I clearly remember reading a pamphlet about a test that might determine with pretty good accuracy whether or not I would benefit from chemotherapy for breast cancer. This was more than a year ago and I hoped, prayed, wished upon a star that I would be a candidate for this test -- and that the result would reveal that I did not need the toxic chemotherapy that I feared with every fiber of my being. But I did not qualify for this test because it's only effective for tumors that are estrogen receptor positive -- and I am negative. So I received chemotherapy and while I've survived it, there still remains an important issue -- did I need it?Tens of thousands of women receive chemotherapy every year when many of them don't really need it. But doctors cannot accurately predict who needs aggressive and harsh treatment so they take the cautious route and treat many women who may not benefit -- and may actually suffer long-term side effects -- from this drug therapy. For women like me, who are estrogen receptor negative, this quandary remains -- and I will never know for sure if I really needed my own chemotherapy. But for those whose tumors are fueled by hormones, the Oncotype DX test -- which in the year since I first read about it, has gained even more attention -- can detect with some degree of certainty the chance that a woman's cancer will recur. If the chance is high -- determined by the test and supporting pathology criteria -- chemotherapy could be warranted. If the chance is low, the breast cancer patient may be spared the torture of this possibly-unnecessary treatment.
Scoring works like this -- 21 different genes from a surgically-removed tumor are studied for interactions that can predict a relapse. A recurrence score greater than 30 makes chemotherapy a safe bet and can increase 10-year survival from 61 to 88 percent. A score of less than 18 indicates that chemotherapy will make no difference in survival rates. The middle scores -- between 18 and 30 -- present a problem. It still is not clear what treatment path women is this gray area should travel.
So there are shortcomings -- women who are estrogen receptor negative and women who are estrogen receptor positive and score between 18 and 30 still may receive the toxic cocktails they do not need. But many women will receive as a result of this test the news of a lifetime -- that chemo is not necessary and that it may actually do more harm than good. And that is what I call progress.
1. In words of nearly the same meaning, I've been saying the same thing on the internet for six years now. "Some tumors send out microscopic outposts while most do not. However, oncologists cannot tell which ones do, so they want to give chemotherapy in nearly every case."
Now there is finally a test, in breast cancer at least, for most women to know they don't really need chemotherapy. This new guideline can help doctors pick who really needs it. "Breast cancer (as well as most cancers) has different causes, arise from different types of cells, is driven by different genes, and tends to be different in women before or after menopause, so 'one-drug(s)-fits-all' is not the solution," says Dr. Robert Carlson, one of the physicians who led a guideline-writing group.
Dr. Larry Norton, breast cancer chief at Memorial Sloan-Kettering Cancer Center, compares it (Oncotype DX) to lab tests that pinpoint a germ so the right antibiotic can be prescribed, called Bacterial Culture and Sensitivity Testing. (see Chemosensitivity Testing)
Oncotype DX has the same data for predictive "accuracy" of Cell Culture Drug Resistance Testing (CCDRT), which was the only data to validate the Oncotype DX test in the first place, which wasn't a prospective study. The Oncotype DX test hasn't been independently validated by any more than the original laboratory group which published the results.
The Journal of Clinical Oncology had published three comprehensive reviews, all of which were largely the exact same paper in which there was no consideration whatsoever of the only type of data which existed to validate any other laboratory test.
If documented clinical "efficacy" is going to be the standard to be demanded of non-proprietary laboratory tests, then clinicians should abandon all tests currently used in their practices. None of the available laboratory tests used in the selection of treatment for cancer patients have ever been tested for "efficacy." This includes estrogen receptor, progesterone receptor, Her2/neu, immunohistochemical staining for tumor classification, Bacterial Culture and Sensitivity testing, CT, MRI and Pet Scans to measure tumor response to treatment, and cell culture assays. The only data supporting any of them relate to test "accuracy," and there is a total lack of information regarding test "efficacy" (randomized trials with outcome measurements for diagnostic tests).
No one is seriously proposing that any of the molecular tests now available (Oncotype DX, EGFR amplification/mutation) should have to be proven "efficacious," as opposed to merely "accurate," before they are used in clinical decisions regarding treatment selection.
All these laboratory tests are a tool for the oncologist. The oncologist should take advantage of all the tools available to him/her to treat a patient. And since studies show that only 25-30% of patients do respond to chemotherapy that is available to them, there should be due consideration to looking at the advantage of using these tests.
In virtually all forms of cancer, clinical trials have failed to identify best drug regimens for use in all individuals with a given form of cancer. There should be an expansion of Medicare and private insurance reimbursement to promote even greater utilization and development of laboratory-based mechanisms for improving the match between tumors and an ever-increasing number of partially effective and very expensive drug therapies.
Posted at 1:57AM on Jun 14th 2006 by Gregory D. Pawelski