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
Who is the best person in a family to start genetic testing on?
Typically the most severely affected (youngest onset or more rare tumor type)… NOT always the patient
**once a hereditary cancer gene mutation is discovered in the family, subsequent famiy members can have single site analysis for the known mutation
What is the purpose of hereditary cancer gene testing?
For prevention of cancer, early detection of cancer, and enhanced treatment of cancer
