How to lower your risk of cancer with diet, exercise, and more

Cancer is the #1 killer of Americans aged 45 to 84. Smoking accounts for about 30 percent of those deaths. Lifestyle—excess weight, inactivity, poor diet, and alcohol—accounts for another 16 percent. Here’s what may help.

Breast

One in eight women will be diagnosed with breast cancer in her lifetime. The five-year survival rate averages 90 percent. That’s because most tumors are detected early.¹

You have a higher risk if you:

• are an older woman
• have excess weight (and you’re postmenopausal)
• are sedentary
• consume alcohol often
• have a relative—especially a mother, sister, or daughter—who was diagnosed with breast cancer
• have mutations in genes (like BRCA1 and BRCA2) found in families with high rates of breast cancer
• had menstrual periods that began before age 12 or menopause that began after age 55
• were older than 30 when you had your first child
• took estrogen and progestin after menopause
• have dense breast tissue (seen on a mammogram)
• have abnormal breast cells (atypical hyperplasia or carcinoma in situ)

Diet, exercise, etc.

Gaining weight—even as little as an extra 10 to 20 pounds—is linked to an increased risk of breast cancer after menopause.² Why?

“We have compelling evidence that higher blood levels of estrogen are associated with an increased risk of postmenopausal breast cancer,” says Regina Ziegler, a former researcher at the National Cancer Institute’s Division of Cancer Epidemiology & Genetics.

“In postmenopausal women, the ovaries no longer produce estrogen,” explains Ziegler, “so the dominant source is estrogens that are made in fat tissue in the breast and elsewhere.” (Dominant, that is, unless women take replacement hormones, which also raise risk.)

Excess insulin and inflammation may also spur tumors to grow.

Among postmenopausal women not taking hormones, those with the highest insulin levels had twice the risk of breast cancer—and those with the highest levels of c-reactive protein (a marker of inflammation) had a 67 percent higher risk—than those with lower levels.^3,4

Also, women who have even a few servings of alcohol a week have a 10 percent higher risk of breast cancer than those who don’t drink. One to two daily drinks were linked to a 19 percent higher risk.⁵

In contrast, “physical activity is protective,” notes Ziegler, “though it’s not clear whether it works by itself or by preventing weight gain.”

Other possible protectors: “The evidence has strengthened that vegetables and fruits may be associated with a reduced risk of breast cancers, especially estrogen-negative and other aggressive tumors,” says Ziegler.⁶ (Estrogen-negative cancers are less common, but more difficult to treat.)

“Though we can’t say definitively that fruits and vegetables can help prevent breast cancer, they’re worth eating to lower the risk of strokes, heart attacks, type 2 diabetes, and obesity.”

Warning signs: a painless lump in the breast or underarm area. Less-common symptoms: breast pain or heaviness, thickening, swelling, redness, discharge, nipple turned inward.

Colon & rectum

It’s a success story. The death rate from colorectal cancer in 2016 was less than half of what it was in 1970.¹ One troubling sign: while colorectal cancer is dropping in older adults, it’s inching up in adults younger than 55.

You have a higher risk if you:

• are 50 or older
• have excess weight
• are sedentary
• eat processed or red meats often
• have a parent, brother, sister, or child who was diagnosed with colon cancer
• have ever had colon polyps
• have ulcerative colitis or Crohn’s disease
• have type 2 diabetes
• smoke tobacco

Diet, exercise, etc.

“It’s so frustrating that colorectal cancer is still such a massive killer around the world, because there is so much we can do to reduce the incidence,” says Amanda Cross, a cancer epidemiologist at Imperial College London.

Your first step: get a colonoscopy or another screening test.

“Screening has had a dramatic effect on the incidence of colorectal cancer in those over age 50,” says Cross. “Before screening, the incidence was increasing. Now it’s coming down.”

And stay in shape. “If you’re active and not overweight, your risk is lower,” says Cross.⁷ Healthy insulin levels may help explain why.

“Physical activity increases insulin sensitivity, which can curb high insulin levels,” she explains.

Excess weight often leads to excess insulin, but people with higher insulin levels have a higher risk even if they’re lean.⁸

More than two servings of alcohol a day for men—or one for women—is also a risk factor.⁷ The acetaldehyde that’s made when the body metabolizes alcohol may be carcinogenic to cells lining the colon.

In 2015, the International Agency for Research on Cancer concluded that each daily (3½ oz.) serving of red meat or (2 oz.) serving of processed meat like bacon, ham, sausage, or hot dogs is linked to roughly an 18 percent higher risk of colorectal cancer. The evidence was stronger for processed meat.⁹

Carcinogenic N-nitroso compounds may be partly to blame.

“Companies now add less nitrite and add ascorbic acid to processed meats to inhibit the formation of N-nitroso compounds, but they can still form in the body,” says Cross.

