Women dread a diagnosis of endometrial cancer, but those who drink at least two cups of caffeinated coffee a day have a lower risk for this cancer of cells lining the uterus.

Researchers surveyed 60,634 Swedish women about their coffee intake. During the 17 years that the patients were followed up, 677 women (about 1 percent) developed endometrial cancer. The average age at diagnosis was 67 years. The researchers found that overall those who daily drank 2 or more cups were significantly less likely to develop endometrial cancer, compared with those who drank fewer cups of coffee. Each additional daily cup was linked to a 10 percent lower risk for endometrial cancer, after allowing for age and other known factors that affect endometrial cancer risk among all the women.

The strongest effect was observed among overweight and obese women, who have the highest risk for endometrial cancer. Coffee drinking seemed to particularly protect overweight and obese women. Each additional cup of coffee seemed to decrease endometrial cancer risk by 12 percent among overweight women and by 20 percent among obese women.

The researchers suggest that coffee may affect blood sugar, fat cells, and oestrogen, all of which play a role in endometrial cancer. However, the current findings need to be confirmed in other populations. Further studies should also include de-caffeinated coffee to separate the effect of coffee and caffeine.