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Prevention: Why & How

Cancer is not inevitable. It is not just “in your genes”! There is much we can do to protect ourselves and our loved ones. Cancer develops when normal cells are transformed, then grow in an uncontrolled way. These cells may evolve rapidly, and may eventually invade and overcome organs, leading to decline and death. The genetic code (DNA) and biochemistry are changed so that cells grow and do not die, and then invade normal tissues. Many factors contribute to this chain of events, and many of these factors can be modified.

Prevent Cancer Now (PCN) helps people to become savvy citizens, and works to ensure that cancer-causing agents not be put in our environment and our products in the first place. We support agriculture, industrial practices and energy sources that are least-toxic and sustainable, and are demanding that our regulators place a high priority on our health and the environment in their decisions. There are many ways to prevent cancer – one step at a time!


Personal tips for cancer prevention

How much cancer can be prevented?

PCN’s approach to cancer prevention

Cancer statistics – why Prevent Cancer Now is doing what it is doing

What is cancer?

Cancer prevention strategies

Contributors to cancer

Mechanisms involved in development of cancer

Approaches to prevention – should exposures be innocent until proven guilty?



Personal tips for cancer prevention

  1. Don’t smoke. If you do smoke, cut back as much as you can, and keep smoke away from others.
  2. Aim to eat a diverse, largely plant-based diet, as fresh, local and organically grown as possible. Drink lots of pure water, filtered if necessary, and avoid sugary drinks and alcohol. Cook vegetables lightly if at all. Don’t burn or char your food. Use glass and stainless steel for food storage and cooking. Avoid plastics.
  3. Be physically active, outdoors if possible – and have fun doing it! Sweating is good.
  4. Make sure you get enough vitamin D, through careful exposure to sunshine, or supplements. Avoid tanning beds.
  5. Choose personal care products wisely, without fragrances, phthalates or other toxins.
  6. Take care indoors. Remove shoes, eliminate mould and dampness and avoid smoke. Dust and clean well, using soap and water, vinegar, baking or washing soda (not along with vinegar) or oxygen bleach for most household cleaning. Look for toxin-free materials for home renovations. Check for asbestos and lead in older buildings, and test your basement for radon.
  7. Be aware of toxins in the workplace. Use personal protection, shower and change at work, and lobby for least-toxic practices. Ask your doctor about melatonin for shift work.
  8. Avoid cancer-causing infections – practice safe sex and don’t share anything that contacts body fluids (needles, pipes, etc.).
  9. Ask your doctor for medical imaging, if needed, that involves the least possible radiation.
  10. Be careful with wireless communications devices. Don’t let children use them.
  11. Learn to deal with stress. Get enough sleep. Cultivate supportive social networks.
  12. Use least-toxic pest control at home, and work to stop pesticide use in your community.

“Live lightly” on this earth.
Learn more and take action to help prevent cancer in your community.


How much cancer can be prevented?

In February 2014, a World Health Organization (WHO) headline proclaimed:

Global battle against cancer won’t be won with treatment alone. Effective prevention measures urgently needed to prevent cancer crisis. (1)

The World Health Organization concluded:

Prevention offers the most cost-effective long-term strategy for the control of cancer. (2)

The WHO is looking to avert tragedy for individuals, families and communities, as well as the costs of lost opportunities, and treatments…so too is Prevent Cancer Now.

Your chances of developing cancer depend upon where you live. Clearly the environment is a key factor.

What these maps mean – what statisticians count

  • Incidence – the number of people who are diagnosed per year
  • Prevalence – the number of people with the disease at any given time
  • Mortality – the number of people who die of the condition per year

If treatment improves and people live with the condition for longer, prevalence goes up. Mortality would decrease at least temporarily, or may fall permanently if affected individuals die of other causes.

For those interested in prevention, incidence is the most important statistic (Figure 1; data no longer available online). Unfortunately the Public Health Agency of Canada now only maps prevalence (Figure 2).

Whenever cancer incidence rates have fallen, prevention was key to reducing cancer-causing exposures at work, home, school or play. Estimates of how much cancer can be prevented range from 30%, up to 95% or more for some tumours.

The 2010 US President’s Cancer Report found that, “the true burden of environmentally induced cancer has been grossly underestimated. (3)”

The American Institute for Cancer Research states that a third or more cancers (depending upon the type of cancer) can be prevented with exercise, good diet, maintaining a healthy weight and of course not smoking.

