Basic Cancer Genetics Flashcards
Inheritance of heretidary cancers
Autosomal dominant (Nearly all)
If one has young age of presentation + unusual combinations of cancers >>> What can be suspected?
Heritable cancer predisposing syndrome
How is the penetrance in hereditary cancers?
Reduced
Example of reduced penetrance in some cancers
80% risk of breast cancer in female carriers of BRCA1 & BRCA2 mutations
80% (males) & 60% (females) risk of colorectal cancer in case of HNPCC
50% risk of endometrial cancer in female HNPCC mutation carriers
What other group of factors is important for cancer risk?
Life style factors
(They are even important for genetically high risk families)
Lifestyle factors for bowel cancer
Smoking
Diet (fresh fruit, vegetables)
In particular, resistant starch
Weight maintenance
Factors of breast cancer
Protective hormonal factors:
- Late age of menarche
- Early age at birth of first baby
- Breastfeeding for more than 6months
- Earlier menopause
Risk factors:
- Overweight
- COCP
- HRT
What is Gorlin syndrome?
Basal cell naevus syndrome > predisposes to >>> skin cancers
If a person has Gorlin syndrome or other conditions that predisposes to skin cancer, how to protect?
Meticulous sun protection
Avoidance of X-ray irradiation
‘Certain tumours are unusual enough to be almost pathognomic for a certain syndrome’ >> such as?
Transitional cell carcinoma of the renal pelvis
Sebaceous tumours
Transitional cell carcinoma of renal pelvis is pathognomic of >>??
HNPCC (Hereditary non-polyposis colorectal cancer)
Sebaceous tumour is pathognomic of >> ?
Muir Torre syndrome
What is Muir Torre syndrome?
HNPCC + skin tumours (keratoacanthomas & sebaceous tumours)
In which cancers, at-risk individuals need to be screened?
HNPCC
Hereditary breast and ovarian cancer
Von-Hippel-Lindau disease
Familial renal carcinomas
Screening of HNPCC
In those who are proven mutation carriers OR those who have 50% risk
- Colonoscopy every 18-24 months
(It varies for other diseases)
Screening of high-risk hereditary breast and ovarian cancer
Mammography
where possible, MRI breast
(benefits of ovarian screening are not proven)
Screening of Von Hippel Lindau disease
Annual renal ultrasound
Urinary catecholamines
Ophthalmic review
MRI brain & spine 2-3yearly
In which cancers, prophylactic treatment can be given?
FAP (Familial Adenomatous Polyposis)
Hereditary breast and ovarian cancer
Prophylactic treatment of FAP
Colectomy between 16 to 30years of age
Why is prophylactic colectomy often performed in FAP (Familial Adenomatous Polyposis)?
Because development of malignancy is almost inevitable
Why is prophylactic colectomy NOT performed in HNPCC?
Because, colonoscopy screening + polypectomy successfully prevent cancer
In patients who are at high risk of hereditary breast and ovarian cancer, what are the prophylactic treatments?
Prophylactic mastectomy
Prophylactic oophorectomy
Prophylactic chemorpevention
What is needed before prophylactic mastectomy/oophorectomy?
Aprropriate counselling
In patients who are at high risk of hereditary breast and ovarian cancer, what is the effect of oophorectomy?
Oophorectomy reduces the risk of breast cancer and ovarian cancer both
In patients who are at high risk of hereditary breast cancer, which chemical is used for prophylactic chemoprevention?
Tamoxifen
(Chemoprevention is only for certain sub-groups of women)