We learn more about cancer all the time. But there's only so much we can do to avoid its seemingly random onset

MARK NICHOLS May 21 2001


We learn more about cancer all the time. But there's only so much we can do to avoid its seemingly random onset

MARK NICHOLS May 21 2001


We learn more about cancer all the time. But there's only so much we can do to avoid its seemingly random onset



For years, the memory of his mothers death in 1979—how she was stricken with colon cancer, and how the disease remained undiagnosed long enough for it to reach her liver—flickered in the back of Wayne Gastons mind. “When the doctors operated,” says Gaston, who sells antique maps in Waterloo, Ont., “they got the primary tumour, but the liver cancer killed her.” As he neared his 50th birthday last year, Caston came across an article recommending regular screening for people with a family history of colorectal cancer. He

talked to his doctor and in July had a colonoscopy-—a procedure in which physicians run an optical device called an endoscope through the colon to search for signs of cancer. In Castons case, they found a small tumour, which surgeons subsequently removed. “The tumour was benign,” says Caston. “But the doctors said it would have almost certainly developed into cancer.” His close call has turned Caston into a screening advocate.“Everybody over 50 should be tested regularly,” he says. “Colorectal cancer is a preventable disease.” And so are other cancers. Canadians have known for decades that they shouldn’t smoke. Most of us also have a pretty good idea of how

to adjust our diets and get enough exercise to discourage a host of ailments, including cancer. But outside any smoke-free office building—or hospital, for that matter—you still see people gathered near the doorway for a cigarette break. Obesity rates are going up, not down. Despite the pleas of health experts, Canadians still don’t exercise as much as they should—and many stubbornly ignore recommendations that they avoid fatty foods and eat more fruit and vegetables. “It’s hard to get people to do these things,” says Dr. David Bell, a Halifax oncologist who treats prostate cancer. “But it’s changing—five years ago you could hardly get a veggie burger anywhere, and now Harvey’s has them.”

Yet for all the measures anyone can take, cancer remains an implacable enemy, striking seemingly at random and often fatally. While Caston has dodged the bullet, the Canadian Cancer Society estimates that physicians will diagnose 17,200 new cases of colorectal cancer this year, and 6,400 men and women will die of the disease as cancers of all kinds cut a lethal swath through Canadians’ lives. The annual number of new cancer cases is rising steadily, with 134,000 new cases—and 65,000 deaths—projected for 2001.

Despite the bleak numbers, however, incidence and death rates for colorectal cancer and some other killers, including lung cancer in men and cervical cancer in women, are actually declining. “The news for individual Canadians is good,” says Dr. Barbara Whylie, a director at the Canadian Cancer Society. “Statistics show Canadians have less chance of dying of cancer than in the past. The bad news is that with the population growing and aging, the number of new cases is rising rapidly.”

Part of the challenge facing anyone trying to do the right thing to avoid cancer is making sense of the plethora of new information, some of it contradicting previously held theories. Last month, a study published in the British journal Grieven challenged the value of some fibre in the diet. Fruit and vegetables still got the thumbs-up, but according to the article, the processed fibres found in granola bars and cereals were ineffective in fending off colorectal cancer. At the same time, scarcely a week goes by without word of something else that might cause cancer. Earlier this month, a U.S. study involving more than 17,000 women turned up hints that breast implants might be linked to cancers of the brain, larynx and lungs. The researchers found no link to breast cancer.

Clearly, there are limits to the time even the

most zealous health watchers can spend keeping up on the latest literature—and ample evidence that, no matter what they do, cancer can still hit anyone, anytime. Nonetheless, a growing understanding of the disease is making it increasingly possible to predict the likeliest victims. Age is the prime indicator. The reason: as the body ages, a lifetimes wear and tear makes cells increasingly prone to the genetic changes that can trigger cancer. “You can almost say that if you live long enough, you’ll get cancer,” says Andrew Coldman, a statistician at the B.C. Cancer Agency in Vancouver. Another key factor is a family history of a particular cancer, which almost certainly points to an increased likelihood of getting the disease.

Acting where they can, family physicians are increasingly counselling patients on how to reduce those risks through diet and lifestyle measures. Even in the absence of hard proof, many experts contend that regular exercise, a diet low in fat and rich in fruit and vegetables, along with regular screening and other factors, can strongly decrease the risk of cancer (page 26). Waterloo’s Caston, a non-smoker who keeps fit by cycling and hiking, is watching his diet carefully since his close encounter with cancer. “I’ve cut down on the french fries and red meat,” he says, “and I’m eating more fruit and vegetables. I’m convinced these things can make a difference to whether you get cancer or not.”

Just over 30 years have passed since U.S. president Richard

Nixon declared war on cancer—and the enemy clearly has not been vanquished. But some enormous scientific advances are just beginning to bear fruit. While researchers have yet to produce the silver bullet that will defeat cancer once and for all, they have found valuable new therapies and gained a deeper understanding of the disease. “We’ve amassed a staggering amount of knowledge,” says Dr. Robert Phillips, executive director of the National Cancer Institute of Canada. “Now we can design cancer drugs scientifically, instead of by trial and error, as in the past.” One of the new breed of drugs that target cancer cells without damaging others is Novartis Pharmaceuticals’ Glivec, which achieved remission rates of more than 90 per cent in patients with a rare form of leukemia during clinical trials. Approved by the U.S. Food and Drug Administration last week, Glivec is under priority review by Health Canada.

Another enormous step came last June with the completion of a draff of the decoded human genome. Work continues on a more complete version that will give researchers a vast new library of genetic knowledge to draw upon. “I think we’re soon going to see major discoveries,” says Christine Pratt, a University of Ottawa researcher. “We are getting to know the biochemical pathways involved in cancer well enough to find areas we can attack.”

Treatment is one approach; prevention, or at least early detec-

tion, is another. For some forms of the disease, including breast and colorectal cancer and another that causes retinal tumours, genetic screening can identify people who have a susceptibility that runs in their families. Early detection of any cancer is crucial, says Victor Ling, head of research at the B.C. Cancer Agency. “Too often by the time cancer is found,” he adds, “it’s very difficult to treat because its been spreading for years.” For patients now known to be at risk, physicians are prescribing a battery of tests that can detect breast, cervical, colorectal, lung, prostate and other cancers before it’s too late.

In the case of lung cancer—the malignancy that takes the largest number of Canadian lives—prevention in close to 90 per cent of all cases is remarkably simple: don’t smoke cigarettes or any other form of tobacco. And although the disease continues to take a savage toll—21,000 new lung cancer cases and 18,000 deaths from the disease are projected in Canada this year—campaigns to wean

people off smoking are paying dividends. Reflecting the fact that men began butting out two decades ago, 77.3 new lung cancer cases are projected this year for every 100,000 men, down from a peak of 97.1 per 100,000 in 1984. For women, who started smoking—and quitting—in great numbers later than men, the rate of new cases is still rising, with 47.4 per 100,000 new cases projected for this year, up from 37.7 per 100,000 a decade ago. “In a few years,” Whylie anticipates, “the rate of increase among women should start dropping as well.”

Meanwhile, the rapidly rising number of older women in the population is pushing up the death toll for breast cancer, a disease that’s more likely to strike after 50. About 19,500 new cases are projected for this year, and an estimated 5,500 women will die of the disease. But mortality rates are falling—from 30 breast cancer deaths for every 100,000 women 20 years ago, to a rate of 26.7 per 100,000 projected for 2001.

Experts attribute much of the improvement to the growing use of mammography to detect breast tumours. But a Health Canada report earlier this month showed that screening isn’t nearly ||, as widespread as it should be. Half the provinces had dismally low mammography rates, with Quebec screening only 11.5 per cent of older women,

Even as the death rate from breast cancer declines, the number of newly diagnosed cases continues to climb

and Ontario only 12.8 per cent. The highest rates were in Saskatchewan (54.7 per cent) and British Columbia (45.5 per cent)—two provinces with breast cancer mortality rates among the lowest in Canada. “I think breast screening can make a huge difference,” says Dr. Karen Gelmon, an oncologist at the B.C. Cancer Agency. “It lets us catch cancers early, when they’re most treatable and curable.”

Others factors, including improved surgical techniques along with healthier diets and more exercise, may also play a role in reducing breast cancer mortality rates. Yet even as the death rate declines, the number of new breast cancer cases continues to climb. One reason, says Gelmon, is that Canadian women are having fewer babies, and bearing them later in life. As a result, they have more menstrual cycles—and more estrogen circulating in their bodies. “We know,” says Gelmon, “that in a majority of cases, estrogen plays a role in promoting breast cancer.”

The male equivalent is prostate cancer—the most common and second most lethal form of the disease among men. It continues to take a terrible toll of lives, despite the existence of a simple screening test. A disease that tends to strike down older men, prostate cancer is expected to kill about 4,300 Canadian men this year, while close to 18,000 new cases will be detected. Many family physicians routinely administer PSA (prostate


specific antigen) tests to detect prostate cancer. Health Minister Allan Rock recently became something of a poster boy for that procedure. Since his father died of prostate cancer several years ago, Rock has undergone regular PSA testing. On Feb. 13, he had prostate surgery after a test detected cancer.

But PSA testing is controversial, because a positive result can persuade some men to undergo prostate removal—even when the cancer has not spread and may never threaten their lives. In fact, two-thirds of men with prostate cancer die of other causes before that disease becomes life-threatening. And men whose prostates are removed run the risk of some degree of incontinence and impotence. But for all the controversy, Halifax’s Bell predicts that over the next 10 years data will show that with the PSA test, “we’re making progress with prostate cancer and saving men’s lives.”

One result of the PSA test’s introduction in the late 1980s was to send incidence rates soaring by identifying thousands of prostate cancer cases that otherwise would have been undetected for years. Now, with so many of the slow-growing cancers I spotted, the rate of new cases has actually plunged g —from a peak of 140 per 100,000 in 1993 to 118 ! per 100,000 projected this year. However, the rate % is once again gradually rising. Why the continuing 1 increase? Once again, lifestyle factors are the key I suspect. “I think the villain is the high-fat, high! calorie North American diet,” says Bell. “In the s Middle East and Asia, where people eat differendy, f prostate cancer rates are lower.”

I In the overall war, one of the most impressive I gains has been against colorectal cancer, with the I rate of new cases and deaths in both men and

Women may be more willing than men to change their habits, and their bodies may respond better to protect them

women declining. Even so, cancers of the colon, or bowel, and rectum still rank as the third deadliest among Canadians after lung and breast cancer for women and lung and prostate cancer in men. This year, an estimated 17,000 Canadians will be diagnosed with the disease, and about 6,400 will die of it. In the past two decades, however, the number of new cases annually has fallen by nearly 20 per cent among women, and eight per cent among men, while mortality rates have nearly halved among women, and dropped about 25 per cent among men.

Experts attribute the improvement to growing public awareness of the disease—and increased screening of patients over 50 by physical examination, stool sample tests and colonoscopies that enable physicians to scan the bowel’s interior for polyps— the pimple-like growths that can turn cancerous. If it’s detected at an early stage, colorectal cancer can often be effectively treated, and even cured. And when it does develop, improved surgical techniques and new chemotherapy drugs have improved survival times. “When I saw one of my patients for the first time, I thought he’d be dead within a month,” says Dr. Ralph Wong, a medical oncologist who treats colorectal cancer at Winnipeg’s St. Boniface General Hospital. “Now it’s a year later and he’s doing fine, thanks to one of the new drug combinations.”

Many experts are convinced the right kind of diet can protect


Canadians from colorectal cancer. “There’s evidence that consuming a lot of fat is bad, and that eating a lot of fruit and vegetables is protective,” says Dr. Tony Fields, an oncologist at Edmonton’s Cross Cancer Institute. “Keeping your body weight under control is important, too,” says Fields, who adds that people who exercise regularly seem to be less likely to get colorectal cancer. Why have women fared so much better in the battle against colorectal cancer? “Women may be more willing to embrace lifestyle changes,” says Fields, “and when they do, it may be that their bodies respond better to protect them.” Women generally seem to take better care of their health than men. Because of a history of breast cancer in her mother’s family, Ottawa consultant Nancy Porter-Cathcart regularly examined herself. In June, 1995, at the age of 44, she discovered a lump in her right breast, and in August, surgeons removed a malignant tumour. After that, Porter-Cathcart, then a senior adviser at Transport Canada, underwent six gruelling months of chemotherapy, followed by five weeks of radiation treatment. “The odds are,” she says, I “that the disease won’t come back. But it could.” » Married with two grown children, Porter-CathI cart now has her own consulting firm and heads a | support group called Breast Cancer Action Ot| tawa. Increased awareness of breast cancer—and I the importance of screening—means women I have a better chance today of beating breast can| cer, she says. “It’s still a terrible disease,” says “ Porter-Cathcart, “but the mortality rate is coming I down—we’re making progress.” And in the war Ï against an insidious killer, every life saved counts § as a resounding victory.