A high intake of grilled/barbecued and smoked meat may increase mortality risk after a breast cancer diagnosis, concludes a new study published online January 5 in the Journal of the National Cancer Institute.
Previous research indicated that cooking meat in these ways may increase the risk of developing breast cancer, but no one had yet studied if these cooking methods may be deleterious to the survival of breast cancer patients, observe the study authors, led by Humberto Parada, PhD, MPH, of the Lineberger Comprehensive Cancer Center at the University of North Carolina, Chapel Hill.
The investigators used data from 1508 women participating in the Long Island Breast Cancer Study Project. The women were interviewed after their diagnosis with first primary invasive or in situ breast cancer in 1996 and 1997, and again approximately 5 years later. Part of the assessments included grilled/barbecued and smoked meat intake — both pre- and post-diagnosis intake.
After a median of 17.6 years of follow-up, there were 597 deaths, including 237 that were breast cancer specific.
High pre-diagnosis grilled/barbecued and smoked meat intake was associated with a 23% increased risk of all-cause mortality (hazard ratio [HR], 1.23; 95% confidence interval [CI], 1.03 - 1.46).
Also, among women with a continued high intake of grilled/barbecued and smoked meat after diagnosis, all-cause mortality risk was elevated at 31% (HR, 1.31; 95% CI, 0.96 - 1.78).
High intake was defined as above the median (44 times a year pre-diagnosis and 36 times a year post-diagnosis) and was compared with low intake in the multivariable analyses.
The study included four types of grilled/barbecued and smoked meats, which were analyzed collectively and individually: grilled/barbecued beef, lamb, and pork; smoked beef, lamb, and pork, such as bacon or ham; grilled/barbecued poultry and fish; and smoked poultry and fish, such as smoked turkey or lox.
Other associations were noted in the study, but none of the estimates were significant.
However, the team did highlight one other finding: breast-cancer–specific mortality was decreased among women with any pre- and post-diagnosis intake of smoked poultry/fish (HR, 0.55; 95% CI, 0.31 - 0.97).
But, overall, the authors concluded that eating high quantities of meat prepared in these three ways may not be advisable for women with breast cancer.
Why are these meats potentially problematic? They are a "prevalent" dietary source of polycyclic aromatic hydrocarbon (PAH) carcinogens, observe the authors. PAHs are a group of over 100 different chemicals and typically are formed when fat and juices from grilled meat drip onto the fire, creating flames and smoke, the authors explain. The PAHs then stick to the surface of the meat. They are also generated in the meat-smoking process.
An expert not involved in the study agreed.
"The PAHs are formed when meat, including beef, pork, fish, or poultry, is cooked using high-temperature methods, such as pan frying or grilling directly over an open flame," said Bhagavatula Moorthy, MD, of Baylor College of Medicine in Houston, Texas, who was asked for comment.
Dr Moorthy, who has done basic science research into PAHs, said that in a study by himself and colleagues, PAH-mediated DNA changes were detected in normal adjacent breast tissues of 41% of women with breast cancer and none in noncancer controls (Environ Mutagen. 2016;39:193-202).
However, a breast cancer clinician not involved with the study, Julie Nangia, MD, also of Baylor, said the new results are not definitive. "The data are very interesting, but I wouldn't tell any of my patients not to eat grilled, barbequed, or smoked meats," Dr Nangia told Medscape Medical News.
"I'm from Texas and we grill all the time. I promise you, we will not be giving it up based on these data," said Dr Nangia.
Currently, Dr Nangia advises patients to not overindulge in eating meat. "Not more than three times a week," she said, acknowledging that there is no high-level evidence that allows clinicians to make specific recommendations. "It's seems like commonsense, and it is basically the same advice I give about alcohol," she said. "It's okay to have these things occasionally, moderately."
Questions from breast cancer patients about meat intake are now frequent, she said, after the World Health Organization's edict in 2015 that processed meats such as hot dogs and bacon are carcinogenic (International Agency of Cancer Research Group 1).
"I tell patients that fresh meat is better than processed meat," said Dr Nangia.
The literature on red meat and the risk of developing breast cancer is not uniform, she added. "Red meat has not definitively been shown to be a risk for breast cancer."
In terms of nutrition and well-being, Dr Nangia is most concerned about her breast cancer patients' intake of high-calorie food, their activity levels, and the associated problem of overweight.
The study authors note that joint breast cancer survivorship guidelines from the American Cancer Society and American Society of Clinical Oncology recommend "a dietary pattern that is high in vegetables, fruits, whole grains, and legumes, and limit alcohol intake to no more than one drink per day.”
They also observe that there is no word in this guidance on high-temperature cooked meat, including intake of grilled/barbecued and smoked meat.
In the study, the high and low meat intake groups had some interesting differences.
Women with a high intake of meat were younger at diagnosis (56.7 vs 60.9 years), and a higher proportion had an annual income of $50 000 or more (57.0% vs 40.4%) compared with women with low intake. The high intake group were also more likely to be married (77.2% vs 60.4%) and current alcohol drinkers (51.9% vs 43.2%).
The study received support from the National Cancer Institute, National Institute of Environmental Health Sciences, and American Institute for Cancer Research.
J Natl Cancer Inst. Published online January 5, 2017. Abstract
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Cite this: Grilled/BBQ Meat and Lower Breast Cancer Survival? - Medscape - Jan 17, 2017.