Monday, December 14, 2015

WHO says bacon causes cancer?

by Neha Pancholi

Note: Here at the PSPG blog, we like to feature writing from anyone in the Penn community interested in the science policy process or science for general interest. This is the 1st in a series of posts from new authors. Interested is writing for the blog? Contact us!

The daily meat consumption in the United States exceeds that of almost every other country1. While the majority of meat consumed in the United States is red meat2, the consumption of certain red meats has decreased over the past few decades due to associated health concerns, such as heart disease and diabetes1,2. In October, the World Health Organization (WHO) highlighted another potential health concern for red meat: cancer.

The announcement concerned both red and processed meat. Red meat is defined as unprocessed muscle meat from mammals, such as beef and pork3. Processed meat– generally red meat –has been altered to improve flavor through processes such as curing or smoking3. Examples of processed meat include bacon and sausage. The WHO confirmed that processed meat causes cancer and that red meat probably causes cancer. Given the prevalence of meat in the American diet, it was not surprising that the announcement dominated headlines and social media. So how exactly did the WHO decide that processed meat causes cancer?

The announcement by the WHO followed a report from the International Agency for Research on Cancer (IARC), which is responsible for identifying and assessing suspected causes of cancer. The IARC evaluates the typical level of exposure to a suspected agent, results from existing studies, and the mechanism by which the agent could cause cancer.

After a review of existing literature, the IARC classifies the strength of scientific evidence linking the suspected cancer-causing agent to cancer. Importantly, the IARC determines only whether there is sufficient evidence that something can cause cancer. The IARC does not evaluate risk, meaning that it does not evaluate how carcinogenic something is. The IARC classifies the suspected carcinogen into one of the following categories4:
  • Group 1 – There is convincing evidence linking the agent to cancer in humans. The agent is deemed carcinogenic.
  • Group 2A – There is sufficient evidence of cancer in animal models, and there is a positive association observed in humans. However, the evidence in humans does not exclude the possibility of bias, chance, or confounding variables. The agent is deemed as a probable carcinogen.
  • Group 2B – There is a positive association in humans, but the possibility of bias, chance, or confounding variables cannot be excluded. There is inadequate evidence in animal models.
  • This category is also used when there is sufficient evidence of cancer in animal models, but there is not an association observed in humans. The agent is a possible carcinogen.
  • Group 3 – There is inadequate evidence in humans and animals. The agent cannot be classified as carcinogenic or not carcinogenic.
  • Group 4 – There is sufficient evidence to conclude that the agent is not carcinogenic in humans or in animals.
The IARC reviewed over 800 studies that examined the correlation between consumption of processed or red meat and cancer occurrence in humans. These types of studies, which examine patterns of disease in different populations, are called epidemiological studies. The studies included observations from all over the world and included diverse ethnicities and diets. The greatest weight was given to studies that followed the same group of people over time and had an appropriate control group. Most of the available data examined the association between meat consumption and colorectal cancer, but some studies also assessed the effect on stomach, pancreatic, and prostate cancer. The majority of studies showed a higher occurrence of colorectal cancer in people whose diets included high consumption of red or processed meat compared to those who have low consumption. By comparing results from several studies, the IARC determined that for every 100 grams of red meat consumed per day, there is a 17% increase in cancer occurrence. For every 50 grams of processed meat eaten per day, there is an 18% increase. The average red meat consumption for those who eat it is 50-100 grams per day.3

The IARC also reviewed studies that examined how meat could cause cancer. They found strong evidence that consumption of red or processed meat leads to the formation of known carcinogens called N-nitroso compounds in the colon. It is also known that cooked meat contains two types of compounds that are known to damage DNA, which can lead to cancer. However, there is not a direct link between eating meat containing these compounds and DNA damage in the body.3

Based on the strong evidence demonstrating a positive association with consumption of processed meat and colorectal cancer, the IARC classified processed meat as a Group 1 agent3. This means that there is sufficient evidence that consumption of processed meat causes cancer.

