Parathyroid hormone (PTH) has been proposed to play a promoting role in carcinogenesis. However, no epidemiologic studies have yet directly investigated its role in colorectal cancer (CRC).
A case-control study nested within the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort was conducted with 1,214 incident, sporadic CRC cases matched to 1,214 controls. Circulating pre-diagnostic PTH and 25-hydroxy vitamin D [25(OH)D] concentrations were measured by enzyme-linked immunosorbent assays. Detailed dietary and lifestyle questionnaire data were collected at baseline. Multivariable conditional logistic regression was used to estimate the incidence rate ratio (RR) with 95% confidence intervals (95%CI) for the association between circulating PTH and CRC risk.
In multivariate analyses (including adjustment for 25(OH)D concentration) with a priori defined cut-points, high levels of serum PTH (≥65ng/L) compared to medium PTH levels of 30–65 ng/L were associated with increased CRC risk (RR=1.41, 95%CI: 1.03-1.93). In analyses by sex, the CRC risk was 1.77 (95%CI: 1.14-2.75) and 1.15 (95%CI: 0.73-1.84) in men and women, respectively (Pheterogeneity=0.01). In sub-group analyses by anatomical sub-site, the risk for colon cancer was RR=1.56, 95%CI:1.03-2.34, and for rectal cancer RR=1.20, 95%CI:0.72-2.01 (Pheterogeneity=0.21). Effect modification by various risk factors was examined.
The results of this study suggest that high serum PTH levels may be associated with incident, sporadic CRC in Western European populations, and in particular among men.
To our knowledge, this is the first study on PTH and CRC. The role of PTH in carcinogenesis needs to be further investigated.
Keywords: parathyroid hormone, colorectal neoplasms, nested case-control studies, observational studies, colorectal cancer