emerge on the surface of cancer cells. Targeted drugs can recognize and attack these receptors. Because the therapy is targeted, it leaves normal cells untouched and causes fewer side effects than more broad-based cancer treatments.

Some of the lung cancer mutations that can be targeted with therapy include:

Other lung cancer alterations that can be targeted include BRAF, RET, NTRK, MET, and KRAS. Researchers are identifying new mutations and working on making new targeted therapies for the treatment of lung cancer and other types of cancer.

How the Pathology Report Is Used

The pathology report is important to the staging of lung cancer. In some cases, the report can provide some or all of the information needed to stage the disease. Usually, additional tests will be needed for staging, including positron emission tomography (PET) and magnetic resonance imaging (MRI) scans of the brain, and bone scans, to determine if the malignancy has metastasized (spread), and what locations it has spread to.

The two main types of lung cancer are staged differently:

  • Non-small cell lung cancers like adenocarcinoma, squamous cell carcinoma, and large cell carcinoma are staged based on tumor size, lymph node involvement, and whether metastasis has occurred. The disease is classified into five stages, with stage 0 being the least severe and stage 4 being the most severe.
  • Small cell lung cancers have only two stages—limited stage and extensive stage—with extensive-stage cancers having far worse outcomes.

Based on the type, stage, and grade of the disease, as well as your molecular test results, your doctors can prescribe the appropriate treatment, whether the aim is curative or palliative (intended to extend survival and reduce symptoms).

A Word From Verywell

Pathology reports can provide valuable information about a lung cancer sample. The report can be used with standardized criteria and algorithms to determine treatment and prognosis.

But, biopsy samples can be interpreted differently by different pathologists. If there are inconclusive or borderline results (or you are simply unsure about the findings), it is reasonable to get a second opinion from a qualified pathologist. If you decide to get a second opinion, contact the pathology lab where you will be seeking the second opinion and ask what materials they will need. This may include the original tissue samples and any slides made after your biopsy or surgery.

In the United States, federal law requires pathology labs to keep cytology slides for at least five years and tissue sample embedded on paraffin block for at least two years.

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