According to the Alternative Health Journal Blog, folic acid, B6 and B12 have been linked to a decreased risk of breast cancer in women. The study began in 1998, and involved 5442 women over the age of 42. The reference is as follows:

Reference:

“Effect of combined folic acid, vitamin B6, and vitamin B12 on cancer risk in women: a randomized trial,” Zhang SM, Cook NR, et al, JAMA, 2008; 300(17): 2012-21.