Many Canadians have questions about cancer risk factors — and it can be hard to separate fact from fiction. You may have heard that stress causes cancer, or that moles are always dangerous, or that cancer runs in families. Some of these concerns are well-founded. Others are myths. This article breaks down the most common questions about cancer risk factors, based on current research, so you can make informed decisions about your health.
Is Cancer Contagious or Hereditary?
Can You Catch Cancer from Someone Else?
No. Cancer is absolutely not contagious. You cannot catch it from another person through touch, air, or any other form of contact. Cancer develops when certain genes mutate inside a person’s own body — it is not something that passes from one person to another.
This is one of the most persistent myths about cancer. However, the science is clear and consistent on this point. You can safely hug, care for, and support a loved one who has cancer without any risk to yourself.
Does Cancer Run in Families?
In most cases, no. Research shows that approximately 95% of cancers are not hereditary. However, between 5% and 8% of cancers do have a family connection. These include certain forms of breast, colon, and prostate cancer.
For a cancer to be considered hereditary, the same type of cancer must appear across multiple generations — typically in people over 50. If you have a strong family history of a specific cancer, talk to your family doctor. They can refer you to a genetic counsellor through your provincial health plan. Early assessment means earlier prevention and screening.
According to Health Canada, knowing your family health history is one of the most useful tools for managing your long-term cancer risk.
Cancer Risk Factors: Stress, Trauma, and Mental Health
Can Stress or Grief Cause Cancer?
This is a nuanced question. Current research has not proven that stress or emotional trauma directly causes cancer. Studies comparing cancer patients to people of similar ages and backgrounds have not found significantly more traumatic life events among those with cancer.
However, some researchers have noted a possible connection between severe emotional trauma and certain cancers. These include breast and cervical cancer in women, and prostate cancer in men. The link is not conclusive, but it is worth noting.
Furthermore, chronic stress can affect your immune system and your health behaviours — things like sleep, diet, and exercise — which are themselves cancer risk factors. So while stress alone may not directly cause cancer, managing it well is still important for your overall health.
Can Infections, Scars, or Injuries Lead to Cancer?
Do Infections Increase Cancer Risk?
Yes, in some cases. Certain infections are well-established cancer risk factors. For example, the human papillomavirus (HPV) is responsible for approximately 85% of cervical cancer cases. HPV is a very common sexually transmitted infection. Fortunately, Canada’s publicly funded HPV vaccination programme offers significant protection — check with your provincial health authority for eligibility in your area.
In addition, a bacterial infection called Helicobacter pylori can cause stomach ulcers. In some people, those ulcers can eventually develop into stomach cancer. If you have been diagnosed with H. pylori, your doctor can treat it with antibiotics. Early treatment reduces your risk significantly.
The World Health Organization estimates that infections account for roughly 13% of all cancers worldwide.
Can Scars or Physical Injuries Turn Into Cancer?
Possibly, in rare cases. Any unexplained change in a scar — especially one from a burn — should be checked by a doctor. Increased cell activity at a scar site can sometimes lead to abnormal cell growth.
Similarly, some cancers of the breast, testicles, or brain lining have been found in people who experienced a physical injury to that area. In these cases, the injury likely revealed a tumour that was already forming rather than causing the cancer itself. Therefore, if you notice something unusual after an injury, do not ignore it.
Tobacco, Diet, and Everyday Cancer Risk Factors
Does Tobacco Only Cause Lung Cancer?
No — this is a common misunderstanding. Tobacco is one of the most significant cancer risk factors known, and its effects go far beyond the lungs. Smoking is linked to cancers of the mouth, throat, larynx, stomach, and bladder, among others.
There is no safe level of tobacco use. Risk begins with the very first cigarette and increases with every additional cigarette smoked and every additional year of smoking. If you smoke and want to quit, your family doctor or walk-in clinic can connect you with free smoking cessation resources available through your provincial health plan.
Does Diet Play a Role?
Probably, yes. Research suggests that certain foods may raise cancer risk. Smoked and heavily processed or cured foods are among the most studied. On the other hand, some foods appear to have a protective effect. Green tea and soy-based foods have been highlighted in research for their potentially cancer-protective properties.
Eating a balanced diet rich in fibre, vegetables, and whole foods is a reasonable and well-supported approach to reducing your overall cancer risk. The Mayo Clinic’s cancer prevention guidelines also emphasise maintaining a healthy weight and staying physically active.
Sun Exposure, Tanning Beds, and Skin Cancer Risk
Is Sun Exposure a Cancer Risk Factor?
Yes, absolutely. Excessive exposure to ultraviolet (UV) rays — especially without sunscreen — is a well-documented cause of skin cancer. People with fair skin are at particularly high risk. However, all skin types can be affected by UV damage.
Wearing broad-spectrum sunscreen, protective clothing, and avoiding the midday sun are simple and effective ways to reduce your risk. These habits are especially important during Canadian summers, when UV levels can be surprisingly high even on partly cloudy days.