The World Health Organization echoes this, with the added recommendation to avoid environmental and occupational carcinogens, and infections.

The Canadian Cancer Society says that half of cancers can be prevented through lifestyle changes. They also say that 5 to 10% of cancers are related to inherited genetic abnormalities, which suggests that 90 to 95% of cancers may be preventable.

Even genetic pre-dispositions are not a death sentence. Dr. Judith Stern of the University of California famously said:

“the genes load the gun, but the environment pulls the trigger.”

In this context, George Church of Harvard Medical School commented that the genetics conversation has evolved from:

“Here is your destiny, get used to it”
“Here is your destiny, and you can do something about it!”

“Doing something about it” lies in your air, water, food and your surroundings – your environment.


PCN’s approach to cancer prevention

Prevention potential – fine print

PCN aims to prevent far more than a third or half of cancers. With a broad approach that goes beyond lifestyle changes to address the environmental causes of cancer, the vast majority of cancers could be prevented. PCN’s Cancer Prevention Tips go beyond basic advice from groups such as the Public Health Agency of Canada (4) to include environmental factors, building on those from the Canadian Cancer Society, the Occupational Cancer Research Centre and the US National Institutes of Health. CAREX (Canada) is working to identify and track carcinogens in Canada. Other organizations that identify possible cancer-causing substances can be found here.

Cancer prevention includes personal strategies such as a high quality diet , exercise (at least half an hour a day, preferably to the extent that you sweat) and getting enough sleep. But it goes beyond that, to minimize exposures in the air, water, food, and the products we use at home, school, work and play, both indoors and in the great outdoors.

Avoiding carcinogens is not always obvious or simple. To be really effective, we must also control cancer-causing and –promoting exposures at their sources. This means that we have to work together, to influence governments and corporations to use the safest ingredients and processes possible.

How much cancer can be prevented depends upon the starting point, as well as knowledge of factors contributing to cancers. For instance, a country with many smokers will face more preventable lung cancers than a country with fewer smokers.

How much cancer will be prevented depends on how hard we are all going to try. For example, even with clear knowledge of the links between smoking and cancer, to realize the potential for prevention you need citizens and physicians speaking out for clean air, the vision and courage to restrict smoking in public places and tax tobacco, and importantly, support for smokers to quit.

It can be hard to instigate and maintain many changes in diet and personal exposures. Poverty and personal circumstances (e.g. education, air pollution in a neighbourhood, availability/affordability of good food and safer products) limit many people’s options and priorities.

Research tells us that overwhelming people with information can make them freeze into inaction like a deer in the headlights. The antidote is to recognize this possibility, and to be empowered by knowledge. Take small steps, for steady progress as it fits in your life.

Despite knowledge and availability of healthy options, individuals sometimes don’t take actions and spend money to avoid what seems like a remote possibility. Environmental testing and remediation cost money and may be inconvenient. For example, arsenic in groundwater and radon in living spaces are two naturally occurring carcinogens that you cannot see, smell, taste or feel. They are only detected with laboratory testing. Similarly, asbestos and lead paint are highly hazardous materials in older buildings, but testing is necessary to identify them. Recognition, remediation, renovation and repair to address any of these hazards require specialized professional skills and equipment, which come at a price.

It is not too late!

Cancer takes a long time to develop, and we can’t rewrite history. Nevertheless, risk of cancer or recurrence falls over time after an exposure (such as smoking) or habit (such as not exercising) has been addressed. Even if you are fighting cancer, cancer prevention actions such as exercise and a healthy diet can help you to feel better, and may improve the outcome.


Cancer statistics – why Prevent Cancer Now is doing what it is doing

Over the last 40 years, more of us have been developing and dying of cancer.

In 2008 cancer surpassed cardiovascular disease to become Canada’s number one cause of death.

European and USA data show that childhood cancers have been increasing over the decades (5,6), as are select cancers such as testicular and thyroid cancers in young adults in both the USA and Canada.

