For colorectal cancer, a systematic review identified RCTs of vitamin E and placebo followed for 7–10 years. There was a non-significant 11% decrease in relative risk. The SELECT trial (men over 55 years, placebo or 400 IU/day) also reported on colorectal cancer. There was a non-significant 3% increase in adenoma occurrence compared to placebo. The Women's Health Study compared placebo to 600 IU of natural-source vitamin E on alternate days for an average of 10.1 years. There were no significant differences for incidences of all types of cancer, cancer deaths, or for breast, lung or colon cancers.