Squamous intraepithelial lesions (SIL) is a term that refers to abnormal changes in the cells on the surface of the cervix. These changes can be found with a Pap test and are divided into 2 categories:
Low-grade SIL. This refers to early changes in the size, shape, and number of cells that form the surface of the cervix. They may go away on their own. Or over time, they may grow larger or become more abnormal, forming a high-grade lesion. These changes may also be called mild dysplasia or cervical intraepithelial neoplasia 1 (CIN 1).
High-grade SIL. This means
there are a large number of seriously changed cells that are precancer cells. Like
low-grade SIL, these changes only happen in cells on the surface of the cervix.
The cells often don’t become cancer for many months, probably even years. But
without treatment, they will become cancer. High-grade lesions may also be called
moderate or severe dysplasia, CIN 2 or 3, or carcinoma in situ.
If abnormal cells on the surface of the cervix are not found and treated, over time they can spread deeper into the cervix, or to other tissues or organs. This is then called cervical cancer, or invasive cervical cancer. Cervical cancer occurs most often in women younger than age 50. Most cervical cancer is either squamous cell carcinoma or adenocarcinoma.
The death rates for cervical cancer have dropped sharply as Pap screenings have become more prevalent. Today, most cervical cancer is found in women who have not had regular screenings, and in women who have not had any screenings.