Alberta Cancer Foundation

Can Cancer Be Prevented?

Every other Saturday, chef Gail Hall leads her cooking class from her condo where she instructs them to the downtown Edmonton farmers’ market just outside her front steps. From there, she leads them from canopy to canopy to purchase fresh, whole foods.

Thirty minutes later they return to her kitchen with those ingredients to cook a healthful four-course meal, including dessert.

Since before organic food was in vogue, the 60-year-old food activist has supported local and sustainable agriculture and educated others about it, advocating a return to local, natural and unprocessed foods. She’s been a label-reader for 10 years, since first noticing that fat-free whipping cream wasn’t whipping the way it ought to, but she’s a voracious reader now, always on the hunt for hidden soy and other estrogen-producing ingredients.

Three years ago Hall was diagnosed with early stage II estrogen receptor-positive breast cancer, meaning the mutated cancer cells bind to estrogen in her body, which can encourage the cancer’s growth. One way to keep her estrogen levels down, her dietician advised, is to avoid estrogenic foods like soy. But that’s not easy.

Perched on a stool alongside the island in her country-style kitchen, she says, “I can’t believe what they’re putting in food.” She spins around to a cabinet and rummages inside, finally pulling out a box of tea bags. She rotates it in her hands like a Rubik’s Cube until she finds the ingredients panel and points to the last two words: soy lecithin. “It’s a ‘freshening agent’ – like, what? – It’s so ludicrous!”

For her, the only mystery greater than what a freshening agent is doing in tea is why she got cancer in the first place.

Though she doesn’t like to, Hall has spent a lot of time wondering about that. She’s lived the healthiest life she could. Sure, it wasn’t stress-free, but she’s been exercising regularly since her 20s, quit smoking several decades ago and never abused alcohol. And if anyone can cook a nutritious meal it’s Gail Hall.

“There are still a lot of unknowns,” says Dr. Heather Bryant, vice president of Cancer Control at the Canadian Partnership Against Cancer (CPAC), a federally funded organization that combines the knowledge of experts, health organizations, survivors and more to implement a national cancer control strategy.

Ten years ago Bryant helped launch Alberta’s Tomorrow Project, a study that follows 30,000 healthy Albertans over three decades, and turns their diets, lifestyle habits, postal codes, places of employment and more into data that will allow for long-term comparisons between those who get cancer and those who don’t.

It’s considered gold-standard research, and in 2008 it was repeated on a national scale with 10 times more Canadians. According to the Canadian Strategy for Cancer Control, improving Canadians’ health could save the government $73 billion dollars over 30 years.

“By and large, the things that we know predispose people to cancer are environmental, Bryant says. “Most of the cancers that we have prevention tools for relate to tobacco, nutrition and physical activity, and other causes over which people have some control.”

CPAC estimates that half of all cancer cases are preventable, and they are usually cancers of the lung, breast, colon and prostate, which account for almost 50 per cent of all cancer deaths. But, Bryant points out, there is no magic armour. Living and work conditions play a role. Genetics do too. And, just like Hall, thousands of people “do everything right” and still get the diagnosis because somewhere along the way a cell multiplied differently and, instead of dying off after division, the switch is left on and the cells proliferate, forming a tumour.

Hall, now healthy again post-treatment, continues to follow the advice of her doctors, not just shunning estrogen-mimicking foods but also maintaining her healthy diet and physical exercise. Occasionally “why?” still crosses her mind.

Was it her Eastern European genes that made her susceptible? Her age? The fact that when she was a teen she was having abnormal periods and so her doctor prescribed an early generation of birth control pills? Or was it bisphenol A (BPA), an estrogenic organic compound commonly used as a softening agent in plastic bottles?

While it’s next to impossible to point to any one cause of cancer in any individual, we can talk about mitigating risk across groups. And more environmental risks are identified all the time. Hall calls BPA “the big one.”

Dr. Paul Demers, scientific director of Carex Canada, a B.C. team creating public profiles on 60 carcinogens, says the state of knowledge in his field is relatively sparse. “We joke that we have more gaps than things in between because there’s so much data that we don’t have in regards to environmental exposure.”

Carex’s goal is to fill those gaps by gathering numbers on how many Canadians are exposed to known, probable and possible carcinogens and how intense their exposure is. For this, they rely on classifications developed by the World Health Organization’s International Agency for Research on Cancer.

But, as Demers says, it’s complicated and there are many unknowns. BPA, he notes, is still a substance listed by the WHO as category three or “not classifiable,” meaning there’s insufficient evidence that it’s carcinogenic. Combined estrogen-progesterone oral contraceptives, however, are category one, “carcinogenic to humans.”

The classification means that the substance increases the risk of cancer in at least one population. In this case, the rise is slight for women currently on the pill. In groups of women like Hall with a history of oral contraceptive use, 10 years and more after they have stopped their risk rates for developing cancer are no different than in women who never took the pill. Further, among those diagnosed, the disease may be less advanced in the group that has taken the pill in the past.

There’s little we can do to protect ourselves from most carcinogens, but Demers, a former environmental activist, says individuals and especially physicians should educate themselves to push for more regulations where needed, or to encourage industries to use fewer known or suspected toxic chemicals.

But, he says, be critical of alarming headlines about the “carcinogen of the week” that do more harm than good. “I’m concerned people are going to burn out, not believe when things really are hazardous, or get overloaded and feel helpless in terms of wanting to take action.”

Bryant also fears that mysteries in her field of prevention lead to ambivalence. “One of the common beliefs is that cancer is a disease of aging, and if you live long enough you’re going to get it. That leads to the kind of thinking where you’re less likely to think you can control the diseases, and you become less likely to take the effort to do so,” she says.

“In treatment and prevention, we sometimes feel like we’re just making baby steps,” Bryant says. “But when you add them up, we actually are making great strides in controlling cancer.”