Meat may harbor other carcinogens.

“There is evidence from animals that two other groups of compounds—heterocyclic amines and polycyclic aromatic hydrocarbons—are carcinogenic,” says Cross. “And both are found in processed and unprocessed red meats cooked at high temperatures.”

Warning signs: diarrhea or constipation, feeling that your bowel doesn’t empty completely, blood (bright red or very dark) in your stool, rectal bleeding, narrow stools, gas pain, cramps, feeling full or bloated, unintended weight loss, fatigue, decreased appetite.

Esophagus

“Esophageal cancer is very rare in the United States,” says Christian Abnet, chief of the metabolic epidemiology branch at the National Cancer Institute. That’s good, because the five-year survival rate is 19 percent.

You have a higher risk if you:

• are over 55
• have excess weight
• are male
• smoke or chew tobacco
• have acid reflux or Barrett’s esophagus

Diet, exercise, etc.

Esophageal cancer is really two diseases.

Smoking and heavy drinking are major risk factors for esophageal squamous cell carcinoma. But it’s esophageal adenocarcinoma that’s on the rise, and the obesity epidemic may explain why.¹

“Obesity causes inflammation and seems to induce reflux disease by putting pressure on your lower esophageal sphincter,” explains Abnet, referring to the doorway between your esophagus and stomach.

“That pressure makes the sphincter more likely to be open,” he adds. “And then you’re more likely to have acid reflux, which seems to be part of the carcinogenic process.”

But people with reflux needn’t panic.

“Reflux is very common,” says Abnet. “About 20 percent of U.S. adults have it. But the vast majority don’t get esophageal cancer.”

Reflux can cause Barrett’s esophagus, which means that the cells lining your lower esophagus have morphed into cells like those that line your stomach or small intestine.

People with Barrett’s are 24 times more likely to get esophageal cancer than others. But only an extra 24 out of every 10,000 of them develop the cancer each year compared to people without Barrett’s.¹⁰

“Some doctors recommend an upper endoscopy to assess whether you have Barrett’s if you’re over 50, had longstanding reflux disease, and are male,” says Abnet. (The risk in women is low.)

“Twenty years ago, people with Barrett’s were told to have an endoscopy every year. There was no evidence for that, but it was done in an abundance of caution because early esophageal cancer can be successfully treated, while late esophageal cancer is rarely successfully treated.”

But now most doctors recommend repeated endoscopies only if a biopsy finds precancerous changes.

“If a thorough endoscopy finds Barrett’s but no precancerous cells, patients may be told to just go about their business, but to check with their doctor in five years to discuss further follow-up,” says Abnet.

Warning signs: painful or difficult swallowing, chest pain, unintended weight loss, hoarseness, cough, hiccups, vomiting, bone pain, black stools.

Death rates for most major cancers

Liver

Liver cancer rates are rising more rapidly than those of any other cancer. Since 1980, the incidence has tripled and the death rate has doubled. The five-year survival rate is only 18 percent.¹

You have a higher risk if you:

• have chronic hepatitis B or C infection
• have excess weight
• have type 2 diabetes
• are a heavy drinker
• smoke tobacco

Diet, exercise, etc.

“Excess weight, nonalcoholic fatty liver disease, and diabetes are greatly contributing to higher rates of liver cancer in the U.S.,” says Katherine McGlynn, senior investigator in the metabolic epidemiology branch at the National Cancer Institute.¹¹

It’s not clear how they might increase risk, but it is clear that they are all linked.

“Excess weight increases fat storage in the liver and the risk of insulin resistance and type 2 diabetes,” says McGlynn.

And those changes are linked to inflammation, which can cause scarring.

“There’s a whole cascade of pathology,” explains McGlynn. “Inflammation can lead to liver disease, starting with scarring and progressing all the way to cirrhosis.”

Heavy drinking and smoking are also risk factors. On the plus side, coffee may protect your liver.¹²

“Coffee has been associated with a decreased risk in study after study,” says McGlynn. “The decrease is seen with both caffeinated and decaffeinated, suggesting that an ingredient other than caffeine is providing the protection.”

What may come as a surprise: since 2012, the Centers for Disease Control and Prevention (CDC) has advised all baby boomers—anyone born between 1945 and 1965—to get a hepatitis C test.¹³

“The virus circulated in the blood supply until 1992,” says McGlynn.

“Before then, anyone who had a blood transfusion or other medical encounter in which they came in contact with blood could have become infected with the virus. And many infections have no symptoms, so people might never know they were infected.”

If you do have hepatitis C (an inflammation of the liver), it can be cured.

“The drugs are expensive,” says McGlynn, “but more insurance companies are covering them because the high price is still cheaper than paying for the long-term consequences.”

