We all wonder about whether or not we're going to get cancer, but does our risk really increase as we age? The simple answer is, yes. According to the American Cancer Society , 78 percent of all cancer diagnoses are in people 55 or older, and one in two men, and one in three women are at risk of getting cancer in their lifetime.

"As you get older, it's a lifetime accumulation of risk factors," says William Dale, M.D., Director of SOCARE , the geriatric oncology clinic at the University of Chicago. "It's a combination of environmental risks such as smoking and eating the wrong things combined with genetic risks like having a family history of a certain cancer. Essentially the longer you live the more chance there is of getting cancer."

However, the good news is that the 5-year relative survival rate for all cancers diagnosed in 2004-2010 was 68 percent, up from 49 percent, according to the American Cancer Society. And more than ever, screenings and prevention are key. The five cancers you should pay close attention to if you are a Boomer or older:

1. Skin cancer

"The most common cancers that we see in people as they age are sun-related skin cancers," says Cary Presant, M.D., a medical oncologist at City of Hope hospital in California and author of Surviving American Medicine . However, skin cancers are treated a little differently in terms of cancer statistics because they range in seriousness. "Melanoma is the most dangerous kind of skin cancer, but statistically, surprisingly few people get melanoma," says Dr. Dale. "Other skin cancers, such as basal cell and squamous are more prevalent, but they are often benign." However, you don't want to mess around with skin cancer. Melanoma has the potential to kill you.

What you can do: "Make certain you are friendly with your dermatologist and get your whole body checked regularly," says Dr. Presant. "Often when you see your primary care physician they don't do a detailed look at all parts of your body. You need a total skin exam, including your scalp, nails, genital area, and in-between your toes."

2. Breast cancer

Breast cancer is the leading cause of cancer in older women, and for all women (with the exception of skin cancer), with over 230,000 women being diagnosed with it this year. "What we do know is that breast cancer in younger women is often more dangerous," says Dr. Presant. "In older women breast cancer tends to be less aggressive." But that's not a reason to be less vigilant about getting a mammogram. In terms of why women get breast cancer, doctors are not certain, but says, Dr. Presant, "There seems to be a cumulative effect in the reduction of the body's immune defenses against cancers, and hormonal changes also play a part." Studies also show that not having children can increase breast cancer risk as can a long menstrual history where you got your period early and/or had it end later in life.

What you can do: Get regular mammograms at least until age 75, says Dr. Presant. "Screening finds many early-stage precancerous lesions that could develop into invasive cancers if left unchecked." He also suggests talking to your doctor about your vitamin D levels. "Some studies show that vitamin D has a preventative effect on breast, prostate, and colorectal cancer, so it's worth talking to your doctor." And if you find a lump or bump, call your doctor to have it checked immediately. Don't just let it go.

3. Prostate cancer

Prostate cancer is the leading cause of cancer in men, with the exception of skin cancer. About 56 percent of prostate cancer cases are diagnosed in men 65 years and older, and 97 percent occur in men 50 and older, according to the American Cancer Society. About one in seven men will be diagnosed with prostate cancer in their lifetime. In terms of what happens as men age, the prostate gets bigger the older men get, and there are hormonal changes, which can increase cancer risk, says Dr. Presant. "Early prostate cancers can often be watched," says Dr. Presant. "Many don't progress, but some are more serious and need to be treated."

What you can do: Have a discussion with your doctor at age 50 about whether to get screened. "If you have difficulty urinating, get up often at night to urinate, or find blood in your urine, talk to your doctor immediately. "Also talk to your doctor about taking vitamin D and a baby aspirin, both of which have been show to help prevent prostate cancer," says Dr. Presant.

4. Lung cancer

Lung cancer is the second leading cause of cancer in both men and women (excluding skin cancer), and causes more deaths than any other cancer. About 2 out of 3 people diagnosed with lung cancer are 65 and older. Lung cancer is a cumulation of smoking or your lungs being exposed to second hand smoke or radon, says Dr. Dale.

What you can do: Screening is the most effective way of reducing your chance of dying from lung cancer, but screening is generally only recommended for people who have a history of smoking or who have been exposed to a lot of second-hand smoke. "The screening is a simple CT scan of the lungs that can see little nodules in your lungs and raise a red flag," says Dr. Presant. Sympotms you should get checked include a persistent cough, chest pain, and shortness of breath.

5. Colorectal cancer

Colorectal cancer is the third leading cause of cancer death in both men and women. In 2011, 90% of cases were diagnosed in people 50 and older. Early colorectal cancer has few warning signs, which is why screening and prevention is so important. If caught early, the survival rate for colorectal cancer is 90 percent.

What you can do: Get a colonoscopy regularly starting at age 50. "A colonoscopy will check for polyps, which can be removed before they can become harmful," says Dr. Present. "Also taking a baby aspirin a day has been shown to help prevent polyps." Other factors can contribute to your risk. "A diet with a lot of red meat and fat, and not enough roughage can factor in," he says. Always report symptoms to your doctor related to your bowels, including blood in your stool, frequent constipation, and pains in your abdomen that don't go away.

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