What Is patientINFORM?

They found that cigarette smoking had no effect on whether a woman might develop ovarian cancer overall, although there did appear to be a higher risk for mucinous ovarian tumors, a rare form of the disease. Researchers could not establish a link with alcohol use, either. They did find that caffeine intake might decrease a woman's risk, but not if a woman used oral contraceptives or postmenopausal hormone therapy.

Why It's Important: Researchers have identified several risk factors for developing ovarian cancer, and many of them—age and family history, for example—are outside a woman's control. Studies like this one might help identify risk factors women can control, like their diet.

This study also aims to clarify conflicting results about the role of diet and other lifestyle factors in predicting ovarian cancer. Links between certain foods or nutrients and ovarian cancer--be it dairy, carrots, or folic acid--remain confusing at best. See our document, Common Questions about Diet and Cancer, for more information on this topic.

What's Already Known: There are several known risk factors for ovarian cancer. Half of all ovarian cancers are found in women over 63. The more weight you have to lose, the higher your risk. A family history of ovarian cancer increases your chance of developing ovarian cancer; certain fertility drugs may also raise the risk.

Taking birth control pills, especially over many years, has been shown to cut ovarian cancer risk, but the role of combined hormone replacement therapy is uncertain, and estrogen replacement therapy could increase risk, especially if taken over a long period of time. For more, see Menopausal Hormone Therapy and Cancer Risk.

We know that alcohol use is linked with cancers of the mouth, pharynx (throat), larynx (voice box), esophagus, liver, and breast, and possibly of the colon and rectum, as well. Drinkers who smoke are at an even greater risk than those who engage in either behavior alone. Coffee, once thought to increase risk for cancer, especially of the pancreas, stomach, and colon, has yet to be linked with any of these, nor has the caffeine from other sources such as soda, chocolate, or tea.

How This Study Was Done: Researchers examined questionnaires addressing smoking and dietary habits that were filed every 2 years by Nurses' Health Study participants over a 28-year period (1976 – 2007). The portion of the questionnaire asking about smoking status first appeared in 1976, and the dietary portion was introduced a little later, in 1980.

On each questionnaire, the women were asked whether they were current or past smokers, and if they had smoked, the age they started and the number of packs smoked per day. Alcohol intake was measured by the amount of beer, wine, or liquor consumed in a year's time. Participants were asked about the amount and type of caffeine-containing foods and beverages they consumed. The researchers also collected data on body mass index, reproductive history, oral contraceptive and postmenopausal hormone use, and family history.

The researchers analyzed data on smoking status, smoking duration, and pack years (calculated by multiplying the number of packs smoked per day by the number of years smoked), then looked to see if those numbers had any bearing on ovarian cancer diagnosis. They did the same for caffeine intake—measured by the cups of coffee, tea, or cola consumed in a week. They assessed the relationship between smoking status and ovarian cancer among 110,454 women, and examined the records of 80,253 women for links between alcohol and caffeine use.

What Was Found: Of the group, 737 reported an ovarian cancer diagnosis, 69 of which were mucinous. The risk of having a mucinous tumor was tied to smoking duration and pack years. Researchers found a link between caffeine intake and lower ovarian cancer risk, but that relationship was only seen among the women who never used oral contraceptives or took hormones after menopause. There wasn't a clear connection between alcohol use and ovarian cancer.

The Bottom Line: While this data may be somewhat comforting to a woman with a family history of ovarian cancer and a personal history of alcohol use and cigarette use, it doesn't offer a clear-cut strategy for women hoping to reduce their risk.

Although smoking isn't linked to a higher risk of developing ovarian cancer according to this study, it is known to cause cancers of the lung, larynx, mouth, pharynx (throat), esophagus, and bladder, and has been conclusively linked to acute myeloid leukemia, and cancers of the cervix, kidney, pancreas, and stomach. It's also a known risk factor for a host of other medical problems, including cardiovascular disease. Alcohol use has been associated cancers of the mouth, pharynx (throat), larynx (voice box), esophagus, liver, and breast, and is especially advised against for women at a high risk for breast cancer.

But should women drink more caffeine? The researchers say their finding of a lower risk should be viewed with caution. While it's been suggested that drinking coffee might protect against everything from type-2 diabetes to memory decline, this study does not provide concrete answers about caffeine's effect on ovarian cancer. 

"Researchers will need to study the mechanism of the observed effect of caffeine to see if they can translate that into clinical recommendations. In the meantime, it is not recommended that women alter their caffeine consumption in an effort to lower risk," said Debbie Saslow, PhD, American Cancer Society, Director of Breast and Gynecologic Cancer, after the study was released.

For more information on the relationship between diet and lifestyle factors and cancer, see our document, Common Questions about Diet and Cancer.

Citation: "Caffeine, Alcohol, Smoking, and the Risk of Incident Ovarian Cancer." Published in the March, 1, 2008, Cancer (Vol. 112, Issue 5:1-9). First author: Shelly S. Tworoger, PhD, Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.