"Breast cancer patients who double the length of time that they take a common medication can sharply reduce their risk of death according to a new study thats predicted to influence medical practice. The study involved an estrogenblocking pill called tamoxifen a standard therapy for the roughly twothirds of breast cancer patients whose tumors are sensitive to estrogen. Taking tamoxifen for five years after diagnosis reduces breast cancer mortality by about onethird. In the new study women with early tumors who took tamoxifen for  years cut their risk of dying from breast cancer by another  compared to women who stopped after five years. In absolute terms  of women on tamoxifen for  years died of breast cancer within five to  years after diagnosis compared to  of those who stopped at five years. Overall women who take tamoxifen for a decade cut their risk of dying from breast cancer nearly in half compared with those who dont take it at all says study coauthor Richard Gray of the University of Oxford in the United Kingdom. Thats significant given that tamoxifen is used by hundreds of thousands of women worldwide says Gray whose study was presented Wednesday at the annual San Antonio Breast Cancer Symposium. Oxford funded the study which included more than  women from  countries While tamoxifen delays tumor growth in some women it appears to cure others Gray says. This is a dream come true for women says V. Craig Jordan a researcher who led tamoxifens development but who wasnt involved in the new study. Its very exciting. Tamoxifen which has been used for decades is far cheaper than most new chemotherapies and biological drugs which cost thousands of dollars a month. A generic version costs about  a month in the USA according to Susan G. Komen for the Cure. In the U.K. tamoxifen costs only  a month. In India its  cents a pill says Jordan scientific director at Georgetowns Lombardi Comprehensive Cancer Center. Jordan says the new findings will quickly change care for some patients. Younger women with more aggressive tumors may want to extend their tamoxifen use says Jennifer Litton an assistant professor at M.D. Anderson Cancer Center in Houston who wasnt involved in the study. Tamoxifen is the only hormonal option for women before menopause Litton says. Doctors may not want to change the care of older patients however she says. Thats because postmenopausal women have the option of tamoxifen or another class of hormonal therapies called aromatase inhibitors or AIs. These drugs are slightly more effective than tamoxifen although they dont work before menopause Litton says. Because the study didnt include AIs doctors cant say how whether tamoxifen would benefit women whove taken them Litton says. Other researchers are conducting trials comparing five versus  years of AIs although these results wont be out for several years. Gray noted that tamoxifen has risks. In his study doubling the length of treament also doubled the risk of endometrial cancer which affects the uterine lining to about . However because this cancer is very treatable death rates were low . of those on tamoxifen for  years died of endometrial cancer compared to . of those taking it for five years. Doctors saw no increase in strokes which has long been a concern with tamoxifen Gray says. Breast cancer survivors have mixed reactions to the results. Some women will be glad to have another treament option says breast cancer survivor Lillie Shockney  administrative director of the Johns Hopkins Cancer Survivorhip Program in Baltimore. Patients get very nervous when they stop any hormonal therapy because they feel like now they arent doing anything says Shockney . The opportunity to do something might be appealing despite the side effects. Shockney says shed like to see research on other ways to prevent recurrences such as weight loss. If someone lost  pounds would that do as much as another five years on tamoxifen Shockney asks. Some patients may be reluctant to prolong their use of a drug that causes so many side effects says Boston breast cancer survivor Alicia Staley. Studies show that only  of women take tamoxifen for five years Litton says. Some switch to an AI although these drugs can also cause problems such as joint pain and osteoporosis. Staley say she tamoxifen gave her many many side effects including severe hot flashes. Dry eyes joint pain weight gain  you name it I had it she says. After  years Staley and her doctor stopped the drug to regain a measure of quality of life. For Shockney tamoxifen took a heavy toll on her marriage causing dryness that made sex unbearably painful. Patients and their partners need to have honest talks with doctors about how extended treatment will affect their relationship she says. If we are going to look at giving women tamoxifen for  years by golly we better get the partners involved Shockney says. Yet Shockney says her husband of nearly  years would have wanted her to do everything possible to survive.  If someone said to my husband I know this has been a rough road for you and a big impact on your sex life but if she stays on it another five years. it could affect her survival he would have said Please please take the pill."