Family History and Cervical Cancer
HPV News December 2005
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Having a close relative with a history of cervical cancer may increase a womanÃ¢â‚¬â„¢s risk for developing the disease, according to recent research from Italy.
Virtually all cases of cervical cancer are related to Ã¢â‚¬Å“high-riskÃ¢â‚¬Â HPV types, but the infection seems to be transient for most women and cancer is a rare outcome. Researchers arenÃ¢â‚¬â„¢t sure why HPV infections persist and cause cervical cellular changes that progress to cancer in some women, but co-factors (such as smoking or infection with other sexually transmitted infections) are thought to play a necessary role.
To examine if a family history of cancer could be linked with cervical cancer, Dr. Eva Negri and colleagues used questionnaires to interview 1,700 women who were patients at a network of hospitals in Milan, Italy. 786 of the women were diagnosed with invasive cervical cancer, and the rest were attending the hospitals for reasons unrelated to gynecologic conditions. The researchers queried the women on behavioral and personal characteristics, and if a sister or mother had ever been diagnosed with cancers of the breast, ovaries, cervix, endometrium, or uterus. The study adjusted for factors including age, smoking, oral contraceptive use, and lifetime number of sexual partners.
The study found having a close relative (mother or sister) with a history of either cervical or uterine cancer was associated with a two-fold increase in the risk of having cervical cancer, but family history of endometrial, breast, or ovarian cancer was not linked to increased risk for cervical disease. The authors say these results are similar to those of other studies.
Cervical cancers usually occur in the Ã¢â‚¬Å“transformation zone,Ã¢â‚¬Â the area of the cervix where the tough, flat squamous cells that line the vagina overlap with the more delicate glandular cells of the uterus. Most cervical cancers are squamous cell carcinomas (SCC), but the American Cancer Society estimates about 10-20% are adenocarcinomas, cancers occurring with glandular cells that can be trickier for Pap tests to detect, as they tend to develop higher in the cervical canal.
The investigators in this study noted that cervical adenocarcinomas were linked more strongly than SCC with a family history of noncervical gynecologic cancers (especially endometrial cancer), which Dr. Negri says is potentially explained by an inherited predisposition to these cancers.
Differences in risk factors between cervical SCC and adenocarcinomaÃ¢â‚¬â„¢s have also been suggested by other research, such as a 2003 study by the U.S. National Cancer Institute linking cervical adenocarcinoma with obesity.
As to why the same cancers are often found within families, Dr. Negri told HPV e-NEWS Ã¢â‚¬Å“There could be two explanations for the familiar aggregation that is observed for almost all cancers: 1) an inherited genetic susceptibility or 2) members of the same family tend to be more similar, in terms of risk factor exposure, than the general population.Ã¢â‚¬Â
She says genetics seem to play the more crucial role, though: Ã¢â‚¬Å“A higher risk for a cancer in those with a family history of the same cancer is often observed in the absence of exposure to main risk factors. Thus, the first explanation (genetic) is considered the cause of the observed aggregation for many cancers. For cervical cancer, however, there are few epidemiological studies.Ã¢â‚¬Â
E. Negri et al.
Risk of cervical cancer in women with a family history of breast and female genital tract neoplasms.
International Journal of Cancer
2005; 117(5): 880-81.