"Over the follow-up period, there were 341 deaths from cancer: 154 among participants who took vitamin D (1.1%) and 187 among those who took the placebo (1.4%). Although this difference was not statistically significant, the difference in cancer deaths between the groups started to widen over time, the researchers reported.
The researchers plan to follow the participants for another 2 to 5 years, to see if a statistically significant difference in cancer deaths emerges. Laboratory studies have suggested that high blood levels of vitamin D may decrease the aggressiveness of cancer cells and the likelihood of metastasis, explained Dr. Manson. If so, longer follow-up will be needed to assess its effects on the risk of death from cancer, she added. Other studies have suggested that regular use of vitamin D supplements may reduce the risk of dying from cancer, she said."
So they're still continuing to follow that up long term to see if it has a longer term effect.