Lung Cancer Cells vs Normal Cells — Pictures and Behavior | MyLungCancerTeam

Connect with others who understand.

sign up Log in
Resources
About MyLungCancerTeam
Powered By

Lung Cancer Grading: How Cancer Cells Look and Behave Compared With Normal Cells

Medically reviewed by Richard LoCicero, M.D.
Written by Aminah Wali, Ph.D.
Posted on August 1, 2022

As part of the diagnostic process for lung cancer, a doctor might discuss cancer cell grading. The grade of cancer refers to how abnormal the cancer cells are, in appearance and behavior, relative to normal cells. There are many tests used to help grade cancer cells, and the results can explain how advanced the cancer is and what treatment options are likely to be effective.

Grading Cancer Cells

To determine the cancer’s grade, a doctor performs a biopsy to surgically remove a tumor or part of a tumor. The tumor sample will then be analyzed under a microscope by another specialist called a pathologist. The pathologist will perform histology on the sample, using laboratory staining techniques to distinguish cancer cells from normal cells in the same tissue.

Based on the appearance and organization of the cancer cells, the pathologist will assign a grade using the following scale:

  • Grade X (undetermined) — The grade cannot be accurately determined.
  • Grade 1 (well differentiated) — Tumor cells look similar to normal cells, are in an organized pattern, and grow slowly.
  • Grade 2 (moderately differentiated) — Tumor cells are somewhat similar to normal cells but have some abnormal features.
  • Grade 3 (poorly differentiated) — Tumor cells are more abnormal and lack regular organization like normal cells.
  • Grade 4 (undifferentiated) —Tumor cells are dividing rapidly and look the most abnormal, no longer resembling normal tissue.

Apart from breast cancer, prostate cancer, and blood cancers, most types of cancer are graded by the same system used to grade lung cancer. A low-grade tumor (grades 1-2) correlates with early-stage disease or slow-growing cancer, whereas a high-grade tumor (grades 3-4) correlates with more aggressive or advanced-stage disease.

Appearance of Lung Cancer Cells

The left panel shows hematoxylin and eosin-stained tissues from normal lung tissue, and on the right is non-small cell lung cancer. Cancer cells are more crowded and are darker due to larger nuclei.
(Medical Images USA, left, Wikimedia Commons, right)


To analyze the appearance of cancer cells under a microscope and determine the cell grade, a pathologist will generally use hematoxylin and eosin (H and E) staining on cells taken from a tumor biopsy. H and E staining allows the pathologist to visualize the shape and organization of the cells, as well as overall tissue structure.

The left panel shows normal lung tissue with hematoxylin and eosin-staining, while the right shows crowded cells of small cell lung cancer. Cancer cells appear darker because of their larger nuclei.
(Medical Images USA, left and right)


After H and E staining, healthy lung cells appear mostly pink and are properly organized to form the normal structures of the lung. In contrast, lung cancer cells appear mostly dark purple due to having large nuclei (the portion of the cell that contains DNA). Cancer cells may also be observed in a crowded, clustered pattern as a result of their irregular growth.

In cancerous lung tissue, cells break through the tissue membrane. (Medical Images USA)


There are many types of cells in the lungs. A pathologist can determine the subtype of lung cancer based on what type of cell has become cancerous and other features that can be seen under the microscope.

Behavior of Lung Cancer Cells

Pathologists can also look at how lung cancer cells appear to be moving and spreading. Unlike normal cells, cancer cells divide rapidly and may migrate to other parts of the body. A pathologist might observe cancer cells moving beyond the normal structures of the lung. This is described as invasive or infiltrating cancer. Invasive lung cancer may spread to nearby lymph nodes or even to more distant organs in a process called metastasis. Invasive cancer is more often associated with tumor cells of a higher grade.

Cancer Grading vs. Staging

Although both are indicators of how the disease is progressing, cancer grading is distinct from cancer staging. Staging is a measure of how advanced the cancer is based on how far it has spread. There are different systems for cancer staging doctors may use, depending on the type of lung cancer.

TNM Staging

TNM stands for tumor, node, metastasis. The TNM staging system is generally used for non-small cell lung cancer (NSCLC), the most common form of cancer, but may also be used for small cell lung cancer (SCLC).

This system takes into account the size of the main tumor (T), if it has spread to a nearby lymph node (N), or if it is metastatic (M) and has spread to other parts of the body.

Limited and Extensive Staging

For SCLC, doctors commonly categorize cancer as either limited stage or extensive stage. In the limited stage of disease, the cancer is located only in a lung or nearby tissues. In the extended stage, the cancer is located throughout the lung and in distant lymph nodes or bones.

