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FACET - European Journal of Cancer Care
May 2005
Cancer genetics – an overview of an
information project
Pithers, A.1 & Mackay, J.2
Slide One
Why is there a need for
a genetic information
project?
• An increasing number of callers to
the CancerBACUP telephone
helpline are concerned about familial
risk
• The majority of people worry
unnecessarily
• Many people are misinformed
regarding risk factors
• Cancer genetics makes up more
than 25% of all referrals to regional
genetic services in the UK
*Click on “View”; “Notes Page” for explanatory notes
slides available at: www.blackwellpublishing.com/journals/ecc
FACET - European Journal of Cancer Care
May 2005
Cancer genetics – an overview of an
information project (continued)
Providing high quality
information
• Booklet
Slide Two
•
Understanding Cancer
Genetics
• ‘Low Risk’ leaflets
•
Cancer (generic)
•
Breast cancer
•
Ovarian cancer
•
Bowel cancer
*Click on “View”; “Notes Page” for explanatory notes
slides available at: www.blackwellpublishing.com/journals/ecc
FACET - European Journal of Cancer Care
May 2005
Cancer genetics – an overview of an
information project (continued)
Slide Three
Understanding Cancer
Genetics
*Click on “View”; “Notes Page” for explanatory notes
slides available at: www.blackwellpublishing.com/journals/ecc
FACET - European Journal of Cancer Care
May 2005
Cancer genetics – an overview of an
information project (continued)
Slide Four
Are you worried about…
cancer?
*Click on “View”; “Notes Page” for explanatory notes
slides available at: www.blackwellpublishing.com/journals/ecc
FACET - European Journal of Cancer Care
May 2005
Cancer genetics – an overview of an
information project (continued)
Slide Five
Are you worried about…
breast cancer?
*Click on “View”; “Notes Page” for explanatory notes
slides available at: www.blackwellpublishing.com/journals/ecc
FACET - European Journal of Cancer Care
May 2005
Cancer genetics – an overview of an
information project (continued)
Slide Six
Are you worried about…
ovarian cancer?
*Click on “View”; “Notes Page” for explanatory notes
slides available at: www.blackwellpublishing.com/journals/ecc
FACET - European Journal of Cancer Care
May 2005
Cancer genetics – an overview of an
information project (continued)
Slide Seven
Are you worried about…
bowel cancer?
*Click on “View”; “Notes Page” for explanatory notes
slides available at: www.blackwellpublishing.com/journals/ecc
FACET - European Journal of Cancer Care
May 2005
Cancer genetics – an overview of an
information project (continued)
Cancer genes –1
Slide Eight
• All cancers are caused by changes
in the genetic material
• Multi-step theory of
carcinogenesis
• In most common cancers these
genetic changes occur sporadically
(i.e. there are no inherited genetic
changes)
*Click on “View”; “Notes Page” for explanatory notes
slides available at: www.blackwellpublishing.com/journals/ecc
FACET - European Journal of Cancer Care
May 2005
Cancer genetics – an overview of an
information project (continued)
Cancer genes – 2
Slide Nine
There are several types of cancer
gene. The main types are:
• Oncogenes
• Tumour suppressor genes
*Click on “View”; “Notes Page” for explanatory notes
slides available at: www.blackwellpublishing.com/journals/ecc
FACET - European Journal of Cancer Care
May 2005
Cancer genetics – an overview of an
information project (continued)
Two-hit hypothesis and
inherited cancer risk
Slide Ten
• First described by Knudson in the
development of cancer in
retinoblastoma
• Between 5 and 10% of cancers
are thought to be linked to an
inherited genetic mutation
• The inherited genes that
predispose for breast/ovarian
cancer and familial adenomatous
polyposis are malfunctioning
tumour suppressor genes
*Click on “View”; “Notes Page” for explanatory notes
slides available at: www.blackwellpublishing.com/journals/ecc
FACET - European Journal of Cancer Care
May 2005
Cancer genetics – an overview of an
information project (continued)
The most common cancers
in which an inherited
genetic mutation may play a
crucial role are:
Slide Eleven
• Breast/ovarian cancers
• Bowel cancer (HNPCC, FAP)
• Others: prostate, pancreatic and
testicular (but no genetic tests
available for these yet)
• Very rare genetic disorders, for
example – Li-Fraumeni
Syndrome, MEN1, von LippelHindau disease,
neurofibromatosis and
retinoblastoma
