Higher Vitamin D Levels Before Diagnosis Linked to Better Prostate Cancer Survival

A large international pooled analysis of over twelve thousand men with prostate cancer adds substantial evidence that men who have higher circulating levels of vitamin D before their diagnosis tend to live longer after developing the disease. The study, which will be presented at AACR Annual Meeting 2026, focused on 25‑hydroxyvitamin D, the major blood marker of vitamin D status, measured in blood samples collected before prostate cancer was diagnosed. The researchers combined data from thirteen different cohort studies carried out in several countries, creating a single large dataset that tracked what happened to men after they were diagnosed and throughout their follow‑up. In total there were 12,635 men with incident prostate cancer, of whom 1,316 died from prostate cancer itself and 2,129 died from other causes, allowing the team to look at both prostate‑cancer‑specific survival and overall mortality.

The analysis used multivariable‑adjusted Cox proportional hazards models, which means the researchers statistically controlled for factors such as age, race, body mass index, smoking, physical activity, and other lifestyle variables, as well as information on the stage and grade of the prostate cancer at diagnosis whenever that was available. They examined vitamin D both as study‑specific or season‑standardized categories and as clinically defined cutoffs: less than 30 nmol/L, 30–50 nmol/L, 50–75 nmol/L, and 75 nmol/L or higher.
Across the full cohort, men with higher pre‑diagnostic 25(OH)D concentrations had a lower risk of dying from prostate cancer, with a hazard ratio of about 0.75 for an 80‑percentile increase in vitamin D levels, and this association remained statistically significant even after full adjustment. The result translated to roughly a quarter lower risk of prostate‑cancer‑specific death for men at the higher end of the vitamin D range compared with those at the lower end, after accounting for known confounders.

For deaths from causes other than prostate cancer, the picture was somewhat different. In the full cohort, higher vitamin D was also associated with a modestly lower risk of other‑cause mortality, with a hazard ratio around 0.85 for an 80‑percentile increase, again with a statistically significant trend. However, when the analysis was restricted to the subset of about five thousand men who had complete information on stage and grade, the association with other‑cause mortality weakened and became non‑significant, suggesting that the link to non‑prostate‑cancer deaths may be more fragile or partly explained by differences in clinical characteristics. Importantly, even in this more tightly controlled subset, the association between higher vitamin D and lower prostate cancer–specific mortality remained, with only a small attenuation in the hazard ratio, indicating that the core finding is reasonably robust to adjustment for key clinical factors.

The authors highlight that this does not prove vitamin D supplementation directly improves survival; instead, it shows a strong observational association that may be influenced by various biases. One concern is that men with higher vitamin D levels may also be more health‑conscious, more likely to undergo regular screening, and therefore more likely to be diagnosed at an earlier stage, which can create an apparent survival advantage. There may also be residual confounding from lifestyle, comorbidities, or other unmeasured factors that cluster with good vitamin D status. Nevertheless, the scale of the study, the prospective design, and the careful adjustment for stage, grade, and lifestyle make it one of the most convincing pieces of evidence to date that higher pre‑diagnostic vitamin D levels are linked to better outcomes in men who go on to develop prostate cancer.

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