Cancer Prevention - Get Behind It!

Wednesday, March 12, 2008
The American Cancer Society is putting together a new Cancer Prevention Study - CPS-3. From the website:

"The American Cancer Society’s Department of Epidemiology and Surveillance Research is inviting men and women between the ages of 30 and 65 years who have no personal history of cancer to join a historic research study. The ultimate goal is to enroll 500,000 adults from various racial/ethnic backgrounds from across the U.S. The purpose of CPS-3 is to better understand the lifestyle, behavioral, environmental and genetic factors that cause or prevent cancer and to ultimately eliminate cancer as a major health problem for this and future generations."

Registration is taking place at Relay for Life events, and state specific enrollment information can be found here.

Previous studies have determined the link between smoking and lung cancer, and obesity and colon, endometrial and postmenopausal breast cancer.

The program will be following participants for at least 20 years. Results from other long term health studies (specifically the Nurse's Health Study) have proven that these long term efforts provide information regarding causal relationships that shorter-term studies simply don't.

Cool beans. I'll be enrolling in June.

14 comments:

Michelle K said...

Ok, but...

They'd better be getting people some other way as well, because it seems to me that with a self-selecting population their data may be skewed. i.e. People who are likely to volunteer for a study may have significantly different health attitudes than the general population. Which may make the results less applicable to the general population.

On the other hand, they may do a better job of reaching minority populations this way. In general, minorities are resistant to participating in health studies, and with good reason I may add (See: Tuskegee Syphilis Study).

So it may help to get minorities into the study, but I wonder very much about how the problem of self-selection is going to affect the results.

Fascinating though. It's always good to see a long term health study start up. They're incredibly expensive to run, and have high drop out rates, but they're excellent for parsing out cause and effect, since you are not requiring people to retroactively remember their actions, and are starting with a pool of healthy volunteers.

Janiece Murphy said...

Michelle, I don't know how they're accounting for bias in this study. I know they only have 23,000 participants so far, and they need 500,000 with the current design.

And yeah, if I was a person of color, I would be suspicious, too.

MWT said...

Could someone enlighten me on what Relay For Life is all about?

I've gathered that it's "an event." Even an "overnight" event. And that it's a relay. And a walk. And that you form teams of 8-15 people for it. And there's a bunch of ceremonies before, during, and after it.

Even Wikipedia is being sketchy. Details??? If I were to show up at the local scheduled event, what exactly should I expect to be doing?

Janiece Murphy said...

MWT, you might want to try http://www.relayforlife.org/relay/ for additional information, but I think you have the gist of it. It's primarily a fund-raiser and awareness events.

MWT said...

I went there. Right after clicking through from your original post. That's where I deduced that it was "an event."

Then I went to Wikipedia and learned that it was "a walking event."

Then I clicked through one of the news articles at the bottom and found "you make teams of 8 to 15 people."

But where do you walk? And how far do you walk? Or is it based on how long you walk if there's "overnight" in the description? Is it one of those things where people sponsor you for how far and/or how long and/or how fast etc. etc. at ten cents a mile/minute/whatever? And how is it a relay, how's that part fit in?

In short, it appears to be one of those things where everybody already knows what it is except for me.

Janiece Murphy said...

MWT, you can count me in that group, too - the one not in the "know."

If I get any additional information wen I register in June, I'll pass it on.

John the Scientist said...

Michelle - absolutley there will be self-selectoin bias, so the model that results may not be statistically powered enough on the higher end variables such as BMI. But the informaoitn will still be useful, because even if it only has statistical power in the BMI range of say, 22 - 28, if there is an increased risk for the slightly overweight it will show that. If there isn't, then the're no need for docs to hound the slightly overweight, and that's good to know too. But it might not be able to tell, for example, a person with BMI of 32 what their risk is. However, those people have other, more pressing health concers (like CV disease and diabetes).


Janiece, stay with it as long as you can. Dropout rates on 4 year longitudinal studies run at about 30%, climbing to over 60% in ten years. The issue there isn't just loss of statistical power. It's also related to Michelle's point -a lot of dropouts due to a single confounding variable will make the sample self select for people who don't have that confounder. If a specific confounder - say dementia or stroke in the elderly - causes dropouts, and those dropouts also get cancer at a higher rate, the study will completely miss that link.

