The findings were published in the Nov. 5 issue of TheJournal of the American Medical Association.
From 1998 to 2005, researchers at the Brigham and Women's Hospital and Harvard Medical School examined 5,442 female health professionals who had a history of cardiovascular disease, or at least three risk factors associated with the disease's onset. The women were 42 years and older.
The researchers hoped to evaluate the effect of folic acid, vitamin B6, and vitamin B12 (vitamins believed to play an important role in cancer prevention) on the risk of cancer among women susceptible to developing heart disease.
At the beginning of the trial, the women were divided into two groups. The first group received a daily supplement of folic acid, vitamin B6, and vitamin B12. The second group received a placebo.
For the next 7.3 years, each of the participants received vitamin packs containing their medication as well as questionnaires on adherence, adverse effects, overall health, and risk factors.
The results show that out of the 5,442 participants, 379 of them developed invasive cancer. One hundred and eighty seven of those had received the supplement combination, and 192 the placebo.
"Compared with placebo, women receiving the active treatment had similar risk of developing total invasive cancer, breast cancer, or any cancer death," wrote the study authors, who include Shumin M. Zhang, MD, ScD.
Interestingly, a significantly reduced risk for total invasive cancer and breast cancer was noticed among women who were 65 years or older when the study began. However, no reductions in risk were seen in women who were younger at the start of the study.
"If the finding is real and substantiated, the results may have public health significance because the incidence rates of cancer are high in elderly persons. The finding is biologically plausible because elderly individuals have increased requirements for these B vitamins," the study authors write.
In the end, the study concludes that the combination of folic acid, vitamin B6, and vitamin B12 didn't affect the overall risk of total cancer, breast cancer, or deaths from cancer among women at high risk for cardiovascular disease.