Understanding Your Lung Cancer Pathology Report

Microscopic sample of one type of lung cancer (squamous cell carcinoma)
National Cancer Institute

How can you read and understand your lung cancer pathology report? In the past, patients weren’t often privy to documents describing their cancer. But those days, thankfully, are gone. Many people are requesting copies of their medical information, and some cancer centers offer a patient portal through which everything from radiology reports to labs can be accessed online. But of all of this information, lung cancer pathology reports can be one of the hardest to decipher as a layperson. So we will try to explain some of the medical jargon so you can truly understand your report.

Pathology Report Basics

A pathology report is the written description of your cancer by a pathologist, after evaluating tissue taken from your body via a biopsy or surgery. Rather than just a yes or no report (is it cancer?) these reports often contain a great deal of information that not only helps your doctor understand your prognosis but the best treatment approach as well. That said, pathology reports aren’t used alone but instead are combined with a history, symptoms, physical exam, radiology studies, and lab studies to get the best overall picture of your cancer.

Every Cancer is Unique

A few notes are helpful before going on. One is that every cancer is different. If there were 30 people with lung cancer in a room, there would be 30 different types of lung cancer, even if each of the person had the same type and stage of lung cancer. The pathology report is one of the tools used to understand your individual cancer. Another important point is that while it is common to get second (and perhaps third or more) opinions about your cancer, a second reading of your pathology report may be overlooked. Getting a second opinion on your biopsy may be every bit as important as getting a second opinion on your treatment.

Name, Date, and Clinical Information

Your pathology report will first include your name, and some basic information as well as probable diagnosis and possible symptoms you have been experiencing.

Specimen

The word specimen sounds scary, but it essentially means the sample of tissue that a surgeon, radiologist, or other physician removes. This section describes the location in the body from which a sample was taken. When a specimen is obtained and received by the pathology department it is evaluated in a few steps.

Macroscopic Evaluation (also called Gross Examination)

As "macro" means large, and "gross" in medical jargon means visible to the naked eye, this examination refers to what the pathologist sees by looking at your tissue sample without the use of a microscope—the large picture in essence. It may include the dimensions, the weight of a tumor, and other characteristics like color and consistency. Some tumors are very obvious (as the picture above shows) but sometimes no abnormalities are seen until the next step is done.

Microscopic Evaluation

The microscopic evaluation contains several important details, and along with molecular profiling, will be discussed further below.

Microscopic Evaluation

After visualizing the sample of your tissue, pathologists often take thin slices which they then evaluate under the microscope. These are sometimes frozen (in order to slice the tissue very thin) and may be treated with a special dye or other material before being placed on a slide. (This process can take some time and is one reason your doctor may not have results while you wait anxiously.) There are several important pieces of information that come from this exam.

Tumor Margins

One common notation is about tumor margins (or surgical margins). This refers to whether or not all of a cancer was removed, and if it was all removed, how far away from the removal site was any evidence of cancer. For example, a report may say that the tumor extended to 1.2 cm from the surgical margin.

Tumor Grade

Tumors may be also ranked by tumor grade. Simplistically, a grade 1 tumor would be one that isn’t very aggressive, and a grade 3 tumor would be most aggressive. With lung cancer, your report may instead have words like well-differentiated, poorly differentiated, or undifferentiated. Well-differentiated tumors contain cancer cells that appear similar to normal cells and tend to grow slowly, whereas undifferentiated tumors contain cells that are very abnormal appearing and tend to grow much more rapidly.

In some cases, cancer cells can be so undifferentiated that it is difficult to determine what type of cell they were originally.

In addition to the general appearance of the cancer cells, pathologists look at many things to determine how aggressive a tumor might be. These include things such as mitotic activity (how rapidly cancer cells appear to be dividing) when determining the grade of a tumor.

Type of Cancer

With lung cancer, there are two major types. Non-small cell lung cancers comprise roughly 80% of lung cancers and the cells have a particular appearance under the microscope. Small cell lung cancers make up most of the remainder and have a different appearance under the microscope.

