Oncotype DX Test: Risk and Recurrence in Breast Cancer, with Gonomic Health’s Kim Popovits

The Recurrence Score predicts the likelihood
of disease aggressiveness, so what we were attempting to do when we did the test for
invasive breast cancer was to figure out which women had disease that would be more aggressive
and could potentially benefit from more aggressive treatment. And what we discovered when we
developed that assay, the 21-gene assay, was that not only could we predict which patients
had a likelihood of their disease recurring over a 10-year period, we did subsequent studies
to show that we could also predict whether those women would benefit from chemotherapy.
We ended up in a situation where we had 50% of women in a low-risk group, 25% in an intermediate-risk
group, and 25% in a high-risk group. Even better than that, we were able to give an
individual score to each patient. When we designed the studies initially, we were hoping
to be able to identify risk groups, and we were very pleased that not only could we identify
certain risk groups, we could actually give women an individual score to show them their
likelihood of recurrence. For example, if you get a Recurrence Score of 7, that correlates
to a specific likelihood of recurrence over a 10-year period. We can also tell you if
your cancer is likely to benefit from chemotherapy. One fact that a lot of people are unaware
of is that about 100,000 women are diagnosed each year with early-stage breast cancer,
ie, estrogen receptor–positive, node-negative breast cancer. Most of those women, prior
to Oncotype DX being available, would have been recommended chemotherapy based on cancer
practice guidelines. What’s unfortunate there is that while most
would have been recommended chemotherapy and most would have received it, most would not
have benefited, because we know that only 3% to 4% of women with early-stage breast
cancer actually benefit from chemotherapy. So we’re treating 100 women to find 3 or
4 who get some benefit, and that’s what we were trying to change.
The Oncotype DX assay allows us to tell 50% of these women that they have very low-risk
disease. Their likelihood of recurrence is very low, and further, we can tell them that
their disease isn’t likely to be impacted by chemotherapy. Conversely, we can tell those
women who are in the high-risk group that they have a high risk for disease recurrence,
and while that’s not necessarily good news, the good thing for these women is that chemotherapy
actually will help them a good bit.

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