Pap Smears and Cervical Cancer: What Every Woman Should Know

by Craig L. Bissinger, MD

How much do you know about the prevention of cervical cancer? Did you know, for example, that although it was once the number one killer of American women, it is now considered preventable by using a simple test? Of the 16,000 newly diagnosed cases and 4,800 women who will die of cervical cancer this year, almost all of them could have been prevented with a pap smear.

As a physician, I find it extremely gratifying to see women taking care of their health. It's hard to believe that there are still millions of women who fail to keep up with annual check-ups. Prevention of disease, with an annual pap smear, is the most effective medicine possible against cervical cancer. To understand why a pap smear is the first line of defense against cervical cancer, it is important to know a few basic points about the test itself.

What Is a Pap Smear?

A pap smear is a test in which a 'smear' of bodily secretions, especially from the cervix, is taken from the body, and examined to detect any abnormal cells.

The cervix is composed of two types of cells. The majority of the cells are flat cells called squamous cells. They encircle the entire cervix with the exception of an area in the center, which is composed of mucus-secreting cells known as columnar cells. The two types of cells come together at an area known as the squamo-columnar junction. I retrieve a sample from this spot because the cells are actively growing and any changes in the cells can be found in here.

The Procedure

When I do a pap smear, I use an instrument called a speculum to inspect the vagina. The instrument resembles a duck's beak with two portions that can be drawn apart to view the vagina and cervix. After carefully inserting the speculum into the vagina, I open and position it so that I can see the cervix (the tip of the uterus). With both a small wooden spatula and a brush, I scrape the surface of the cervix to obtain a sample of skin. It is a quick and relatively painless process. Women often describe the feeling as an 'internal pinch' when the brush touches the cervix. After I¹ve obtained the sample, I rub the cells onto a glass slide and then I 'fix' the sample to the slide with a spray.

Human Papilloma Virus

The two cell types, squamous and columnar cells, are constantly reproducing and creating new cells. This process of cell division progresses normally until something triggers a change. In almost all cases, the changes are caused by a virus known as human papilloma virus (HPV), also known as genital warts. The virus is introduced through sexual intercourse and has the unique ability to infect the dividing cells of the cervix. Once inside the cell, HPV inserts itself into the DNA of the cervical cells and alters their ability to produce new cells. A simple way to understand the role of HPV is to imagine the virus as a foreman on a production line. The foreman has given new instructions to the workers to alter the way a part is made. In the case of HPV, defective cells are Œthe new parts¹, and they will in turn produce more and more defective cells. Over the course of many years, the cells tend to become cancerous. This process takes a long time, and an annual pap smear can detect some of these changes early on.

What Happens in the Lab?

The specimen is sent to a laboratory where it is treated with special stains to highlight the cells for study. A specially trained technician will examine the slide to determine if it is normal. The results are then given to the physician who performed the pap smear. In order to maintain a high level of quality, 10% of all the slides are reviewed at the laboratory. In addition, many labs have physicians known as pathologists who review a select sample of the slides, especially the abnormal ones, to ensure the accuracy of the tests.