Women who eat a lot of processed meats, such as salami and hot dogs, are at a higher risk of ovarian cancer, according to a new Australian study.
At the same time, those who eat a lot of fish have a lower risk of the deadly tumors, Dr. Penny M. Webb of Gynecological Cancers Group at Queensland Institute of Medical Research in Brisbane, Australia, and colleagues found.
In their report in the American Journal of Clinical Nutrition, the team also found no link between red meat and the cancer, and just a slightly lower risk among women who consumed large amounts of poultry.
"This suggests that by following common dietary guidelines to reduce the intake of processed meats and increase the intake of poultry and fish, women may also reduce their risk of ovarian cancer," Webb and colleagues write.
Researchers re-analyzed data from older studies from more than 2,000 women with ovarian cancer and nearly 2,200 without it who were asked about their diets.
They found that women who ate four or more servings per week of processed meat had an 18 percent higher risk of ovarian cancer than those who ate one or fewer servings per week. Also, women consuming four or more fish meals per week had 24 percent less risk of ovarian cancer than those who ate less than one fish meal per week.
The absolute risk difference, however, was quite small: "In Australia, the risk of developing ovarian cancer before the age of 75 for a woman who eats a lot of processed meat is about 1 percent, compared to about 0.8 percent for those who eat little processed meat," Webb told Reuters Health by email.
Most studies of ovarian cancer risks have focused on lifetime exposure to estrogen, according to Marji McCullough, of the American Cancer Society, meaning women who enter puberty early, and go through menopause late, have a higher risk. "Very few dietary risk factors have been identified for this highly fatal cancer," McCullough told Reuters Health by email.
It's unclear why processed meats and fish would have any effect on ovarian cancer. "There are many theories, but no good evidence as yet," Webb said. "Processed meat contains compounds that could damage cells and thereby cause cancer. Conversely, the omega-3 fatty acids found in fatty fish are thought to be good for health in many ways and may possess anti-cancer properties."
McCullough noted that processed meats preserved with nitrites and nitrates can form nitrosamines, known causes of cancer in animals.
So should women cut out cold cuts? "The association we saw with processed meat is not that strong, so I do not think that women should immediately stop eating all processed meat to reduce their risk of ovarian cancer," Webb said.
"However, we know that there are also other health benefits associated with eating white meat and fish so I think that women should aim for a healthy diet that includes less processed meat and higher levels of poultry and fish," she continued. "This will have a number of health benefits and may also lower their risk of ovarian cancer."
McCullough said the findings are consistent with existing American Cancer Society dietary recommendations: limiting red and processed meats in the diet, and consuming a wide variety of vegetables and fruits.
She noted that there already are good reasons to limit consumption of red meat and processed meat to lower risk for colon cancer and heart disease. "It would be wise to limit processed meats to the occasional event, rather than to consume them as part of one's usual diet," McCullough said.