There was a positive association between consumption of red meat and colorectal cancer in several epidemiological studies. However, the possibility of chance or bias could not be excluded from these studies. Furthermore, the best-designed epidemiological studies did not show any association between red meat consumption and cancer. Despite the limited epidemiological evidence, there was strong mechanistic evidence demonstrating that red meat consumption results in the production of known carcinogens in the colon. Therefore, red meat was classified as a probable carcinogen (Group 2A)3.

It will be interesting to see how the WHO announcement affects red meat consumption in the United States and worldwide. But before swearing off processed and red meat forever, there are a few things to consider.

First, it is important to bear in mind that agents classified within the same group have varying carcinogenic potential. Processed meat was classified as a Group 1 agent, which is the same classification for tobacco smoke. However, estimates by the Global Burden of Disease Project attribute approximately 34,000 cancer deaths per year to consumption of processed meat5. In contrast, one million cancer deaths per year are due to tobacco smoke5. While the evidence linking processed meat to cancer is strong, the risk of cancer due to processed meat consumption appears to be much lower than other known carcinogens. Second, the IARC did not evaluate studies that compared vegetarian or poultry diets to red meat consumption5. Therefore, it is unknown whether vegetarian or poultry diets are associated with fewer cases of cancer. Finally, red meat is high in protein, iron, zinc, and vitamin B123. Thus, while high red meat consumption is associated with some diseases, there are also several health benefits of consuming red meat in moderation. Ultimately, it will be important to balance the risks and benefits of processed and red meat consumption.


1http://www.npr.org/sections/thesalt/2012/06/27/155527365/visualizing-a-nation-of-meat-eaters
2http://www.usda.gov/factbook/chapter2.pdf
3Bouvard et al. Carcinogenicity of consumption of red and processed meat. The Lancet Oncology, 2015. 16(16): 1599-1600.
4http://www.iarc.fr/en/media-centre/iarcnews/pdf/Monographs-Q&A.pdf
5http://www.who.int/features/qa/cancer-red-meat/en/

Thursday, December 3, 2015

Ready to Adapt: Experts Discuss Philadelphia Epidemic Preparedness

by Jamie DeNizio and Hannah Shoenhard


In early November, public health experts from a variety of organizations gathered on Penn’s campus to discuss Philadelphia’s communication strategies and preparation efforts in the event of an epidemic outbreak. In light of recent crises, such as H1N1 and Ebola in the US, AAAS Emerging Leaders in Science and Society (ELISS) fellows and the Penn Science Policy Group (PSPG) hosted local experts at both a public panel discussion and a focus group meeting to understand the systems currently in place and develop ideas about what more can be done.
Are we prepared?: Communication with the public
Dr. Max King, moderator of the public forum, set the tone for both events with a Benjamin Franklin quote: “By failing to prepare, you are preparing to fail.” Measures taken before a crisis begins can make or break the success of a public health response. In particular, in the age of the sensationalized, 24-hour news cycle, the only way for public health professionals to get the correct message to the public is to establish themselves as trustworthy sources of information in the community ahead of time.
For reaching the general population, the advent of social media has been game-changing. As an example, James Garrow, Director of Digital Public Health for the Philadelphia Department of Public Health, described Philadelphia’s use of its Facebook page to rapidly disseminate information during the H1N1 flu outbreak. The city was able to provide detailed information while interacting with and answering questions directly from members of the public in real time, a considerable advantage over traditional TV or print news.

However, Garrow was quick to note that “mass media still draws a ton of eyeballs,” and that any public health outreach program would be remiss to neglect traditional media such as TV, radio, and newspapers. At this point, social media is a complement to, but not a replacement for, other forms of media engagement.
Furthermore, those typically at greater risk during an epidemic are often unable to interact with social media channels due to economic disadvantage, age, or a language barrier. In Philadelphia, 21.5% of the population speaks a language other than English at home. Meanwhile, 12.5% of the population is over the age of 65 (U.S. Census Bureau). The focus group meeting specifically discussed how to reach these underserved groups. Some suggestions included having “block captains” or registries. “Block captains” would be Philadelphia citizens from a particular block or neighborhood that would be responsible for communicating important information to residents in their designated section. In addition to these methods of monitoring individuals, there was general agreement that there is a need for translation-friendly, culturally-relevant public health messages.

