CTA: Is the key challenge with DCIS that you don’t want to miss it but you don’t want to overtreat it?

Dr Chao: That’s exactly right. After all, historical data will show that radiotherapy, while reducing the chances of having recurrence of either future DCIS or invasive breast cancer, has never been shown to reduce mortality. So, despite that, there is a fairly uniform tendency to treat almost all patients with DCIS with radiotherapy after lumpectomy. This has been called into question as to the necessity of such radiotherapy for all patients.


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CTA: Does this test have the same cutoff scores, low, intermediate, and high risk?

Dr Chao: Yes. Perhaps the most relevant cutoff is just simply the cutoff for the low DCIS Score, where in our validation studies we’ve shown that these patients tend to have a lower risk of either invasive breast cancer or DCIS recurrence. Approximately 70% of patients in our validation studies had a low DCIS Score result. That’s quite reassuring for those patients.

Now, for patients with DCIS, it is also important to look at other features, both the patient’s age and the characteristics of the DCIS tumor; the tumor size, for example. These features can also affect the decision to use radiotherapy or not.

CTA: Is there anything else that readers should know about Oncotype DX in terms of how it’s being used now, future plans, or, if people aren’t using it, why they should be using it?

Dr Chao: I’ll make a statement about the decision to test a particular patient or not. We’ve talked about different countries and different propensities to use the test. Obviously, this is a question of both individual and societal values. In general, I would say that most patients could potentially benefit from this test. It’s been shown that the Recurrence Score results are quite independent from traditional pathological features.

You can easily find a low Recurrence Score despite the presence of many poor pathological features, such as high grade, large tumor size, or young age. This is an important finding, because for those patients who have such a low Recurrence Score, the prospective data that we have suggest that this is a patient who can still safely forego chemotherapy.

In fact, this was the basis for the American Joint Committee on Cancer (AJCC) incorporation of the Oncotype DX test in its recently published AJCC Cancer Staging Manual: Edition 8.7 The Recurrence Score result was identified as an important measure of outcome, suggesting that patients who have a score of less than 11 can potentially be down-staged to a stage 1A, despite having pathologic or tumor features that might have otherwise have classified them as a stage 2 cancer. What that really means is that it is important to obtain a Recurrence Score result because it’s an essential piece of information that is needed to properly stage the patient. The AJCC staging criteria are due to be implemented in early 2018.

References

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