What does it mean when tumors change receptor status in retesting?

Forty-one percent of breast cancer tumors changed receptor status following neoadjuvant chemotherapy (before surgery) in a recent study presented at the 2013 Breast Cancer Symposium in San Francisco (Abstract 48).  For example, this means that an estrogen-receptor-negative tumor might have changed to an estrogen-receptor-positive tumor, or vice versa.  Specifically:

• 20 percent changed from hormone receptor positive to HER2-positive or triple-negative

•12.5 percent changed from HER2-positive to triple-negative;

• 2 percent changed from triple-negative to HER2-positive.

A change in receptor status change was associated with improved recurrence-free survival but had no impact on overall survival.

At a median follow-up of 40 months, 5-year overall survival was 73 percent for patients with a change in receptor status and 63 percent for those with no change; 5-year recurrence-free survival was 63 percent and 48 percent. 

To clarify: patients whose tumor changed receptor status had fewer recurrences, but they did not live longer overall. So, basically, for those of us who are interested in living through cancer—as in, all of us—the results are pretty much a washout.   Remember, though, overall survival means those who are still alive at the end of the study, with deaths related to any cause, not just cancer.  

What is most significant to me, though, is the whole issue of tumor status change in the first place.  Did the tumors actually change, or were the tests  inaccurate to begin with? Or was the second test flawed? Lajos Pusztai, MD, PhD, of Yale Cancer Center told Ob. Gyn. News that the problem could just be technical problems with the testing.  And, he says, when tumors are retested, they change receptor status 20 percent of the time, whether they have been treated or not.

So if your doc mails your tumor sample to a different lab, you have a 20 percent chance that its receptor status will be different in retesting.  That is, if you originally tested estrogen-receptor-negative, and had those results sent to a different cancer center, your tumor could end up testing as estrogen-receptor-positive in the new analysis.

But, Pusztai says, you should still have the same therapy, even if your receptor status varies:

“It would be dangerous to actually withhold endocrine therapy or anti-HER2 therapy when tumors turn negative on a second assay. You don’t know which assay may be wrong. Be very careful in making decisions based on conflicting results.”

To this I say, WHAT, WHAT, WHAT?????  TNBC tumors get some heavy chemo—does he say we should go through with that even if we might not actually have TNBC?  Is this why some TNBC tumors respond to tamoxifen—because they weren’t actually TNBC?

I say, challenge any inconsistency.  If you can afford it, get retested and, if there is a discrepancy, ask for a third test.   Cancer treatment is no picnic and you want to be sure your treatment is geared correctly to your cancer.

• Read more about TNBC in my book, Surviving Triple-Negative Breast Cancer.

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