Navigation Links
Ability to metabolize tamoxifen affects breast cancer outcomes, Mayo Clinic-led study confirms

ROCHESTER, Minn. -- For nearly a decade, breast cancer researchers studying the hormone therapy tamoxifen have been divided as to whether genetic differences in a liver enzyme affect the drug's effectiveness and the likelihood breast cancer will recur. A new study by researchers from the Mayo Clinic Cancer Center and the Austrian Breast and Colorectal Cancer Study Group provides evidence that genetic differences in the enzyme CYP2D6 play a key role in how well tamoxifen works.

"Our findings confirm that, in early breast cancer treated with tamoxifen, genetic alterations in CYP2D6 lead to a higher likelihood of recurrence and death," says Mayo Clinic oncologist Matthew Goetz, M.D., lead author of the study in the journal Clinical Cancer Research.

In the clinical trial, Dr. Goetz and his colleagues studied the rates of cancer recurrence and death in two groups: postmenopausal women with primary estrogen receptor-positive breast cancer who received tamoxifen for five years and those who received tamoxifen for two years followed by the aromatase inhibitor anastrozole for three years. Anastrozole is a breast cancer drug whose metabolism does not require the CYP2D6 enzyme.

The study showed that women who were born with genetic alterations of CYP2D6 that abolish the enzyme's critical metabolizing activity and who took tamoxifen for five years had recurrence of breast cancer, or died at a rate 2.5 times higher than women with normal CYP2D6 enzyme activity. Women with intermediate levels of the CYP2D6 enzyme had rates of recurrence or death 1.7 times higher than women with normal CYP2D6 activity. Importantly, Dr. Goetz notes, that genetic alterations in CYP2D6 did not affect the likelihood of recurrence or death in women who switched to anastrozole after two years of tamoxifen.

"Switching from tamoxifen to an aromatase inhibitor may be one reason for the discrepant studies surrounding CYP2D6 and tamoxifen -- as information about whether a patient took an aromatase inhibitor after tamoxifen was not available in most of the prior studies," says senior author James Ingle, M.D., of Mayo Clinic, an expert on hormone therapies for breast cancer.

A blood test can determine whether a woman has alterations in CYP2D6 and predict how efficiently her body will convert tamoxifen to endoxifen. Approximately 5 to 7 percent of European and North American populations are considered poor metabolizers of tamoxifen.

"The results of this successful high-level international research collaboration are an important step forward in our quest to individualize breast cancer treatment and provide tailored care to women with breast cancer," says Michael Gnant, M.D., professor of surgery at the Medical University of Vienna and president of the Austrian study group.

So what should a woman do if she is unable to effectively metabolize tamoxifen into its most active form? Dr. Goetz believes that the current recommendation of switching from tamoxifen to an aromatase inhibitor is likely to result in the greatest benefit in women with decreased CYP2D6 metabolism. For CYP2D6 poor metabolizers, avoiding tamoxifen altogether and starting out with an aromatase inhibitor may be the best approach, he says.

Dr. Goetz's group is working with the National Cancer Institute to develop endoxifen as an alternative to tamoxifen. If women can be given endoxifen, the active part of tamoxifen, it won't matter how tamoxifen gets metabolized, he says.


Contact: Joe Dangor
Mayo Clinic

Related medicine news :

1. Kentucky Social Security Disability Benefits Lawyer with The Frank Jenkins Law Office Voices Support for Recent Expansion of Compassionate Allowance Program
2. Ability to sit and rise from the floor is closely correlated with all-cause mortality risk
3. New IDSA guidelines aim to reduce death, disability, and cost of prosthetic joint infections
4. Attitudes predict ability to follow post-treatment advice
5. Exercise affects reproductive ability in horses
6. Tackling urban sustainability on global scale
7. New Canless Air Sytem Offers Solutions to Business Sustainability and the Bottom Line
8. NJ Accident Lawyers at Console & Hollawell React to New Motorcycle Crash Data from the U.S. Government Accountability Office
9. Upbeat View on Old Age May Help Seniors Bounce Back From Disability
10. Researchers find decline in availability and use of key treatment for depression
11. GHSU researcher assesses driving capability in MS patients
Post Your Comments:
(Date:6/24/2016)... ... , ... People across the U.S. are sharpening their pencils and honing their ... in which patients and their families pay tribute to a genetic counselor by nominating ... of Genetic Counselors (NSGC) Annual Education Conference (AEC) this September. , In April, ...
(Date:6/24/2016)... New York, NY (PRWEB) , ... June 24, ... ... lifestyle publication Haute Living, is proud to recognize Dr. Barry M. Weintraub as ... believes that “the most beautiful women in the world, and the most handsome ...
(Date:6/24/2016)... ... June 24, 2016 , ... Strategic Capital Partners, LLC (SCP) ... obtaining investment capital for emerging technology companies. SCP has delivered investment events ... in more than a million dollars of capital investment for five companies. ...
(Date:6/24/2016)... ... 2016 , ... Venture Construction Group (VCG) sponsors Luke’s Wings ... at the Woodmont Country Club at 1201 Rockville Pike, Rockville, Maryland, 20852. The ... members that have been wounded in battle and their families. Venture Construction Group is ...
(Date:6/24/2016)... (PRWEB) , ... June 24, 2016 , ... ... is supporting the upcoming 2016 Miss Arizona pageant as its official Medspa Sponsor. ... Scottsdale, Tempe, Mesa, and Chandler, Arizona. , Dr. Olson says the decision ...
Breaking Medicine News(10 mins):
(Date:6/23/2016)... June 23, 2016 Bracket , a leading ... next generation clinical outcomes platform, Bracket eCOA (SM) 6.0, ... June 26 – 30, 2016 in Philadelphia ... Clinical Outcome Assessment product of its kind to fully integrate ... Bracket eCOA 6.0 is a flexible platform for electronic ...
(Date:6/23/2016)... LONDON , June 23, 2016 ... environments  Oticon , industry leaders in ... the launch of Oticon Opn ™, the world,s ... world of possibilities for IoT devices.      ... Opn, Oticon introduces a number of ,world firsts,: ...
(Date:6/23/2016)... , June 23, 2016  Experian Health, ... and transforming the patient payment and care ... innovative new products and services that will ... revenue cycle offerings. These award-winning solutions will ... workflows, remain compliant in an ever-changing environment ...
Breaking Medicine Technology: