Women who regularly use acetaminophen -- the active ingredient in Tylenol and several other painkillers -- may be 30 percent less likely to develop ovarian cancer than those who use the drug rarely or not at all.

That’s what Stefanos Bonovas, MD, MSc, and colleagues report in July’s issue of the British Journal of Clinical Pharmacology. Bonovas works in Greece at the pharmacology department of the University of Athens’ medical school.

But the Greek researchers aren’t advising women to start taking acetaminophen to prevent ovarian cancer. The possible link between acetaminophen use and reduced ovarian cancer risk “cannot yet be regarded as one which would prompt a public health recommendation,” write Bonovas and colleagues.

They caution that the new findings need to be confirmed and much more information should be gathered first.

About Ovarian Cancer

Ovarian cancer is the most fatal gynecological cancer, largely because doctors don’t have a good screening method to detect the disease in its early, more treatable, stages, Bonovas’ team notes.

The American Cancer Society reports the following statistics for ovarian cancer in the U.S.:

8th most common cancer in women (excluding skin cancer) 5th cause of cancer deaths in women 20,000 new cases expected in 2006 15,000 deaths expected in 2006 Most patients aged 55 or older Slightly more common in white women than in black 1 in 67 lifetime risk of a woman getting ovarian cancer

Research Review

Bonovas and colleagues decided to do an in-depth look at a possible link between reduced ovarian cancer risk and acetaminophen use after hearing mixed results from observational studies.

They collected eight studies on the topic for analysis. All were done between 1998 and 2004. Six were from the U.S., one came from the U.K., and another was from Denmark.

The studies varied widely in size, ranging from 10 ovarian cancer patients to more than 1,500. For comparison, Bonovas’ team also included much bigger groups of women without ovarian cancer.

The studies’ methods also differed. Four tracked acetaminophen use by questionnaire. Two relied on interviews. The last two studies gathered information from drug databases. Questionnaires and interviews aren’t always accurate, note Bonovas and colleagues.

None of the studies directly tested acetaminophen to prevent ovarian cancer, meaning they were observational -- not experiments in which some women were asked to take acetaminophen and a control group was given a placebo.

Review’s Results

Bonovas and colleagues bundled all of the data together.

They found that, regardless of age, women who regularly used acetaminophen were 30% less likely to have ovarian cancer, compared with those who didn’t use acetaminophen.

Irregular acetaminophen use didn’t show the same pattern.

However, each study defined “regular” acetaminophen use differently. For instance, one study’s standard was acetaminophen use more than once daily for at least a year. Another study applied the “regular use” label for women who took acetaminophen at least five days per month.

Since the studies varied widely in design, the researchers aren’t drawing firm conclusions or offering advice. They also note that long-term acetaminophen use may raise the risk of liver and kidney problems.

Acetaminophen might deserve a direct test for ovarian cancer protection, but the risks and benefits of such a test need careful examination, given the “sparse” and mixed data from observational studies, write Bonovas and colleagues.

By Miranda Hitti, reviewed by Louise Chang, MD

SOURCES: Bonovas, S. British Journal of Clinical Pharmacology, July 2006; vol 62: pp 113-121. American Cancer Society: “How Many Women Get Ovarian Cancer?” News release, Blackwell Publishing Ltd.