Significant progress is being made in the prevention and treatment of ovarian and breast cancer, according to findings discussed at a global oncology conference. \"The studies presented at this meeting show impressive progress in disease control and prevention of breast cancer,\" said Dr. Andrew Seidman, professor of medicine at Cornell University. \"Also, two consistent studies demonstrated the benefit of adding bevacizumab (Avastin) to standard chemotherapy for ovarian cancer,\" he added. Avastin, produced by Swiss biotech giant Roche, blocks the development of blood vessels needed for tumor growth. A clinical trial showed a 52 percent reduction in the risk of progression of recurrent ovarian cancer in women who took Avastin in combination with platinum-based chemotherapy. The most striking finding at the 47th annual meeting of the American Society of Clinical Oncology was that Aromasin, which blocks the production of estrogen, reduced by 65 percent the risk of breast cancer in high risk post-menopausal women. Close to three-quarters of breast cancer tumors need estrogen to grow. Annually, there are 1.3 million new cases of breast cancer and nearly 500,000 women die worldwide. In the United States, only lung cancer accounts for more deaths in women. Paul Goss of Harvard Medical School and lead author of the study on exemestane sold under the brand name Aromasin said it\'s the \"first major clinical trial\" in the past 10 years on breast cancer prevention. \"Exemestane may be considered a new option for the prevention of breast cancer,\" Goss said during a press conference. The clinical study was conducted from 2004 to 2010 and enrolled 4,560 women from the United States, Canada, Spain and France who had at least one major risk factor such as being age 60 or older, or having prior breast cancer tumors, including breast cancer with mastectomy. Half the participants received Aromasin, produced by US pharmaceutical giant Pfizer, and half were given a placebo. After a period of three years, the Aromasin group had about one third as many invasive cancers as those in the placebo group a result corresponding to what researchers expected at the beginning of the trial, Goss said. Aromastate inhibitors like exemestane are distinct from other anti-estrogen therapies such as tamoxifen and raloxifene, which have been approved by the US Food and Drug Administration as preventative therapies for women at high breast cancer risk. Exemestane, too, has been approved by the FDA, for use in early breast cancer patients. The most common side effects reported by Aromasin users include fatigue, hot flashes, insomnia and joint pain. Also Saturday, researchers said extra radiation treatment lowers the rate of breast cancer recurring in women who have had tumors surgically removed. More than 1,800 women participated, receiving whole breast radiation (WBI) alone or WBI along with radiation to the surrounding lymph nodes. Five years later, women who received radiation treatment to the breast and lymph nodes had a 41 percent lower rate of recurrences near the tumor site and a 36 percent lower rate of cancer recurrences in other parts of the body. \"These results are potentially practice-changing,\" said Timothy Whelan, an oncology professor at McMaster University of Canada and lead author of the clinical study. Dr. Howard Scher, a leading cancer researcher from Memorial Sloan-Kettering Cancer Center in New York presented the findings of a study on cancer cells. The number of cancer cells that have broken off from the tumor and reached the blood stream affects the survival rate of patients suffering from advanced stages of prostate cancer, he said. One of the problems preventing progress in the fight against cancer is identification of reliable early indicators that may signal whether a treatment can prolong the life of a patient, Scher explained. A Phase III trial known as COU-AA that involved 1,195 patients showed that the drug Zytiga developed by US laboratory Johnson and Johnson significantly improved overall survival in patients with metastatic castration-resistant prostate cancer. The drug helped reduce the number of circulating tumor cells from \"unfavorable\" to \"favorable\" counts, the researchers said. The findings could affect development of future treatment procedures because these markers could be used to evaluate the effectiveness of a new therapy in prolonging the patient\'s life, replacing clinical trials that are longer and more expensive.