Abstract 5003: Serum parathyroid hormone and risks of colorectal adenoma, adenoma recurrence and colorectal cancer, results from the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial

Abstract

Abstract Background: Serum parathyroid hormone (PTH) may be related to risk of incident colorectal cancer. However, no study has prospectively examined whether serum PTH is differentially related to risks of different stages of colorectal carcinogenesis (incident adenoma and metachronous adenoma). Further, it is unclear if PTH is associated with risk of incident colorectal neoplasia in individuals receiving endoscopic screenings. To address these important scientific inquiries, we have conducted three nested case-control studies within the Prostate, Lung, Colorectal, and Ovarian (PLCO) cancer screening trial. Methods: The PLCO is a large, multicenter, population-based randomized trial designed to determine the effects of screening on cancer-related mortality with a median of 12.5 years of follow up. We evaluated the associations between serum PTH and the risks of incident colorectal adenoma (755 cases and 514 controls), metachronous adenoma (755 cases and 755 controls) and incident colorectal cancer (755 cases and 514 controls) within PLCO participants aged 55 to 74 years. Odds ratios (OR) and 95% confidence intervals (95%CIs) were estimated using unconditional logistic regression models after adjusting for potential confounding factors. Results: Compared to low serum PTH (<30 ng/L), higher concentrations of serum PTH were associated with significantly reduced risk of incident colorectal cancer with the ORs (95% CIs) being 0.65(0.48-0.88) and 0.52(0.35-0.76) for PTH ≥30 ng/L and PTH≥65 ng/L (p for trend, 0.001). The inverse associations appeared significant for both women and men. However, overall, serum PTH was not related to risk of incident adenoma and metachronous adenoma. Conclusion: In conclusion, compared to the lowest PTH levels, higher serum PTH were related to reduced risks of incident colorectal cancer among an US population who received endoscopy, but not incident colorectal adenoma and metachronous adenoma. Citation Format: Xiangzhu Zhu, Martha J. Shrubsole, Edward Giovannucci, Todd L. Edwards, Qi Dai. Serum parathyroid hormone and risks of colorectal adenoma, adenoma recurrence and colorectal cancer, results from the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5003. doi:10.1158/1538-7445.AM2017-5003