|How do oral contraceptives affect cervical cancer risk?|
Most cervical cancers (80 to 90 percent) are squamous cell cancers. Adenocarcinoma is the second most common type of cervical cancer, accounting for the remaining 10 to 20 percent of cases. Adenocarcinoma develops from the glands that produce mucus in the endocervix. While less common than squamous cell carcinoma, the incidence of adenocarcinoma is on the rise, particularly in younger women.
More than 12,000 women in the United States will be diagnosed with cervical cancer each year, and more than 4,000 of women will die. Cervical cancer is the second most common type of cancer for women worldwide, but because it develops over time, it is also one of the most preventable types of cancer. Deaths from cervical cancer in the United States continue to decline by approximately 2 percent a year. This decline is primarily due to the widespread use of the Pap test to detect cervical abnormalities and allow for early treatment. Most women who have abnormal cervical cell changes that progress to cervical cancer have never had a Pap test or have not had one in the previous three to five years.
How do oral contraceptives affect cervical cancer risk?
|How do oral contraceptives |
affect cervical cancer risk?
Long-term use of oral contraceptives (5 or more years) is associated with an increased risk of cervical cancer. An analysis of 24 epidemiologic studies found that the longer a woman used oral contraceptives, the higher her risk of cervical cancer. However, among women who stopped taking oral contraceptives, the risk tended to decline over time, regardless of how long they had used oral contraceptives before stopping.
In a 2002 report by the International Agency for Research on Cancer, which is part of the World Health Organization, data from eight studies were combined to assess the association between oral contraceptive use and cervical cancer risk among women infected with the human papillomavirus (HPV). Researchers found a nearly threefold increase in risk among women who had used oral contraceptives for 5 to 9 years compared with women who had never used oral contraceptives. Among women who had used oral contraceptives for 10 years or longer, the risk of cervical cancer was four times higher.
Virtually all cervical cancers are caused by persistent infection with high-risk, or oncogenic, types of HPV, and the association of cervical cancer with oral contraceptive use is likely to be indirect. The hormones in oral contraceptives may change the susceptibility of cervical cells to HPV infection, affect their ability to clear the infection, or make it easier for HPV infection to cause changes that progress to cervical cancer. Questions about how oral contraceptives may increase the risk of cervical cancer will be addressed through ongoing research.