How Is Grading Used in Lung Cancer?

Doctors use cancer cell grading to better understand how lung cancer might grow and spread, so they can decide on the most effective treatment plan. A high-grade tumor calls for a more aggressive treatment strategy to keep disease from spreading.

Grading is also used to inform the prognosis (outlook) of lung cancer. Low-grade tumors are associated with a better prognosis, while high-grade tumors have worse overall survival. Determining the cancer grade and stage is an important part of the diagnostic process to ensure people with lung cancer have the best chance of survival.

Talk With Others Who Understand

MyLungCancerTeam is the social network for people with lung cancer and their loved ones. More than 6,000 members come together to ask questions, give advice, and share their stories with others who understand life with lung cancer.

Have you or a loved one been diagnosed with lung cancer? Share your experience in the comments below, or start a conversation by posting on MyLungCancerTeam.

Posted on August 1, 2022
All updates must be accompanied by text or a picture.

We'd love to hear from you! Please share your name and email to post and read comments.

You'll also get the latest articles directly to your inbox.

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Richard LoCicero, M.D. has a private practice specializing in hematology and medical oncology at the Longstreet Clinic Cancer Center, in Gainesville, Georgia. Review provided by VeriMed Healthcare Network. Learn more about him here.
Aminah Wali, Ph.D. received her doctorate in genetics and molecular biology from the University of North Carolina at Chapel Hill. Learn more about her here.

Related Articles

If you’ve recently been diagnosed with a Pancoast tumor, you may be wondering what this means for...

Pancoast Tumors: 6 Facts About Cancer in the Top of the Lung

If you’ve recently been diagnosed with a Pancoast tumor, you may be wondering what this means for...
Did you know that a lung abscess can look like lung cancer on an X-ray? Lung abscesses come from ...

Lung Abscess vs. Lung Cancer: How Do Doctors Tell the Difference?

Did you know that a lung abscess can look like lung cancer on an X-ray? Lung abscesses come from ...
Did you know lung cancers can spread beyond the chest? The term “metastasis” refers to cancer tha...

When Lung Cancer Spreads to the Adrenal Glands: What To Expect

Did you know lung cancers can spread beyond the chest? The term “metastasis” refers to cancer tha...
Lung cancer and hypertension (high blood pressure) can be related conditions for some people. If ...

Can Lung Cancer Cause High Blood Pressure? 6 Facts To Know

Lung cancer and hypertension (high blood pressure) can be related conditions for some people. If ...
Emphysema is a form of chronic obstructive pulmonary disease (COPD). It shares certain characteri...

Emphysema vs. Lung Cancer: 3 Differences and 3 Similarities

Emphysema is a form of chronic obstructive pulmonary disease (COPD). It shares certain characteri...
Thanks to advances in modern medicine, doctors are learning more about lung cancer every day. The...

EGFR-Positive Lung Cancer: 5 Facts To Know

Thanks to advances in modern medicine, doctors are learning more about lung cancer every day. The...

Recent Articles

MyHealthTeam does not provide health services, and if you need help, we’d strongly encourage you ...

Crisis Resources

MyHealthTeam does not provide health services, and if you need help, we’d strongly encourage you ...
Loss of appetite is a common symptom of living with lung cancer, and it can also be a side effect...

Loss of Appetite With Lung Cancer: 13 Tips To Improve Eating

Loss of appetite is a common symptom of living with lung cancer, and it can also be a side effect...
Choosing the right hospital for lung cancer treatment is one of the most critical decisions you c...

Best Hospitals for Lung Cancer Treatment: 7 Features To Look For

Choosing the right hospital for lung cancer treatment is one of the most critical decisions you c...
If you’re an older adult with lung cancer, you might have specific needs related to aging. It’s i...

8 Facts About Lung Cancer in Older Adults: Treatment Options, Prognosis, and More

If you’re an older adult with lung cancer, you might have specific needs related to aging. It’s i...
Lung cancer rates differ, depending on where you live. These differences are based on a number of...

What Countries Have the Highest and Lowest Lung Cancer Rates?

Lung cancer rates differ, depending on where you live. These differences are based on a number of...
Doctors and scientists are constantly finding new and better ways to treat lung cancer. In the pa...

New Lung Cancer Treatments: 8 Advancements in Research

Doctors and scientists are constantly finding new and better ways to treat lung cancer. In the pa...
MyLungCancerTeam My lung cancer Team

Thank you for subscribing!

Become a member to get even more:

sign up for free

close