What It Means if You Have Precancerous Cells

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?

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:

• Cervical intraepithelial neoplasia (CIN): May develop into cervical cancer
• Barrett's esophagus: May develop into esophageal cancer
• Atypical lobular hyperplasia: May develop into breast cancer
• Adenomatous polyps in the colon: May develop into colon cancer
• Actinic keratoses: May develop into squamous cell skin cancer
• Oral epithelial dysplasia: May develop into mouth or throat cancer.
• Dysplastic moles: May develop into melanoma
• Bronchial epithelial dysplasia: May develop into lung cancer
• Atrophic gastritis: May develop into stomach cancer
• Bowen's disease: May develop into invasive skin cancer

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:

• Monoclonal gammopathy of undetermined significance (MGUS): May develop into multiple myeloma 
• Benign ovarian germ cell tumors: May develop into ovarian cancer

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

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.

Chemical Exposure

Substances known to cause cancer are called carcinogens. Among these are chemicals used in industrial settings, such as factories or mines, while others may be found around your house, community, or natural environment.

Those known to cause cancer are called "known human carcinogens," while those that are strongly suspected of causing cancer are deemed "possible human carcinogens."

Examples of known human carcinogens are:

• Asbestos
• Arsenic
• Benzene
• Beryllium
• Vinyl chloride

Examples of possible human carcinogens include:

• Chloroform
• DDT 

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 to Treat Precancerous Cells

The treatment of precancers depends on where in the body the cells are located. In some cases, close monitoring is all that is needed to see if dysplasia progresses or goes away without any treatment. Other cases are treated just to be safe or after weighing the benefits and risks of treatment.

Cryotherapy and Surgery

Often, precancerous cells can be removed with a procedure called cryotherapy. This involves freezing the cells with temperatures of -150 F to -240 F to kill them.

When cryotherapy is unsuitable (such as for larger dysplastic lesions), surgery may be used to remove affected tissues and some of the surrounding tissues. This is called an excisional surgery performed under local anesthesia.

Even if dysplastic cervical cells are removed, it is still important to monitor for future problems with Pap smears. Similarly, if Barrett’s esophagus is treated with cryotherapy, you will still need to have regular check-ups to check for recurrence.

Chemoprevention

For some conditions, your healthcare provider may recommend chemoprevention. This involves medications that reduce the risk of precancerous cells coming back again after treatment.

With an H. pylori infection, for example, antibiotic drugs may be prescribed to kill the bacteria that can lead to precancer and stomach cancer in some people.

Some studies suggest that aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs) may help reduce the risk of cancer in people at average risk, including colon, ovarian, prostate, liver, skin, esophageal, pancreatic, and breast cancer.

Lifestyle Changes

The progression of precancers can be affected by environmental factors. These 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 more rapidly.

Quitting cigarettes can also reduce the risk of many cancers, not just lung cancer. This is true no matter how long you may have smoked.

Smoking and cervical cancer is one such example. While smoking does not "cause" cervical cancer, smoking combined with an HPV infection increases the odds that cancer will develop.

Summary

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.