Obesity, diet linked to deadly cancers.

Esophageal cancer usually kills its victims within 6 months of diagnosis. Since the early 1970s, the incidence of one form of this malignancy has tripled among white men, the group at highest risk in the United States. A new study now suggests that obesity may foster this form of the cancer, while diets high in fiber and fresh produce seem to offer comparable protection against it.

Another study finds that produce and olive oil may help protect against breast cancer, the second leading cause of cancer deaths in U.S. women.

Linda Morris Brown of the National Cancer Institute in Bethesda, Md., led a four-state team of researchers who used questionnaires on diet and medical history to hunt for esophageal cancer risks in men.

Two malignancies predominate in the esophagus -- the digestive tract between the pharynx and the entrance to the stomach. Squamous cell carcinoma, which preferentially strikes blacks, develops high in the esophagus. In contrast, Brown's team found, adenocarcinoma -- which usually develops lower in the esophagus -- tends to claim heavy victims.

To the researchers' surprise, the new study turned up 184 cases of adenocarcinoma -- 174 of them in white men. The researchers compared their data on these white men with information on 750 cancerfree white men matched by age. In the Jan. 18 Journal of the National Cancer Institute (JNCI), Brown's team reports that the heaviest 25 percent of the men in the study had more than three times the cancer risk of the thinnest quarter.

How heavy was the top quartile? Based on a weight-to-size ratio, a 6-foot man needed to weigh about 215 pounds to qualify. Upon further investigation, Brown and her coworkers found that the most obese men in that quartile faced almost four times the cancer risk of men in the thinnest quartile.

Calorie and fat consumption didn't appear to correlate with adenocarcinoma risk. But men who ate the most fiber and the most vitamin C from vegetables displayed just half the risk of those eating the least. And those in the highest quartile for consuming cruciferous vegetables, raw vegetables, or raw fruits had just 30 to 40 percent of the lowest quartile's cancer risk.

Going into this study, "we had no idea what diet would show," Brown says. "Weight also proved a total surprise. I would have thought that, as with those having squamous [cancer], these men would appear malnourished."

"Vegetables also seem protective against breast cancer," notes Dimitrios Trichopoulos of the Harvard School of Public Health in Boston.

He and his colleagues compared the diets of 820 Greek women with breast cancer and 1,548 others admitted to the same Athens-area hospitals for reasons other than cancer. In the Jan. 18 JNCI, they report a 12 percent decrease in breast cancer risk between each successively higher quintile (20 percent of women) of vegetable consumption. An 8 percent decrease in risk occurred with each quintile increase in fruit consumption.

Though many studies have reported similar trends, Trichopoulos notes, the benefits never appeared quite as high and strong as those seen here.

What's more provocative, his team found that women who eat olive oil only once a day face a 25 percent higher risk of breast cancer than women who consume it twice or more daily.