High levels of CRP relate with advanced disease and poor prognosis of cancer patients. CRP serum levels were measured in 684 cancer patients who had undergone complete surgery or inoperable patients. Patients with inoperable tumors had significantly higher CRP levels (1.21 +/- 2.2 vs. 0.40 +/- 0.4 mg/dL; p < 0.0001). No association with gender, diabetes, autoimmune disease, thyroid disease or allergy was noted. Significantly higher CRP levels were noted in operated patients with hypertension (0.55 +/- 0.5 vs. 0.35 +/- 0.4; p = 0.001), coronary disease (0.73 +/- 0.8 vs. 0.39 +/- 0.4; p = 0.01) and obesity (0.51 +/- 0.5 vs. 0.37 +/- 0.4; p = 0.04). On the contrary, analysis in the group of inoperable patients showed that hypertensive patients had significantly lower CRP levels (0.64 +/- 1.0 vs. 1.36 +/- 2.4; p = 0.008). Although the tumor itself is the main factor defining increased CRP levels in cancer patients, hypertension, coronary disease and obesity are also linked with high CRP levels. Anti-hypertensive drugs appear as potent suppressors of the tumor-induced CRP production.