What It Means if You Have Precancerous Cells

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A precancerous cell is a cell with certain abnormalities that makes it more likely to become cancerous. These abnormalities don't mean that it will become cancer—in fact, most don't—but the diagnosis allows healthcare providers to monitor you closely and act quickly if cancer does occur. In some cases, the affected tissues may be removed proactively.

Precancerous cells can occur in nearly any part of the body, including the skin, breasts, colon, and cervix. Unlike cancer cells, they do not invade nearby tissues or spread to distant organs.

This article explains what precancerous cells are and what causes them. It also describes the different types of precancerous cells and what can be done to treat them.

what are precancerous cells

Verywell / Ellen Lindner

What Are Precancerous Cells?

The term "precancer" may sound scary, but it simply means that there are cells that have grown abnormally, causing their size, shape, or appearance to look different than normal cells. These changes may increase a person's risk of developing cancer, but there is usually no way to tell if they will ever become cancer.

In many cases, the abnormal cells will remain the same or even return to normal. Most precancerous cells do not morph into invasive cancer cells.

Precancerous conditions can range from benign neoplasias (tumors that don't invade neighboring normal tissues or distant organs) to dysplasia (a cluster of highly abnormal cells).

When dysplasia is severe, it may be referred to as carcinoma in situ, a classification that some people describe as "early cancer" and others regard as precancer.

If precancerous cells are removed before they become cancerous, then your risk of cancer should, in theory, be eliminated. But that is not necessarily true since the underlying cause may remain and place you at risk of other precancerous cells.

To this end, it is important to know if you have precancerous cells so that you can be regularly monitored, whether the cells are removed or not.

Types of Precancerous Conditions

The majority of cancers (roughly 85%) develop in epithelial cells. These are the cells found in the skin, mucus membranes, and lining of most organs.

Precancers that commonly develop in epithelial cells include:

Non-epithelial cancers can involve blood or specialized cells like germ cells found in the ovaries. Precancers that may develop in non-epithelial cells include:

What Causes Precancerous Cells?

There are quite a few factors that can cause cells to become precancerous. They vary depending on the type of cell involved.

In most cases, there will be a host of factors that contribute to the risk, including genetics, hormones, infections, cancer-causing agents (carcinogens), and even stress. These work together to transform normally replicating cells into abnormally replicating cells.


Infections with viruses, bacteria, and parasites are responsible for 15% to 20% of cancers worldwide.

Among them, human papillomavirus (HPV) can cause inflammation leading to precancerous cells in the cervix and other mucosal membranes. While most HPV infections clear before any abnormal changes occur. some may progress and cause precancerous growths on the cervix, anus, penis, mouth, and throat. The vast majority of cervical cancers are associated with HPV.

Another example is Helicobacter pylori (H. pylori). This common bacteria causes inflammation of the stomach that can lead to chronic atrophic gastritis. In some people, this can progress to stomach cancer.

Chronic Inflammation

Chronic (persistent) inflammation can lead to precancerous changes in tissues.

An example is gastroesophageal reflux disease (GERD), a chronic form of acid reflux that can lead to a precancerous condition known as Barrett’s esophagus. Among people with Barrett’s esophagus, approximately 0.5% per year will develop esophageal cancer.

Another example is inflammatory bowel disease (IBD). The persistent inflammation caused by IBS can lead to the formation of colon polyps. Those with dysplasia that grow quickly, excessively, or irregularly have a greater chance of becoming colon cancer.

When Do Cells Become Cancerous?

Most of the time, there is no way to tell if or when a precancer cell will turn cancerous. The answer depends largely on the type of cell involved as well as the degree of abnormal changes known as the grade.

Grading is a methodology used to determine how abnormal cells look under the microscope. The grading system can vary based on the cell type but typically evaluates architectural changes (changes in tissues and cell grouping) and cytological changes (changes in individual cells).

The various changes are given numerical scores based on how normal or abnormal they are. Lower scores are given to more normal tissue or cells, while higher scores are assigned to more abnormal tissues or cells. These scores are added up to determine the overall dysplasia grade.

For oral epithelial dysplasia, the grading breaks down as follows:

  • 0-10: No dysplasia
  • 11-25: Mild dysplasia
  • 26-45: Moderate dysplasia
  • Above 45: Severe dysplasia

While there are different grading systems for different conditions, their principles remain the same: The higher the grade, the more likely a precancerous cell will turn cancerous.

The grade can also help determine if immediate treatment is needed or if a watch-and-wait approach is more appropriate.

How Serious Are Precancerous Cells?

Precancerous cells may or may not turn into cancer. Because the cells are abnormal, it's important to have them monitored or, in some cases, removed to help reduce your future risk of cancer.

The decision will not only be based on the pathology report but also a shared decision by you and your healthcare provider as to whether waiting or treating is the most appropriate choice.

How to Treat Precancerous Cells

The treatment of precancerous cells also depends on where in the body they are located. In some cases, close monitoring is all that is recommended to see if the level of dysplasia progresses or if it goes away without any treatment.

Often, the precancerous cells will be removed by a procedure such as cryotherapy 410 (freezing the cells) or surgery to remove the region where the abnormal cells are found.

Even if the abnormal cells are removed, it’s important to keep in mind that whatever caused the cells to become abnormal in the first place may affect other cells in the future. Thus, careful monitoring over the long term is important.

If abnormal cervical cells are treated with cryotherapy, it will still be important to monitor for future problems with Pap smears. And if Barrett’s esophagus is treated with cryotherapy, you will still need to have the health of your esophagus tissue monitored in the future.

For some abnormalities, your healthcare provider may recommend chemoprevention. This is the use of a drug that reduces the risk of cells becoming abnormal again later.

Treating an H. pylori infection, for example, will remove the bacteria from the stomach. It appears to reduce the precancerous cells and the development of stomach cancer.

Researchers are looking at the use of several medications and vitamins to see if their use in former and current smokers will lower their risk of developing lung cancer in the future.

Remember too that, in some cases, the progression of precancerous changes may be affected by environmental factors. They include the foods we eat, how much exercise we get, and the lifestyle choices we make. A diet rich in foods containing certain vitamins, for example, may help the body clear the HPV virus more rapidly.

Similarly, it's important to consider tobacco and other substances that may be responsible for precancerous changes. Avoiding them may reduce the risk that abnormal cells will progress or that other precancerous cells will develop in the future.

An example is the correlation between smoking and cervical cancer. While smoking does not appear to cause cervical cancer on its own, smoking combined with an HPV infection increases the chance that cancer will develop.


Precancerous cells are cells that show abnormal changes but have not yet developed into cancer cells. In many cases, they won't. But cancers can develop from these changes, so it's important to find them through routine screenings and other measures.

The abnormal changes seen in these cells arise from a number of causes, which may include infection, inflammation, or environmental exposure. Some precancerous cells will require only monitoring. Treatment for others will depend on where they are and what may have caused them.

Be sure to discuss any precancerous cells and the appropriate next steps with your healthcare provider.

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By Lynne Eldridge, MD
 Lynne Eldrige, MD, is a lung cancer physician, patient advocate, and award-winning author of "Avoiding Cancer One Day at a Time."