Transcript Genetics of Breast Cancer Updatedx

Type Of Cancer:
Location:
Carcinoma
Epithelial Cells
Sarcoma
Connective Tissue
Leukemia
Circulatory / Lymphatic
Benign tumours
generally slow growing and enclosed in a fibrous
capsule
 relatively harmless, although their location can make
them serious (such as a tumour located in the brain)
 not considered cancerous (they are not malignant)
 given names that usually end in "oma" (although
melanoma is a malignant skin cancer)
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Malignant tumours
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grow rapidly, invading neighbouring tissues
can spread, to other sites of the body
named using the type of tissue, cell type, and origin
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Cancer can be caused by 3 factors:
› Gene Mutations
 Ex: mutations in BRCA1 &BRCA2 which can
lead to hereditary Breast & Ovarian Cancer
› Environmental Factors
 Ex: Tobacco, Radiation, Chemicals
› Viruses
 Ex: HPV – Cervical Cancer; Hepatitis B and C –
linked to Liver Cancer
Oncogene: a gene that, when
mutated, disposes normal cells to
change into cancerous tumor cells
 DNA Repair Genes: DNA damages in
frequently dividing cells are a prominent
cause of cancer because mutations are
more likely to occur
 p53 Gene: if damaged or mutated,
tumor suppression is severely reduced
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Tumor Suppressor Gene: a gene that
protects a cell from one step on to the
path to cancer. When this gene is
mutated, a loss or reduction in its
function is caused, and the cell can
progress to cancer
Every woman has an 11% chance of
developing breast cancer during her
lifetime
 Most cases of breast cancer are
sporadic; only 5-10% of all breast cancer
cases are hereditary
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The normal female breasts are paired
structures that contain fat and glandular
tissue designed to secrete milk. Cancer
of the breast is one of the more common
cancers in women. Risk factors: a family
history of breast cancer, early age at first
period, and late menopause.
The Result…
Are human genes belonging to a class of
genes known as tumor suppressors.
 These genes are linked to hereditary
breast and ovarian cancer
 The names BRCA1 and BRCA2 stand for
breast cancer susceptibility gene 1 and
breast cancer susceptibility gene 2
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The BRCA1 gene, when properly
functioning, can help prevent breast
cancer, but abnormal variations can
significantly increase the risk of
developing breast cancer. Females born
with the affected gene face a 50-80 per
cent risk of contacting breast cancer
and a 40-60 per cent chance of
developing ovarian cancer.
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There are more than 800 mutations in the BRCA2
gene (Many associated with increased risk of breast
cancer).
Many BRCA2 mutations insert or delete a small
number of nucleotides in the gene, disrupting protein
production
This results in an abnormally small, nonfunctional
version of the BRCA2 protein.
Researchers believe that the defective BRCA2
protein is unable to help repair damaged DNA or fix
mutations that occur in other genes. As these defects
accumulate, they can allow cells to grow and divide
uncontrollably and form a tumor.
Harmful BRCA1 mutations may also
increase a woman’s risk of developing
cervical, uterine, pancreatic, and colon
cancer.
 Harmful BRCA2 mutations may
additionally increase the risk of
pancreatic cancer, stomach cancer,
gallbladder and bile duct cancer, and
melanoma.
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Even though these genes are genetic,
not every woman who are in a family
known for breast cancer and/or ovarian
cancer carries a harmful BRCA1 or
BRCA2 mutation
 Not all breast cancers are due to harmful
mutated genes
 Additionally, not every woman who has
a harmful BRCA1 or BRCA2 mutation will
develop breast and/or ovarian cancer.
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Mutations in several other genes,
including TP53, PTEN, STK11/LKB1, CDH1,
CHEK2, ATM, MLH1, and MSH2, have
been associated with hereditary breast
and/or ovarian tumors.
 However, the majority of hereditary
breast cancers can be accounted for by
inherited mutations in BRCA1 and BRCA2
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Surveillance
 Prophylactic Surgery
 Chemoprevention
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Genetic discrimination occurs when people
are treated differently by insurance companies
or employers because they have a gene
mutation that increases their risk of a disease,
such as cancer.
However, in 2008, GINA was enacted to
protect U.S. citizens against discrimination
based on their genetic information in relation
to health insurance and employment
The law does not cover life insurance, disability
insurance, and long-term care insurance. In
addition, the law does not cover members of
the military.
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Many research studies are being
conducted to find newer and better
ways of detecting, treating, and
preventing cancer in BRCA1 and BRCA2
mutation carriers. Additional studies are
focused on improving genetic
counseling methods and outcomes. Our
knowledge in these areas is evolving
rapidly