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Four Proven Ways to Prevent Cancer

January 14, 2022

In my practice, people often ask me about ways to prevent cancer. Sometimes it’s a patient finishing his cancer treatment, hoping to do all he can to keep his cancer from coming back. Sometimes it’s a patient’s family member wanting to know how to lower their own cancer risk.

Explaining all the different ways to prevent cancer is a difficult thing to do. There are thousands of studies that have been published about what causes cancer and what we can do to prevent it. On top of that, a bazillion unproven theories are circulating the internet and presenting themselves as fact. I have a Doctorate and over 20 years of experience in oncology, and it’s difficult for me to sort through it all. I’m not sure how anyone without some sort of health background ever makes sense of it.

Over time, I hope to share with you everything you care to know to lower your risk of cancer as much as humanly possible—and how to be healthier, feel better, and live longer, in general. But for today, we will start with the four ways to prevent cancer that have been proven by high-quality research over and over and over again.

If you can do just these four things you will decrease your risk of being diagnosed with cancer by at least 30%. Furthermore, you will reduce your risk of dying from cancer by at least 50%. I also guarantee that you will feel better and decrease your risk for a lot of other chronic diseases, too!

1. Don't Smoke

I know the vast majority of you already know this, but the absolute most important of all the ways to prevent cancer is to STOP SMOKING. Even better is to never start smoking in the first place.

It is a fact that you are 10 to 20 times more likely to die from cancer if you smoke. And if no one smoked, we would decrease the number of cancer deaths in our country by 30%. That’s 200,000 people a year!

I want to quickly say here that I use the word cigarettes a lot in this article, but all forms of smoking tobacco—including pipes and cigars—are equally as risky.

"I Don't Believe Smoking Causes Cancer"

Sadly, I hear these words fairly frequently. These days most people know that smoking increases the risk of cancer. However, there are still a few people out there that don’t want to believe it.

Did you know that smoking did not become mainstream until after the invention of the cigarette machine in the late 1800s? Before this, lung cancer was exceedingly rare.

Lung cancer accounted for less than 1% of all cancers at the turn of the 20th century. Unfortunately, as the use of cigarettes rose, so did the incidence of lung cancer. It is now the second most common type of cancer and the number one cause of cancer death.

Do yourself a favor. If you are one of the people who are reluctant to believe that smoking causes cancer—just trust me, it, positively, without a doubt causes lung cancer. Yes, other things can cause lung cancer, and some people that never smoke get lung cancer, but smoking is THE number one culprit.

It's Not Just Lung Cancer

If you smoke, you aren’t just at risk for lung cancer. You are also at increased risk for being diagnosed with and dying from leukemia, cancers of the mouth, voice box, esophagus, liver, pancreas, stomach, kidney, bowel, ovaries, bladder, and cervix.

It’s Not Just Cancer Either

I know this post is about how to prevent cancer, but let me just say—if you smoke, you are also significantly increasing your risk of a multitude of other diseases. These include heart disease, stroke, COPD, chronic bronchitis, emphysema, diabetes, osteoporosis, rheumatoid arthritis, macular degeneration, and cataracts. And these are just a FEW examples of the negative effects smoking has on your health.

Does Quitting Do Any Good?

Yes! By quitting smoking, you reduce your risk of cancer of the bladder, mouth, throat, and esophagus by half after the first five years. During this same time frame, your risk for cervical cancer and stroke returns to normal, as well.

Ten years after you quit smoking, you are half as likely to die from lung cancer. Your risk of larynx or pancreatic cancer decreases significantly, as well. If you quit smoking before age 40, you are 90% less likely to die prematurely than those that continue to smoke. Over age 40? You can reduce your risk of premature death by 65% if you stop smoking by age 54. It is (almost) never too late.

What About Secondhand Smoke?

Secondhand smoke is a human carcinogen and inhaling secondhand smoke causes lung cancer in nonsmokers. If you live with a smoker, your risk of developing lung cancer increases by about 30%.

Secondhand smoke also can lead to premature death in nonsmoking adults and children by increasing the risk of heart disease and stroke, increasing the risk of a pregnant woman having a low birth weight baby, and raising the risk of children dying of SIDS.

Are E-Cigarettes a Safe Alternative?

