ASCO 2016

Large disparities found in BCRA testing across ethnicities

Dr Tuya Pal - Moffitt Cancer Center, Tampa, USA

The study that I’m going to be presenting on is a study looking at young breast cancer survivors from a diverse population. So what we did is we recruited breast cancer survivors aged 50 and below diagnosed between 2009 to 2012 within the state of Florida with invasive breast cancer. In these women what we did was we over-sampled individuals that were both of black ancestry as well as Hispanics. So overall we recruited about 400 black women with early onset breast cancer, there were about 250 Hispanic women and about 1000 non-Hispanic white women. What we did in these women is we looked to see at the time that they entered our study who had accessed genetic testing, so primarily BRCA testing which is something that would be indicated in many of these women and at least a referral per national guidelines would be indicated in any woman with invasive breast cancer diagnosed at or below age 50.

So we looked to see who had had BRCA testing and what we found was just over 60% of the Hispanics and non-Hispanic whites had BRCA testing at time of entry into our study but about 30% of the blacks had had BRCA testing which is much lower than what we saw in the Hispanic and non-Hispanic whites. So that shows us there is a disparity in who is getting testing for the BRCA genes.

And to clarify, that’s a disparity in tests being offered or tests being taken?

That’s the thing, for our study we weren’t able to say exactly whether they were offered it necessarily or whether they chose to take it or not take it. So that’s the difference between uptake versus access. We do have data that tells us that, looking at provider recommendation, that is a very important aspect to getting tested and among the blacks there is some evidence here that suggests that blacks may not have been getting that recommendation as often as the other groups.

Would there be any reason for patients not taking the BRCA testing, for example, if they are going through current phases of therapy, for example if they are receiving chemotherapy or surgical resection to start with that they wouldn’t make use of the DNA testing on offer?

I can’t think of a reason because really many women use this information to guide their treatment. So in individuals with a new diagnosis of breast cancer often they’ll chose their treatment based on their BRCA status. So if they have a BRCA mutation often these women will decide to do a risk reducing mastectomy versus a lumpectomy or unilateral mastectomy. So I can’t think of a reason that because of their treatment they would not have gotten access to testing or gone forward with testing.

And just for a bit of background on BRCA incidence, can we maybe just quickly review how likely it is that those would be present in DNA testing for broad populations?

In women who are aged 50 or below with invasive breast cancer overall we expect that 5-10% of these women would have a BRCA mutation. That’s why this population in and of itself was already at high risk for having the mutation and, per national practice guidelines, any woman at or below age 50 should be either referred for genetic counselling and/or receive genetic testing.

So with that information in mind what would be the next step?

On top of looking at receipt of genetic testing we went further to look at of these women we were able to determine who had a BRCA mutation. We started with a big population and then based on the results of our survey and then medical records verification we were able to see who in the population had a BRCA positive test. In those women we also looked at our baseline data to see what was their uptake of cancer risk management. Because with the BRCA mutations what that means is any individual with a BRCA mutation has a very high risk of both breast cancer as well as ovarian cancer. In these women who have already had a breast cancer diagnosis the chance of developing another breast cancer is much higher than what we would see in the general population. So there are proven cancer risk management options to manage these higher risks and mainly for breast cancer risk management we have screening options, we have surgical options. For ovarian cancer risk management the main option is surgery. 

So what we looked at was what was the uptake of cancer risk management options in these women with BRCA mutations across the three races. In terms of breast cancer risk management what we found was among the Hispanics and non-Hispanic whites the rates of risk reducing mastectomy were 90% or over; among the blacks they were almost 80%. But then when we looked at the additional percentage that had had screening, high risk screening, either through MRI with mammogram those numbers became a lot more equal and then when we looked further into our data to see there were about four black women that had not had screening or surgery but they were still in active treatment. So they were too early to have had the screening. So, again, we didn’t see much in terms of disparities in uptake of cancer risk management options across the three populations. What we did see is in the group when we looked at the BRCA mutation carriers that had had risk reducing oophorectomy what we found was about 70% of the non-Hispanic white women as well as the Hispanics had had a risk reducing oophorectomy but among the blacks it was just over 30%. That is a very large disparity and we controlled for time since diagnosis, we controlled for many of the variables that could be associated with uptake of risk reducing oophorectomy and we still had statistically significant differences in uptake between the black women compared to the Hispanics and non-Hispanic white women.

So again the issue here to me is what are the reasons for this disparity? If these women are making an informed decision to not have their oophorectomy, that’s OK, versus are they getting the right information to make an informed decision. So that is really the next step of our research and, again, it will be important to follow up cohorts such as ours where you can see what happens over time. Because breast cancer is a devastating diagnosis so if these women choose to act on this information a little bit later that’s OK but we just need to understand why we’re seeing this finding because when you think about genetic testing and disparities the health benefits don’t arise because of the test, they arise because of what you do about the test. So if you get the test and you don’t do anything about it you’ve not benefitted at all. So that’s why when we’re talking about health disparities and genetic testing across different races we need to figure out what it is that they’re doing with this information once they get tested and not just about getting them tested. So that’s where our findings are novel where we really haven’t, at this point, much of the research that has been done has been done at academic centres or through health systems where you have many aspects already covered, whereas ours was population based which means we recruited across the state from many, many different hospitals. So, again, that makes our data quite generalizable within our population but this is one snapshot in time and I do think it’s important to look at follow up.

Well, following up will certainly be definitely something I’ll be keeping an ear out for.

It was a surprise when we saw these differences because even after we controlled for the many factors that could have been playing into our results. Then again you have to remember our sample sizes, we started from a very big population but then it was a subset that were BRCA carriers. So of our carrier population I think it was about fifty or so white women and then thirty-ish or so black women and the Hispanic numbers were even smaller than that. So it is still a limited sample size but even with that limited sample size was saw huge differences in the uptake of risk management for the ovaries.

Is there anything that you would like to add in conclusion or any additional information that you feel we might not have covered?

I do think BRCA testing is a choice but it’s really important that all populations have the opportunity to be given this choice to access the testing. Then in follow-up of that when we’re talking about cancer risk management again it is a choice but they need to be given the appropriate information to be able to make the decision that’s right for them.