Non-small cell lung cancers are further divided into adenocarcinomas, large cell carcinomas, and squamous cell carcinomas depending upon the type of cell the cancer originated in, the appearance under the microscope, as well as lab tests that look at certain markers (see below). A confusing point for many people when looking at their pathology report is that tumors don’t always fit neatly into one category or another. For example, the report may say that a tumor is a non-small cell lung cancer with some characteristics of small cell lung cancer.

Less commonly, tumors such as carcinoid tumors of the lung may be found.

In Situ vs. Invasive/Infiltrating

Another note you may see on your report is that the tumor is in situ or that it is infiltrating or invasive. In situ describes cancer that is only present in the cells where it started. Many scientists consider these to be precancerous cells rather than cancerous cells. Lung cancer that is diagnosed at this stage is considered stage 0. 

The vast majority of the time with lung cancer, a tumor is described as infiltrating or invasive. This means that the tumor has spread past the tissue that it developed in and has the ability to spread (metastasize) to other parts of the body. The term invasive can be very frightening, but even small stage I lung cancers are considered invasive.

Pathologists may also note something referred to as angiolymphatic invasion. This describes whether the tumor has invaded nearby blood vessels and/or lymphatic vessels.

Lymph Node Involvement

If you have had surgery to remove your tumor, lymph nodes may have been removed to see if they are cancerous (positive) or non-cancerous (negative). This will be noted in the report with details such as whether the lymph nodes were near the tumor, or distant, and may play a big part in the treatment your oncologist recommends.

Many people are frightened if they read that a tumor has "metastasized to lymph nodes." The presence of metastases (spread) to lymph nodes does not mean that a lung cancer is metastatic (stage IV). In fact, a stage II lung cancer that has spread to lymph nodes would have a pathology report stating "metastases to lymph nodes."

Staging

Sometimes a stage is given as part of your pathology report. In order to determine stage, pathologists look at a combination of tumor size, lymph node involvement, and whether or not the tumor has spread to other parts of the body (metastasized). There are a few different ways your cancer may be described.

Non-small cell lung cancer is divided into 4 primary stages. To determine these stages physicians use something called TNM staging. With this system T stands for tumor size, N stands for the presence and number of positive lymph nodes, and M stands for distant metastases.

With small cell lung cancer, there are only 2 stages: extensive stage and limited stage.

Protein/Gene Markers

There are several additional tests your pathologist may perform on your tumor to help determine what type of lung cancer it is, or whether your tumor is actually cancer that arose in another part of your body and spread to your lungs. A few examples of these include TTF-1, p63, CD56, and chromogranin.

Molecular Profiling

Recently, advances have taken place in the treatment of lung cancer through an understanding of specific genetic mutations (or other genomic anomalies) which "drive" the growth of cancer. For some people, particularly people with adenocarcinoma, targeted therapies may be available to treat the disease. These treatments are often used orally and tend to have far fewer side effects than chemotherapy.

Different testing methods have been used to detect genomic changes in lung cancers. At the current time, next generation sequencing is thought to detect the greatest number of potentially treatable alterations and is cost effective. That said, test results may take from two to four weeks until they are available. In some cases, oncologists will do rapid tests for a few specific alterations in the hope that treatment can be started earlier.

Some mutations and other genomic alterations that may be found with lung cancer include those in:

If you have not had genetic testing done on your tumor, talk to your oncologist or get a second opinion, preferably at one of the larger National Cancer Institute designated cancer centers. Unfortunately, advances in lung cancer treatment are occurring so rapidly that it is challenging for a lung cancer oncologist, let alone a general oncologist to stay abreast of all of the changes. In some cases, being aware of the most recent research can have a significant impact on your outcome.

Diagnosis

The final part of the pathology report is the diagnosis in which the pathologist summarizes the findings. This will usually include the type of cancer, the grade (how differentiated it is) whether any lymph nodes were positive, and the stage.

In some cases, a preliminary diagnosis is given, as further testing (such as PET and other tests) are required in order to precisely define the stage of a lung cancer.

Next Step

If you have recently been told you have lung cancer, check out these first steps to take, consider a second opinion, and always ask a lot of questions. Don't ever feel you are taking too much of your doctor's time—that’ what she is paid for. If your questions aren't adequately answered, find a doctor who can answer them.

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