Many smokers turn to e-cigarettes as a “healthier” alternative to traditional cigarettes. However, the solutions in e-cigarettes release acetaldehyde and formaldehyde, which are known carcinogens. E-cigarettes haven’t been around long enough for us to know if they are any safer than real cigarettes, but studies have shown that the short-term effects on the lung are very similar.

Until long-term data is available, I would say that you should stay away from e-cigarettes and assume they pose the same risks as traditional cigarettes.

2. Maintain a Healthy Weight

After not smoking, the next most powerful way to prevent cancer is to maintain a healthy weight. Less than half of Americans realize that obesity is the second leading cause of cancer in our country.

If you are overweight, you are not only more likely to be diagnosed with cancer, but you are also more likely to die from that cancer. Excess body weight causes about 35% of all cancer diagnoses and at least 1 out of every 5 cancer deaths.

Being overweight doubles the likelihood that you will be diagnosed with esophageal cancer, gastric cancer, liver cancer, and kidney cancer. If you are overweight, you are also at a much higher risk for myeloma, meningioma, pancreatic cancer, colon cancer, rectal cancer, gallbladder cancer, post-menopausal breast cancer, ovarian cancer, and thyroid cancer.

How to Define a Healthy Weight

Research shows that your risk of cancer increases if your BMI (Body Mass Index) is greater than 27.5. Your BMI is calculated by taking your weight (in kilograms) and dividing it by your height (in meters).

If you want to know your BMI, there are many BMI calculators available on the internet that you can use. Click here for one of my favorites.

There IS Such a Thing as Too Skinny

Thinner is not always better. Being underweight increases your risk for cancer, too. The best way to prevent cancer is to maintain a BMI greater than 18.5, but less than 27.5.

How Being Overweight Works to Cause Cancer

First, if you are overweight, you are likely to have high levels of insulin and insulin-like growth factor. These hormones promote cell growth in your body and enhance tumor cell proliferation.

Second, excess weight almost guarantees that you have chronic inflammation throughout your body. Over time, this inflammation causes damage to your DNA and leads to cancer.

Third, your immune system doesn’t function at its best when you aren’t at a healthy weight. This means that cancer-causing infections are more likely to escape detection. It also means your immune system is less likely to find early cancer cells and eliminate them.

Fourth, your fat cells secrete excess amounts of estrogen, increasing your risk of breast, ovarian, and other cancers.

Finally, your fatty tissue produces excess amounts of other hormones and proteins known to stimulate cancer formation and tumor cell growth.

Will Losing Weight Decrease My Risk?

Yes! Multiple studies have proven that it is never too late to get yourself to a healthy body weight.

3. Avoid Excess Alcohol Consumption

Not always popular, but number 3 on the list of ways to prevent cancer is to limit how much alcohol you consume.

A recent study shows that less than 20% of Americans know that alcohol can cause cancer. Alcohol is a class 1 carcinogen—meaning that the data has proven that it causes cancer in humans.

Alcohol is the cause of 3.5% of all cancers in the United States and your risk for alcohol-related cancer depends on how much and how often you drink. If you smoke and drink regularly, you are in double trouble—smoking and alcohol use combine to increase your risk well beyond what it would be if you only did one or the other.

How Much Is Too Much?

If you are a man, the data shows that anything over two drinks per day increases your risk of disease. If you are a woman, your risk increases after just 1 drink per day. One alcoholic beverage is considered 12 ounces of beer, 8-9 ounces of malt liquor, 5 ounces of wine, or 1.5 ounces of 80-proof distilled spirits.

What Types of Cancer Does Alcohol Cause?

If you drink regularly, you are significantly more likely to be diagnosed with cancers of the head and neck (mouth, throat, and voice box), esophagus, liver, breast, colon, and rectum.

Research has proven that your risk of colorectal cancer goes up 7% for every 10 grams of alcohol you consume per day. (Ten grams is slightly less than one drink.)

It has also been shown that even low levels of regular alcohol consumption increase the risk of breast cancer for women. For every 10 grams of alcohol, a woman consumes per day, her risk of breast cancer rises 12%.

How Exactly Does Alcohol Cause Cancer?

First of all, the ethanol in alcoholic drinks breaks down to acetaldehyde in the colon. Acetaldehyde is known to be a probable human carcinogen that can damage your DNA and other proteins that usually protect your body from forming cancers.

Second, alcohol can generate free radicals that damage DNA and proteins through something called oxidation. (This is why antioxidants are good at preventing cancer—more on that in another post).

