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The #1 Reason You Could Get Cancer, According to Science

The #1 Reason You Could Get Cancer is….Smoking.

You think of cancer as inevitable, like death and taxes, emphasis on the former. The statistics are indeed scary: In 2019, cancer overtook heart disease as the leading cause of death in middle-aged adults living in wealthy countries. Almost 4 in 10 Americans will be diagnosed with cancer this year, and nearly 600,000 will die of the disease. Yet you shouldn't feel helpless: In fact, 30 to 50 percent of cancer cases are fully preventable, the World Health Organization says. How? By avoiding these most common cancer-causing habits. Read on for the #1 cause and the rest of this life-saving list—and to ensure your health and the health of others, don't miss these Sure Signs You Had COVID and Didn't Know It.




The most common cancer is lung cancer, and the most common cause of lung cancer is smoking. Tobacco smoke contains 7,000 chemicals, and at least 70 of them are carcinogens, raising your risk of cancer in nearly every part of the body. According to the WHO, tobacco use is the single greatest avoidable risk factor for cancer death; it kills nearly 6 million people a year worldwide. 

The Rx: If you smoke, stop. (It's never too late: Studies show that even smokers who quit as senior citizens extend their lives.) If you don't use tobacco, don't start.


Eating Too Much Sugar

Sugar in spoon

Americans eat too much added sugar, and it may lead to an increased risk of cancer. The latest Dietary Guidelines for Americans recommends consuming no more than 12 teaspoons of sugars a day. The average American gets 17 teaspoons! Eating too much added sugar can lead to obesity and inflammation—two cancer risk factors.

The Rx: Cut down on added sugars in your diet. That's easier to do, now that food manufacturers are required to list them as a separate line on Nutrition Facts labels. Check them on every packaged product you buy. 


Eating Processed Meat

Fresh sliced bacon with spices on white background

In 2015, the International Agency for Research on Cancer officially classified processed meat as a human carcinogen; they're prepared with chemicals that have been found to damage cells in the colon and rectum. In fact, eating just 1.8 ounces a day can increase your risk of colorectal cancer by 18 percent. What counts as processed meat? Ham, sausage, hot dogs, pepperoni and salami, beef jerky and deli meats, including turkey and roast beef.

The Rx: The MD Anderson Cancer Center recommends eating processed meat less frequently or not at all, and increasing the number of plant-based or meatless meals you eat each week. 


Eating Processed Foods

Woman reaching for chip and holding soda in processed junk food array on table with popcorn

"Processed foods are packed with myriad toxic chemicals which can increase cancer risk," says Yeral Patel, MD, a board-certified family medicine physician in Newport Beach, California. "Consumption of processed foods causes inflammation—one of the leading contributors to cancer—and these foods also lack key micronutrients (essential vitamins and minerals) on which our bodies depend to rid themselves of harmful toxins."

The Rx: Fill your diet with as many whole foods as you can, and ensure the packaged foods you buy contain as few ingredients as possible. 


Working the Late Shift

Young exhausted,depressed,concentrated woman sitting in her room or office with french windows in the dark at the lamp

Women who work the night shift have a 19 percent higher risk of cancer, according to a 2018 meta-analysis of studies published in the journal Cancer Biomarkers and Prevention. Researchers theorize that staying up at night disrupts production of the sleep hormone melatonin, which may protect against the disease.

The Rx: If you work the graveyard shift, you may want to switch to daylight hours.

RELATED: Signs You're Getting One of the "Most Painful" Cancers


Using Talcum Powder

talcum powder to hand

A study in the journal Epidemiology found that using talcum powder (baby powder) on the area surrounding the genitals increased the risk of developing ovarian cancer by 33 percent. Another study found that using talcum powder raised endometrial cancer risk by 24 percent. Why? Some researchers theorize that talc, the mineral that is mined to make talcum powder, is often contaminated with asbestos, a potent carcinogen.

The Rx: Avoid talcum powder. For personal hygiene, use a natural alternative such as cornstarch instead. 


Using Plastic

plastic containers

Some plastic containers contain BPA, a synthetic hormone that can disrupt the body's endocrine system and potentially increase the risk of breast cancer. 

The Rx: It's not definitive that plastic actually causes cancer. But it's a good idea to choose plastics that are BPA-free and to use alternative containers, such as glass, whenever possible. 


Eating Fries and Chips

Fries with mayo and ketchup

Acrylamide is a chemical found in tobacco smoke and industrial products. It's also formed when vegetables, like potatoes, that contain certain sugars are heated. Those foods include french fries, potato chips, crackers, breads, cookies and breakfast cereals. Animal studies show that acrylamide can damage DNA, raising cancer risk. Although the research isn't definitive in humans, why risk it?

The Rx: Reducing the amount of processed foods you eat in general is a proven way to reduce cancer risk and improve heart health. (Read: You should be cutting down on those fries, chips and cookies anyway.) 

RELATED: The #1 Cause of Obesity


Poor Oral Hygiene


A 2018 study published in the Journal of the National Cancer Institute found that gum disease is associated with a 24 percent increase in lung and colorectal cancer. Why? Researchers theorize gum disease may change immune response or distribute harmful bacteria throughout the body.

The Rx: Practice good oral hygiene: Brush and floss twice a day, and see your dentist twice a year.


Stressing Out

Worried woman at home alone

There isn't strong evidence that stress can directly cause cancer. But, the National Cancer Institute notes, stressed people are likely to develop bad habits such as "smoking, overeating, or drinking alcohol—all of which increase cancer risk.

The Rx: Take active steps to reduce stress, including exercise, socializing, doing relaxation exercises or talking with a mental-health professional. 

RELATED: 9 Everyday Habits That Might Lead to Dementia


Eating Charred Meat

Spicy Grilled Jerk Chicken with Lime and Spices

According to the National Cancer Institute, studies have found that flame-grilling or frying meat at high temperatures can form chemicals that can damage DNA, increasing your risk of cancer.

The Rx: Avoid blackened meats. Baking, roasting and broiling are safer cooking methods. If you can't live without the barbecue, don't overcook. Marinating your meat for 30 minutes before grilling, and/or zapping it in microwave for 60 seconds after, drastically reduces cancer-causing compounds caused by flame-grilling.


Using Parabens

A hand holds a blue jar and a magnifier, where the harmful ingredients of a detergent are written in close up.

According to research published in the Journal of Applied Toxicology, parabens—chemical preservatives used in toothpastes, shampoos, deodorants and cosmetics—are easily absorbed through the skin and can boost the growth of breast cancer cells.

The Rx: Look for products that are paraben-free. Common parabens include methylparaben, propylparaben, ethylparaben and butylparaben.


In the Bedroom

A couple near the window, under one blue blanket

Sorry to break it to you. According to a study published in the Journal of Clinical Oncology, cases of oropharyngeal cancer have risen in the United States over three decades, and HPV (human papillomavirus) is the culprit

The Rx: The good news: Research has shown that the HPV vaccine protects against oral cancer in addition to cervical cancer. Get your children vaccinated as recommended. And the FDA recently approved the vaccine up to age 45.


Inhaling Secondhand Smoke

Closeup portrait headshot woman pinches nose with fingers hands looks with disgust

Just like smoking itself, inhaling secondhand smoke causes lung cancer. It has also been linked to an increased risk of breast cancer, nasal sinus cavity cancer and nasopharyngeal cancer in adults and leukemia, lymphoma and brain tumors in children, the National Cancer Institute says.

The Rx: Avoid secondhand smoke whenever possible. Researchers at Stanford University suggest moving at least six feet away from smokers to lower your exposure.


Excessive Drinking

Friends Eating Out In Sports Bar With Screens In Background

According to the National Cancer Institute, drinking alcohol can increase your risk of cancer of the mouth, throat, esophagus, larynx, liver, and breast. The more you drink, the higher your risk of getting cancer.

The Rx: Health experts, including the American Cancer Society, recommend moderate drinking: No more than two alcoholic drinks a day for men, and one for women. 


Not Exercising Regularly

Couple Walking Along Suburban Street Holding Hands

"One of the biggest causes of cancer is leading a sedentary lifestyle," says Patel. "The human body needs to move. Exercise is crucial to help eliminate harmful toxins from the body." 

The Rx: "Simply breaking a sweat by walking (or doing some kind of cardio) for 30 to 40 minutes a day is enough exercise to reduce risk," says Patel.


Chronic Inflammation

Sick woman having a stomach ache

Inflammation is a good thing—it's the first step as the immune system clicks into gear to heal a wound. But chronic inflammation throughout the body, when there is no injury, can damage DNA and lead to cancer. What causes chronic inflammation? Smoking, excessive drinking and a poor diet rife with processed foods and added sugar.

The Rx: Don't smoke, drink moderately or not at all, and eat an anti-inflammatory diet such as the Mediterranean Diet, which emphasizes fruits and vegetables, lean protein and healthy fats and de-emphasizes added sugars and processed foods.


Excessive Sun Exposure

elderly women Wearing blue sunglasses Walking around the sea

Sunlight produces ultraviolet (UV) radiation, which is the number one cause of skin cancer, including squamous cell and basal cell carcinoma. Getting a sunburn just once every two years can triple your risk of melanoma, the deadliest type of skin cancer.

The Rx: Wear sunscreen of at least 30 SPF during prolonged sun exposure. Avoid tanning beds. Do a self-check once a month for any moles or freckles that have changed shape, size, appearance or color or are bleeding. And have your healthcare provider do a full-body check for signs of skin cancer once a year.


Being Overweight

Man with hand on his stomach to depict indigestion

According to the International Agency for Research on Cancer, 13 cancers are associated with being overweight or obese, including esophagus, thyroid, postmenopausal breast, gallbladder, stomach, liver, pancreas, kidney, ovaries, uterus, colon and rectum. Researchers aren't sure how excess fat leads to cancer, but the statistics are stark and clear: A CDC analysis found that 40 percent of cancers diagnosed in the United States are now associated with being overweight or obese.

The Rx: Maintain a healthy weight as a lifestyle, via regular exercise and a sensible diet grounded in plenty of whole foods.

RELATED: The #1 Cause of Diabetes, According to Science


Not Eating Enough Fruits and Vegetables

Assortment of fresh fruits and vegetables

According to a study published in the journal Cancer Prevention Research, "consumption of fruit and/or vegetables has been inversely associated with head and neck, esophageal, stomach, and colorectal cancer risk." Researchers hypothesize that's because fruit and vegetables are rich in fiber, antioxidants and detoxifying enzymes.

The Rx: At every meal, aim to fill half your plate with fruits and vegetables. The current Dietary Guidelines for Americans recommends eating at least 2 ½ cups of vegetables and 2 cups of fruit every day. And to get through this pandemic at your healthiest, don't miss these 35 Places You're Most Likely to Catch COVID.

Michael Martin
Michael Martin is a New York City-based writer and editor. Read more about Michael
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