Components of the systemic inflammatory response, combined to form inflammation-based prognostic scores (modified Glasgow Prognostic Score (mGPS), Neutrophil Lymphocyte Ratio (NLR), Platelet Lymphocyte Ratio (PLR), Prognostic Index (PI), Prognostic Nutritional Index (PNI)) have been associated with cancer specific survival. The aim of the present study was to compare the prognostic value of these scores.Patients (n=27,031) who had an incidental blood sample taken between 2000 and 2007 for C-reactive protein, albumin, white cell, neutrophil, lymphocyte and platelet counts, as well as a diagnosis of cancer (Scottish Cancer Registry) were identified. Of this group 8759 patients who had been sampled within two years following their cancer diagnosis were studied.On follow up, there were 5163 deaths of which 4417 (86%) were cancer deaths. The median time from blood sampling to diagnosis was 1.7 months. An elevated mGPS, NLR, PLR, PI and PNI were predictive of a reduced cancer specific survival independent of age, sex and deprivation and tumour site (all p<0.001). The area under the receiver operator curves was greatest for mGPS and PI. Specifically, in colorectal cancer, an elevated mGPS and PI were predictive of a reduced cancer specific survival independent of age, sex, deprivation and tumour stage (both p<0.001).The results of the present study show that systemic inflammation-based scores, in particular the mGPS and PI, have prognostic value in cancer independent of tumour site. Based on the present results and the existing validation literature, the mGPS should be included in the routine assessment of all patients with cancer.