*Click on “View”; “Notes Page” for explanatory notes
slides available at: www.blackwellpublishing.com/journals/ecc
FACET - European Journal of Cancer Care
May 2005
Cancer genetics – an overview of an
information project (continued)
Slide Twelve
Main messages to those
referred to cancer
genetic services:
• How the NHS delivers cancer
genetic services
• How is risk assessed
• Why not everyone can have a
genetic test and why you often
don’t get meaningful results from a
genetic test
• Many people have to continue living
with uncertainty
• Psychosocial consequences of living
with uncertainty
*Click on “View”; “Notes Page” for explanatory notes
slides available at: www.blackwellpublishing.com/journals/ecc
FACET - European Journal of Cancer Care
May 2005
Cancer genetics – an overview of an
information project (continued)
Slide Thirteen
Genetic testing
•
A two step process; mutation searching
and predictive testing
•
If you don’t have cancer yourself or
don’t have a living relative with cancer,
you cannot be tested on the NHS
•
Only if a mutation is found (and this is
often not the case) can predictive testing
be offered to other family members
•
Only about 1 in 10 genetic tests finds a
mutation using our present technology
(even in high risk families)
•
Difference between a negative and
inconclusive test
*Click on “View”; “Notes Page” for explanatory notes
slides available at: www.blackwellpublishing.com/journals/ecc
FACET - European Journal of Cancer Care
May 2005
Cancer genetics – an overview of an
information project (continued)
What if no mutation is
found?
Slide Fourteen
• The test might have missed the
mutation
• The entire gene hasn’t been tested
• There is a faulty gene in the family
that has not been identified yet
• The cancer in the family or person
isn’t actually due to an inherited
gene and the clustering of cases of
cancer has occurred by chance
*Click on “View”; “Notes Page” for explanatory notes
slides available at: www.blackwellpublishing.com/journals/ecc
FACET - European Journal of Cancer Care
May 2005
Cancer genetics – an overview of an
information project (continued)
Slide Fifteen
The importance of
explanation of risk
• You don’t inherit cancer from your
family, but you might inherit an
increased risk of developing cancer
• How risk is explained and
understood is vital to the
effectiveness of any genetic
information provision
• Focus on genes must not diminish
the importance of environmental
factors
*Click on “View”; “Notes Page” for explanatory notes
slides available at: www.blackwellpublishing.com/journals/ecc
FACET - European Journal of Cancer Care
May 2005
Cancer genetics – an overview of an
information project (continued)
Slide Sixteen
Some important issues
to consider
• The difference between screening
and prevention Familial
consequences (who to tell,
parentage issues etc.)
• Insurance implications
• Other possible forms of
discrimination
• Pharmacogenetics – the future
*Click on “View”; “Notes Page” for explanatory notes
slides available at: www.blackwellpublishing.com/journals/ecc
FACET - European Journal of Cancer Care
May 2005
Cancer genetics – an overview of an
information project (continued)
Slide Seventeen
Cancer genetics –
summing up
• Cancer genetics referrals now
form a major part of genetic
services Only 5-10% of cancers
are clearly linked to a genetic
mutation
• Cancer genetic testing does not
banish uncertainty
*Click on “View”; “Notes Page” for explanatory notes
slides available at: www.blackwellpublishing.com/journals/ecc
FACET - European Journal of Cancer Care
May 2005
Cancer genetics – an overview of an
information project (continued)
Slide Eighteen
References and further
reading
•
Harper P.S. (2004) Practical Genetic Counselling (6th edn),
Arnold Publishers, London, UK.
•
Skirton, H. & Patch, C. (2002) Genetics for Healthcare
Professionals, Bios Scientific Publishers, Oxford, UK.
•
Kingston, H.M. (2002) ABC of Clinical Genetics (3rd ed),
BMJ Books, London, UK.
Websites
•
CancerBACUP www.cancerbacup.org.uk
•
British Society for Human Genetics www.bshg.org.uk
•
Public Health Genetics Unit www.phgu.org.uk
•
Association of British Insurers www.abi.org.uk
(produces the publication Insurance and Genetic Tests –
what you need to know)
•
National Institute for Clinical Excellence
www.nice.org.uk
*Click on “View”; “Notes Page” for explanatory notes
slides available at: www.blackwellpublishing.com/journals/ecc