Ovarian Cancer and Chlamydia: What’s the Link?

Medically Reviewed by Laura J. Martin, MD on July 18, 2022
4 min read

Ovarian cancer is a relatively rare cancer, but the second most common gynecological cancer. It starts in the ovaries, the nearby fallopian tubes, or tissue called the peritoneum that covers the organs in the abdomen. Experts don’t know for sure what causes ovarian cancer, but recent research has found a strong connection between chlamydia, a sexually transmitted infection (STI), and ovarian cancer.

Here’s what’s known so far about risk and how to protect yourself.

A common STI, chlamydia is a bacterial infection that you can get through any type of sex (oral, anal, vaginal) with an infected person. When doctors find that a patient has chlamydia, they can treat it with antibiotics. But chlamydia can go undetected for a while in some people. It doesn’t always cause symptoms, so it’s possible to have chlamydia and not know.

Left untreated, chlamydia can damage your reproductive system and make it hard to get pregnant.

Recent research shows that a past or current chlamydia infection could as much as double your risk for ovarian cancer.

In a study of 337 women with ovarian cancer and 337 women without, 1 in 5 of the women with cancer had chlamydia while 1 in 8 women without cancer had chlamydia. About 8% of the women with cancer and 4% of the women without had chlamydia along with one other STI. This suggests that chlamydia plus one other STI might further increase ovarian cancer risk, but only slightly.

Other research analyzed the results of two different studies that included 404 women with ovarian cancer and 715 without, and showed that chlamydia infection doubled the risk for ovarian cancer. On deeper investigation, the researchers found that cancer risk went up with increasing levels of antibodies to chlamydia. This suggests that more severe chlamydia infections bring greater risk for ovarian cancer.

Ongoing inflammation, from any number of causes, is a risk factor for numerous types of cancer. An inflammatory infection of the female reproductive organs, called pelvic inflammatory disease (PID), raises risk for ovarian cancer.

PID can develop as a result of several different bacterial infections, both sexually and nonsexually transmitted ones. Women get PID when bacteria enter the vagina but then move upwards out of the vagina or cervix and into the reproductive organs.

Chlamydia is the most common cause of PID in developed countries. This may explain the STI’s link to ovarian cancer. The bacteria may make its way out of the vagina and cervix and into the fallopian tubes. Researchers who study the link between ovarian cancer and chlamydia note that many ovarian cancers in fact begin in the nearby fallopian tubes and not directly in the ovaries.

More research is needed to determine whether early detection and treatment of chlamydia could help prevent later development of ovarian cancer. Researchers speculate, however, that it might be the case. They believe early detection may make a difference because women typically get chlamydia at young ages, while ovarian cancer doesn’t usually show up until a woman is over age 60. Also, higher levels of chlamydia antibodies, which may suggest more severe or longer-term infection, seem to be associated with higher risk of cancer.

You can find chlamydia early and potentially prevent cancer and infertility through routine visits to your gynecologist. The CDC recommends the following chlamydia screening schedule:

  • Sexually active women under age 25 should get tested every year.
  • Women 25 and over with risk factors, such as new or multiple sex partners, should get tested every year.
  • At-risk pregnant women should be tested at the beginning of pregnancy and throughout their pregnancy if needed.

Doctors can effectively treat chlamydia with antibiotics.

There is no test for PID. Your doctor will diagnose you based on your symptoms, physical exam, medical history and other test results. You should see your doctor for an exam if you have any of these symptoms:

  • Pain in your lower abdomen
  • Fever
  • Vaginal discharge with a bad odor
  • Pain and/or bleeding when you have sex
  • Burning sensation when you urinate
  • Bleeding between periods

Not everyone has noticeable symptoms. For some people, they are very mild. Even without symptoms, if you suspect that you or your sexual partner has been exposed to an STI, you should see your doctor to find out whether you need any tests for STIs, including some that could lead to PID.

Doctors can treat PID with antibiotics, too. It will stop the ongoing infection and inflammation, but it won’t undo any damage to your reproductive organs that has already occurred. That’s why it’s important to stay on track with routine preventive care appointments with your gynecologist. Early detection and treatment of STIs could help prevent PID or catch it before it does serious damage.

You can prevent chlamydia, and potentially ovarian cancer, to begin with through safer sex and hygiene practices, which include the following tips:

  • Use a condom. Male latex condoms or female polyurethane condoms, when used properly during every sexual encounter, lower the risk of infection.
  • Limit the number of sexual partners you have. The more sexual partners you have, the higher your risk of exposure to chlamydia and other STIs.
  • Avoid douching. Using a douche can reduce the number of good, helpful bacteria in your vagina, which can increase your risk of getting an STI.

There’s no ovarian cancer screening for women at average risk who don’t have any symptoms. Typically you won’t have symptoms until the cancer is very advanced. Those symptoms might include:

  • Bloating, swelling in the belly
  • Quickly feeling full when eating
  • Weight loss
  • Discomfort in the pelvic area
  • Fatigue
  • Back pain
  • Changes in bowel habits, such as constipation
  • A frequent need to urinate

If you have any of these symptoms daily for more than a few weeks, you should see your doctor.