Should I have a genetic testing for breast cancer?

I am often asked in the breast cancer clinic by my patients: "Should I have genetic testing for Breast Cancer? or What is the risk of breast cancer for my daughters?"

My usual answer was that breast cancer is common, around 1 in 9 women will develop breast cancer during her lifetime. Let's talk about your family history. Do you have any family history of breast cancer? If yes, then I used to ask which family members and their age. Any family history of Ovarian or prostate cancer? Who and what age? I would then refer women to genetic services if family history or young age suggested that there may be an increased risk.

But now the American Society of Breast Surgeons has updated its guidelines for genetic testing. This guideline recommends that all women with newly diagnosed breast cancer are tested for BRCA1, BRCA2 and PALB2 mutations (and other genes as appropriate based on the clinical scenario and family history).

What does this mean and should we in New Zealand also change the genetic testing guideline?

Approximately 10% or all cancers are due to inherited genetic mutations. This number is likely to be underestimated and if we tested all newly diagnosed women, we may find that this risk increases or decreases. We definitely do not know the risk in New Zealand, especially in minority populations.

BRCA1 and BRCA2 mutations are the most common mutations that are associated with an increased risk of developing breast cancer. There are also other genes that increase the risk like PALB2, CHEK2, PTEN, ATM, TP53, CDH1, NBN, NF1, STK11 etc, but the risk in these mutations is not as high as in BRCA mutations.

In the first instance, we have to talk to patients whether they want genetic testing and what impact the results of testing may have on them or their offspring and relatives. Patients need to be told what the possible outcomes of the genetic testing is and what does that mean for them.

Results that are positive - will need management recommendations to plan for that mutation. This may involve plan from different surveillance tests for different conditions within that genetic syndrome, possible chemoprevention (if exists) and risk-reducing surgery. You can find more on the NCCN guidelines on Detection, Prevention and Risk Reduction.

Variants of unknown significance (VUS) result - this means that the test is inconclusive. The test has discovered a mutation within the gene, but at this stage, we do not know whether this mutation carries an increased risk of developing cancer. With time we will know more whether this mutation carries increased risk, but often this takes anywhere between 5-10years (commonly) or even longer.

Negative results but family history suggest the possibility of genetic predisposition - we should follow these patients according to their risk, rather than the presence of a negative test. This may mean that these patients have a genetic predisposition in a gene that so far is not know to have an association with increased risk of breast cancer.

Negative results and family history does not suggest the possibility of genetic predisposition - these patients have the same risk as a normal population (1 in 9 women).

What is the cost of genetic testing in New Zealand vs the USA?

Genetic testing depends on the type that you need to be performed. In NZ it's hard to get figures for this, but it's likely to be around $1500.00 to $2500.00 dollars per person.

It's hard to estimate or get the cost of breast cancer per person, especially in the public sector. In private it costs between $15,000 - to $25,000 just for surgery (and this is not including reconstruction). And then there are possible radiation therapy costs, chemotherapy costs, follow-up costs, any possible complication costs etc. What about other costs to a person going through this treatment - impact on family, time off work, the psychosocial impact of breast cancer etc. The cost is impossible to calculate. Because it is difficult to calculate the cost, it's hard to calculate the cost of benefit (all the tests that are performed, all the stress that these people have every time they come for a clinic appointment, cost of risk-reducing surgery etc). At this stage, private insurance companies will not pay for genetic testing either, this has to funded by a patient.

Should we update the guidelines? It's hard to say at the moment.

It would be great to have genetic information of all cases of breast cancer, especially in rates of mutations in minority groups. Without these, it is impossible to say Yes or No. What is the impact of genetic testing on these people? What is the long-term cost to their family - like private insurance costs as well as the stress of knowing that you have a mutation and stress of knowing that you do not have mutation when your siblings or other relatives do?

My recommendations are that you talk to your specialist with regards to the risk. And if you are not able to have a publicly funded test, and you wish to have one and pay for it, then just talk to your specialist to refer you to the genetic services to request genetic testing.