Serum Vitamin D Level Status by Prostate Cancer Grade and Stage Among Native Africans

Abstract

Background: Vitamin D deficiency is widely speculated to be associated with prostate cancer (PCa) incidence, progression, aggressiveness, and metastatic potentials. However, evidence of this is limited among the black population. Hence, this study was spurred by the dearth of data in this regard. Methods: This was a prospectively designed/executed casecontrolled descriptive study carried out in the University of Port Harcourt Teaching Hospital (UPTH) in the Niger Delta subregion of Nigeria. Serum Vitamin D level status was determined/compared between the 380 histologically-verified positive PCa cases and the smoking/sex-matched 380 histologically-verified negative controls using descriptive and comparative statistical tools. The relationship/association between PCa grade/stage and Vitamin D level status was ascertained using crude and adjusted regression models. Data were managed and analyzed with the Statistical Package for Social Sciences version 23 and a p-value of <0.05 was deemed statistically significant. Results: The histologically-verified positive PCa patients had significantly lower mean Vitamin D level status (PCa patients: 24.55 ± 3.47 vs. controls: 49.73 ± 4.08; p<0.001) but higher mean prostate volumes, BMI status, plasma intact PTH levels, and total PSA levels compared to the histologically-verified negative controls. A decreasing trend of serum Vitamin level status was observed with worsening/increasing PCa grade and stage (p<0.05) among the biopsy positive PCa cases. An inverse relationship existed between Vitamin D level status and PCa grade/stage among the Vitamin D deficient PCa subgroup (p<0.05) but not the sufficient/insufficient PCa subgroups (p>0.05). Among the Vitamin D deficient PCa patients, this inverse relationship continued to strengthen with worsening PCa grade/stage. When compared with the PCa patients with the lowest PCa grade (ISUP grade 1) and stage (T1), an increased likelihood of Vitamin D deficiency was significantly associated with worsening PCa grade (ISUP 2 to 5) and stage (T2 to T4) on crude multiple logistic regression model which was subsequently amplified following adjusting for observed confounders. Conclusion:The study findings corroborate the epidemiologic evidence of the association of Vitamin D deficiency with PCa grade and stage; factors that define PCa aggressiveness and metastatic potentials. However, more robust studies among populations of the black race are highly recommended to validate conclusions from this current study.