Background: The presence of a systemic inflammatory response (SIR) in patients with advanced cancer is an increasingly recognised prognostic domain and is commonly assessed by the Glasgow Prognostic Score (GPS) and the Neutrophil Lymphocyte Ratio (NLR). However, little work has been carried out to evaluate their role in the field of palliative RT. The aim of the present study was to compare the prognostic value of the GPS and NLR in patients with advanced colorectal cancer receiving palliative pelvic RT. Methods: From a database of all patients undergoing RT in the West of Scotland (2010-2015) patients receiving palliative pelvic RT for colorectal cancer were examined (n = 175). Patients were excluded if they died within 30 days of treatment (n = 15). Demographic data, time from treatment to death/last clinic visit, medical comorbidities, tumour and RT location/dose, CRP, albumin, and differential blood counts were all recorded. GPS, mGPS and NLR were calculated and Cox regression analysis conducted in SPSS. Results: Of the remaining 160 analysed 85 (53%) were male and the median age was 77 (Range: 34-98). The most common clinical indications for palliative radiotherapy were pain (n = 78), bleeding (n = 71) and obstruction/tenesmus (n = 29). Medical comorbidities varied with the most common being hypertension (n- = 75), IHD (n = 36) and diabetes (n = 19). At the time of analysis 130 (81%) of the patients were dead with median survival of 9 months (Range: 1-62 months). On univariate survival analysis Male sex (p = 0.021), GPS (p = 0.015), mGPS (p = 0.028) and NLR ≥ 5 (p = 0.045) but not age > 75 (p = 0.059), Tumour Site (p = 0.637), Performance Status (p = 0.747), ASA (p = 0.525), Delivered Fractions of Radiotherapy (p = 0.062), Dose of RT (p = 0.486) and low Haemoglobin (p = 0.383) were significantly associated with poor survival. On multivariate analysis of the significant variable only male sex (HR: 1.59, 95%CI 1.07-2.36, p = 0.021) and the GPS (HR: 1.47, 95%CI 1.09-1.98, p = 0.011) remained independently associated with survival. Conclusions: In the palliative RT setting systemic inflammation based scores (GPS, mGPS and NLR) had prognostic value and the GPS had independent prognostic value.