For example, during the open forum, Giang T. Nguyen, leader of the Penn Asian Health Initiative and Senior Fellow of the Penn Center for Public Health Initiatives, emphasized the importance of building ties with “ethnic media”: small publications or radio channels that primarily cater to immigrant communities in their own languages. He noted that, in the past, lack of direct contact between government public health organizations and non-English-speaking communities has led to the spread of misinformation in these communities.

On the other hand, Philadelphia has also successfully engaged immigrant communities in the recent past. For example, Garrow pointed to Philadelphia’s outreach in the Liberian immigrant community during the Ebola outbreak as a success story. When the outbreak began, the health department had already built strong ties with the Liberian community, to the point where the community actively asked the health department to hold a town hall meeting, rather than the reverse. This anecdote demonstrates the importance of establishing trust and building ties before a crisis emerges.
With regards to both general and community-targeted communication, the experts agreed that lack of funding is a major barrier to solving current problems. At the expert meeting, it was suggested that communication-specific grants, rather than larger grants with a certain percentage allotted for communication, might be one way of ameliorating this problem.
Are we prepared?: Communication between health organizations

The need for established communications networks extends beyond those for communicating directly with individuals. It is crucial for the local health department and healthcare system to have a strong relationship. Here in Philadelphia, the health department has a longstanding relationship with Penn Medicine, as well as other universities and major employers. In case of an emergency, these institutions are prepared to distribute vaccines or other medicines. Furthermore, mechanisms for distribution of vaccines already in place are “road-tested” every year during flu season. As an example, Penn vaccinated 2,500 students and faculty for the flu in eight hours during a recent vaccination drive, allowing personnel to sharpen their skills and identify any areas that need improvement.

In addition to the strong connections between major Philadelphia institutions, there is also a need for smaller health centers and community centers to be kept in the loop. These small providers serve as trusted intermediaries between large public health organizations and the public. According to the experts, these relationships are already in place. For example, during the recent Ebola crisis, the CDC set up a hotline for practitioners to call if one of their patients returned from an Ebola-stricken country with worrying symptoms. “You can’t expect everyone in the entire health system to know all they need to know [about treating a potential Ebola case],” said Nguyen, “but you can at least ensure that every practice manager and medical director knows the phone number to call.”

Can we adapt?
Ultimately, no crisis situation is fully predictable. Therefore, what matters most for responders is not merely having the proper protocols, resources, and avenues of communication in place, but also the ability to adjust their reaction to a crisis situation as it evolves. As Penn behavioral economics and health policy expert Mitesh Patel pointed out at the end of the open forum, “It’s not are we ready?, it’s are we ready to adapt?
The topic of adaptability was also heavily discussed at the focus group meeting. A lack of a central communication source was identified as a potential barrier to adaptability. So was a slow response from agencies further up the chain of command, such as the CDC. However, experts also disagreed about the precise degree of control the CDC should have at a local level. For example, representatives from local government agencies, which are more directly accountable to the CDC, expressed a desire for the CDC to proactively implement strategies, instead of attempting to direct the local response once it has already begun. Many physicians and hospital representatives, on the other hand, were of the opinion that plans formulated by the people closest to the crisis may be superior due to their situational specificity and lack of red tape. Despite this point of contention, experts agreed that there is a need for some consensus and coordination between hospitals in a particular region on how to respond to a large-scale health event.

One gap in Philadelphia’s preparedness identified by the experts in the focus group is its ability to case manage novel diseases—a challenge, since often the transmission route of novel diseases is not known. Some experts in the meeting also expressed doubt that Philadelphia is prepared for a direct biological attack. However, numerous epidemic-response frameworks already in place could potentially be repurposed for novel or deliberately-spread pathogens. In these cases, even more so than in “typical” epidemic situations, the experts identified adaptability as a key factor for success.

At the end of the open forum, the panelists affirmed the belief that Philadelphia is as prepared as it can be for an infectious disease crisis.  Furthermore, it seemed they had also moved the opinions of the event’s attendees: before the forum, attendees rated Philadelphia’s readiness at an average of 3.1 on a 6-point scale (with 0 being “not at all ready” and 6 being “completely ready”), while afterwards, the same attendees rated Philadelphia’s readiness at an average of 3.9 on the same scale (p=0.07, paired t-test).