Vitamin D levels and survival in colorectal cancer (CRC).

Background: Higher serum D levels are associated with decreased incidence of CRC. However, the prevalence of vit D deficiency at CRC diagnosis is not documented; most published studies measured vit D levels years prior to CRC diagnosis. We therefore conducted a retrospective study of baseline vit D levels in newly diagnosed stage IV CRC patients(pts) to determine whether serum vit D levels at diagnosis predict survival. Vit D levels of 40-60 ng/mL are considered optimal for bone health, and recent data suggest that levels near 40 ng/mL may increase survival in pts with breast cancer. The optimal level of vit D for CRC pts is not known.

Methods: MSKCC maintains an extensive bank of frozen sera. For this study, stored sera from CEA measurements obtained between February 2005 and March 2006 were screened for study inclusion. The first 250 pts with CEA drawn ± 30 days of stage IV CRC diagnosis and for whom survival data were available were included in this analysis. Vit D levels were determined on all samples. Information regarding metastatic sites, chemo received, body mass index and demographic data were obtained from patient charts.

Results: Of the 250 pts, 153 had died as of April 2009. On univariate analysis vit D was significantly associated with survival when analyzed as continuous variable (p = 0.036). Patients with vit D deficiency (< 30 ng/mL) had survival outcomes approximately 1.5 times worse than those with normal levels. The median vit D level for all 250 patients was 21.5 ng/mL; 207 patients (83%) were vit D deficient (defined as < 30 ng/mL). Only 7 patients had serum vit D levels > 40 ng/mL. Vit D levels were not significantly associated with age, gender, BMI or race.

Conclusions: A majority of patients with newly diagnosed stage IV CRC are vit D deficient at the time of diagnosis. For patients with stage IV CRC, higher vit D levels at diagnosis are associated with better overall survival. Whether aggressive vit D repletion would improve outcome in vit D deficient CRC patients remains unknown. Clinical trials addressing this question are warranted. We are about to initiate such a study.

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