According to the National Cancer Institute, human papilloma virus, or HPV, causes more than 90 percent of cervical cancers. Although prevention efforts have reduced both the incidence and mortality rates of cervical cancer dramatically, it remains a serious health threat. Institute data show the median age for diagnosis to be 48 years, with less than 15 percent of women diagnosed under age 35.
Background
Cervical cancer is usually a slow-growing cancer occurring in the tissues between the uterus and the vagina. Because there are usually few symptoms, detection is through a sample taken of cervical tissues examined under a microscope, the Pap test. Although according to the American Cancer Society, early detection and treatment has reduced the incidence of cervical cancer deaths by 70 percent since 1955, it remains a serious disease. The NCI estimated 12,200 new cases and 4,210 deaths in 2010.
Risk Factors
The NCI attributes 90 percent of all cervical cancers to HPV infection. However, most adults have HPV at some point but do not develop cervical cancer. Two HPV strains, 16 and 18, are responsible for 70 percent of all cervical cancers. Other factors increase the risk of HPV infection, including early sexual activity, multiple partners and having many children. Smoking, according to the American Cancer Society, doubles the risk.
HPV Infection
A National Health and Nutrition Examination Survey published in the Journal of the American Medical Association in 2007 and reported in an NCI bulletin, provided estimates of HPV prevalence. Among women between ages 14 and 59, 26.8 percent tested positive for any strain of HPV, and 15.2 percent tested positive for a high-risk strain. Overall, prevalence of HPV infection was highest among women ages 20 to 24.
Cervical Cancer Incidence
According to NCI's Surveillance Epidemiology and End Results, between 2003 and 2007, the median age at cervical cancer diagnosis was 48. Incidence increases with age until approximately age 55 when it drops off again. Approximately half, 49.8 percent, of cases are diagnosed in women between ages 35 and 54. Less than 15 percent of cases are among women under age 35.
Cervical Cancer Deaths
The likelihood of dying from cervical cancer increases with age. According to the NCI, white women between ages 45 and 70 have the highest death rates as do black women in their 70s. The mortality rate for black women is more than double that of whites.
Screening
Because of early screening with the Pap test, which can detect precancerous lesions, cervical cancer is preventable. Unfortunately, not all women take advantage of the Pap test. According to the American Cancer Society, between 60 and 80 percent of women in the U.S. diagnosed with invasive cervical cancer have not had a Pap test in the past five years and some have never had one. Women less likely to have Pap tests include the elderly, blacks, low-income women and recent immigrants.
HPV Vaccine
In June 2006, the Food and Drug Administration approved an HPV vaccine that is almost 100 percent effective in protecting against two types of HPV responsible for 70 percent of cervical cancers. The vaccine targets girls and women before they become sexually active, ages 9 to 26.
References
- National Cancer Institute: Surveillance Epidemiology and End Results: SEER Stat Fact Sheets Cervix Uteri
- National Cancer Institute: Cervical Cancer
- American Cancer Society: What Is Cervical Cancer?
- National Cancer Institute: Study Estimates Overall HPV Prevalence in U.S. Women: 2007
- National Cancer Institute: FDA Alerts: FDA Approves HPV Vaccine
- National Cancer Institute: National Cancer Institute: Cervix Uteri, Racial/Ethnic Patterns of Cancer in U.S., 1988-1992
