Soda Causes Cancer, Could it be?

A study done in Singapore has found that drinking 2 or more sodas per week is associated with nearly twice the risk of pancreatic cancer than staying soda free. The study was published this month in the journal Cancer Epidemiology, Biomarkers, & Prevention and reported on WebMD.

It's no surprise that the beverage industry is doing all it can to discredit the study; however, the methods used seem surprisingly sound. In fact, while the American Beverage Association claims that other studies have shown no association between soda and pancreatic cancer, a 2005 study out of Harvard School of Public Health found that soda (i.e. sugar sweetened beverage) consumption was associated with increased risk of pancreatic cancer in women, particularly those who were overweight.

Pap Test PSA: Video

Saw this PSA from the Michigan Department of Community Health (on BroganBlog) and thought it was a pretty clever 30 second ad. Why do I think it works:

1. Good use of humor. (Come on, you laughed a little, right?)
2. Simple, clear message. 
3. Songs just get stuck in your head.
4. Links to birthday so you don't just think about getting tested once, but once a year.

What do you think about this PSA? Was there anything missing?

Mammography Guidelines Revisited

Reaction to the updated mammography guidelines -- see previous posts on the topic -- from the US Preventive Services Task Force (USPSTF), a panel of experts charged with determining guidelines for cancer screening, has reached partisan proportions. Republicans are trending toward outrage and Democrats sympathy.

Making Mammography Screening Guidelines: Two approaches

So how did the "experts" at the US Preventive Services Task Force (USPSTF) come up with the "new" mammography guidelines, anyway?

As you read in yesterday's post, the decision was based primarily (or fully) on the findings from epidemiological data (i.e. population-level health research, rather than medical case studies, case histories).

While an epidemiologist (...a "social epidemiologist," really) at heart, I am taking a decision sciences class that is completely fascinating and speaks to the pitfall of relying on critical research reviews and other ways to "understand the evidence" in a traditional way. For example, rather having the USPSTF make recommendations based on their understanding of epidemiological literature alone, it could use that literature to inform a decision sciences or decision analysis approach, instead.

Here's what I'm thinking...

So without getting to far into it, here's the basic decision science methodology, as I (a newbie) understand it. You create a lot of "trees" that reflect the probability of a particular outcome for a decision that you may make. For example, you can model the survival (the outcome) of a woman with breast cancer that receives a mammogram every year (decision #1) versus a woman that receives a mammogram every two years (decision #2). You can determine how survival is difference given certain predisposing characteristics (or risk factors -- family history of breast cancer, for example) and also consider what her survival would be if she tests positive and truly has breast cancer, as well as if she tests positive and does not have breast cancer.

There are problems with this approach, of course -- for example, if you are basing your decisions off of faulty probabilities or inaccurate scientific data. Nonetheless, decision analysis is well poised to deal with issues related to testing (or screening, such as mammography) where receiving a false positive result (you are told you have the disease when you really don't) is common or when a false negative result (you are told you don't have the disease when you really have it) is common.

I doubt USPSTF used a decision analysis approach given what I've read on their website. What do you think about it? Should we move in a decision analysis direction or should the traditional epidemiological approach be sufficient to make these public health decisions?

Now I get to complete my decision sciences mid-term. Yippee!

Mammography Screening Myths Exposed

The US Preventive Services Task Force (USPSTF) released "new" mammogram guidelines this week. The guidelines have received major backlash from the American Cancer Society and many cancer survivors.

Below is are some of the mammography screening myths floating around:

A Question of Sustainable Screening

This month my first first-author publication was published in the Journal of Women's Health! I am extremely excited as it was the product of a two-year effort and became a really insightful article with the help of some really intelligent colleagues and collaborators. While I want to share with you highlights from the article, I'd also like to share some reflections on what I learned through the process.

The article examined what factors predict mammography re-screening (in the past 2 years) among Latinas living in California. This paper began as a study of all Latinas, but by the final iteration it focused on Latinas had at least one mammogram. Here are some of the major findings and considerations:

• Multiple factors influence mammography screening; those screened were older (60+ years), more educated, had health insurance, and reported having a 'usual source of care'.
• The most common reasons for not having a recent mammogram were cost, inconvenience, and lack of knowledge.
• Latinas who interviewed in Spanish were more likely to have been recently screened than those who interviewed in English (suggesting language might not be such a barrier to preventive health care use once access is attained).
• Increasing access to mammography screenings (both by reducing the cost and increasing the convenience) will likely improve re-screening among Latinas.

