• Weight, lack of exercise raise risk of colorectal cancer

    By Catherine Winters, MyHealthNewsDaily 

    The heavier a person is and the less exercise he or she does, the greater the likelihood of developing a specific type of colorectal cancer, a new study finds.

    Researchers at the Dana-Farber Cancer Institute in Boston analyzed data on weight and physical activity from questionnaires sent every two years to more than 109,046 women who participated in the landmark Nurses' Health Study, an ongoing study about women's health that is following nurses. The questionnaires also went to more than 47,684 men who participated in the Health Professionals Follow-Up Study, an ongoing study about men's health that includes more than 50,000 men who work in health care. Data collection began in 1976 for the women and in 1986 for the men.

    When follow-up ended in June 2004, 2,263 cases of colorectal cancer — 842 in men and 1,421 in women — had been diagnosed.  The researchers analyzed 861 of the cancers to determine if any contained a molecular biomarker, called CTNNB1, which has been linked to cancer and obesity. Fifty-four percent of the tumors were CTNNB1-negative and 46 percent were CTNNB1-positive.

    Researchers next examined how body mass index, or BMI, and physical activity levels affected a person's risk of developing CTNNB1-negative or CTNNB1-positive colorectal cancer. What they found: The higher a person's BMI, the greater the likelihood he or she would develop a CTNNB1-negative cancer. Each 5.0 kg increment in BMI — about 11 pounds — was associated with a 34 percent higher risk for CTNNB1-negative colorectal cancer, said lead study author Shuji Ogino, an associate professor of pathology at Dana-Farber Cancer Institute in Boston.

    By contrast, the more physical activity a person did, the lower the risk for CTNNB1-negative colon cancer. Study participants did aerobic activities such as walking (at a usual pace), jogging, running, bicycling, swimming laps, playing racquet sports and lower-intensity activities such as yoga, toning and stretching.

     Each exercise was assigned a metabolic equivalent task (MET) score, which is a measure of exercise intensity. The higher the MET score, the more calories an activity burns.  For example, sitting quietly is the equivalent of one MET; walking at a pace of 1 to 2 miles per hour is the equivalent of about 2 METS; slow jogging is about 6 METS; cycling at less than 10 mph is about 4 METS; swimming moderately fast to fast laps is about 6 to 10 METS; and running approximately six miles per hour is about 10 METS.

    In the study, every 10 METs per hour increase in physical activity was associated with a 7 percent reduction in the risk for CTNNBI-negative colorectal cancer. People who accumulated about 18 MET hours per week in exercise, saw approximately a 20- to 30- percent reduction in risk, said Ogino, who is also an associate professor in the department of epidemiology at the Harvard School of Public Health.  That's the equivalent of about 30 minutes of moderate-intensity physical activity on most days of the week.

    Neither BMI nor physical activity level was associated with CTNNB1-positive cancer.

    Previous research has shown that doing regular physical activity and maintaining a healthy weight are associated with a decreased risk of colorectal cancer, but it has been unclear why. "We now have a biomarker we can subtype," Ogino said "No other prospective study has found this."

    Just how BMI and exercise affect the risk of CTNNB1-negative cancer is unclear. One theory is that higher circulating levels of insulin and insulin-like growth factor in people who are heavy or who are physically inactive may promote cancer cell survival and proliferation.

    Currently, there is no way to accurately measure risk for CTNNB1-negative colorectal cancer. That said, Ogino recommends doing regular physical activity to reduce the overall risk for colorectal cancer. "Physical activity is more easily controlled than body weight," he said. "Physical activity is easy to incorporate into your life and hopefully it will decrease weight, too."

     Not counting skin cancer, colorectal cancer is the third most common cancer diagnosed in American men and women. Overall, people have a 1 in 20 lifetime risk of developing the disease.

    According to the American Cancer Society, an estimated 102,480 new cases of colon cancer and 40,340 cases of rectal cancer will be diagnosed in 2013. Some 50, 830 people will die from colorectal cancer.

