Office of Cancer Communications

Building 31,Room 10A24

Bethesda, MD 20892

National Cancer Institute

Monday, February 22, 1999

FOR RESPONSE TO INQURIES
NCI Press Office
(301) 496-6641

 Backgrounder

Cervical Cancer: Backgrounder

Facts and Figures

  • In 1999, an estimated 12,800 cases of invasive cervical cancer are expected to occur in the United States, with about 4,800 women dying from this disease.

  • In the United States, currently the highest age-adjusted incidence rate occurs among Vietnamese women (43 per 100,000), probably reflecting lack of prior screening. Incidence rates of 15 per 100,000 or higher also occur among Alaska Native, Korean, and Hispanic women. (For all U.S. women, the rate is about eight per 100,000.)

  • Mortality declined 45 percent between the periods 1972-74 and 1992-94, while incidence declined 43.3 percent from 1973 to 1995.

  • While death rates for African Americans have declined more rapidly than for whites, the African American death rate (6.7 per 100,000) continues to be more than twice that of whites (2.5 per 100,000). The higher African American death rate is due to the high number of cervical cancer deaths among older black women.

  • Worldwide, cervical cancer is the second or third most common cancer among women (cervical cancer and colorectal cancer are virtually tied for second place after breast cancer). In some developing countries, it is the most common cancer. About 400,000 new cases are diagnosed each year, predominantly among the economically disadvantaged, in both developing and industrialized nations.

Risk Factors

  • HPV: The primary risk factor for cervical cancer is infection with certain types of the human papillomavirus (HPV). Large studies have found HPV C primarily HPV16, 18, 31, and 45 C in virtually all cases of cervical cancer (more than 93 percent). However, it is important to note that not every HPV infection is destined to become cervical cancer; in fact HPV infection is very common, while cervical cancer is not.

  • Age: Rates of cervical carcinoma in situ (cervical cancer that has not invaded surrounding tissues) reach a peak in both black and white women between the ages of 20 and 30 years. After the age of 25 years, the number of cases of invasive cervical cancer increases with age in white women and black women, but it increases strikingly with age only in black women. The chance of dying of cervical cancer increases as women get older.

  • Pap test history: Women who have never had a Pap test or who have not had one for several years have a higher-than-average risk of developing cervical cancer.

  • Sexual history: HPV is a sexually transmitted virus. Women who first had sexual intercourse at an early age or who have had many sexual partners have a higher-than-average risk of developing cervical cancer. Women whose husbands have had many sexual partners are also at increased risk, according to several studies.

Screening and Early Detection

  • The majority of cervical cancers develop through a series of gradual, well-defined, precancerous lesions. During this usually lengthy process, the abnormal tissue is easily detected by the Pap test and removed.

  • Pap tests, like other early detection tests, are not 100 percent accurate. Estimates of the false negative rate range widely. Law suits and publicity over false negative Pap tests in the 1980s led to federal legislation, the Clinical Laboratory Improvement Amendments of 1988 (CLIA), which mandate certain quality control procedures in all laboratories that process tests.

  • In addition, new automated aids to reading and checking Pap tests and new ways to collect the specimens have been developed with the aim of reducing the false negative rate. The FDA has approved the marketing of several of these technologies. Some physicians and laboratories have begun to use them while companies continue to refine them. Little data are available on their cost effectiveness.

  • Regular Pap tests help counter the problem of false negatives C i.e., if an abnormality is missed on one test, it is likely to be found on the next before it has progressed to cancer.

  • According to NCI=s official statement on cervical cancer screening, Astudies suggest that the death rate of cervical cancer will decrease if women who are or have been sexually active or who are in their late teens or older have regular Pap tests@ (PDQ, Screening for Cervical Cancer, August, 1998).

  • The American Cancer Society (ACS) recommends that the Pap test be performed annually along with a pelvic exam in women who are, or have been, sexually active or who have reached age 18. After three or more consecutive annual exams with normal findings, the Pap test may be performed less frequently at the discretion of the physician, according to the ACS guidelines. There is no upper age limit for Pap tests.

  • As of January 1998, Medicare covers Pap tests once every three years for all Medicare beneficiaries.

Public Health Issues

  • Many women still do not have regular Pap tests. Data from the 1994 National Health Interview Survey (NHIS) show that about a fifth of women ages 18-64 had not had a Pap test in the past three years.

  • The unscreened populations include older women, the uninsured, ethnic minorities, especially Hispanics, elderly African-American women, and poor women, particularly those in rural areas.

  • About half of the women with newly diagnosed invasive cervical cancer not had a Pap test in the past five years.

  • NCI has developed a campaign to increase public awareness that older women continue to be at risk for developing cervical cancer and should have regular Pap tests. Women ages 65 and older account for nearly 25 percent of all cervical cancer cases and 41 percent of cervical cancer deaths in the United States, but they have much lower screening rates than younger women. In the 1994 NHIS, 57.3 percent of women ages 65 and older said that they had had a Pap test in the past three years, compared to 81.1 percent of younger women.

Current Research

  • Although infection with certain types of HPV increases the risk of cervical cancer, most infected women do not develop cancer. Researchers are, therefore, looking at co-factors that may work with HPV to promote carcinogenesis. Co-factors may include immune system functioning, smoking, nutritional factors, hormonal factors, and the presence of other sexually transmitted diseases.

  • Immunologic and other co-factors are the focus of a current, large NCI study in Costa Rica. Investigators have screened about 10,000 women to obtain data on the incidence and prevalence of HPV infection and co-factors that increase the risk of cervical cancer. This project is also evaluating some of the new diagnostic technologies.

  • Researchers are developing vaccines targeted against the HPV, both to prevent and to treat cervical cancer. Several different treatment vaccines are under development at centers around the world. At NCI, planning is under way for an Institute-sponsored, multicenter trial to test a vaccine as adjuvant treatment after radiation therapy or surgery.

  • Among the prevention vaccines in development, three have reached the stage of being tested in people. One of these, developed at NCI, has been tested in a phase I trial, and the preliminary results show that it stimulated production of HPV antibodies and was safe. If these results are confirmed after further follow up and analysis, a phase II study will test the NCI vaccine in a larger group of women in the United States and Costa Rica, leading perhaps to a full phase III trial in Costa Rica.

  • NCI is conducting a large randomized trial to find the best way to manage the mild abnormalities that often show up on Pap tests and may, in rare instances, progress to cancer if left untreated. The study, called the ASCUS/LSIL Triage Study or ALTS, is comparing three approaches: 1) immediate colposcopy C a procedure in which a physician examines the cervix through a magnifying instrument and biopsies any abnormal areas; 2) repeating the Pap test every six months (because most abnormalities return to normal without treatment); and 3) testing for cancer-associated types of HPV as a means to differentiate between abnormalities that need immediate colposcopy and those that can be best followed with repeat Pap tests.

Treatment Studies

  • Studies are comparing different kinds and combinations of chemotherapy drugs to include in the treatment of invasive cervical cancer.

  • Investigators are also looking at the impact of both surgery and radiation therapy on quality of life and at ways to improve quality of life after treatment.

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