Kristin Turner, MSc, CGC, CCGC (biography and disclosures)
What frequently asked questions I have noticed
Cancer risk stratification is an important aspect of my career as a genetic counsellor at the BC Cancer Agency. Identification of hereditary cancer families in BC is important to provide individuals at elevated cancer risk with appropriate screening and risk management recommendations. Equally important is the opportunity to reassure individuals at average risk and encourage them to follow general population cancer screening guidelines.
With recent news that Angelina Jolie underwent the very personal decision of prophylactic double mastectomy due to a mutation she carries in the BRCA1 gene, many patients may be asking: Should I be tested for the BRCA1 gene? Is the cancer in my family hereditary? How should I manage my cancer risks?
While cancer is common, hereditary cancer is not. Only 5-10% of all cancers in BC are caused by an inherited gene mutation. Individuals who may be at risk for hereditary cancer can be referred to the Hereditary Cancer Program at the BC Cancer Agency for genetic counselling. The Hereditary Cancer Program referral criteria are available on the new website: www.screeningbc.ca/Hereditary.
While hereditary cancer is rare, approximately 15-20% of cancers are believed to be related to a more moderate “familial” susceptibility (i.e. caused by a combination of multiple genetic and environmental factors). Individuals who have a more moderate risk may still require increased cancer screening above that of the general population; however, they may not be eligible for referral to the Hereditary Cancer Program. This has created challenges for some family physicians in determining appropriate recommendations. What do you do when your patient does not meet HCP referral criteria but does have a family history of: 1) colorectal cancer? 2) breast cancer?
Data that answers these questions
1) Family History of Colorectal Cancer (CRC)
While individuals who have one second degree relative (e.g. aunt/uncle, grandparent, etc.) diagnosed with colorectal cancer have a lifetime colorectal cancer risk comparable to that of the general population (6-8%), an individual with one affected first degree relative has a 2-3 fold increase risk to develop the disease themselves (Taylor et al 2010). In other words, a patient who reports two maternal uncles with CRC in their 60s can be reassured that their risk is comparable to the 6-8% general population lifetime risk. Even with 3 affected second degree relatives, the risk for CRC is estimated to be only 1.48 fold (Taylor et al 2010). On the other hand, a patient who reports a sister with colorectal cancer in her early 50s would be considered at increased risk.
The BC Ministry of Health Guidelines for colorectal cancer screening were updated in March 2013 and are available at www.screeningbc.ca/colon. These updated guidelines classify individuals into one of two categories: average risk patients or increased risk patients.
Increased risk patients, based on family history information, include individuals with one 1st degree relative ≤ age 60 with CRC or advanced or multiple adenomas, or two or more 1st degree relatives with CRC at any age. The guideline recommends that these patients undergo colonoscopy every 5 years starting at age 40, or 10 years earlier than the age of youngest affected relative at diagnosis.
Average risk patients include individuals who meet none of the family history criteria above (or have personal risk factors) for increased risk. Thus, average risk patients include individuals with second degree relative(s) diagnosed with CRC. Fecal immunochemical test (FIT) every 1-2 years is recommended for average risk asymptomatic patients aged 50 to 75 years. Effective April 1, 2013 the fecal immunochemical test (FIT) is publicly funded. This is the first step in the launch of the new provincial Colon Screening Program. A colonoscopy is also an acceptable screening option every 10 years for average risk asymptomatic patients according to the guideline.
The guideline does not address all clinical situations. Colonoscopy frequency may be increased based on findings (i.e. polyps) or at the discretion of an individual’s care providers. For example, an individual who has one first degree relative diagnosed with CRC in their 60s and two second degree relatives (on the same side of the family) diagnosed with CRC in their late 50s may wish to consider colonoscopy every 5-10 years.
2) Family History of Breast Cancer
In BC, genetic testing for Hereditary Breast and Ovarian Cancer syndrome (BRCA1 and BRCA2) is offered on a clinical basis to individuals who meet specific testing criteria: please refer to the Hereditary Cancer Program (HCP) referral criteria found at: http://www.screeningbc.ca/Hereditary/ForHealthProfessionals/HereditaryCancerSyndromes.htm
For individuals who have a family history of breast cancer who do not meet HCP referral criteria, empiric risk models can provide breast cancer risk estimates (e.g. Claus, Gail, Tyrer-Cuzik, IBIS, and BOADICEA Models). The two most historical models are the Claus and Gail models. As a genetic counsellor, I often use these models but could a busy family physician incorporate these models into their practice?
