C-Reactive Protein Is a Poor Marker of Baseline Inflammation in Prostate Cancer and Response to Radiotherapy or Androgen Ablation

Introduction C-reactive protein (CRP) is an acute-phase reactant used as a general marker for inflammation. Isolated levels have been associated with prostate cancer development, prostate-specific antigen (PSA), Gleason score, and treatment response. We seek to establish whether CRP levels reflect inflammation caused by prostate cancer by comparing levels at various points of time before, during, and after therapy. Materials and methods A total of 209 patients had a complete blood count (CBC), PSA, and CRP taken at up to four different time points. Labs were performed up to one week prior to androgen ablation via leuprolide injection (pre-AA), up to one week prior to radiotherapy (RT) (pre-RT), within one week of RT completion (post-RT), and three months following RT completion (FU [follow-up]). Results Significant relationships were found between CRP and WBC pre-AA (p-value=0.0050), pre-RT (p-value=0.0170), and post-RT (p-value=0.0113), but not at FU (p=.096). CRP had no significant relationship with PSA or lymphocytes at any time points. PSA was significantly affected by androgen ablation but lymphocytes, WBCs, and CRP were not. No CRP levels were associated with risk groups or FU-PSA. Lymphatic radiation fields significantly decreased WBCs and lymphocytes but not CRP. PSA, WBC, and lymphocytes all significantly decreased from pre-RT to post-RT, followed by a significant recovery. CRP did not significantly change during any of these periods and was not significantly related to changes in PSA, WBCs, or lymphocytes. Conclusion CRP is not a sensitive marker of the acute inflammatory effects of non-metastatic prostate cancer and treatment response with androgen ablation or radiation therapy.