Cancer is a big topic around the science and pseudoscience communities. Cancer, which is really like 250 different diseases, is oversimplified. And treatments and preventions range from science based to simply useless (and thereby, dangerous). Preventing cancer deaths – the outcome we all desire – has been studied in detail, and I want to examine what we can do for this disease.
I’ve written a lot about cancer. Yes, there are a few ways to reduce your cancer risk, but it’s rather limited. A lot of highly promoted ideas, like avoiding processed meat, only slightly reduce your absolute risk for getting certain cancers.
And no, smoking marijuana does not reduce your risk for any cancer nor treat any cancer, but it may actually slightly increase your risk. And, just because it’s become a “thing” again on the internet, acidic blood does not cause cancer.
Despite the tropes and memes on Facebook, probably the most pseudoscientific pushing website on the planet outside of Natural News, physicians and real scientists are basically winning the war on cancer. Incidence and mortality are down for most cancers, which I’m sure would surprise many readers.
A recently published study examines lifestyle choices that can really have an impact on cancer incidence and mortality, confirming what we knew and suspected. But it’s good to have a large study authenticating it. Let’s review it.
What is cancer?
Let’s start with a little science, just to make sure we’re all on the same page.
Simply, cancer is a disease in which cells of the body grow in an uncontrolled manner, forming a tumor that may spread to different parts of the body. “Cancer” is not one disease – there are around 250 types of cancer, depending on how we characterize a particular cancer. Each of these cancers have different etiologies, different pathophysiology, different treatments, and different outcomes.
When one sees something that says “XYZ prevents cancer,” your skepticism should go into overdrive. Which cancer? What’s the mechanism? What’s the quality of evidence?
All cancers are caused by mutations in the DNA of cells in the body. Most of the time, cells deal with these mutations by “fixing” the DNA. Or the mutation is so serious that the cell simply dies (it’s really one cell, and cells die in your body constantly). If the mutated cell lives and divides, the body has immune defenses against most mutations–so it’s gone before you would even know that it’s there.
Technically, with 46-68 trillions of cells in the average human body – even if an individual cell mutation is extraordinarily rare, the law of large numbers means that you could have literally hundreds or thousands of cancer cells living in your body at any moment in time, dying naturally, or being destroyed by the immune system, or not causing any problems at all.
There are just so many cells in the body, and the cellular replication mechanism being slightly less than perfect, mutations will happen. Genetics, environmental challenges, and viruses can increase the mutation rate – smoking is a perfect example.
The odds against a cancer growing is even lower than I’m stating. For a cancer to survive from a single cell, to a mass of cells, requires nutrition (forcing the body to feed it with blood vessels). To do that, it needs another mutation of the cell. Then it needs to grow unrestricted by the normal growth control systems of the body–another couple of specific mutations. The cancer also needs to hide from the immune system, more mutations.
I could go on and on, but it could take up to 10 individual and correctly placed mutations for a cell to transform from a normal cell to a cancer cell.
Again, with trillions of cells, it becomes mathematically possible, but very hard to do. Looking at cancer from a strictly mathematical point of view – to pile up 4 or more mutations that all are advantageous to the cancer cell is almost unimaginable.
But with so many cells and so many contributing factors, like the environment, the chances do increase. Outside agents, like viral infections, tobacco smoke, radiation (more broadly than just radioactive energy, but ultraviolet and other types of radiation), and human physiology can cause (or allow to cause) so many mutations that eventually one leads to an increase in the number of mutated cells, then a growing viable cancer.
Report on preventing cancer deaths
In a new paper published in JAMA Oncology by Drs. Mingyang Song and Edward Giovannucci of Harvard Medical School, found that about half of cancer deaths could be prevented with just four lifestyle choices.
The study included a total of approximately 90,000 women and 46,000 men from 2 cohorts, starting in 1986, with each participant interviewed every two years. The breakdown of the cohorts were:
- 16,531 women and 11,731 men were in the low-risk group with a a healthy lifestyle,
- 73,040 women and 34,608 men made up the high-risk group
The researchers found that approximately half of cancer deaths in the United States could be prevented if all Americans quit smoking, quit (or at least seriously curtailed) alcohol, maintained a healthy weight, and exercised around 150 minutes per week.
Furthermore, implementing these measures could reduce the number of cancer incidence by 40-70%.
For men that embrace this lifestyle, it could avert approximately 67% of cancer deaths, while lowering cancer incidence by about 63%. For women, the mortality rate would fall by 59%, and incidence would drop by 41%.
In 2016, the National Cancer Institute (NCI) estimates that there will be approximately 1.7 million new cases of cancer diagnosed, and nearly 600,000 people will die from the disease in the USA. If all Americans implemented the lifestyle changes suggested in the article, we could prevent around 300,000 deaths, and reduce cancer diagnoses down to around 1 million.
Sure, that’s not perfect, but it is still a huge decrease in both risk and mortality. And that has a lot of consequences – increased lifespan, increased economic productivity, reduced healthcare burdens, and many other personal and societal benefits.
The details within the study are important:
- Following the four lifestyle recommendations reduce lung cancer risk by 85% in women and 90% in men.
- It reduces colorectal cancer risk by 60% in women and 50% in men.
- Women who followed these recommendations reduced their risk of pancreatic cancer by 53%, endometrial cancer by 37%, ovarian cancer by 34%, and breast cancer by 15%.