The Claus Model is not available online but the original article (http://www.ncbi.nlm.nih.gov/pubmed/8299086) has reference tables that can be printed and used for a reference. The tables provide age-specific general estimates of breast cancer risk. This model estimates breast cancer risk based on degree of relationship and age at diagnoses of those affected. It should be used with caution in certain populations; it does not incorporate family history of more than two affected relatives or personal risk factors (e.g. LCIS, ADH, age of menarche, etc.). It was also developed in a Caucasian population and may not be applicable to all patient populations.
The Gail Model is available online (http://www.cancer.gov/bcrisktool) and through an App (iOS and android: http://www.mediquations.com). This model provides 5-year and lifetime general estimates of breast cancer risk for women ≥35 years of age. This model uses personal risk factors (i.e. current age, age of menarche, previous breast biopsies, age at first live birth and race/ethnicity) as well as history of a single affected first degree relative in its calculation. This model should not be used for women with a prior history of breast cancer, LCIS, or DCIS. Also, the model does not incorporate family history of more than one affected first degree relative and does not incorporate age at cancer diagnosis in its calculation.
For individuals with a moderate risk of breast cancer (often and arbitrarily defined as greater than a 20% lifetime risk), current breast screening recommendations in British Columbia include clinical breast exams every 6-12 months beginning no later than age 20, and annual mammograms beginning at age 40 or ten years before the earliest diagnosis of breast cancer in the family (not before age 30). Women are encouraged to be breast aware and may find monthly breast self examinations to be useful.
Availability and eligibility for breast MRI varies widely across jurisdictions. Ontario recently announced expansion of the Ontario Breast Screening Program (OBSP) to include specialized MRI screening for women aged 30 to 69 who are considered at high “familial” risk (i.e. 25% or greater empirical lifetime risk) for breast cancer. In BC, women who have inherited (or are at 50% risk of inheriting) a “hereditary” gene mutation (e.g. BRCA1 or BRCA2) are eligible for breast MRI screening. Breast MRI screening is not currently recommended for women at moderate “familial” breast cancer risk in British Columbia.
Take a detailed family history! Accurately collected family history information is integral to an assessment of familial cancer risk classification and in making subsequent screening recommendations. The family history should include a minimum of three generations from both the maternal and paternal sides and include ages at cancer diagnosis, type of cancer, and ethnicity.
Before you can suggest ‘increased’ cancer screening based on family history information, you need to know what is suggested to individuals at average risk in the general population. Review the new website: www.screeningbc.ca and watch for updates!
If you have any questions regarding familial or hereditary cancer risk, please do not hesitate to contact the Hereditary Cancer Program to speak with a nurse educator or a genetic counsellor. In addition to the links found throughout this article, the following resources/references may also be helpful.
Resources for patients:
“Does Cancer Run in My Family”- http://www.screeningbc.ca/NR/rdonlyres/7A1CA594-5605-4F3C-AE51-6CDA3172A3C0/60604/DoesCancerRuninmyFamily.pdf
“Breast Cancer in the Family – What You Need to Know”- http://www.willow.org/assets/u/Hereditary_Booklet.pdf
Resources for physicians:
BC Ministry of Health Guidelines – Colorectal Screening for Cancer Prevention in Asymptomatic Patients. http://www.bcguidelines.ca/pdf/colorectal_screening.pdf
BC Ministry of Health Guidelines – Follow-up of Colorectal Polyps or Cancer. http://www.bcguidelines.ca/pdf/colorectal_followup.pdf
Empiric Colorectal Cancer Risk Estimation – see Taylor et al. (2010), Gastroenterology; 138:877-885. http://www.ncbi.nlm.nih.gov/pubmed/19932107
App: Mediquations ($5, App Store) offers the Gail breast cancer prediction tool. http://www.mediquations.com/iPhone_iPodTouch_iPad/index.html