Some Canadian Cancer Statistics:

  • In 2012, on average, almost 500 Canadians were diagnosed with cancer and about 200 people died every day.
  • Of the newly diagnosed cases, more than half were lung, colorectal, prostate and breast cancers.
  • The risk of cancer increases with age. About 40% of new cancer cases and 60% of cancer deaths will occur among those who are 70 years of age and older.
  • Cancer can occur at all ages, and more young people are getting it. The fastest growing rate of cancer is among young women with thyroid cancer. Testicular cancer and non-Hodgkin’s lymphoma are increasing among young men.
  • Finally, cancer kills Canadians too early in their lives. Adding up the years between premature death and the normal lifespan across all Canadians, over one-quarter (27%) of all years of life lost in 2006, were from cancer.


What is cancer?

Cancer develops when normal cells are transformed, then grow in an uncontrolled way. These cells may evolve rapidly, and may eventually invade and overcome organs, leading to decline and death. Key steps include:

  • the genetic code (DNA) is “read” differently and biochemistry is changed;
  • DNA is increasingly corrupted with mutations;
  • normal processes to control numbers, location and longevity of cells are circumvented and disabled; and
  • colonies of transformed cells affect normal tissues, allowing cancer cells to form tumours.

Cancers are named according to the tissue in which they originate:

  • Carcinoma begins in the skin or in tissues that line or cover internal organs;
  • Sarcoma begins in bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue;
  • Leukemia arises from blood-forming tissue, typically in the bone marrow;
  • Lymphoma and myeloma begin in the cells of the immune system; and
  • Central nervous system cancers begin in the brain and spinal cord).


Cancer prevention strategies

At Prevent Cancer Now we see too many young, well nourished, fit, lean, non-smoking, moderate- or non-drinking people developing cancer. Young mothers, fathers and children are getting cancer.

Why might cancer occur, and how do we prevent it? Clues lie in exposures that feed the hallmarks of cancer – inflammation, immune modulation, endocrine disruption and epigenetics. Big words about fundamental biology, but ultimately a straightforward strategy.

More needs to be done.


Contributors to cancer

Cancer is the culmination of a complex process, influenced by many factors. The more we know about what can contribute to cancer, the more we can avoid it!

Cancer-causing (carcinogenic) exposures

For decades, many organizations such as the International Agency for Research on Cancer (IARC) have examined exposures one at a time to see if single agents cause cancer. We are starting to understand how real life multiple exposures interact to magnify toxicities. These organization have identified hundreds of exposures of concern, including:


  • Ionizing Radiation is known to cause cancer. Ask about low-exposure options to minimize exposure to X-rays used in imaging (medical x-ray images, CT scans and airport scanning). Radioactive substances also damage DNA. These substances, include many chemicals from nuclear power plants and explosions, radon in the home, and isotopes used in medicine (at lower doses for imaging, and higher doses for treatment).
  • Non-Ionizing Radiation comes from a wide range of source, including the sun, microwave ovens and radio waves. Ultraviolet radiation causes skin cancer, so practice sun safety. Also minimize exposure to radiation from wireless communications.

Infectious agents

A burgeoning field of research examines how infections are associated with cancer (7). Rates of stomach and cervical cancer have dropped largely by reducing infections, through sanitation, protective measures (e.g. condoms), and diagnosis and treatment (e.g. antibiotics for Heliobacter pylori). Avoid risky behaviours (e.g. unsafe sex, sharing of drug paraphernalia). An interesting counterpoint is that some viral infections cause cancers to die, which is an exciting line of therapeutic research (8).

Infectious agents that cause cancer:

  • Viruses:
    • Epstein-Barr virus (EBV) [nasopharynx, Hodgkin’s and Burkitt’s lymphoma]
    • Human T-lymphotropic virus (HTLV-1) [acute T-cell leukemia]
    • Hepatitis B and C Viruses (HBV and HBC) [liver cancer, lymphomas]
    • Human papilloma virus (HPV) [Cervical, ano-genital, oral cancers]
    • Human Immunodeficiency virus (HIV), Human herpes virus 8 (HHV-8) [Kaposi’s sarcoma, Non-Hodgkin’s lymphoma]
    • Human herpes virus 8 (HHV-8) [Kaposi’s sarcoma]
  • Bacteria
    • Helicobacter pylori [stomach cancer, lymphoma]
  • Fungal mycotoxins
    • Aflatoxin B, ochratoxin [gastrointestinal, liver and bladder cancers]
  • Parasites
    • Schistosoma haematobium, liver flukes [bladder, liver cancers]

Endocrine disrupting chemicals (EDCs)

Endocrine disrupting chemicals interfere with our hormone systems. Hormones affect every stage of development – how cells grow, mature, repair themselves and die. Hormones also govern metabolism and reproduction. For example, chemicals like bisphenol-A mimic oestrogen and contribute to breast cancer. Other endocrine disruptors, including some pesticides, also interfere with hormones such as androgens or thyroid hormone, and may contribute to prostate and thyroid cancers. Some chemicals mimic more than one type of hormone.

