Association between baseline C‑reactive protein level and survival outcomes for cancer patients treated with immunotherapy: A meta‑analysis

The prognostic impact of baseline C-reactive protein (CRP) in patients with cancer receiving immune checkpoint inhibitors (ICIs) is unclear. The present meta-analysis aimed to review the prognostic value of baseline C-reactive protein (CRP) levels for patients with cancer receiving immunotherapy. Electronic databases, including PubMed, EMbase, Cochrane Library, Web of Science, Chinese National Knowledge Infrastructure, WanFang, Chinese Literature Biomedical Database and Weipu Database, were used to identify cohort studies on the relationship between the baseline CRP levels and ICI survival outcomes from inception to November 2020. Literature screening, data extraction and quality evaluation of studies were independently performed by two reviewers. Subsequently, a meta-analysis was performed using STATA 14.0. A total of 13 cohort studies comprising 2,387 patients with cancer were included in the present meta-analysis. The results indicated that high baseline CRP levels (serum CRP measured within 2 weeks before ICI treatment) were associated with low overall survival (OS) and progression-free survival (PFS) rate among patients treated with ICIs. The subgroup analysis based on cancer type showed that high baseline CRP levels were associated with poor survival outcomes of multiple types of cancer, such as non-small cell lung cancer (6/13; 46.2%), melanoma (2/13; 15.4%), renal cell (3/13; 23.0%) and urothelial carcinoma (2/13; 15.4%). Similar results were observed in subgroup analysis based on the CRP cut-off value of 10 mg/l. In addition, a higher mortality risk was reported in patients with cancer and CRP ≥10 mg/l (hazard ratio, 2.76; 95% CI, 1.70-4.48; P<0.001). Compared with patients with low baseline CRP levels, increased baseline CRP levels were associated with low OS and PFS rate in patients with cancer receiving ICIs. Furthermore, CRP ≥10 mg/l indicated a worse prognosis. Therefore, baseline CRP levels may serve as a marker for the prognosis of patients with certain types of solid tumor treated with ICIs. Due to the limited quality and quantity of included studies, more prospective well-designed studies are required to verify the present findings.