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26 Mar 2018

Chlamydia, a common sexually transmitted disease, can double a woman’s risk of ovarian cancer.

This is according to new research undertaken by the American Association for Cancer Research (AACR).

Women who had chronic chlamydia infections had twice the risk of ovarian cancer compared to women with no evidence of ever having been infected, researchers found in a report to be fully released at the American Association for Cancer Research in April this year.

“Our data is lending support for there being a role of pelvic inflammatory disease in ovarian cancer and the prime cause of pelvic inflammatory disease, particularly in the U.S, is chlamydia infection,” the National Cancer Institute’s Dr Britton Trabert told a briefing ahead of the meeting.

“We are seeing a doubling in ovarian cancer risk with a prior history of pelvic inflammatory disease.”

The AACR research undertook a retrospective analysis of two different cohorts and control groups, one of them, conducted in Poland, included 279 women with ovarian cancer and 556 matched controls. The other, data from an American National Cancer Institute (NCI) case-control study, included 160 women diagnosed with ovarian cancer during follow-up and 159 matched controls.

The AACR said that there needs to be a greater understanding about what causes ovarian cancer to improve screening and treatment and, ultimately, improve survival.

Chlamydia is treated with a single course of antibiotics but if left unchecked can lead to pelvic inflammatory disease and even infertility in women and testicle infections in men.

Over time, chlamydia causes widespread inflammation that can cause infertility. Now, this new piece of research suggests it may also cause cancer.

While ovarian cancer is not common, every year in Australia approximately 1,600 women are diagnosed with it and more than 1,000 succumb to the disease. If found in its early stages, women have an 80 per cent chance of being alive and well after five years. Unfortunately, 75 per cent of women are diagnosed in advanced stages. There is no early detection test for ovarian cancer. 

Chlamydia, however, is very common. The latest data from The Kirby Institute shows Chlamydia was the most frequently notified sexually transmissible infection (STI) in Australia, with a total of 71,751 notifications in 2016. Three-quarters of these notifications were among people aged 15–29 years.

The Kirby Institute’s research also found the annual rate of notification of chlamydia in the Aboriginal and Torres Strait Islander population in the Northern Territory, Queensland, South Australia and Western Australia was 2.8 times that in the non‑Indigenous population in 2016. And in female sex workers, chlamydia incidence increased by 35 per cent between 2012 and 2016.

The Kirby Institute says the data strongly suggests a need for testing to be routinely offered to sexually active adolescents and young adults as the vast majority of infections in young people (15–29 years) remain undiagnosed and untreated.

The AACR research can be found here:!/4562/presentation/4037AACR%202018%...

The Kirby Institute’s HIV, viral hepatitis and sexually transmissible infections in Australia: Annual Surveillance Report 2017 is available here:


Published: 26 Mar 2018