Endocrine disrupting chemicals act at exceedingly low levels – levels commonly seen in our environment and in human samples (e.g. blood, urine). These low levels used to be dismissed as unimportant, and when chemicals are being registered or approved for use, toxic effects are not tested at these everyday, low levels.

It is now clear that the effects of high doses of hormones that are used in testing may be different, or even opposite, from what happens with low levels of exposure. Indeed, even the American Chemical Society says that current chemical testing processes are not valid, as they do not test the effect of low-dose exposure to endocrine disrupting chemicals. Complicated dose-response “makes it impossible to predict the effects of low-dose exposures based upon high-dose experiments (9),” yet this is the basis for allowing substances in today’s products! Many common chemicals may disrupt hormone actions.

RELATED: “Proof of Safety” versus “Innocent Until Proven Guilty” for Endocrine Disruptors – EU actions trigger controversy, AN OUNCE (Fall 2013)


Mechanisms involved in development of cancer

Landmark work on Hallmarks of Cancer(10) describes how and why hijacking of cellular machinery results in cancer. This includes genetic instability, inflammation, as well as recruitment of “normal” cells in the tumour micro-environment.

Pathways that contribute to development of cancer can provide clues both to prevention and treatment; these are objectives of the Halifax Project.

Evasion of natural control mechanisms

Mistakes are made when DNA is copied, but cells normally double-check and repair genetic material. In rapidly dividing cells, mistakes might get missed and can progress to cancer.

Abnormal cells are usually detected and destroyed by the immune system, but cancer cells become “invisible” to immune surveillance.


Inflammation may be a result of particles such as asbestos or air pollution, infections, allergies, a wide range of pollutants, and poor diet. Inflammation and other toxic effects can vary from person to person, depending upon your ability to metabolize and excrete toxins. Autoimmune conditions are interrelated with chronic inflammatory diseases and cancer.(11)

Immune suppression

Immune suppression is linked to most cancers, although cancers of the immune system such as leukemia and lymphoma are somewhat more complex. Our immune system eliminates most potentially cancerous cells before they really get going, and is the reason that cancers are ultimately cured. The immune system can also cause adverse conditions such as autoimmune diseases and inflammation, so we’re looking for balanced and appropriate immune responses.

Endocrine disruption

Exposure to hormone mimicking chemicals promotes cancer when sensitive cells such as breast, prostate or thyroid are stimulated to grow quickly.

Epigenetic effects

The way DNA is used (“expressed”) to produce particular proteins (basic biochemical building blocks, including enzymes) is the “epigenome.” Chemicals can cause genes to be either suppressed or over-expressed, affecting the biochemical balances in the body that keep cancer in check. The expression of your genes, as much as the genes themselves, determines your risk of disease. Some epigenetic effects can be passed through generations, from either the mother’s or the father’s side.

In 2015, the Halifax Project published two seminal series of peer-reviewed research papers by 350 researchers from 31 countries:

The Halifax Project makes clear that cancer prevention will not be achieved with today’s single-chemical, proof of harm approaches. Cancer prevention hinges upon least-toxic approaches and best-practices in all endeavours.


Approaches to prevention – should exposures be innocent until proven guilty?

Finding that a particular exposure definitely causes cancer is a high scientific bar to achieve, and is only reached after many years of study. In the meantime, many people are harmed and may die. A pragmatic, precautionary approach would be to minimize unnecessary, problematic exposures.

Substances and radiation should not be considered innocent until proven guilty. The Precautionary and Substitution Principles are entrenched in Europe and other places, but not in much of North America.