    The study is published today (Feb. 26) in the journal Cancer Research.

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  • Many keep smoking after cancer diagnosis

    By Diane Mapes

    It took asthma, COPD, emphysema and finally, lung cancer to get Toni Manes, a retired cosmetologist, to try to quit smoking.

    Unfortunately, the 58-year-old was so hooked, she couldn't kick the habit even after part of her left lung was removed.

    "I remember my surgeon told me 'If you ever smoke again, your husband should break your fingers,'" says the Philadelphia resident, who was diagnosed and had surgery in 2010. "And I was like, 'Okay, I'm not going to smoke again.'  But then I came home from surgery, recuperated for a few weeks and started up again. I couldn't help myself."

    According to a new study in the American Cancer Society journal CANCER, Manes is just one of many patients who've found themselves smoking after diagnosis.

    Researchers looked at 2,456 lung cancer patients and 3,063 colorectal patients and discovered that at time of diagnosis, 38 percent of the lung cancer patients and 15 percent of the colorectal patients were smokers.

    Courtesy of Toni Manes

    Lung cancer patient Toni Manes continued to smoke after her diagnosis.

    Five months later, despite a cancer diagnosis, 14 percent of the lung cancer patients were still lighting up (ditto for 9 percent of the colorectal patients).

    'Why stop now?'
    "People think it's a no-brainer and are surprised that cancer patients continue to smoke after they're diagnosed," says Elyse R. Park, a clinical health psychologist and associate professor of psychiatry at Massachusetts General Hospital/Harvard Medical School and lead researcher for the study. "But people still struggle to quit even after they're diagnosed. There are a lot of barriers to quitting, including a lot of stigma."

    Park says many of the people who can't quit are "hard-core" smokers, i.e., they smoke a high number of cigarettes a day. Many, also, are surrounded by other smokers.

    "These people are nicotine addicted, so it's tough for them," says Park. "They also have a lot of self-blame for causing the disease. There are feelings of fatalism. They think, 'Why stop now?' And a lot of people are very judgmental about lung cancer patients causing their own disease."

    According to the Lung Cancer Foundation of America, 60 percent of new lung cancer diagnoses happen to non-smokers, 15 percent of whom have never smoked a day in their life (the rest are former smokers who quit 10, 20 or even 30 years prior to diagnosis). The American Lung Association estimates that active smoking is responsible for close to 90 percent of lung cancer cases; radon causes 10 percent, and occupational exposures to carcinogens account for approximately 9 to 15 percent.

    Manes says following surgery, she went on to do three rounds of chemotherapy, followed by radiation. And even though she continued to smoke throughout, she worked with her oncologist at Thomas Jefferson University Hospital on ways to quit.

    "We tried everything," she says. "Hypnosis, Chantix, patches, cessation groups, acupuncture, the gum, the lozenges -- and none of that stuff did anything for me. I was depressed and didn't want to face that I had cancer. I saw a death sentence for myself. What difference did it make if I smoked or not?"

    Park says she hopes her study will pave the way for more smoking cessation programs and treatment options for patients who are smoking at the time of their diagnosis.

    "One of the reasons it's hard to quit is that people think they have enough to worry about," she says. "But it's the best time to quit because it has the potential to improve their cancer treatment, from breathing easier and feeling less fatigue to reducing the chance of infection after surgery."

    Parks says studies also show that quitting smoking can increase the efficacy of chemo and radiation and may even double the chances of survival for lung cancer patients.

    "We're hoping to integrate evidence-based tobacco treatment into cancer care," she says. "So you don't just ask a patient, 'Do you smoke, yes or no?' But you try to get them to quit as part of their treatment. It's a tough time, but we're hoping to find ways to sit with patients and get them pharmacological and behavior counseling treatment."

    The good news? There's some evidence Park's approach might just work.

    "On October 31, 2011, I got a sinus cold again and with every puff, I was choking," says Manes. "So I put on a patch and humbled myself before God and begged him to help me. I needed some kind of inner strength. On the 31st of this month, it'll be three months that I've been smoke-free."