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CD 1, Tracks 13-14

DR RAVDIN: Sandy Swain wrote an editorial following publication of the results from the Oncotype DX assay with the NSABP-B-20 data set entitled “A Step in the Right Direction” (Swain 2006).

She estimates that this assay could potentially spare 50,000 women per year treatment with chemotherapy on the basis of prognosis alone (Swain 2006). I would agree with her, but we also have ways of doing this on the basis of tumor size and grade.

She also commented that estrogen receptor measurements by IHC are not quantitated. So even if you wanted to use some of these other methods, they might not be as reliable as the Oncotype DX test. Some patients with high ER also have a high recurrence score. So if you simply used high ER as a correlate for chemotherapy responsiveness or, in this case, resistance, you would be fooled sometimes.

Dr Swain’s conclusion was that the recurrence score appears to be beneficial in predicting which patients will benefit and which will not (Swain 2006). However, the recurrence score is only the beginning. I believe we’d all agree that this is a very useful test, but I hope it is something that will be refined.

If you agree with Sandy Swain’s editorial, you might conclude that all patients with node-negative, ER-positive disease should be tested with the Oncotype DX assay. The major caveat is that NSABP-B-20 did not use modern regimens that we utilize in the clinic today. The chemotherapy in that trial was M F or CMF, and it was always used in combination with tamoxifen (Paik 2006), so tamoxifen might have had confounding effects on the results.

How much benefit was seen from the chemotherapy in this trial? If you look at the 10-year results, you see effectively no benefit in the low-risk group. The high-risk group showed a dramatic benefit — about a two thirds reduction in the risk of the development of metastatic disease (Paik 2006).

DR GEYER: I believe the recurrence score helps in counseling a woman about the importance of chemotherapy for her situation. If she has a high recurrence score, chemotherapy is the dominant part of her therapy. If she has an intermediate recurrence score, I believe the main part is the hormonal therapy, but that’s not to say chemotherapy isn’t helpful.

We need to develop an understanding of the importance of the various components. The Oncotype DX results provide counseling information about the risk-to-benefit ratio that is relevent when women run into toxicities, for example — how far should they persevere through toxicities.

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