Cancer Genetics Flashcards
What percent of cancers are genetic mutations? What percent are due to a hereditary component?
100% are genetic mutations!
10% are hereditary (attributed to the inheritance of a single gene)
How can you characterize the majority of cancer?
Sporadic; onset after 50 years (and only one person in the family to have that cancer)
What percent of cancer is considered familial?
About 30%; due to multiple genes and environmental factors
Describe a hereditary predisposition versus and acquired cancer
Hereditary predisposition= Germline acquired from parents (autosomal dominant)
Acquired cancers require “two hits” (somatic recessive mutations)
What are the common “red flags” a family might have a hereditary cancer syndrome?
- Younger than expected age of dx
- Many affected family members
- More than one generation affected
- Pairing of cancers in the family (Br & ov, Colon & endo)
- More than one cancer in the same person
- Ashkenazi Jewish heritage
What is the role of a cancer genetic counselor?
- Explore the psychological impact of genetic testing
- Work closely with insurance companies
- Address genetic discrimination concerns
- Introduce medical management options
- Talk about implications for family members
- Discuss the option of DNA banking
What are some types of genetic testing?
- Single site analysis (if you know what the mutation might be)
- Multisite analysis (Ashkenazi Jewish)
- Sequencing
- Deletion/duplication testing
- Next Generation sequencing
- gene panels
- whole exome sequencing
- whole genome sequencing
Describe next generation sequencing
- massively parallel sequencing
- create 100s to 1000s of reads per base pair (like proof reading a book 100s of times -> more likely to catch mistakes)
- provides enhanced resolution, throughput, and speed
- generates large amounts of data quickly in a cost effective manner
What are the benefits and risks of genetic testing?
Benefits:
- provides risk information for individuals and families
- provides information useful for medical management
- leads to cancer prevention and early detection
- may actually relieve anxiety
Risks:
- emotional (fear/anxiety)
- insurance discrimination
What are the limitations of genetic testing?
- genetic testing is not able to detect all causes of hereditary cancer
- continues risk for sporadic cancers
- some management strategies not proven effective
What is GINA?
Genetic Information Nondiscrimination Act
*A federal law passed in 2008 that protects individuals from genetic discrimination in health insurance and employment
**Does NOT apply to life insurance, long term care insurance, or disability insurance
What are some helpful genetic resources?
Information on genetic conditions:
- OMIM (“Online mendelian inheritance in man”, ncbi)
- Genetics home reference
- Gene reviews (ncbi)
- NCCN (national comprehensive cancer network) guidelines
On genetic testing:
- Genetests.org
- Genetic testing registry (ncbi)
What are some risk assessment models that can aid in patient breast cancer management?
- Gail model
- Claus tables
- BRCAPRO
- Tyrer-Cuzick (IBIS)
- BOADICEA
What does a negative gene test result mean for a patient?
Does NOT necessarily mean the patient has no increased risk for cancer… results must be interpreted in light of the personal and family history
