Meditations of an oncology geek

How can cancer be prevented?

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23 April 2011

This week’s article was not inspired by one person, but from many illuminating conversations with friends and family. It’s a little on the long side, but I will admit that I had a very fun time researching the topic, as cancer prevention and general wellness is very near and dear to my heart.

Cancer is a nasty disease, especially once it has begun to metastasize and spread. The best treatment for cancer is to not get it at all, or detect it early. So how do you prevent getting cancer? There’s a lot of information out on the Internet on the subject, but the University of Google often falls short on hard scientific studies. In that capacity, I chose a few areas to research for this article.

Prevention: Understanding Cancer Risk
Can an umbrella save your life? Maybe. If you go out into the rain, you get wet. Get wet or stay wet often enough, and you’ll get sick. An umbrella won’t stop you from getting wet, but it will prevent you from getting too wet. And maybe it will keep you from getting so wet that you catch a chill and get sick. Cancer risk is a little like rain. It’s all around us, and it’s nearly impossible to be a living, breathing human being without getting wet from the rain from time to time. But, there are choices you can make and things you can do to create your umbrella against cancer. It cannot prevent you from ever getting cancer, just like an umbrella can’t prevent you from getting wet. But both can lessen your risk of getting sick, and leave you in a much healthier and happier state of being.

Smoking and trying to compensate with healthy activities is sort of like trying to stop a falling anvil with your umbrella. If you smoke, please stop. Now, I don’t smoke, nor have I ever, but I know from research on addiction and from exposure to smokers that quitting is easier said than done. Point taken. Find some way to quit. There is a plethora of information and support programs available online and elsewhere. If you smoke, quitting is the single greatest act you can undertake to lessen your cancer risk. Everything else is would have a negligible effect.

Now, for the rest of us, there are a few things we can do.

Right: There are fairly solid studies, both epidemiological and biochemical, to suggest that green tea can lessen cancer risk for common cancer types

Prevention: Antioxidants
In theory, eating lots of antioxidants can prevent damage to your DNA. This phenomenon works elegantly in a test tube, and on cancer cells in a petri dish, but there are not yet any large-scale, randomized, double-blind studies on humans to definitively link antioxidants and cancer prevention.

There are a number of reasons for this, but the bottom line is that we don’t live in test tubes and petri dishes. Anything we consume is subject to uptake through the gut (or lack thereof) and must pass through the biological sieve that is the liver before entering the bloodstream and becoming available for most cells to use.

While there are no randomized trials, there have been some good studies conducted on the correlation of consumption of green tea and prostate cancer. The authors recruited 130 prostate cancer patients and 274 people as controls, and provided a questionnaire about their green tea consumption, and even went so far as to weigh the amount of leaves brewed and cups of green tea consumed. The authors discovered a strong trend: the cancer patient group contained much fewer green tea drinkers, and the severity of disease inversely correlated with amount of tea consumed. However, the authors were careful to note that “It may be argued that tea drinkers may have healthier dietary patterns and that green tea could be a marker of another aspect of diet that is protective against prostate cancer.” In a nutshell, a study like this establishes correlation, but not causation.

While antioxidants might be beneficial, and there might be future clinical trials on human subjects that demonstrate a good positive correlation between certain antioxidants and cancer prevention, for now we must rest on the results we have. Lots of fruits and vegetables in your diet are usually good for your health, and green tea consumption has not been demonstrated to be particularly harmful, but intensive vitamin pill regimens have yet to follow suit in robust scientific data to support cancer prevention in humans.

Prevention: Exercise
Exercise, specifically two to three hours (at least) of aerobic exercise per week, CAN REDUCE YOUR CANCER RISK. By aerobic, I mean the type where you have to control your breathing, but are not necessarily gasping for air. This includes light running, swimming, cycling, cross country skiing, hiking, snowshoeing, vigorous dancing, and brisk walking. This does NOT include yoga, meditation, snorkeling, rock climbing, slow walking, and most dancing.

Right: Just look at all those happy people, actively lessening their cancer risk!

In reality, you could get this amount of exercise if you frequently bike to work, or go for a few lunchtime runs, or go up and down the stairwell of your building a few dozen times per week. You don’t have to be an Olympian (or look like one) and you don’t need to become an exercise freak, but you absolutely need to have that moderate exercise several times per week, rounding out to at least two to three hours total time in motion spent exercising.

While the correlation between exercise and reduced cancer risk is fairly well documented, there is at least one definitive biochemical mechanism that has been discovered so far, which helps to establish causation and not just correlation. Studies like Cherkas et al. 2008 have found that genetically “identical” twins that differing exercise level have different length telomeres. Telomeres are the caps on chromosomes that keep DNA from unraveling and causing genetic damage that can lead to aging and cancer. It’s a widely accepted proxy for your “biological” age as opposed to chronological age.

The twins that exercised more had longer telomeres, implicating a longer biological rope on life and being fewer steps away from getting age-related cancer. This correlation increased with the amount of aerobic exercise, up to five hours per week.

Prevention: Aspirin
Aspirin is perhaps the most successful drug of all time. It is a general pain killer and anti-inflammant. As described in a previous article the body generally recognizes cancer as a wound, and elicits an immune response to the “rescue.” In actuality, the particular type of immune response known as inflammation actually fuels cancers with nutrients and growth factors. Moderate immune suppression has been demonstrated in studies of Rapamycin (a powerful immune-suppressant) administration in mice to reduce cancer burden, growth, and spread. Rapamycin is currently used off-label by some oncologists for cancer treatment, and the race is on for big pharmaceuticals to develop patentable modifications of Rapamycin for a new generation of anti-cancer drugs.

A milder anti-inflammant, Aspirin, has recently been demonstrated by Rothwell et al. to reduce the risk of death from cancer by at least 7% for those age 65 and older. Those taking aspirin took at least 75mg a day (considered a safe, low dose by most standards) for 5 years. With over 25,000 people taking part in the study, the statistics are pretty solid.

It is also likely that the result could have been greater if aspirin was administered over a longer time period and could be more concentrated on certain types of cancer, etc. These studies are likely underway as I write this.

Prevention: Sunscreen
Because I do not want to risk sounding banal, I will not go into detail on the science behind sunscreen. It works. But please make sure to get sunscreen that has UVA protection as well. UVA causes melanoma, the most aggressive type of skin cancer, responsible for 75% of skin cancer deaths. Oddly, the FDA in the US does not require UVA protection in sunscreen! But, most manufacturers include UVA protection now anyway. Just be sure to read the label.

Whatever you do to lessen your cancer risk, always keep in mind that there are some biological threats that are simply out of your control. Cancer prevention is a great way to increase your chance of living a longer, healthier life. But, it is no substitute for regular doctor check-ups and body surveillance.

-Ryon

p.s. please feel free to submit your cancer-related questions. Most of the material on this blog is generated by the curious minds of my readers!

Written by Ryon

April 23rd, 2011 at 6:29 pm

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5 Responses to 'How can cancer be prevented?'

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  1. Brilliant!

    KP

    23 Apr 11 at 8:01 pm

  2. Ryon,

    Does low-dose aspirin create a high hemorrhage risk in the cases of trauma? I am a fellow cyclist and worry about things like massive brain bleeding if I am on aspirin and end up hitting my head in an accident.

    Is this a risk like warfarin is, or is it negligible in comparison?

    Rick

    13 Jun 11 at 3:35 pm

  3. Hi Rick,

    Ask your doctor if 75mg would be a safe dose for a cyclist. I am not an expert on the matter in regard to trauma, but I should add that the dose of aspirin for anti-cancer effect has not been optimally titrated yet. It’s possible that there could be greater protection with an increased dose, or there might not be any loss in efficacy with a lower dose. But, that has yet to be determined. I should also caution against going on an aspirin regimen without consulting your doctor.

    Ryon

    20 Jun 11 at 12:36 pm

  4. Hey, I just wanted to note that I am in fact Dr. Ian Quigley at the Salk, and I don’t study inflammation, nor do I take aspirin to ward off cancer. I am all for people taking preventative measures, but please don’t cite me as an authority on the issue.

    Ian Quigley

    27 Sep 13 at 1:12 pm

  5. My sincerest apologies, Dr. Quigley. I had confused you with a different Dr. Quigley. Since I could not find my original notes on his lecture from February 2010, I have not included the anecdote. I apologize for the mix-up and have removed the reference.

    Ryon

    2 Oct 13 at 12:53 pm

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