Is cervical cancer an infectious disease, caused by a virus passed from person to person?

Most people think of cancers and infectious diseases as being two distinctly different categories of diseases. Cancer is usually thought of as being caused things such as smoking, low-fiber diets, exposure to cancer-causing chemicals, genetic predisposition and bad luck.

Infectious diseases are caused by exposure to microorganisms such as bacteria, viruses and parasites.

Actually, cancer and infectious disease are not as distinctly different as scientists once believed. It’s now known that about 20 percent of cancers are caused by infectious microorganisms.

A virus called HTLV-1 has been linked to adult T-cell leukemia/lymphoma. The Helicobacter pylori bacteria increases a person’s risk of stomach cancer (though most people who develop ulcers as a result of Helicobacter pylori never develop cancer). Chronic infection with Hepatitis B and Hepatitis C viruses are known to cause liver cancer in some cases.

And it’s proven that certain high-risk types of human papillomavirus (HPV) cause cervical cancer in women. These sexually transmitted HPV types are also linked to cancers of the genital area, mouth and throat.

There are about 100 different types of HPV. Some of these cause the common warts found on hands and feet. Other low-risk HPV types cause warts in the genital area or around the anus, in both men and women. These warts appear as painless, flesh colored bumps on the skin. There may be just a few small bumps, or warts can be quite large growths.

A few types of HPV – especially high-risk types 16 and 18 – can cause cancer of the cervix in women. They are also linked to cancer of the penis in men, though this is quite rare.

Cervical cancer is detected in more than 12,000 women in the United States, and over 4,000 women die of it each year. This number was higher before Pap smears became a common screening test for cervical cancer.

The cervix is the bottom part of the uterus, which forms a canal between the uterus and the vagina.

Pap smears are usually done as part of a routine pelvic examination. A sample of cells from the cervix is taken. In a laboratory, the cells are examined for abnormalities.

There are several types of abnormal cervical cells. Depending on the type of abnormality, health care providers may recommend treatment, taking a closer look (colposcopy and biopsy) or retesting with another Pap smear in several months. Many abnormalities resolve on their own, without treatment. However, some abnormalities may progress into cervical cancer, so careful monitoring is important.

In the last few years, testing for high-risk types of HPV has been done for some women who have abnormal Pap smears. This can help clarify whether the abnormal cervical cells are due to a low-risk HPV type, in which case cancer is unlikely, or a high-risk HPV type, in which progression to cancer is more likely.

For women who have cancerous or precancerous cells (called “dysplasia”) seen on a Pap smear, this HPV typing is not necessary since it is assumed that they have a high-risk HPV type. There are several types of treatment for cervical dysplasia: cryotherapy, electrosurgical excision, a cone biopsy or laser treatment.

Few cases of cervical dysplasia are considered an emergency. Cervical cancer is slow growing, so sometimes watchful waiting is a reasonable strategy, since abnormalities may resolve without treatment.

The good news about cervical cancer being an infectious disease is that a vaccine is being developed to prevent the high-risk types of HPV. If this vaccine proves to be safe and effective, it can be given to children before they become sexually active, and thus prevent infection with high-risk HPV, which will dramatically reduce cervical cancer rates.

For more information on HPV, see the American Social Health Association Web site at

(www.ashastd.org/learn/learn_hpv.cfm).

Kathryn B. Brown is a family nurse practitioner with a master’s degree in nursing from OHSU.