The reason for that is that the influenza virus has a rapid rate of mutation, forcing companies that manufacture the vaccine to make their best guess as to which flu types will be more prevalent in a given season.
In a global study conducted by Dr. Steven Narod, senior scientist at Women's College Research Institute in Toronto, the United States had the highest rate of prophylactic mastectomy in BRCA1 and BRCA2 mutation carriers.
In the trial, which included 55 patients, tumors dramatically shrank in 9 of 16 very advanced patients with the gene mutation who got high doses--a better response rate than doctors have remembered seeing in a trial for advanced melanoma.