Are Tanning Beds Safe?
No. Tanning beds use ultraviolet A (UVA) rays to create a tan. These rays cause premature ageing of skin cells and can trigger the changes that lead to skin cancer. There is no such thing as a “safe tan” from a tanning bed.
Several Canadian provinces have already banned tanning bed use for minors. Health experts recommend avoiding tanning beds entirely, regardless of age.
Should You Watch Your Moles?
Yes. A mole is typically a benign skin growth. However, any mole that changes in size, shape, or colour — or that bleeds — should be examined by a doctor as soon as possible. These changes can be early warning signs of melanoma, a serious form of skin cancer.
Use the simple ABCDE rule: Asymmetry, Border irregularity, Colour changes, Diameter larger than a pencil eraser, and Evolution (any change over time). If a mole checks any of these boxes, see your doctor.
Hormonal Treatments and Cancer Risk
Many Canadians wonder whether birth control pills or hormone replacement therapy (HRT) raise their cancer risk. The evidence on this topic is still evolving.
Numerous studies have not found a clear link between oral contraceptives and breast cancer. However, some research has noted a slight increase in risk when contraceptives are used before a first pregnancy. As for HRT, there is currently no definitive evidence proving a direct link between hormone therapy and cancer. That said, every person’s health situation is different.
If you are concerned about how hormonal treatments may affect your individual cancer risk factors, speak openly with your family doctor or gynaecologist. They can help you weigh the benefits and risks based on your personal and family health history.
When to See a Doctor
You should speak with your family doctor or visit a walk-in clinic if you notice any of the following:
A mole that changes shape, colour, or size, or that bleeds
An unexplained change in a scar, especially after a burn injury
A lump or swelling that is new or growing
Persistent pain in a specific area with no clear cause
Unusual fatigue, unexplained weight loss, or changes in bowel habits
A strong family history of breast, colon, or prostate cancer
Most provincial health plans cover screening programmes for certain cancers, including breast, cervical, and colorectal cancer. Ask your family doctor which screenings are recommended for your age and risk level. Catching cancer early makes a real difference in outcomes.
This article is for general information only and is not a substitute for professional medical advice. Always speak with a qualified healthcare provider about your personal health concerns.
Frequently Asked Questions About Cancer Risk Factors
What are the most common cancer risk factors in Canada?
The most common cancer risk factors in Canada include tobacco use, excessive UV exposure, certain viral and bacterial infections like HPV and H. pylori, unhealthy diet, and in a small number of cases, inherited genetic mutations. Maintaining a healthy lifestyle and attending recommended cancer screenings through your provincial health plan are two of the best ways to reduce your personal risk.
Can stress cause cancer?
There is currently no conclusive scientific proof that stress directly causes cancer. However, chronic stress can negatively affect your immune system and lead to unhealthy behaviours that are themselves cancer risk factors. Managing stress through exercise, sleep, and mental health support is good for your overall wellbeing.
Is cancer hereditary?
Most cancers — about 95% — are not hereditary. Between 5% and 8% of cancers, including certain types of breast, colon, and prostate cancer, have a known family connection. If multiple relatives on the same side of your family have had the same type of cancer, speak with your family doctor about genetic counselling, which may be covered through your provincial health plan.
Does HPV always lead to cervical cancer?
Not always, but HPV is one of the strongest known cancer risk factors for cervical cancer, responsible for approximately 85% of cases. Many people clear an HPV infection on their own without developing cancer. Regular Pap tests and HPV vaccination — available through provincial health programmes in Canada — are highly effective at preventing cervical cancer.
Are tanning beds a cancer risk?
Yes, tanning beds are a recognised cancer risk factor. They emit ultraviolet A rays that damage skin cells and can trigger the development of skin cancer, including melanoma. Health authorities in Canada strongly advise against using tanning beds, and several provinces have banned their use for people under 18.
When should I see a doctor about a mole?
You should see your family doctor or visit a walk-in clinic if a mole changes in size, shape, or colour, or if it starts to bleed or itch. These changes can be early signs of melanoma, one of the more serious skin cancers. Early detection is one of the most important cancer risk factors you can actually control — so do not wait if something looks different.
Key Takeaways
Cancer is not contagious. You cannot catch it from another person.
Most cancers are not hereditary, but 5–8% have a family connection. Know your family history.
Tobacco is a cancer risk factor for many cancers, not just lung cancer. Quitting at any age reduces your risk.
HPV is a major cause of cervical cancer. Vaccination and regular Pap tests offer strong protection.
Sun exposure and tanning beds both raise the risk of skin cancer. Use sunscreen and avoid tanning beds.
Watch your moles. Any change in size, shape, colour, or bleeding warrants a doctor’s visit.
Diet matters. A high-fibre, plant-rich diet may help reduce cancer risk over time.
Stress alone does not cause cancer, but managing your mental health supports your overall wellbeing.
Talk to your family doctor about cancer screening programmes available through your provincial health plan.