This was an incredible learning experience; one that I am so thankful to have had prior to graduate school and dissertation defenses. Nonetheless, there are a few key 'lessons learned' that I'd like to share. I hope these will serve as a reminder for myself and provide some comfort to others who will likely endure the same challenges and frustrations.

1. Listen. Embrace opportunities to invite in others to be a part of the publication process. I was so grateful to connect with collaborators at the CA Department of Public Health who were running mammography screening programs. It gave us a lot more confidence in our understanding of the problem and the interpretation of our data. 
2. Persist. Publishing this article was  a roller coaster ride. At first you think that your idea is the greatest one yet. Then, either through reviewers' comments or constructive criticism, you begin to doubt. It takes courage to work through the tough issues that need to be dealt with to improve the paper.
3. Revise! As focused as I thought the paper was when we began, there was way too much in there for a 2500 word article. Revisions focused the paper and resulted from thoughtful critique from reviewers and coauthors.
4. Relax. Once you submit that article there is no point in checking the website every day to see if the status of the article has changed (I never did that...). Enjoy the waiting because once you get the manuscript back your next few weeks are shot.

I am looking forward to working on some more publications, but I'm excited to have this blog so I can discuss public health issues that interest me any time. 

If you could publish in any area -- magazine, newspaper, journal -- what would you write about?

Mouthwash: Friend or Foe?

There is something about that tingling, burning sensation of Listerine that always keeps me coming back. I just don't "feel" like that other stuff is working. However, according to a recent study published in the Dental Journal of Australia using mouthwash containing large amounts of alcohol is associated with greater risk for developing oral cancer.

A possible link between mouthwash use and oral cancer was brought to my attention while riding the T Tuesday morning by Metro. I did a quick PubMed search and found several articles -- even REVIEW articles -- on the issue that date back to 1991. This is not a new idea, however this finding is quite controversial. I decided to review 3 articles on the subject (I was limited by those journals subscribed to by HSPH at this point).

#1

 The first article, a 1996 review in the American Journal of Epidemiology, proposed a spurious (non-causal) association between mouthwash use and oropharyngeal cancer. The authors (one of whom worked for Procter and Gamble; the work was sponsored by a Pfizer company) argued that alcohol and tobacco use likely accounted for the association between mouthwash use and oral cancer. For example, consider that smokers are more likely than nonsmokers to use mouthwash to eliminate their bad breath, and that smoking is strongly associated with oral cancer -- it is. While it may seem that mouthwash was linked to cancer, really it may have just been the tobacco use.

#2

In 2003, an article was written and published in the Journal of the American Dental Association (this study was also financially supported by a Pfizer company) to review the literature examining the mouthwash-oral cancer relationship. Nine studies were considered - six showed no association between mouthwash use and oral cancer, and three showed a positive association. In addition, this article re-analyzed data from a large population-based National Cancer Institute study with nearly 1500 cases and a similar number of controls. The re-analysis showed that mouthwash had the same moderate effect on both "true"/mucosal and "pseudo"/nonmucosal cases of oral cancer; whereas other known risk factors (alcohol and tobacco use) for mucosal type oral cancer were quite strongly and predictably related to "true" cases, but not to the "pseudo" cases.  Of course, confidence intervals are not presented.

These two studies with their industry backing leave me wanting...let's hope #3 wraps things up.

#3

I can make this quick. The final article was published online (2008) ahead of the Oral Oncology print yet featured no new evidence since the 2003 review. The author suggested there is no epidemiological evidence that mouthwash causes oral cancer.

Summing It Up:

•  None of these studies address issues of reverse causation. It is likely (think about it...) that the onset of oral health issues (cancer, lesions, etc) result in greater use of mouthwash, and not the other way around.
• Studies do not differentiate between alcohol-based and other mouthwash types, weakening the claim that it is the alcohol-based mouthwashes that are the culprit.
• There is no clear relationship between quantity or frequency of mouthwash use and greater risk of oral cancers.
• More rigorous studies are needed to suggest that the relationship is not a result of recall bias, under-estimation of tobacco or alcohol use, and other potential confounders.

I'll stick with my mouthwash of choice -- for now. Of course, if you are really interested in oral health issues check out the source articles for yourself!

PS. If someone can send me that Australian journal article I'd love to take a look!

Update: So I took a look at the Australian Dental Association article, which suggested that there is sufficient evidence to implicate high-alcohol content mouthwashes in the development of oral cancer. However, the studies they cited were not recently published, leading me to believe that the evidence upon which they base their claims are the same ones that these previous lit reviews reject. It is possible that high-alcohol containing mouthwash is dangerous for certain vulnerable groups. However, more rigorous scientific evidence should be produced to support that hypothesis.