Navigation Links
Common Breast Cancer Gene Test May Be Flawed, Study Says

By Amanda Gardner
HealthDay Reporter

FRIDAY, Nov. 4 (HealthDay News) -- A widely used breast cancer test may not be accurate in identifying a gene that is critical in determining which life-saving treatment a woman should get.

The Oncotype DX, marketed by Genomic Health, results in a number of false-negatives for the HER2 gene, according to a study published Oct. 18 in the Journal of Clinical Oncology.

Women who test positive for the gene typically receive the targeted therapy Herceptin (trastuzumab) along with other medications to reduce their chances of recurrence and death.

"Women could be getting the completely wrong treatment," said study lead author Dr. David J. Dabbs, a professor and chief of pathology at Magee-Womens Hospital of the University of Pittsburgh Medical Center.

But, according to Dr. Lori J. Goldstein, director of the Breast Evaluation Center at Fox Chase Cancer Center in Philadelphia, the Oncotype DX test, which actually measures 21 different genes, was not designed to test for HER2, nor is it intended as a substitute for two other widely used and accepted lab tests.

"None of us would request Oncotype for the sole purpose of getting HER2," she said. "We're usually ordering it for other reasons and, as part of that test, we get HER2."

Oncotype has been shown to be reliable in identifying estrogen receptor-positive and progesterone-positive tumors, she added.

The only two valid assays for HER2 are immunohistochemistry (IHC) and fluorescent in situ hybridization (FISH). Both are approved by the U.S. Food and Drug Administration (FDA).

Genomic's Oncotype employs reverse transcription polymerase chain reaction (RT-PCR) to check for HER2.

HER2 is overactive in 15 percent to 20 percent of breast cancers and usually signals more aggressive disease, according to background information in the study.

To test the accuracy of Oncotype DX in assessing HER2 status, the researchers compared results from all three tests for 843 patients who had had samples tested at three laboratories, one in Pittsburgh and two in Ohio.

When results were negative with IHC and FISH, they were also generally negative with Oncotype.

But all 23 equivocal results as reported by IHC and FISH came out negative with Oncotype, the investigators found.

Only 28 percent of positive IHC and FISH results also came up positive with the Oncotype, while 33 percent came out as equivocal and 39 percent as negative.

"Anyone who has had this test performed needs to make sure that their hormone-receptor analyses were done by other FDA-approved methods and not rely upon this test alone," said Dabbs.

Overall, though, only a small proportion of tumors among the 843 women were HER2-positive, noted Goldstein, which could have biased the results.

And, in a statement provided to HealthDay, Genomic Health disagreed with the findings, proposing that the "conclusions appear to be one-sided" and require additional data.

The discordances between tests are "not uncommon" and because of those discrepancies the company began including RT-PCR measurement of HER2 in Oncotype "with the goal of providing added clarity in cases where HER2 results by IHC and FISH are uncertain or conflicting," according to the statement.

HER2 status "should be assessed in all patients by IHC and/or FISH," the company also stated.

A 2010 study funded by Genomic Health found that RT-PCR results actually did agree with FISH results.

More information

The U.S. National Library of Medicine has more on breast cancer.

SOURCES: David J. Dabbs, M.D., professor and chief, pathology, Magee-Womens Hospital, University of Pittsburgh Medical Center; Lori J. Goldstein, M.D., director, Breast Evaluation Center, Fox Chase Cancer Center, Philadelphia; Oct. 11, 2011, statement, Genomic Health; Oct. 18, 2011, Journal of Clinical Oncology

Copyright©2010 ScoutNews,LLC.
All rights reserved  

Related medicine news :

1. Adapting to clogged airways makes common pathogen resist powerful drugs
2. A common cholesterol drug fights cataracts, too
3. U.S. National Guard Connects Nationwide with Desktop Alert's Command and Control Mass Notification Systems and Common Alerting Protocol (CAP)
4. US21, Inc. is Granted a Wholesale Distributor Permit from the Commonwealth of Virginia Board of Pharmacy
5. New therapeutic target for most common solid cancer in childhood?
6. Migraine More Common in Women with MS
7. Contrast-enhanced MRI could play a key role in differentiating between common types of arthritis
8. Six "Common Sense" Points Not Included In The Health Care Discussion? Should They Be?
9. Six "Common Sense" Points Not Included In The Health Care Discussion? Should They Be?
10. Common osteoporosis drugs are associated with a decrease in risk of breast cancer
11. Commonwealth Leverage Group and Helium Interactive Form HIE Go-To-Market Partnership
Post Your Comments:
Related Image:
Common Breast Cancer Gene Test May Be Flawed, Study Says
(Date:12/1/2015)... ... 02, 2015 , ... Ruth Pearson was struggling. She had been laid off ... assistance and quickly losing hope of recovering her former life, Pearson was desperate for ... attending a women’s retreat when she experienced a particularly impactful worship service. Without help ...
(Date:12/1/2015)... ... December 01, 2015 , ... On Tuesday ... to NASDAQ to educate the personnel on spinal decompression therapy and offer his ... a nonsurgical procedure. The benefits come from creating negative intradiscal pressure which is ...
(Date:12/1/2015)... ... December 01, 2015 , ... Henderson, a ... to receive Gigabit Internet through a partnership this year with Aeneas Internet and ... is an attractive destination for entrepreneurs who want to build a business. Whether ...
(Date:12/1/2015)... ... , ... Florida Hospital Tampa is the first health care provider in the region ... , vBloc® Therapy is a vagal blocking therapy, delivered via the Maestro® System, for the ... (BMI) of at least 40 to 45 kg, or a BMI of at least 35 ...
(Date:12/1/2015)... (PRWEB) , ... December 01, 2015 , ... Califia ... today announced that its iconic bottle has won top honors in Beverage World Magazine’s ... The Company also announced that it has been selected as a 2015 U.S.A. Taste ...
Breaking Medicine News(10 mins):
(Date:12/1/2015)... --> --> ... by Type of Drug (Monoclonal Antibodies, Interferon-Alpha, Interleukins, Vaccines, (Therapeutic ... Analysis - Global Forecast to 2020", published by MarketsandMarkets, the ... Million by 2020 from USD 40,281.6 Million in 2015, at ... Browse 37 market data T ...
(Date:12/1/2015)... 2015 Assurex Health, Inc. today announced ... healthcare providers an expanded range of options in ... from depression, anxiety, bipolar disorder, posttraumatic stress disorder ... i .   --> ... addition of two new drug classes, 17 FDA-approved ...
(Date:12/1/2015)... , Dec. 1, 2015  Six months of adjunctive metformin ... type 1 diabetes, according to new research from T1D ... it may have a beneficial effect on measures of obesity, ... issue of the Journal of the American Medical Association ... the effect of metformin on overweight and obese adolescents with ...
Breaking Medicine Technology: