Pap Smear

Screening tests for cancers can detect people at high risk for certain forms of cancer, detect cancers at an earlier more treatable stage or actually prevent cancer by detecting precancerous cells so they can be removed before an actual cancer develops. A really good screen for cancer performs all three of those tasks and ultimately decreases morbidity and death from the particular cancer. Pap smears are an example of a really good screening test. Our knowledge of the causes and progression of precancerous lesions of the cervix along with newer technology to perform a pap test have combined to improve screening for cervical cancer.

The traditional Pap smear consisted of smearing cell taken from the cervix onto a microscope slide. This method has been extremely effective in decreasing the incidence of cervical cancer but still has a fairly high false negative rate. However because cervical cancer is a slow growing cancer as long as women had a pap smear every year most cases of precancerous cervical lesions will ultimately be detected. Newer methods use liquid based technology, where the cells are put into a liquid media to be evaluated by the pathologist. These samples are easier to read and theoretically detect more cervical lesions than the traditional Pap smear. They have not been shown to decrease the rate of cervical cancer.

Liquid based pap smears have an added advantage that the same sample can be used to test for the presence of high risk types of the human papilloma virus (HPV). There are many subtypes of HPV. Several types have been associated with the development of cervical cancer; these are called "high risk" subtypes. For years gynecologists have debated the best way to evaluate women whose pap smears show atypical squamous cells of undetermined significance (ASCUS). Now we can test these women for HPV and if negative for the high risk types of HPV recognize that they are extremely low risk for having any precancerous cervical lesion and simply repeat there pap in a year. Conversely if high risk HPV is present they are at higher risk for cervical lesions and a referral for colposcopy made. A colposcope is what I call "binoculars on wheels." It allows us to magnify our view of the cervix and any suspicious areas that are seen can be biopsied.

In addition to ASCUS, abnormal pap smears can show a low grade squamous intraepithelial lesion (LGSIL) or a high grade squamous intraepithelial lesion (HGSIL). Women with these findings do need to have a colposcopy to evaluate their cervix for the presence of HGSIL which is considered a precursor to cervical cancer. Treatment decisions are never made until a cervical biopsy confirms the presence of either a low or high grade cervical lesion. If left untreated high grade lesions have the potential to develop into a cancer. Treatment removes the abnormal cells preventing the development of cervical cancer.

The single biggest risk factor for a woman developing cervical cancer is not having had a pap smear done within 5 years of the cancer diagnosis. Indeed that is what we see in clinical practice. The few cases of cervical cancer I have seen since being in private practice were in women who had not had regular pap smears. The Women’s Health Network is a government funded program offering free cervical and breast cancer screenings to women who qualify based on lack of insurance coverage, age and income. For more information call 508-830-2314. Improving access to Pap smear screening will help decrease the 5000 deaths from cervical cancer that occur each year in the United States.