Chlamydia Infection May Boost Cervical Cancer Risk

Women who become infected with chlamydia appear to be at an increased risk of developing cervical cancer, according to European researchers. Dr. Keng-Ling Wallin of Karolinska Hospital in Stockholm, Sweden, and colleagues found that 8 percent of women with cervical cancer had a history of infection with chlamydia. In contrast, no study participants who were cervical cancer-free reported ever being diagnosed with chlamydia.

Wallin's team tested Pap smears of 118 women diagnosed with cervical cancer for the presence of chlamydia, both before and after they were diagnosed with cancer. The researchers also examined previous and more recent Pap smears from 118 women who never developed cervical cancer. According to their calculations, the disparity between the two groups translates into a 17-fold higher risk of cervical cancer among women who had acquired chlamydia, relative to those who were never diagnosed with the STD. The full report, "A Population-Based Prospective Study of Chlamydia Trachomatis Infection and Cervical Carcinoma," was published in the International Journal of Cancer (2002;101:371-374).

Researchers have long known that women with HPV are much more likely than others to develop cervical cancer, but the link between the cancer risk and other STDs has remained unclear. Wallin explained that chlamydia infection may increase a woman's chances of developing cervical cancer by somehow altering her immunity and rendering her more susceptible to HPV. It is also possible that those with chlamydia also have other factors, such as multiple STDs, that could affect cancer risk.

Therefore, she said, chlamydia itself may not increase a woman's chances of developing cervical cancer. Furthermore, she noted, chlamydia is relatively common, while cervical cancer is rare -- so every woman diagnosed with chlamydia need not believe she will develop cervical cancer. If future studies find the same results, Wallin said, health officials may wish to increase the rates of chlamydia testing and treatment to prevent cervical cancer.

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