EDINBURGH, Scotland, June 18 Hormone therapy can extend life in ovarian cancer patients, giving women an alternative to chemotherapy, a University of Edinburgh study in Scotland says.The study, published in Clinical Cancer Research, found targeted use of an anti-estrogen drug could prolong the life of some patients by up to three years, and delay the use of chemotherapy in others.Letrozole hormone therapy -- already used successfully in the treatment of breast cancer -- attacks cancer by turning off its estrogen supply and now scientists believe that in those ovarian cancers which are highly sensitive to estrogen, this blocking mechanism could slow the growth and spread of disease.Study leader John F. Smyth, of the University of Edinburgh, used a blood-borne tumor marker, CA-125, to track the progress of tumors during hormone treatment. Twenty-five percent of the women showed no tumor growth after six months of anti-estrogen therapy and 33 percent of the group with the showed a positive response which delayed the use of chemotherapy.Copyright 2007 by UPI