Warning signs: bulge or hard lump below rib cage on right side, abdominal pain or swelling, yellow skin or whites of eyes, loss of appetite, unintended weight loss, weakness, fever.

Lung

Since 1990, death rates for lung cancer have dropped roughly in half in men, and they’ve dropped by about a quarter in women since 2002, thanks to declines in smoking. But lung cancer is still the No. 1 cancer killer...by far.¹

You have a higher risk if you:

• smoke or have smoked tobacco
• have had long-term exposure to radon, asbestos, diesel exhaust, air pollution, radiation, or secondhand smoke

Diet, exercise, etc.

Roughly 80 percent of lung cancer deaths are caused by smoking.¹ Smokers are 25 times more likely to be diagnosed with the disease than nonsmokers.

“The impact of smoking dwarfs all other risk factors,” says Meir Stampfer, professor of epidemiology and nutrition at the Harvard T.H. Chan School of Public Health.

Less smoking, not better treatment, largely accounts for falling death rates. Five-year survival rates are still only around 20 percent.

Links with diet and weight are uncertain. In a recent study of roughly 1.4 million people, smokers who reported eating more saturated fat had a higher risk, while those who ate more polyunsaturated fat had a lower risk.¹⁴

And in an analysis of 1.6 million people, those with larger waists had a higher risk, regardless of their weight.¹⁵

“It’s too early to know if a large waist or saturated fat promotes lung cancer or if unsaturated fats curb the risk,” says Stampfer.

“But we have plenty of evidence that avoiding abdominal obesity and replacing saturated fats with unsaturated fats can lower the risk of heart disease and type 2 diabetes.”

Warning signs: persistent cough, shortness of breath, chest pain, coughing up bloody mucus, voice change, frequent lung infections like pneumonia.

Ovary

The five-year survival rate is only 47 percent, in part because most patients are diagnosed after the cancer has spread.

You have a higher risk if you:

• have a mother or sister who was diagnosed with ovarian or breast cancer
• have been diagnosed with breast cancer
• have mutations in genes (like BRCA1 and BRCA2) that are found in families with high rates of ovarian cancer
• took estrogen alone or with progestin after menopause
• have excess weight

Diet, exercise, etc.

Excess weight is linked to a higher risk of ovarian cancer.¹⁶ “But it’s not a strong risk factor,” says Shelley Tworoger, associate center director of population science at the Moffitt Cancer Center in Tampa.

Beyond weight, no clear links with diet have emerged.

“Taking oral contraceptives is associated with a lower risk,” says Tworoger.¹⁷

“And women with a family history of cancer, particularly breast or ovarian, should speak to a doctor about genetic testing.” Genetics aside, there are no good screening tests.

“Several large trials have shown no survival benefit for transvaginal ultrasound and CA 125 as a potential marker for ovarian cancer,” says Tworoger.

What might matter: knowing the symptoms, says the CDC’s “Inside Knowledge about Gynecologic Cancer” campaign.

“A large majority of ovarian cancer patients have symptoms like bloating, feeling full quickly, or abdominal pain for a substantial period of time before they’re diagnosed,” says Tworoger. “If those symptoms persist for no identifiable reason, it’s worth getting tested.”

Warning signs: abdominal swelling, persistent bloating, pain in the abdomen, back, or pelvis, the need to urinate often or urgently, feeling full quickly.

Pancreas

Pancreatic cancer accounts for just 3 percent of cancer diagnoses, but the third highest number of cancer deaths. “It’s got the worst five-year survival except for some rare cancers,” says the National Cancer Institute’s Christian Abnet.

You have a higher risk if you:

• have a parent or sibling diagnosed with pancreatic cancer
• have excess weight
• have type 2 diabetes
• smoke or chew tobacco
• have chronic pancreatitis

Diet, exercise, etc.

“Avoiding excess weight is important for pancreatic cancer,” says Abnet. “That also helps prevent type 2 diabetes, which is linked to pancreatic cancer.”

Why might extra pounds matter? “Obesity induces inflammation, a hallmark of cancer,” notes Abnet. People with a large waist also have a higher risk, regardless of their weight.¹⁸

“In people with abdominal obesity, you’re getting more inflammation and more fatty tissue infiltrating organs,” Abnet explains.

The link with type 2 diabetes is unclear, he adds.

“Does diabetes increase the risk of pancreatic cancer or does the beginning of cancer in the pancreas cause diabetes? We don’t know.”

And so far, researchers haven’t found a way to do early screening. “You can’t do regular pancreatic biopsies,” says Abnet.

Warning signs: abdominal pain that may radiate to the back, yellow skin and eyes, unintended weight loss, nausea, vomiting.

Prostate

One in nine men will be diagnosed with prostate cancer in his lifetime.¹ But the five-year survival rate is 98 percent. In fact, many of those men need no treatment at all (see the April 2018 cover story).

You have a higher risk if you:

• are over 50
• have a father, brother, or son who was diagnosed with prostate cancer
• are of African ancestry

Diet, exercise, etc.

“The evidence has gotten a bit stronger that overweight men are not more likely to be diagnosed with prostate cancer, but they are more likely to die of it,” says Harvard’s Meir Stampfer.¹⁹

“That’s also true for physical inactivity.²⁰ Reducing your risk of dying of prostate cancer is an added bonus to the myriad of good reasons to maintain a healthy weight and not be inactive.”

Stampfer cautions against taking selenium supplements.

“We have good evidence that they raise the risk of dying of prostate cancer, so men should definitely avoid them. ^21,22

“And I would avoid separate calcium supplements and juices or milk with added calcium.” Some studies find a higher risk of prostate cancer in men who get more than 2,000 milligrams of calcium a day.²³

Should men get a PSA (prostate-specific antigen) test to screen for prostate cancer? The U.S. Preventive Services Task Force advises men aged 55 to 69 to discuss the pros and cons with their doctor, given the risk of overdiagnosis and overtreatment.

“I recommend a PSA test every few years for men who expect to live at least 12 to 15 more years,” says Stampfer. “If your PSA is below 1.0 at age 60, the risk is so low that you can stop testing.”

His worry: “The incidence of advanced disease at diagnosis seems to be going back up. Some potentially preventable prostate cancer deaths are being missed. Some guys who didn’t get a PSA test may have missed their chance to be diagnosed and treated earlier.”

But if you have a high PSA—or a biopsy showing cancer—don’t panic.

“The decision to do a biopsy shouldn’t be automatic,” says Stampfer. “And if a biopsy finds cancer, you should have more tests and consider active surveillance rather than rushing into surgery.”

Warning signs: weak or interrupted urine flow, difficulty starting or stopping urine flow, need to urinate often especially at night, sudden urge to urinate, blood in the urine, pain or burning with urination, pain in the back, hips, or ribs that doesn’t go away.

Uterus

Diagnoses and death rates are climbing.¹ Black women have double the death rate of white women, possibly because they are more likely to have an aggressive type of tumor and are often diagnosed later.

You have a higher risk if you:

• have excess weight
• are sedentary
• started menopause after age 55
• took estrogen without progestin after menopause
• have type 2 diabetes

Diet, exercise, etc.

“Obesity is the single most important risk factor for endometrial cancer,” says Immaculata De Vivo, professor of epidemiology at the Harvard T.H. Chan School of Public Health.²⁴ (The endometrium is the lining of the uterus.)

“It’s one of the cancers that are on the rise because obesity is the main driver,” says De Vivo. “It’s astonishing to me that it accounts for so much of the risk.”

Exercise may help curb risk, in part by preventing weight gain.

“We’ve also seen a protective effect of coffee,” says De Vivo. For example, in the Nurses’ Health Study, women who drank four or more daily cups of coffee—the amount in two Starbucks grandes—had a 25 percent lower risk than those who drank less than one cup a day.²⁵

To help catch endometrial cancer early, see your doctor if you have vaginal bleeding after menopause. “Postmenopausal bleeding is not normal,” notes De Vivo.

But don’t panic. In one recent meta-analysis, postmenopausal bleeding occurred in about 90 percent of women with endometrial cancer, but only 9 percent of women with bleeding were diagnosed with the cancer.²⁶

Warning signs: abnormal vaginal bleeding or spotting, discharge, pain during sex, while urinating, or in the pelvic area.

The bottom line

To reduce your risk of cancer:

• Stay away from tobacco.
• Lose (or don’t gain) excess weight.
• Limit alcohol to two servings a day for men or one for women.
• Limit red and processed meats.
• Fill half your plate with veggies or fruit.
• Shoot for 20 to 40 minutes a day of any exercise that gets your heart beating faster.
• When you’re out in the sun, apply a shot glass of “broad spectrum” sunscreen (SPF 30+) every two hours.
• Avoid tanning beds.
• Make sure children get vaccines to prevent HPV (human papillomavirus) and HBV (hepatitis B).
• Go to cancer.org to see the American Cancer Society’s guidelines for when to get a colonoscopy, mammogram, or other screening tests.
• Go to cancer.gov (the National Cancer Institute) or AICR.org (the American Institute for Cancer Research) to learn more.

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¹⁵J. Natl. Cancer Inst. 110: djx286, 2018.
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Photos: Monkey Business/stock.adobe.com (top), Sebastian Kaulitzki/fotolia.com (breast, esophagus, liver, ovary, pancreas, uterus), pankajstock123/fotolia.com (colon), nerthuz/fotolia.com (lungs), CLIPAREA.com/fotolia.com (prostate), anna_shepulova/stock.adobe.com (vegetables).