What Are CIN 1, CIN 2, CIN 3?
Are They Cancer?

What Does CIN Mean?

The term CIN is the abbreviation of the words Cervical Intraepithelial Neoplasia. It refers to a cellular change confined within the epithelial cells of the cervix.

Although the term contains the word "neoplasia," that is, cancer, CIN refers to a condition that has not yet turned into cancer. These changes are limited to the surface layer of the cervix and there is no invasion into the deeper tissues.

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The Bethesda System and the New Terminology

Today, in pathology reports, the Bethesda System is used alongside the old CIN classification. In this system, the term "lesion" is preferred instead of "neoplasia."

• LSIL (Low-grade Squamous Intraepithelial Lesion) → is equivalent to CIN 1.
• HSIL (High-grade Squamous Intraepithelial Lesion) → is equivalent to CIN 2 and CIN 3.

In most pathology reports, both systems are written together.

What Is the Difference Between the CIN Grades?

CIN 1 (LSIL)

It is a low-grade cellular change. It is usually due to a transient HPV infection and can be suppressed by the immune system.

CIN 2

It is a moderate-grade change. The cellular disruption is more pronounced.

CIN 3

It is a high-grade change. It is considered a cancer precursor but is still not invasive cancer.

Natural Course: Does It Regress on Its Own?

In patients whose smear or biopsy result is CIN 1 (LSIL):

• 62.7% return to normal on their own (regression)
• 18.6% remain the same
• 18.6% progress to CIN 2/CIN 3

The probability of CIN 1 progressing to cancer is approximately 0.15%.

The risk of CIN 2/CIN 3 (HSIL) lesions turning into cancer is reported to be approximately 1.44%.

Approximately 35.03% of patients diagnosed with CIN 2/CIN 3 may regress to CIN 1 over time.

Is Treatment Always Necessary?

CIN 1 is usually followed up. Especially in young patients, the immune system can clear HPV.

For CIN 2 and CIN 3 lesions, treatment is planned according to age, pregnancy plans, the HPV type and colposcopy findings. When necessary, LEEP, conization or ablation methods can be applied.

Is CIN Cancer?

CIN is not cancer. However, especially CIN 2 and CIN 3 have the potential to turn into cancer over many years if they are not properly followed up and treated.

For this reason, regular smear tests, HPV testing and colposcopic follow-up are extremely important.