Comparing the high C3 group to the low C3 group in lung cancer patients, we found that the levels of serum CRP (82.37 (61.89, 90.91) vs. 51.90 (43.19, 60.21), p < 0.05) and IL-6 (89.80 (66.57, 127.13) vs. 53.69 (31.61, 57.68), p < 0.05) were significantly higher in the high C3 patients. Here, CRP is linked to lung carcinoma.