Post-menopausal women who are prescribed Tamoxifen to combat breast cancer face a greater risk of recurrence if they have a specific genetic variation federal health advisers warned on October 18, 2006 A panel of FDA advisers strongly suggested the agency change Tamoxifen’s label to warn post-menopausal women of the newest potential risk. New studies discovered that Tamoxifen does not work as well in women with breast cancer who carry a variant of a gene called CYP2D6. Approximately 7% to 10% of women with breast cancer may have this particular form of the gene, which affects how their bodies process the drug.
“The bottom line is, the consensus was that the information is important enough to be included in the label,” said FDA pharmacology chief Dr. Lawrence Lesko. On the other hand, the clinical pharmacology panel left it to the FDA to decide whether the drug’s label should recommend genetic testing of post-menopausal breast cancer patients before they are prescribed Tamoxifen. Still, the FDA will consider adding such language perhaps in the form of a suggestion to the label, Lesko said. Lesko said the label changes could take six months to put in place. Since 2003, the FDA has taken three other drugs before the panel to discuss adding genetic-specific information to their labels. They include the blood-thinner warfarin; updates to its label are forthcoming, Lesko said.
Tamoxifen (Generic: Nolvadex) is a commonly prescribed drug to treat breast cancer increases the chances of stroke, new research shows. Tamoxifen has been linked to cause the following side effects: pulmonary embolism (blood clots in the lung) and cancer of the uterus (womb). Tamoxifen has been prescribed to more than half of all patients suffering from breast cancer, can in some cases actually fuel tumor growth and enhance the probability of a relapse, Swedish researchers recently stated. Since the 1970s Tamoxifen has been widely prescribed to combat breast cancer since it has shown to counteract the cancer-promoting effects of estrogen in the breast by binding itself to the estrogen receptor in the cancerous cell, thus impeding tumor progression.
Based upon new research carried out at the Malmo University Hospital, UMAS, in southern Sweden, Tamoxifen can have the opposite effect on certain types of tumors. “The results show that Tamoxifen is a very resourceful treatment for most patients. But for approximately 15% of tumors that contain many copies of the cell-splitting gene cyclin D1 tamoxifen however appears to have the opposite effect,” researcher Karin Jirstroem said in a statement.
The study conducted by Jirstroem and her colleagues was based on assessments of patients from southern Sweden who had been treated with the drug. It was recently published in the US medical journal Cancer Researcher.
After analyzing nine prior studies the researchers find that Tamoxifen use was associated with an 82% increase in ischemic [clot-related] stroke risk and a 29% increase in the risk for all strokes. The study is published in the October issue of the journal Neurology. The increase in risk translated into seven additional strokes among 1,000 patients taking the drug for five years, according to study co-author Cheryl D. Bushnell, MD.
Millions of women have taken Tamoxifen during the last 30 years, but the risks and benefits of the drug have long been debated. Since the drug can act like an estrogen in certain tissue, it can increase the risk of blood clots and endometrial cancer. It has been unclear whether Tamoxifen use increases a woman’s stroke risk. A recently published review of studies showed almost a 50% increase in the risk of all types of stroke, but Bushnell and colleague Larry Goldstein, MD, of Duke University Medical Center guessed the risk of blood clot-related strokes might be higher.
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