- Similarly, men who implemented this lifestyle reduced their risk of bladder cancer by 62%, prostate cancer by 40%, and kidney cancer by 36%.
This study partially refutes the controversial “bad luck” hypothesis of cancer – see Dr. David Gorski‘s critical review of the hypothesis if you want more information. According to Dr. Gorski, cancers probably result from “a combination of random probabilistic processes, environmental exposures, and heredity, (which) is a non-controversial statement.”
This study convincingly establishes that a few lifestyle choices appear to have a significant effect on reducing the risk and mortality of the disease. It’s not going to prevent 100% of cancers, but it will lower your absolute risk, which is the best you can do.
Also, because I need to explain the limitations of this study, there were two key points. First, the study population were American healthcare workers, who are overwhelmingly in one demographic group – moderate income whites. So this data may or may not be applicable to other groups.
And second, the data was taken from questionnaires given to each of the participants – there’s just no way to observe hundreds of thousands of people eating and exercise behaviors. But the results are so clear, that it probably overwhelms any bias.
American unhealthy lifestyles
Many Americans still embrace unhealthy lifestyle choices. Approximately 40 million Americans (about 17%) still smoke tobacco, which contributes to the deaths of 480,000 Americans per year. I cannot comprehend how anyone spends hard-earned money to engage in a disgusting habit that kills not only themselves, but also, through second-hand smoke, others.
According to the CDC, an estimated 38% of American adults are obese, with a body mass index (BMI) greater than 30. That means over 80 million American adults have an unhealthy weight, which, as I have shown, greatly increases the rate of cancer risk and mortality.
The same can be said about exercise (which is probably related to obesity). About 22.5% of American adults participate in no physical activity outside of their job requirements.
With respect to heavy alcohol use, the CDC also has bad news about Americans. Although approximately 60% of American adults consume less than 1 alcoholic drink per week, nearly 20% drink heavily. Moreover, about one-quarter of American adults acknowledge engaging in binge drinking – which is defined as four or five servings of alcohol at one time – during the past month. An “unhealthy lifestyle” would be more than one serving of alcohol for women, and two for men, per day. However, if the risk is linear from 0 drinks to 1 drink per day, even light drinking may contribute to an absolute increase in risk for cancers.
Even though this study was about Americans, don’t think that residents of Germany, France or Japan can ignore these recommendations. Smoking causes cancer no matter where you live. And no, if you don’t drink, exercise a lot, and are skinny, but still smoke, you still are at a pronounced risk of getting cancer from tobacco.
And as non-Americans embrace the American lifestyle, obesity rates are climbing all over the developed world.
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The TL;DR version
In an accompanying editorial in JAMA Oncology, Graham A. Colditz and Siobhan Sutcliffe, of the Washington University School of Medicine, made some important points:
[infobox icon=”quote-left”]Cancer is preventable. In fact, most cancer is preventable—with estimates as high as 80% to 90% for smoking-related cancers, such as lung and oropharyngeal cancer, and as high as 60% for other common, lifestyle-related cancers, such as colorectal and bladder cancer. This large excess of cancer is not inevitable but rather can be tackled by a broad range of interventions at multiple levels, including strategies at the clinician level, the individual level, the community level, and the society level through regulatory change.
As a society, we need to avoid procrastination induced by thoughts that chance drives all cancer risk or that new medical discoveries are needed to make gains against cancer. We must embrace the opportunity to reduce the collective cancer toll by … changing the way we live.”[/infobox]
So, if you implement these four healthy lifestyle choices, will you never get cancer? Not completely, but you significantly reduce your absolute risk of getting many cancers. If you smoke, and you stop smoking, that’s going to be the one thing you can do that could have an almost immediate impact.
Will drinking a blueberry kale smoothie prevent cancer? No, but if it gets you to stop smoking and drinking, lose weight, and exercise more, then it does help indirectly.
What about cancer preventing vaccines? Yes, I pontificate at length about the solid evidence that HPV and Hepatitis B vaccines prevent cancer. But that’s not a lifestyle choice, it’s a medical procedure. So do get those vaccines so you drop down the risk of even more cancers.
Is it easy to quit smoking, reduce drinking, lose weight and exercise? Well, as I say on occasion, “if it were so easy, everyone would do it.” But if you want science-based evidence on how to actually reduce your risk of cancer and cancer mortality, this is it.
Or you could take the easy way, drink blueberry kale shakes. That won’t do anything for your cancer risk.
- Colditz GA, Sutcliffe S. The Preventability of Cancer: Stacking the Deck. JAMA Oncol. 2016 May 19. doi: 10.1001/jamaoncol.2016.0889. [Epub ahead of print] PubMed PMID: 27195793.
- Song M, Giovannucci E. Preventable Incidence and Mortality of Carcinoma Associated With Lifestyle Factors Among White Adults in the United States. JAMA Oncol. 2016 May 19. doi: 10.1001/jamaoncol.2016.0843. [Epub ahead of print] PubMed PMID: 27196525.
- Tomasetti C, Vogelstein B. Cancer etiology. Variation in cancer risk among tissues can be explained by the number of stem cell divisions. Science. 2015 Jan 2;347(6217):78-81. doi: 10.1126/science.1260825. PubMed PMID: 25554788; PubMed Central PMCID: PMC4446723.