​What is CIN?

Cervical intraepithelial neoplasia (CIN) is a precancerous condition, where abnormal cells grow on the surface of the cervix. It is most common in women of childbearing age, usually affecting those between the ages of 25 to 35.

The cervix is the lower part of the uterus, that forms an opening between the uterus and the vagina. “Intraepithelial” means that abnormal cells are present on the epithelial tissue on the surface of the cervix. “Neoplasia” means the growth of new cells. CIN is also known as cervical dysplasia.

Most people with CIN do not go on to get cancer. If they do, it takes a long time, often years, to develop. This means that doctors have time to find the problem areas and remove them.

Classifications of CIN

CIN is classified according to the amount of epithelial tissue affected:

• CIN 1 or low-grade neoplasia: Dysplasia has affected about one-third of the epithelium’s thickness.
• CIN 2: Abnormal changes are present in between one-third and two-thirds of the epithelial layer.
• CIN 3: The most severe form, affecting more than two-thirds of the epithelium.

Symptoms of CIN

There are usually no symptoms of CIN, and the abnormal cells are found during a routine pap smear.

Causes of CIN?

CIN is usually caused by an infection with the human papilloma virus (HPV) – a virus that infects at least 75% of women at some point in their adult lives. The immune system will usually kill off HPV by itself, but if it doesn’t, it can lead to CIN. There are many strains of HPV, but HPV-16 and HPV-18 are the strains most likely to cause CIN. Other risk factors for CIN include:

• Age
• Smoking 
• Taking immunosuppressant drugs 

Diagnosing CIN

A routine pap is needed to detect abnormal cells on the cervix. If found, your doctor will perform a colposcopy to examine the cervix more closely, as well as the surrounding areas. A biopsy may be performed, during which a doctor will take a piece of tissue for examination in a lab. 

Treating CIN

The severity (classification) of CIN, the patient’s age and their general health, will affect which treatment is given. Some procedures to treat CIN may affect fertility, so options will always be discussed with you. 

CIN 1 is often not treated, as the condition resolves itself and very rarely leads to cancer. You may be asked to attend more regular pap smears so that your doctor can monitor for any further abnormal cells. If your doctor decides to treat CIN 1, the abnormal cells will be destroyed either by laser or the use of a probe which either burns away or freezes the cells. 

CIN 2 and CIN 3 require removal of the abnormal cells, to prevent them becoming cancerous in the future. There are several different types of procedure used to remove the cells, including:

• Loop electrosurgical excision procedure or LOOP: A small loop of wire that is electrically charged will remove tissue, which can then be examined more closely. Rarely, patients may experience complications, such as bleeding or stenosis (a narrowing of the cervix). 
• Cone biopsy or conization: A surgical procedure which removes a cone-shaped tissue piece in more severe case of CIN. The risk of complications is slightly higher following this procedure. 
• Hysterectomy: In cases where CIN keeps returning, or other procedures haven’t been successful, the uterus can be removed. 

Treatment for CIN is usually successful, and the chance of recurrence is low. Progression to cancer is rare, and takes many years. Following treatment for CIN, doctors recommend pap smears every 6 months for 2 years, then resuming yearly. 

Can CIN be prevented?

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