The Medical Minute: Cervical cancer -- another preventable problem

January 24, 2007

By John Messmer
Penn State Family and Community Medicine
Penn State Milton S. Hershey Medical Center
Penn State College of Medicine

A woman's uterus or womb opens into the vagina through the cervix. The surface of the cervix is tissue very much like skin. At the point where the cervix opens to form the passage from the uterus, this skin-like covering transforms into another kind of tissue, which is better suited to the inside of the uterus. This "transitional zone" is where most cervical cancer develops.

Most cervical cancer is caused by infection with the human papilloma virus (HPV). There are about 70 different HPV viruses that can infect the skin and membranes, with certain strains affecting specific areas. For example, common warts of the hands and feet are caused by HPV types 1 and 2. However, the virus from hand warts does not lead to infection of the genitals or cancer of any kind. Types 6, 11, 16 and 18 cause 90 percent of genital warts, and 70 percent of cervical cancer is caused by types 16 and 18.

HPV infections are extremely common. About 80 percent of sexually active people have had an HPV infection, but most of the time the immune system eliminates it. So, having genital warts does not necessarily mean cancer will develop.

As with many other cancers, there are things that increase the chance it will occur. Cervical cancer is more likely in smokers. Some of the harmful substances that reach the lungs enter the blood and affect other organs. Being a smoker or living with one increases the risk that the immune system will not kill the HPV virus. If the immune system is suppressed from disease or from medical treatment, the chance of cervical and other cancers is higher. Infection and irritation of the cervix increases risk, and having multiple sexual partners increases the likelihood of contracting HPV. Unfortunately, while condoms reduce the risk of many sexually transmitted diseases, they have not been shown to reduce the risk of HPV.

Fortunately, detection of cervical cancer at a time when it is curable is quite easy and reliable, but too often women do not seek screening, even when they have insurance coverage. About 12,000 women in the United States will develop cervical cancer annually, and almost 4,000 will die from it.

Pap smears are still the recommended method of screening for cervical cancer. During a pelvic examination, a plastic or metal speculum is inserted into the vagina to move the vaginal walls apart so the cervix can be seen. A small plastic brush is gently swabbed on the cervix, picking up cells which will be sent to a lab for evaluation. The classic Pap smear was made by smearing the cells onto a microscope slide, applying a stain and evaluating under a microscope for abnormalities. Many new technologies have changed the processing of Pap samples in ways that appear to improve the technique and perhaps reduce the risk of errors.

As normal cells become malignant, they first show a change called dysplasia. There may be cells that are not exactly normal but are not dysplastic; these are called "atypical." Most atypical cells revert to normal in a year or two, as do many of the mildly dysplastic changes. Unfortunately, no one can say which ones will become normal at the time they are found. The addition of HPV testing increases the ability to find those at higher risk. Depending on the individual woman's own risks, a finding of atypical or dysplastic cells might prompt a more specialized exam called colposcopy.

In colposcopy, a magnifying instrument enlarges the view of the cervical cells so the doctor can find areas that look abnormal in order to take a tiny piece of tissue from these areas for examination. If the area is severely dysplastic or if cancer has just started in the spot (called "in situ"), the inner core of the cervix can be removed in the office, effectively curing the problem. It takes about 10 years to progress from atypical cells to in situ cancer, so a finding of a noncancerous abnormality should not cause panic.

When cancer is not detected and treated early, it can begin to invade the cervix, the uterus, the vagina and the rest of the pelvic tissue. Invasive cancer is treated with surgical removal of the cancer in most cases, radiation and chemotherapy, depending on how advanced it is. Cure is less likely in invasive cancer.

Women should start having regular Pap smears within a few years of first sexual contact or age 21 -- whichever is first, although some experts think a woman with no sexual contacts could wait until age 25. A minority of cervical cancers develop in women who are celibate. Although annual exams are commonly advised, some authorities think that the interval could be extended to three years in a woman with several normal Paps and no evidence of HPV infection in order to reduce the nation's cost of providing preventive gynecologic care. Others fear that it will be difficult to remember and schedule triennial exams, particularly since the examination itself, while not generally painful, is not something many women put high on their list of priorities. This might result in some women having the exam at much longer than appropriate intervals, allowing some cancers to go undiagnosed. Plus, the annual gynecologic check-up covers other health issues besides cancer screening.

Women who have had a hysterectomy for reasons other than cancer may discontinue Pap smears, but an annual well-woman exam might still be reasonable. Each woman should seek advice from her own physician. Since cervical cancer is very rare in elderly women, some physicians will stop performing Pap smears for women after 65 or 70 if they have had normal exams for several years.

There are many ways to reduce the risk of cervical cancer. A monogamous sexual relationship is safer than multiple contacts. Avoiding tobacco is essential to reduce risk, although tobacco is a much bigger contributor to heart disease, which is still the No. 1 killer of women. A diet rich in vegetables and fruits provides micronutrients that strengthen the immune system.

Recently available is a vaccine that provides complete protection against the strains of HPV responsible for 70 percent of all cervical cancer and 90 percent of vaginal warts. Getting a person's immune system to respond to a vaccine is not always easy, so all possible strains that cause cancer could not be included yet. So women who receive this vaccine will still require Pap exams. The vaccine is recommended for girls starting at age 9, when they are unlikely to have had any sexual contact, up to age 26. It might work for older women, but it has not been studied adequately. Even a woman who has had sexual contact might benefit, but the chance is greater if she has not already been infected.

One drawback is the cost -- about $360 for the three-shot series. Some insurers are not yet covering it, and some do not reimburse medical providers enough to pay for the cost of purchasing the vaccine. Additionally, parents may not see the need to vaccinate a daughter who is not currently sexually active. Yet we vaccinate all infants against hepatitis B virus in order to reduce the risk of liver cancer, which is rarer than cervical cancer.

Cervical cancer has been fairly easy to detect early and now may be almost completely preventable with regular exams and vaccination. For more information on cervical cancer, go to http://www.cancer.gov/cancertopics/types/cervical on the Web.

(Media Contacts)

Last Updated March 19, 2009