Sporadic breast cancer

Question 1

How does sporadic breast cancer come about?

Answer 1

Accumulation of acquired “driver” mutations

Question 2

Population risk of breast cancer

Answer 2

12%

Question 3

What testing do we as a genetics lab offer for sporadic breast cancer?

Answer 3

HER2 FISH testing

Question 4

What is HER2?

Answer 4

Epidermal growth factor receptor

Question 5

Is HER2 an oncogene or tumour suppressor?

Answer 5

Oncogene

Question 6

Location of HER2

Answer 6

17q

Question 7

Is there a drug treatment available for HER2 positive cancers?

Answer 7

Yes- Trastuzumab (Herceptin)

Question 8

HER2 is amplified/over expressed in what % of breast cancers?

Answer 8

25%

Question 9

Testing strategy for HER2

Answer 9

IHC (pathology) based on how much protein expressed
2+ (equivocal) sent to genetics for testing
FISH testing performed using enumeration probe

Question 10

Who are HER2 results reported to?

Answer 10

Pathology

Question 11

Information on probe colours used for HER 2

Answer 11

HER2 - red

Chromosome 17 centromere - green

Question 12

What is classed as a HER2 positive FISH result

Answer 12

Ratio of HER2:centromere of greater than or equal to 2 OR average HER2 copy number per cell greater than or equal to 6

Question 13

Considerations to be taken into account when testing HER2 samples

Answer 13

DCIS/LCIS - treatment only works on invasive tumour. Treatment for confined tumours would be lumpectomy.
Heterogeneity - different levels of amplification in different areas of tumour (rare)

Question 14

4 classifications of sporadic breast cancer

Answer 14

ER+, PR+, HER2+, Triple negative