Monday, April 18, 2011 at 3:50 AM
All this week, ideastream is presenting "MiddleAging," an examination on radio, TV and the web about physiological changes that happen during our mid-40s to mid-60s. One change people encounter as they age is their risk of cancer goes up. Health reporter Anne Glausser explains why, and what we can do about it.
When you hit middle age you may find yourself going to the doctor more than ever, not necessarily because you’re sick but because you’re now of an age when you need to get screened--doctors poking, prodding and x-raying for signs of cancer…and among them, doing his job, is Dr. Timothy O’Brien, director of MetroHealth’s Cancer Care Center.
O’BRIEN: Certain cancers go through early curable stages and if they’re detected early—that’s what screening programs are all about—you can cure the patients before it gets widespread, incurable.
This vigilance paid off big-time for Karen Kulju, one of O’Brien’s patients. Kulju is 50 yrs old and has stage 2 breast cancer. She found the lump in her breast herself:
KULJU: If I wouldn’t have done the self breast exam, I probably would have waited another year to come in which is the norm for women my age and then you really don’t know at that stage of the game how it could have progressed.
Clinton Smith, another patient of Dr. O’Brien’s, also paid his physician an extra visit.
SMITH: I was over 50, and I asked for a colonoscopy because I never had had one.
Smith’s wife coaxed him to get the screening, and
SMITH: That’s when they found the cancer, stage 3 colon cancer.
With early detection, both Kulju and Smith are successfully fighting their “middle age” cancers. But what is the biology behind this public health message? Why does our risk of cancer increase as we age?
One way to think of it is that the cells in our bodies are continuously making copies of themselves as other cells die off. After years and years of perfect work though this human copying machine becomes more prone to making errors here and there, errors that sometimes lead to cancer…these cellular hick-ups or blips can have a hereditary cause, can be the result of what the body has been exposed to or simply can be because the “copier” itself is getting older.
Dr. Nathan Berger, director of the program in aging and cancer at Case Western Reserve University, explains.
BERGER: Cancer is a disease of genetic mutations and the longer we go, the more our cells divide, the more likely we are to acquire genetic mutations. We’re surrounded by all sorts of insults and environmental attacks, all of which increase the possibility of a chance mutation in any given organ, leading to cancer.
The increased cancer risk starts with damage to our blueprint of life: deoxyribonucleic acid, or DNA, is housed in the nucleus of our cells and contains instructions for cell development and function. Over time those instructions can be damaged by all sorts of chemicals and radiation.
One source of DNA damage, especially as we age, is cumulative exposure to ultraviolet sunlight—invisible to the naked eye, this sunlight carries low level radiation which can lead to skin cancer; risks of cellular mutation also come from tobacco smoke, exposure to substances like asbestos, viral and bacterial infections, and even certain additives and preservatives in foods. By the time we hit middle age we’ve encountered and accumulated lots of these environmental risks that could harm our genetic coding.
DNA can seem downright fragile, from this long list of things that can damage it. But actually —the body is pretty resilient, and has built-in repair mechanisms for DNA.
The problem is, says Berger, these repair mechanisms decline with age:
BERGER: Our body as we get older in many people loses its ability to heal some of these lesions and we also lose our ability for immune recognition and destruction of these cancerous changes.
So as everyday life piles on the damage to our DNA, we are simultaneously losing our natural capacity to self-heal. And this makes us all the more susceptible to cancer.
The thing is humans didn’t used to have to worry much about this. Most people didn’t live long enough to develop cancer. The average life span during the Roman Empire is estimated at 28 and even as recently as 1900 it was only 45. Today the life-span in America is more than three decades longer.
With longevity the risk of cancer increases…naturally. We can’t stop or control it but there’s a growing body of evidence that we can improve the odds against cancer with certain behavioral changes even if we don’t start till middle age…though it’s better to start earlier. The list includes: Stop smoking, wear sunblock, eat a balanced diet with plenty of fruits and vegetables and whole grains. And, get off the couch: physical activity can actually have a preventative effect.
Case oncologist Nathan Berger.
BERGER: People who are physically active are less likely to get cancer and people who are more physically active have a better prognosis when they have cancer.
One research project, to better understand this phenomenon, is taking place at labs like this one at Case where scientists are following the trail of some tiny but really buff specimens:
Parvin Hakimi was part of the team that engineered a breed of mice with a gene that allows them to be super-active; regular exercise freaks.
HAKIMI: They are very very active.
Researchers wanted to find out how this super-fit mouse contends with cancer, and what they’re seeing is significant. Dr. Berger:
BERGER: So these mice they’re resistant to cancers, they do better when we transplant cancers to them, they look better, they live longer, they have babies when they’re 3 yrs old which is unheard of in mice.
Exactly why this is happening is unclear and researchers are investigating how to translate these animal findings to humans. Still, the possibility that daily exercise and staying fit may help ward off cancer is hopeful news as the baby boom generation begins to cross the threshold from middle age to elderly. As one physician cautioned, we’re about to face a surge of elderly people ….which means, an ever larger population of cancer patients. That’s a huge impetus for researchers to find cures and for those in middle age to stay fit.
Anne Glausser, 90.3