November 2, 2012.
Initial experimentation with vitamin D treatment in four bladder cancer cell lines resulted in the observation of an arrest of growth and higher levels of FGFR3 in cells with low expression of the protein. (The presence of FGFR3 overexpression and mutations characterize a group of nonmuscle-invasive bladder cancers with good prognosis.) The researchers then compared 1125 patients with urothelial bladder cancer with 1,028 control subjects who participated in the Spanish Bladder Cancer/EPICURO Study. Plasma samples obtained at the time of diagnosis were analyzed for 25-hydroxyvitamin D3 and tumor tissue was analyzed to determine FGFR3 mutational status and expression.
Participants were categorized as having vitamin D levels that were sufficient at 30 ng/mL or higher, insufficient at 20-29.99 ng/mL, slightly deficient at 15-19.99 ng/mL, moderately deficient at 10-14.99 ng/mL, or severely deficient at less than 10 ng/mL. Those with 25-hydroxyvitamin D levels that were slightly, moderately or severely deficient had an over 50 percent greater risk of bladder cancer in comparison with participants whose levels were sufficient. The association of vitamin D deficiency with bladder cancer appeared to be stronger among smokers and for those with muscle-invasive tumors, particularly among those with low FGFR3 expression.
"This is the largest study assessing the risk of UBC in relation to 25-hydroxyvitamin D3 levels and the first one analyzing this association in the context of the molecular features of the tumor and the biological effects of vitamin D," the authors announce. "Because FGFR3 mutation and overexpression are markers of better outcome, our findings suggest that individuals with low levels of plasma 25(OH)D3 may be at high risk of more aggressive forms of urothelial bladder cancer."
