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Specialist Advice — 16 minutes

Is cancer a question of genetics or lifestyle?

February 20, 2024

Michel Cameron, PhD
Michel Cameron, PhD
Associate Director, Pharmacogenomics, Medical Science Liaison
LinkedIn

Cancer is the first leading cause of death in Canada.[1] Medical science estimates that 30 to 50% of people will be diagnosed with cancer during their lifetime, but it is difficult to determine why some are at greater risk of developing the disease. However, multiple aggravating factors are known and documented, including genetic predisposition and lifestyle habits.

Cancer linked to family genetics

Cancer is characterized by the growth of abnormal cells. They then divide uncontrollably, destroying healthy tissue and potentially spreading throughout the body.

These cells are the result of genetic mutations in the DNA. These mutations may be present from birth, but usually appear during the person’s lifetime.[2]

Hereditary cancer

Some families carry a genetic mutation passed on from one generation to the next. Heredity accounts for five to 10 percent of all cancer cases.[6] In these situations, a number of indicators can help determine if a genetic mutation occurs within the same family:

  • Family members are diagnosed with cancer at a young age.
  • Multiple family members are diagnosed with the same or a similar type of cancer.
  • A family member has been diagnosed with more than one type of cancer (such as breast and ovarian cancer).
  • The cancer occurs in both organs of a pair (such as both breasts, kidneys or eyes).
  • Family members have an uncommon or rare type of cancer.
  • More than one case of childhood cancer occurs among the same siblings (brothers and sisters).

Familial cancers

Although they affect some families more than others, familial cancers are different from hereditary cancers. They could be linked to genetic factors shared by a family, without a known genetic mutation necessarily being involved. They could also be associated with a family’s lifestyle habits or the environment where they live (e.g. multiple smokers in the home, polluting factory nearby, etc.).

It is also likely that the combination of a familial genetic factor and certain lifestyle habits leads to an increase in cases of cancer in certain families.

For these reasons in particular, doctors need to know the family history of their patients when there is a likelihood of cancer, so that they can better target the tests to perform. 

In addition, genetic screening can be used to check for the presence of mutations that increase the risk of cancer. However, a mutation does not necessarily mean that cancer will develop. Many other factors come into play that may raise or lower the risk of cancer.[3]

Smoking, diet and alcohol: Aggravating factors

While a number of cancers are linked to heredity, most are thought to be caused by lifestyle. Research suggests that nearly half of all cases of cancer could be prevented by quitting smoking and alcohol and, more generally, by adopting healthy habits.[5]

Environmental risks harder to calculate

Environment is also believed to play a major role in the risk of cancer. Prolonged exposure to ultraviolet radiation, asbestos, radioactive substances or products in the workplace may promote certain types of cancer.[4]

Studies have not yet precisely identified the risks associated with other agents such as pesticides or genetically modified organisms (GMOs), and the scientific community is divided on this matter. Consequently, the precautionary principle takes precedence, since the danger itself cannot be ruled out. 

Genetics and precision medicine

Regardless of the cause, cancer has traditionally been treated based on its location in the body (breast, lung, etc.). Nowadays, precision medicine focusses on the cancer’s main characteristics. Since no two people or cancers are identical, why prescribe the same treatment?

As a result, personalized medicine adapts the treatment according to the genetic profile of the individual and their cancer. This makes it possible to mitigate certain side effects while maximizing the therapy’s chance of success. This way, by relying on genetic testing and pharmacogenetics, it is now possible to develop more effective precision drugs that are tailored to the patient’s case.

It is even possible to conduct genetic tests to assess the likelihood of a cancer returning after a treatment, or detect it in its early stages.

Unfortunately, these medical practices remain very expensive. What’s more, precision medicine is sometimes offered only in one-time, limited clinical trials. Nonetheless, this is certainly a major breakthrough in the fight against cancer.[5]

What to remember about the risk of cancer

Over the past few decades, science has made enormous progress in treating and curing cancer. However, we are still struggling to prevent cancer and establish reliable and quantifiable correlations between lifestyle habits and the disease. For example, it is difficult to estimate the number of hours of sun exposure that the skin can tolerate before skin cancer appears, and that number will vary from one person to another.

However, medicine has well identified the main factors likely to increase the risk of cancer, although once again, their impact is not the same for everyone. Here they are classified by category:

Age : Most cases of cancer are diagnosed after age 65. This is because the majority of cases take decades to develop. Cell renewal also decreases with age, thereby protecting the body less effectively against this threat.

Lifestyle habits : The foods we eat and beverages we drink, the cleaning products we use, along with our consumption patterns in general, all have an influence on our health.

Family history : In some families, genetic mutations are conducive to developing cancer. Certain habits, exposure to the sun or toxic products, along with genetic factors shared by multiple members of the same family, can also come into play.

Environment : Living or working near asbestos, for example, can increase the risk. 

Health status : Chronic diseases such as ulcerative colitis, hepatitis B or human papillomavirus (HPV) are aggravating factors for some types of cancer.[1]

Ultimately, few types of cancer can be attributed with certainty to genetics or lifestyle. Most likely, cancer results from a combination of these two factors, i.e. a genetic predisposition (other than an inherited mutation) combined with one or more harmful habits.

For this reason, it is important to maintain a balanced diet and a healthy lifestyle to reduce some of the risks. With your doctor’s advice, you can also arrange for examinations, screenings or genetic tests based on your personal history. Vaccination against hepatitis B or HPV can also help prevent the disease. 

For professional support, we’re here for you.

We offer services that can help your doctor identify which genetic tests, screenings or examinations to recommend based on your personal history.

Do you have a medical prescription for one of these tests? Book an appointment online or contact Biron Health Group’s customer service at 1 833 590-2712.

This revised edition reflects an updated version from the original version published on February 10, 2022, on our website. We have incorporated recent facts to offer you current and pertinent information.

Sources6
  1. Statistics Canada. « Leading causes of death, total population, by age group », https://www150.statcan.gc.ca/t1/tbl1/en/tv.action?pid=1310039401&request_locale=en [accessed on February 7, 2022].
  2. Mayo Clinic. “Cancer,” https://www.mayoclinic.org/diseases-conditions/cancer/symptoms-causes/syc-20370588 (accessed on February 7, 2022).
  3. Canadian Cancer Society. “Cancer risk in families,” https://cancer.ca/en/cancer-information/what-is-cancer/genes-and-cancer/cancer-risk-in-families (accessed on February 7, 2022).
  4. Ministère de la Santé et des Services sociaux. “Lutte contre le cancer,” updated on January 21, 2015, https://www.msss.gouv.qc.ca/ministere/lutte-contre-le-cancer/prevenir-le-cancer (accessed on February 7, 2022).
  5. Canadian Cancer Society. “Precision medicine,” updated in February, 2021, https://cancer.ca/en/research/understanding-cancer-research/precision-medicine (accessed on February 7, 2022).
  6. Canadian Cancer Society. “Genes and cancer,” updated in February, 2021, https://cancer.ca/en/cancer-information/what-is-cancer/genes-and-cancer (accessed on February 7, 2022).
Michel Cameron, PhD
Michel Cameron, PhD
Associate Director, Pharmacogenomics, Medical Science Liaison
LinkedIn
Seeking to make the science of genetics accessible for everyone, in 2014 Michel Cameron co-founded BiogeniQ, a company specialized in genetics, where he directed the design and development of pharmacogenomics tests. Today this company is owned by Biron. Michel Cameron holds a Ph.D. in pharmacology from the Université de Montréal and completed postdoctoral studies in pharmacogenomics at the Montreal Heart Institute’s Pharmacogenomics Centre.