Third, alcohol increases the level of estrogen circulating in your blood, and these increased estrogen levels can stimulate breast cancers to develop and grow.

Fourth, alcohol often contains other carcinogenic contaminants, such as nitrosamines, asbestos, phenols, and hydrocarbons.

Fifth, alcohol acts to irritate and damage tissues (especially in the mouth and throat). This irritation can lead to DNA damage, as well.

Finally, alcohol damages the liver, causing inflammation and other damage that can cause cancer.

But Isn't Red Wine Good for Me?

There is some evidence that drinking one glass of red wine per day for women and no more than two glasses of red wine per day for men can be good for your heart. Remember, these are 5-ounce glasses of wine! More than that does more harm than good.

Cancer Risk After Quitting Alcohol

Unfortunately, the effects of regular alcohol consumption on your cancer risk are long-lasting. It could take years for your risk of cancer to return to the same risk as someone that never regularly consumed alcohol. Several studies have shown that your risk of cancer does not start to decrease for about ten years after you quit drinking.

The lesson here is that if you are consuming more alcohol than is healthy, you should stop NOW—before it’s too late to undo the damage.

4. Move More

Physical activity has an enormous impact on your cancer risk and moving more is one of the most important ways to prevent cancer. By incorporating a relatively small amount of exercise into your weekly routine, you can decrease your risk significantly.

How Much Does Exercise Reduce My Risk?

A LOT! But, the exact amount depends on which type of cancer we are talking about. We see one of the largest benefits of regular physical activity in 2 cancers: colon and breast.

For colon cancer, you decrease your risk of being diagnosed with this disease by 30% if you exercise regularly. If you already have colon cancer and you are physically active, you are 50% less likely to die of your disease. I’d say that’s pretty amazing!

For breast cancer, the results are even more impressive. More than two dozen studies have shown that if you are a physically active woman, then you are 30-40% less likely to be diagnosed with breast cancer. If you already have breast cancer or have had breast cancer in the past, you are 40-50% less likely to recur if you exercise regularly. That’s as much benefit as some of the cancer drugs that we often prescribe our patients to prevent their cancer from coming back! It’s incredible to me that we don’t educate our patients more about this!

In addition to breast and colon cancer, a recent study published in the Journal of the American Medical Association found that regular activity decreased the risk of many other types of cancer—endometrial, esophageal, liver, stomach, kidney, myeloma, cancers of the head and neck, rectum, bladder, and prostate. There were 1.4 MILLION people evaluated in this study, making it one of the largest studies EVER looking at the effects of physical activity on cancer risk.

How Much Activity Is Enough?

The data has shown over and over and over again that you should aim for at least 75 minutes of vigorous activity per week or 150 minutes of moderate-intensity activity.

Vigorous activities would be something like jogging, spinning, or singles tennis. Moderate-intensity would be something like walking, leisurely riding a bicycle, or doing water aerobics.

You can lower your risk even further by exercising more than these recommended amounts. In the study mentioned above, the people that exercised the most had the lowest risk of cancer. This group got around 2.5 hours of vigorous-intensity exercise per week or 7 hours of moderate-intensity exercise.

How Physical Activity Works to Prevent Cancer

Oh, let me count the ways.

Exercise lowers the levels of many hormones (like insulin and estrogen) that play a fundamental role in promoting cancer development.

Being physically active decreases the levels of growth factors that are known to cause cancer development and progression.

Physical activity also reduces inflammation in your body, which is known to promote not only cancer but a lot of other chronic diseases, too.

Staying active improves how your immune system functions. This allows your body to find cancers early or keep them from forming in the first place.

By moving regularly, you reduce the amount of time food takes to travel through your system. This decreases the amount of time carcinogens have to cause damage to your colon.

Is it OK if I Run 5 Miles Every Morning but Sit the Rest of the Day?


Sedentary behavior increases the risk of cancer and other chronic diseases, including heart disease and diabetes. This is true even if you get the recommended amount of exercise in other parts of your day. You should get up and move a little for a few minutes every hour.

Now Go Get Healthy!

There you have it! Four ways to prevent cancer that you can start working on today!

I hope each of you will evaluate where you are in your own life with each of these four risk factors. If you are not where you need to be, take the steps you need to get there.

I cannot emphasize how important it is for you to take action to improve your health. You can have all the knowledge in the world, but it does you no good if you don’t use it.