The other issue is that people of lower socio-economic status are more likely to drop out, and that cohort is more liely to engage in behaviors that put them at risk.

I'm willing to bet that they expect at least an 80% dropout rate over the 20 years, giving them a total 20 year sample of ~100,000.

Janiece Murphy said...

John, I was wondering about the high goal on the number of test subjects and assumed it would have something to do with drop-out rates. I'll stick with the study for as long as I'm able. If the Mad Cow takes over, though, I may forget the fill out the periodic surveys!

Michelle K said...

Re Relay for Life, IIRC, you have a group of people, and you work things out so at least one member of the group is walking at all times. Hence, the "relay" portion. So if you have twelve people, and the Relay lasts 24 hours, everyone will need to walk about 2 hours.

Here, the relay takes place at the WVU track, so you're walking in circles, but the place is well lit, and there are tons of people so 1)it's safe, and 2) there are people for you to talk with, so you don't get bored.

The fund raising comes from getting people to pledge money for your walking. This is the part I don't know about. I'm not sure whether the pledges are based on miles walked or time walked or the team finishing. Since I walk a 15 minute mile (11 if I'm walking really fast), I could get quite a few miles in a 2 to 4 hour period. :)

Michelle K said...

John,

I think that the fact it's a longitudinal survey does counter some of the self-selection bias, especially since people will lose and gain weight throughout the course of the survey.

I simply thing the bigger issue will be getting people who are more likely to already exercise to some small degree and to eat a more balanced diet. So I think the results would cater more towards genetic factors more than environmental factors.

But don't get me wrong, it's still pretty awesome, and I hope they reach their goal. I just think it'll be much harder to keep track of people than, say, the Framingham study or the nurses health study.

John the Scientist said...

Michelle - this is their third cohort, so maybe they've learned a few things baout retention. Funny, I searched the litereatuer and have not seen any retention figures.

I agree, there will be a bias towards higher socio-economic status with higher compliance with voluntary health improvement measures. And just the fact that the study subjects are giveing regular updates inspires them to do even better than their natural state, which will contribute to a placebo-like effect in the study, masking some varibales with small contributions to risk. But every study has noise, and you have to start somewhere.

Tania said...

Like Michelle said, most of the relays take place on school tracks, with huge groups of people around, ttnts, media types, and lots of other hoopla. Usually cancer survivors will do a lap or a leg of the relay.

Jules said...

Janiece,

(In the interest of full-disclosure, I do work for the American Cancer Society).

Thanks for your posting about CPS-3. We at the American Cancer Society depend greatly on individuals such as yourself helping to spread the word about this new study, and we're very appreciative. I myself am enrolled in the study, as I personally believe that - as someone who has seen so many friends and family members cope with cancer - that it's the least I can do to help. If I can be a part of something that may help to determine causes of or ways to prevent cancer, count me in.

Of course, should you or any of your blog readers wish to receive more information about enrollment in CPS-3, feel free to visit our website.

To clarify about Relay For Life: Relay For Life is the American Cancer Society's signature fundraising event. Relay For Life represents the hope that those lost to cancer will never be forgotten, that those who face cancer will be supported, and that one day cancer will be eliminated.

There are various components to Relay (like the survivor's lap one of your posters mentioned), and there are nearly 5000 Relays that will take place this year in the United States. Information on things like how to form teams, what teams do, if you are a survivor how you can participate in a survivor's lap and ceremony in your area, etc. can be found at: http://www.cancer.org/docroot/PAR/Content/PAR_1_Relay_For_Life.asp

There's also a video about Relay, that provides you with a visual as to what it's all about:
http://www.relayforlife.org/relay/crfb

I will add that you do not have to be a Relay team member or participant to enroll in CPS-3. The Relay venue was selected in particular communities because it provides a venue for large-scale enrollment for the study - but anyone, from anywhere in the community - can enroll in CPS-3 if they meet the eligibility requirements.

Again, our thanks for your help in spreading the word!

Janiece Murphy said...

Welcome, Jules, and thanks very much for the additional information about the Relay for Life and the CPS-3 study.

I'll be blogging about my experience periodically, so feel free to stop by and contribute as you see fit.