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Prévention du Cancer du Sein

MAJ 2004
Le raloxifène (EVISTA*) réduit le risque de cancer du sein chez les femmes âgées
Source : American Society of Clinical Oncology (ASCO) annual meeting, New Orleans, June 6, 2004
Résumé :
Le résultat de longues études cliniques a confirmé que le raloxifène (EVISTA*)réduit le risque de cancer du sein chez les femmes ménopausées présentant une ostéoporose. De ce fait, le raloxifène pourrait être indiqué dans la prévention du cancer du sein chez ces catégories de femme. Rappelons que le raloxifène est indiqué principalement dans le traitement de l'ostéoporose post-ménopausique avérée avec au moins une facture ostéoporotique.

Source : Cummings JAMA 1999 june 25
Les patientes traitées par le raloxifène, modulateur sélectif des récepteurs aux oestrogènes pour ostéoporose post-ménopausique pendant 3 ans, ont une diminution de 76 % du taux de découverte d'un cancer invasif du sein, d'après une étude publiée dans JAMA. .
Les travaux d'oncogénétique pourraient alors retrouver un intérêt majeur.

Le raloxifène aurait des effets oestrogéniques sur l'os, le métabolisme lipidique, la coagulation, mais reste sans effet oestrogénique sur le sein et sur le tissu endométrial. La molécule se fixe sur les récepteurs d'oestrogènes et bloque les effets sur le sein et l'endomètre mais active les récepteurs qui ont un effet bénéfique sur l'os.

Trois années de traitement diminuent le risque de fracture vertébrale, mais pas les autres fractures, diminuent le cholestérol total et le LDL.
Un tel traitement augmente le risque de complications thromboemboliques, trois fois plus élevées dans le groupe raloxifène par rapport au placebo, ce qui contre-indique le traitement chez les patientes ayant des antécédents thromboemboliques.

Source :
Eli Lilly and Co.’s osteoporosis drug Evista ® (raloxifene hydrochloride) appears to reduce the incidence of newly-diagnosed invasive breast cancer, potentially the most serious type of breast cancer, by 63 percent among postmenopausal women taking the therapy for more than three years.

Additional three-year findings from the largest of these placebo-controlled studies show that Evista also has significant benefits on vertebral (spinal) fractures and cholesterol levels.

The new breast cancer data will be reported tomorrow (Dec. 12) at the 21st San Antonio Breast Cancer Symposium by V. Craig Jordan, Ph.D., director, Lynn Sage Breast Cancer Research Program, Robert Lurie Comprehensive Cancer Center, Northwestern University and chairman of the Evista Oncology Advisory Board.

"This is a significant breakthrough in women's health," Jordan said. "Not only is Evista helping a woman prevent bone loss and the development of vertebral fractures after menopause, but it's also continuing to reduce her risk of breast cancer over time. The reductions in breast cancer risk seen to date in these trials are extremely important and provide invaluable information for the additional large-scale testing of Evista in the prevention of breast cancer."

These data, an update from those presented earlier this year at the American Society of Clinical Oncology, were gathered from 10,575 postmenopausal women enrolled in 10 randomised, double-blind, placebo-controlled osteoporosis studies. The women, who ranged in age from 31 to 80, were taking daily Evista therapy for a median follow-up of 40 months and a maximum follow-up of 55 months. Overall, there was a 55 percent reduction in risk for all types of breast cancer among postmenopausal women taking Evista.

Approximately 7,700 of these women are participating in the six-year Multiple Outcomes of Raloxifene Evaluation (MORE), an ongoing osteoporosis treatment study. The remainder are healthy postmenopausal women enrolled in osteoporosis prevention trials. Women were not enrolled in these trials based on breast cancer risk.
Mammograms were routinely performed on an annual or biannual basis in all placebo-controlled trials of at least 12 months in duration.
Data from the three-year analysis of the MORE study confirms additional benefits with Evista therapy. As observed earlier, women taking Evista were no more likely to have vaginal bleeding than those taking placebo. Vaginal bleeding is a side effect common to conventional hormone replacement therapies.
In addition, Evista did not increase endometrial cancer risks.
Estrogen therapy alone has been linked to an increased risk of endometrial cancer and postmenopausal women with a uterus must usually take a progestin drug along with the estrogen to reduce this risk. Evista does not require concurrent use of any progestin drug.
Women taking Evista continued to realise significant reductions in total cholesterol (about eight percent), LDL (more than 12 percent) and fibrinogen (more than 12 percent). Evista had a neutral effect on triglycerides and HDL.
By three years of treatment, Evista therapy supplemented with calcium and vitamin D reduced an osteoporotic woman's risk of a first spinal fracture by 55 percent and an osteoporotic woman's risk of second or subsequent spinal fractures by 30 percent compared with women receiving only placebo supplemented with calcium and vitamin D. Spinal fractures are the most common of all osteoporosis-related fractures and tend to strike women at a younger age than fractures of the hip, wrist and ankle.

"This finding should send a strong message to women that mineral supplements alone may not be enough to protect your bones if you are at risk for osteoporosis after menopause," Jordan said. "Taken together, Evista data validate the potential of SERMs to prevent osteoporosis and reduce the likelihood of fractures, and at the same time, reduce the incidence of breast cancer," he added.

Evista is currently indicated for the prevention of postmenopausal osteoporosis. Evista is the only selective estrogen receptor modulator (SERM) available in the U.S. to protect postmenopausal women against the rapid loss of bone that occurs after menopause and often leads to thinning bones, osteoporosis and fractures. Evista is approved for marketing in 36 countries world-wide.

As with most therapies, Evista is associated with some side effects, the majority of which were reported as mild. A rare but serious side effect is blood clots in the veins, which occurred in clinical trials at a rate similar to that reported for current users of estrogen or hormone replacement therapy. The most-commonly reported side effects in clinical trials were hot flashes and leg cramps, although most women did not find these events serious enough to discontinue therapy. Evista is contraindicated in women who are or may become pregnant because preclinical data suggest Evista can cause fetal harm. Related Links: Eli Lilly and Co.
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