Precautionary principle

Government regulators, risk assessors and cancer societies generally rely on a standard for proof of harm similar to a court’s “beyond any reasonable doubt.” PCN looks at a broader range of indicators of potential concern. Pragmatic actions are necessary in response to plausible concerns. We can no longer do nothing, with cancers piling up, while we wait for causal certainty to emerge despite vested interests muddying the evidence. This would be closer to “on the balance of probabilities” in a court, and is an application of the Precautionary Principle.

We have toxicity information on only a small fraction of the 80,000+ chemicals in commerce. In Europe, the burden of proof has been shifted to industries to provide strong evidence that their substances and products are safe, under the REACH (Registration, Evaluation, Authorization and Restriction of Chemicals) legislation and program. REACH calls for substitution of the most dangerous chemicals when suitable alternatives are identified.

Substitution principle

If there are several products, all of which achieve a given purpose, how do we choose which to buy? PCN believes that we should choose the least toxic, most sustainable option, and ban the most hazardous ones. This is the Substitution Principle. It has been implemented in Sweden and other countries. The Substitution Principle “skims off” and bans needless, risky products and substances (such as some food colourings and flame retardants). The Substitution Principle pushes industry to find better strategies and products, protects workers’ health, and drives innovation and continuous improvement. An equally rigorous, innovative approach should be applied in Canada, as individuals make daily choices, by corporations, and in governance.

Right to know

Finally, citizens have a right to know what is in their air, water, food and products that they purchase. Labelling of ingredients and production processes (e.g. organic farming, or sustainable resource extraction) is necessary to promote informed choices. Workers have a right to know what is in their workplace, families have a right to know about exposures in daycares, schools and public places. In order for governments to make informed decisions, and for scientists to conduct medical and environmental research, it is necessary to monitor and report publicly contaminants in the environment.



  1. World Health Organization. Global battle against cancer won’t be won with treatment alone. Effective prevention measures urgently needed to prevent cancer crisis [Internet]. 2014 [cited 2014 May 1]. Available from: http://www.iarc.fr/en/media-centre/pr/2014/pdfs/pr224_E.pdf
  2. World Health Organization. Cancer prevention [Internet]. WHO. 2014 [cited 2014 May 3]. Available from: http://www.who.int/cancer/prevention/en/
  3. President’s Cancer Panel. National Cancer Institute. U.S. National Institutes of Health, Division of Extramural Activities. Reducing Environmental Cancer Risk. What We Can Do Now [Internet]. 2011. Available from: http://deainfo.nci.nih.gov/advisory/pcp/pcp.htm
  4. Public Health Agency of Canada. Chronic Diseases – Cancer [Internet]. 2013 [cited 2014 May 3]. Available from: http://www.phac-aspc.gc.ca/cd-mc/cancer/index-eng.php
  5. Kaatsch P, Steliarova-Foucher E, Crocetti E, Magnani C, Spix C, Zambon P. Time trends of cancer incidence in European children (1978–1997): Report from the Automated Childhood Cancer Information System project. Eur J Cancer. 2006 Sep;42(13):1961–71.
  6. Steliarova-Foucher E, Stiller C, Kaatsch P, Berrino F, Coebergh J-W, Lacour B, et al. Geographical patterns and time trends of cancer incidence and survival among children and adolescents in Europe since the 1970s (the ACCIS project): an epidemiological study. The Lancet. 2004 Dec 17;364(9451):2097–105.
  7. O’Connor SM, Taylor CE, Hughes JM. Emerging Infectious Determinants of Chronic Diseases. Emerg Infect Dis. 2006 Jul;12(7):1051–7.
  8. Bell J. Oncolytic Viruses: An Approved Product on the Horizon? Mol Ther. 2010 Feb 3;18(2):233–4.
  9. American Chemical Society. Testing for Endocrine Disruption. Public Policy Statement 2009-2012 [Internet]. 2009 [cited 2010 May 13]. Available from: http://portal.acs.org/portal/PublicWebSite/policy/publicpolicies/promote/endocrinedisruptors/CNBP_023441
  10. Hanahan D, Weinberg RA. Hallmarks of Cancer: The Next Generation. Cell. 2011 Mar 4;144(5):646–74.
  11. Franks A, Slansky J. Multiple Associations Between a Broad Spectrum of Autoimmune Diseases, Chronic Inflammatory Diseases and Cancer. Anticancer Res. 2012 Apr;32(4):1119–36.



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