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ISRN Oncology
Volume 2013 (2013), Article ID 239241, 7 pages
http://dx.doi.org/10.1155/2013/239241
Clinical Study

Evaluation of Serum Calcium as a Predictor of Biochemical Recurrence following Salvage Radiation Therapy for Prostate Cancer

1Department of Radiation Oncology, Mayo Clinic Florida, Jacksonville, FL 32224, USA
2Section of Biostatistics, Mayo Clinic Florida, Jacksonville, FL 32224, USA
3Department of Urology, Mayo Clinic Florida, Jacksonville, FL 32224, USA
4Department of Radiation Oncology, Mayo Clinic Rochester, Rochester, MN 55905, USA

Received 21 February 2013; Accepted 12 March 2013

Academic Editors: J. Bentel, A. E. Bilsland, B. Comin-Anduix, A. E. Pinto, and L.-M. Sun

Copyright © 2013 Jennifer L. Peterson et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Background. Previous reports have shown a positive association between serum calcium level and prostate cancer mortality. However, there is no data regarding whether higher serum calcium levels are associated with increased risk of biochemical recurrence (BCR) following salvage radiation therapy (SRT) for prostate cancer. Herein, we evaluate the association between pretreatment serum calcium levels and BCR in a cohort of men who underwent SRT. Methods. We evaluated 165 patients who underwent SRT at our institution. Median dose was 65.0 Gy (range: 54.0–72.4 Gy). We considered serum calcium as both a continuous variable and a 3-level categorical variable (low [≤9.0 mg/dL], moderate [>9.0 mg/dL and ≤9.35 mg/dL], and high [>9.35 mg/dL]) based on sample tertiles. Results. We observed no evidence of a linear association between serum calcium and BCR (relative risk (RR): 0.96, ). Compared to men with low calcium, there was no significantly increased risk of BCR for men with moderate (RR: 0.94, ) or high (RR: 1.08, ) serum calcium levels. Adjustment for clinical, pathological, and SRT characteristics in multivariable analyses did not alter these findings. Conclusion. Our results provide evidence that pretreatment serum calcium is unlikely to be a useful tool in predicting BCR risk following SRT.