Familial cancer syndromes Flashcards
What is an epigenetic alteration?
An enduring change in gene expression that does not involve the DNA sequence
i.e. methylation of the promoter region of genes with inactivation of the genes (increasingly recognised at the somatic alterations in cancer)
Is the RET gene causing MEN 2 an oncogene with dominant gain of function or a tumour suppressor gene with recessive loss of function?
an oncogene
Is BRCA an oncogene with gain of function or a tumour suppressor gene with recessive loss of function?
TSG
Is MMR genes an oncogene with gain of function or a tumour suppressor gene with recessive loss of function?
TSG
What types of cancer does BRCA1 increase risk
Breast cancer (40-80% lifetime risk) Ovarian cancer (20-40% lifetime risk) Prostate cancer (1.5- 2 x increase risk) Primary peritoneal cancer 2% after salpingoophorectomy
BRCA2 causes increase risk of which cancers
Breast cancer (40-60% lifetime risk)
Ovarian cancer (10-20%)
Breast cancer in males (6% lifetime risk)
Pancreatic cancer (3.5%)
Prostate cancer (4 x increase relative risk)
Melanoma risk also increased
Note if biallelic mutation causes Fanconi anaemia!
Which chromosome contains BRCA1
Chromosome 17
Which chromosome contains BRCA2
Chromosome 13q
How is BRCA associated prostate cancer different?
Tends to be more aggressive with T3/4 disease and node positive more often and mets at diagnosis more likely.
Less likely to be managed with active surveillance as not low risk
How does BRCA gene actually work to increase risk?
Normally involved in DS DNA repair. Function as tumour suppressor genes. Inactivation leaves DNA damage unrepaired–>cancer.
See sporadic OC but not often sporadic BC
What are the typical features of a BRCA1 tumour?
High grade more likely hormone receptor negative pushing borders ;ess DCIS medullary/atypical medullary histo Stain + for basal keratins = basal epithelial subtype
BRCA2 tumours do not have specific phenotypic features
What histological type of ovarian Ca is more common with the BRCA mutations?
Serous papillary (85% vs 40% in sporadic) Mucinous adenoCa and borderline tumours are NOT associated.
Clinically, what are the differences between BRCA associated OC and sporadic?
More likely to respond to platinum agents, and re respond when relapse
Increased progression free survival and overall survival
What are the recommendations regarding testing for the BRCA genes in invasive epithelial Ca?
All non-mucinous cancers under the age of 70
Who qualifies for publicly funded BRCA testing?
three or more cases of breast or ovarian ca in first or second degree relative
or
two or more cases of breast or ovarian cancer in first or second degree relative with at least one high risk feature (male BC, under age 40, bilateral BC, ovarian cancer.)
There are also computer programs to calculate risk, and then often use 10% as cutoff
What surveillance strategies are used in known BRCA carriers?
Breast self examination and clinical examination 6 monthly from age 25-10 (no evidence)
Breast imaging- yearly MG and MRI from 25-30 years (higher sensitivity than MG under age 50 but no proven survival benefit and high false positives)
Ca125 and TVUS not done
Bilateral mastectomy best protection (but residual about 5%). Best to do before age 50- risk declines as age increases so less benefit if operate later on.
Risk reducing oophorectomy age 40
Limit alcohol
Breast feed for at least one yr if possible
Can offer pre-implantation genetic diagnosis with IVF
tamoxifen pre-men or raloxifene post men daily for 5 years reducesrisk moderate breast cancer by 40%
What effect does bilateral salpingoophorectomy have in BRCA?
4% risk in BRCA1 carrier before age 40 so can consider BSO selectively at age 35
Reduces risk OC by 80% and all cause mortality at age 70
Residual risk primary peritoneal cancer 2-5%
Decreases risk of BC if performed before menopause
Need to watch bone health
What is PALB2?
new gene that looks like BRCA2 35% risk to age 70 of breast cancer a loss of function mutation not sure re: male, pancreatic, ovarian ca will be added to panels
Chemoprevention in high risk women with BRCA?
Called “risk reducing medication”
Tamoxifen in pre and post menopausal women and raloxifene in post menopausal women reduce risk hormone positive cancer by 30-40% but no proven survival benefit
Tamoxifen reduces risk of second cancer in BRCA mutation carriers even if hormone negative
Younger women have greater risk benefit ratio
Can you give HRT after bilateral SPO in BRCA carriers?
yes and you should to age 50 to reduce cardiovascular risk but NEVER give if prior breast Ca
Can you give OCP in BRCA carriers?
Yes- this reduces risk of ovarian cancer too
weigh increase risk of BC against benefits of contraception
What is Li Fraumeni syndrome?
p53 mutation- leading to a “breast sarcoma syndrome”
chromosome 17
autosomal dominant inheritance
Penetrance cancer 90% by age 60
rare
can be de-novo
pre-menopausal breast cancer often HER2 positive
sarcomas
GBM
adrenocortical and other pediatric cancers
should have breast MRIs and prophylactic mastectomies
CRC
Australian colorectal ca risks?
Male 1 in 18
Female 1 in 23
FAP- what does the inside of the bowel look like?
hundreds or thousands of adenomatous polyps in the large bowel
90% have CRC by age 45
Suspect if more than 10–>APC gene testing