Dysplasia refers to abnormal changes in the size, shape, and organization of adult cells. It is frequently seen in the context of certain diseases and may sometimes represent an early stage in the development of cancer. However, dysplasia itself is not cancer, and some types of dysplasia regress without ever progressing to cancer. This article will examine the relationship between dysplasia and cancer in more detail.
What is dysplasia?
Dysplasia occurs when cells look abnormal under a microscope but are not cancerous. It indicates problems with the normal maturation process of cells. There are several different classification systems for dysplasia:
Mild dysplasia
In mild dysplasia, there are changes in less than 25% of cells when examined under a microscope. The changes are confined to the bottom layer of cells. This type of dysplasia may resolve on its own without progressing.
Moderate dysplasia
In moderate dysplasia, 25-75% of cells show abnormalities when viewed under a microscope. More of the thicker, middle layers of cells are involved. Moderate dysplasia has a higher chance of progressing to cancer compared to mild dysplasia.
Severe dysplasia
In severe dysplasia, over 75% of cells are abnormal and a majority of the thickness of the tissue shows changes. Severe dysplasia is more likely to progress to cancer if not treated, but it is not cancer yet.
Common causes of dysplasia
Some of the more frequent causes and locations of dysplasia include:
Cervical dysplasia
Cervical dysplasia occurs in the lining of the cervix in the uterus. It is most commonly caused by human papillomavirus (HPV) infection. Cervical dysplasia may regress, persist unchanged, or progress to cervical cancer.
Bronchial dysplasia
Bronchial dysplasia occurs in the bronchi or airways of the lungs. It is often seen in people at high risk of lung cancer, such as smokers. Bronchial dysplasia may lead to squamous cell lung cancer if left untreated.
Esophageal dysplasia
Esophageal dysplasia arises in the lining of the esophagus. Chronic irritation of the esophagus from gastric reflux is a major cause. Esophageal dysplasia can progress to adenocarcinoma of the esophagus.
Oral dysplasia
Oral dysplasia occurs in the lining of the mouth and throat. Main risk factors are smoking and alcohol consumption. Oral dysplasia may transform into oral squamous cell carcinoma.
Skin dysplasia
Skin dysplasia develops in sun-exposed areas of the skin. It is associated with ultraviolet radiation exposure and sun damage. Some skin dysplasias can turn into squamous cell carcinoma of the skin.
Is dysplasia always precancerous?
Dysplasia is often described as a precancerous condition because it sometimes progresses to cancer. However, dysplasia does not always inevitably lead to cancer. There are a few key points about the precancerous nature of dysplasia:
Mild dysplasia may regress
Mild dysplasia, especially when caught early, can resolve on its own without ever turning into cancer. One study showed that up to 57% of mild cervical dysplasia regressed within 2 years.
The risk rises with increasing severity
More advanced dysplasia is more likely to advance to cancer. For example, about 43% of severe cervical dysplasia may progress to cancer if untreated, but only 1% of mild cervical dysplasia advances.
Dysplasia may persist without changing
Some dysplasias remain stable over time and do not become cancerous. One review found that 49% of oral dysplasias showed no change over 5 years.
Early detection is key
Finding dysplasia early, before it has a chance to advance, gives the best chance of preventing cancer progression. Screening programs that detect precancerous changes can identify dysplasia when it is still reversible.
Some tissues are more prone to cancer progression
The propensity for dysplasia to transform into cancer differs between organs. For instance, lung dysplasia progresses to cancer more readily than oral dysplasia. The likelihood also increases with certain risk factors like smoking.
Treatment can remove precancerous dysplasia
Many cases of dysplasia can be treated effectively to interrupt the sequence before cancer develops. Treatments like surgery, infrared coagulation, and topical medicines can remove dysplastic lesions.
How is dysplasia diagnosed?
Some of the techniques used to detect dysplasia include:
Biopsy
The gold standard method is tissue biopsy, in which a small sample is removed and examined under a microscope by a pathologist. The pathologist looks for cellular abnormalities to determine the presence and severity of dysplasia.
Cytology
In cytology, cells are collected and stained on a microscope slide for evaluation. An example is the Pap smear, where cells are swabbed from the cervix to check for cervical dysplasia.
Special stains
Sometimes special dyes or stains are applied to biopsy specimens to highlight abnormal patterns that are predictive of dysplasia.
Advanced imaging
Tools like bronchoscopy, endoscopy, or colposcopy with Lugol’s iodine allow visual inspection of dysplasia on mucosal surfaces of the bronchial tubes, gastrointestinal tract, or cervix.
HPV testing
Testing for high-risk strains of human papillomavirus DNA helps identify individuals at risk for cervical dysplasia.
How is dysplasia treated?
Some approaches used to treat precancerous dysplasia lesions include:
Surgery
Surgical procedures can remove affected areas with dysplasia. For example, loop electrosurgical excision is used to remove cervical dysplasia by wire loop.
Freezing
Cryosurgery uses liquid nitrogen to freeze and eradicate abnormal cells. It is applied for some cervical and oral dysplasias.
Burning
Thermal ablation methods like electrocautery, infrared coagulation, and laser therapy destroy dysplastic lesions by heat. They are used for oral, cervical, and esophageal dysplasia.
Medications
Topical medicines like imiquimod or fluorouracil cream stimulate an immune response against skin dysplasia cells when applied regularly.
Surveillance
Mild, stable dysplasia may just be monitored with regular repeat examinations and biopsies to check for progression.
Takeaways
Here are some key points about dysplasia:
- Dysplasia refers to precancerous changes in cell appearance under the microscope.
- It may regress, remain stable, or progress to cancer depending on factors like severity and location.
- Early detection provides the best opportunity for interrupting progression.
- Treatment can remove concerning lesions before they become cancer.
- Dysplasia is not equivalent to cancer, but is often considered a warning sign to monitor closely.
Although the term dysplasia denotes increased cancer risk, it does not mean that cancer is inevitable. With proper screening and management, many dysplastic changes can be controlled before developing into cancer.