Watch our video on genetics and inherited breast cancer risks featuring Kathleen Buckley, a genetic counsellor at GRH's regional cancer centre.

What is hereditary cancer?

Hereditary cancer is caused by a change (known as a mutation) in a cancer related gene that is passed down from generation to generation through a family.

A hereditary cancer may have a higher risk in the development of some cancers.  Sometimes different cancers may be related in a hereditary pattern (eg. breast/ovary, colon/endometrial).

Are all cancers hereditary? 

No, only five to 10 per cent of all cancer are hereditary; 90 to 95 per cent of cancers happen by chance.

Non-hereditary cancers occur for many reasons, including:

  • Age (our risk increases as we age);
  • Lifestyle (certain lifestyle habits can increase our risk; high fat/low fibre diet, smoking/use of tobacco products, excessive alcohol, exposing skin to the sun’s rays without protection, being inactive or overweight);
  • Environment (we may be exposed to harmful substances in our living and working environments, many of which are unknown to us); and 
  • Chance (many cancers happen for unknown reasons, or chance)
What happens at a genetic counselling appointment for hereditary cancer? 

After you have completed a family health questionnaire, the genetic counselor will:

  • Review your personal and family history of cancer;
  • Assess and explain your personal risk for hereditary cancer;
  • Give you recommendations for cancer screening;
  • Review whether you or other family members are eligible for genetic testing;
  • Discuss the risks, benefits and limitations of genetic testing; and
  • If you are eligible for genetic testing, the counselor will explain the results and next steps.
Who should receive genetic counselling for hereditary cancer? 

People that have:

  • Many family members with the same or related cancers on one side of the family especially breast/ovarian or colon/uterine(endometrial) as well as other abdominal (organs like colon, rectal, stomach, pancreas, small bowel, ovary kidneys, ureter)  cancer;
  • Many generations affected by cancer on one side of the family (just mother’s side or just father’s side) ;
  • Cancer at a young age, e.g. breast or colon cancer diagnosed before age 35;
  • Invasive serous ovarian cancer (a specific type of ovarian cancer);
  • Breast or ovarian cancer and are of Jewish descent;
  • A family member who has had more than one kind of cancer;
  • A family member who has been told they have multiple colon polyps (more than 10) or "polyposis";
  • Rare cancers, such as male breast cancer; and
  • A family that has been told that they have a mutation (change) in a gene causing hereditary cancer.

If you think your family history of cancer may be hereditary, ask your doctor (oncologist or primary care physician) for a referral to a genetic counsellor. Before receiving an appointment you will be contacted by phone and will receive a family history questionnaire to collect more information about your family history to help decide if an appointment is needed. 

What is genetic testing for hereditary cancer?

Genetic testing for hereditary cancer is the analysis of a blood or tissue sample to determine if there is a genetic cause for cancer in a family.

Some families who are considered high risk for hereditary cancer will be offered genetic testing.

Genetic testing is NOT offered to everyone who receives genetic counselling.

How much does genetic counselling/testing cost? 

Genetic counselling appointments are covered by OHIP for individuals who fulfill referral criteria (Ontario Health Insurance Plan).

Genetic testing is also covered by OHIP, but is only available under very specific defined conditions. Your genetic counsellor will tell you if you are eligible for a genetic test.

Does it matter which side of the family the cancer is on? 

No. Cancer (or other health problems) on your father’s side or mother’s side are equally important. We inherit our genes from both parents equally, whether we are male or female. We also often share many of the same lifestyle habits and environment with both sides of the family. When you review your family history with your doctor, remember to mention health problems on both sides of your family.

How can I be referred for cancer genetic counseling? Can I make my own referral for cancer genetic counselling?

If you do not have a family doctor or other primary health care provider, you may contact the genetics clinic at 519-749-4370 extension 2832 to discuss your family history and determine if a cancer genetic counselling appointment is right for you.

After review of the referral, certain referrals may be redirected to one of the larger provincial genetics programs.

If you have more questions about a referral please contact the genetics clinic at 519-749-4370 extension 2832.

If you're a referring physician, visit our refer a patient page to obtain a referral form.

What if I am worried about a genetic problem in my family other than cancer? 

We only accepts referrals for genetic counselling for individuals with a family history of cancer. If you would like a referral not related to cancer, please contact the regional genetics programs at McMaster University Medical Centre – Hamilton (905-521-5085 / fax 905-521-2651) or medical genetics of Southwestern Ontario at London Health Sciences Centre – London (519-685-8140 / fax 519-685-8214). 

How can I learn more about a career in genetic counselling? 

If you are interested in a career in genetic counselling or would like to learn more about genetic counselling in general, click on the links below (links open in new window):