Higher risk of death linked to eating more smoked or grilled meat before breast cancer

UNC Lineberger's Marilie D. Gammon, PhD, and Humberto Parada, PhD, report in JNCI: The Journal of the National Cancer Institute that breast cancer patients who ate barbecued, grilled and smoked meats at higher annual amounts in the decade before their diagnosis had a greater risk of death from any cause.

Higher risk of death linked to eating more smoked or grilled meat before breast cancer click to enlarge Marilie D. Gammon, PhD, is a UNC Lineberger member and professor in the UNC Gillings School of Global Public Health. Credit Tom Fuldner/UNC Gillings.
Higher risk of death linked to eating more smoked or grilled meat before breast cancer click to enlarge Humberto Parada, PhD, is a postdoctoral research associate at UNC Lineberger.

A new study has uncovered breast cancer-related risks associated with eating barbecued, grilled and smoked meats, which are a source of chemicals known as polycyclic aromatic hydrocarbons that are also found in cigarette smoke and vehicle exhaust.

University of North Carolina Lineberger Comprehensive Cancer Center researchers report in JNCI: The Journal of the National Cancer Institute that breast cancer patients who ate barbecued, grilled and smoked meats at higher annual amounts in the decade before their diagnosis had a greater risk of death from any cause.

Specifically, women who ate higher than average annual amounts of annual grilled, barbecued and smoked meat before diagnosis had a 23 percent higher risk of any cause of death than women who had low consumption before diagnosis.

Their findings also suggest that women who reduced their consumption of these foods after diagnosis didn’t see any improved outcomes, said the study’s first author Humberto Parada, PhD, a postdoctoral research associate at UNC Lineberger.

“The risk we saw was most strongly linked to pre-diagnosis intake of these foods,” Parada said. “We would have expected that some of these associations might have been attenuated among women who had high intake before diagnosis and switched to low, but that wasn’t the pattern we observed.”

Meats cooked at high temperatures are sources of polycyclic aromatic hydrocarbons, or PAHs, according to the National Cancer Institute. PAHs are a type of chemical created when coal, oil, gas, wood, and tobacco are burned, according to the U.S. Environmental Protection Agency. No population studies have stablished a definitive link between PAH exposure from cooked meat and cancer, according to the NCI, although previous epidemiologic studies have found links connected with eating large amounts of meats cooked at high temperatures. UNC Lineberger researchers wanted to investigate the potential impact of eating foods containing PAHs on the survival of women with breast cancer.

“We’ve observed increased risks linked to developing breast cancer, but we wanted to see if eating foods known to be a source of PAHs were also affecting prognosis,” said the study’s senior author Marilie D. Gammon, PhD, a UNC Lineberger member and professor in the UNC Gillings School of Global Public Health. “We found that grilled and smoked meats are possible prognostic factors for breast cancer, and this hypothesis deserves to be looked at by others.”

For the study, UNC Lineberger researchers drew on interviews with 1,508 women diagnosed with breast cancer in 1996 or 1997 as part of the Long Island Breast Cancer Study Project. The women were interviewed initially shortly after diagnosis, and then five years later, about their intake of grilled, barbecued and smoked meats. About 17 years later, 597 of the women in the study had died. Of that group, 237 deaths were related to breast cancer.

The researchers’ analysis found that women who had high average annual intake of grilled/barbecued and smoked meat of any kind before diagnosis had an increased risk of death from any cause. Women with any annual intake of poultry or fish before diagnosis had a lower risk of death overall and from breast cancer.

They also compared risk for women before and after diagnosis, finding that women who had high intake of just smoked beef, lamb and pork before, but low intake after diagnosis had a 34 increased risk of all-cause death, and a 71 percent increased risk of dying from breast cancer.

Looking at intake of all barbecued, grilled or smoked meat before and after diagnosis, they did not have statistically significant findings. However, they did see trends. Women who had high intake before and after diagnosis had a 31 percent higher risk of death from any cause compared to women with low intake across the board. But the risk increase was similar to risk for women who switched to low intake after diagnosis. While those findings were not statistically significant, researchers believe they could mean that pre-diagnosis intake is driving risk – meaning that women who changed their behavior after diagnosis did not see any benefits. 

They cautioned that their findings are not enough to make recommendations about dietary changes, and called for additional studies on this topic.

“We can’t really make recommendations about some of these dietary patterns for what women should and shouldn’t do,” Parada said. “This was the first study that’s looked at this association, and in epidemiological research, we really need multiple studies to confirm a finding.”

In addition to Gammon and Parada, other authors include Susan E. Steck, Patrick T. Bradshaw, Lawrence S. Engel, Kathleen Conway, Susan L. Teitelbaum, Alfred I. Neuget and Regina M. Santella.

The study was supported by the National Cancer Institute, the National Institute of Environmental Health Sciences, and the American Institute for Cancer Research.