184 Background: There has been a four-fold increase in incidence of prostate cancer (PC) in men age 70 or older in England in the last 30 years. Which treatment (surgery, radiotherapy, or surveillance) is right for which patient depends on a number of factors including the risk of death from competing causes and fitness for the proposed treatment. Objective assessments such as those included in a Comprehensive Geriatric Assessment (CGA) might be helpful in this regard. The primary objective of this study is to describe CGA scores of a cohort of older men with PC. The secondary objectives are to examine if a single score (the Vulnerable Elders Survey [VES-13]), is a suitable screening test for a full CGA and to assess whether scores predict radiotherapy toxicity. Methods: Patients age 70 and older with localised PC completed a CGA prior to commencement of radical radiotherapy. The CGA assessed WHO performance status (PS), activities of daily living (ADL), instrumental activities of daily living (IADL), Charlson co-morbidity index, number of medications, mini-nutritional assessment (MNA), social network index (SNI), G8 score, and VES-13. Participants had acute radiotherapy toxicity assessed 12 weeks post-treatment completion. Results: As of September 2013, 100 patients had been recruited. Median age was 74.5 (range 70 to 82). Ninety five percent of patients had a PS less than two. Using the VES-13 tool, 5.2% scored greater than two. 22.6% scored less than 14 on G8 scoring. Additionally, 13.5% were not fully independent on ADLs, 4.2% were not fully independent on IADLs, 32.3% scored greater than one on the Charlson Index, 12.3% had a history of depression or dementia, and 52.9% were on more than three prescription medications. Fourteen percent were at risk of malnutrition and 2.3% were malnourished according to MNA scores, 25.0% had SNI scores less than three and 9.3% of patients had fallen at least once in the preceding three months. Twelve week follow-up data regarding acute radiotherapy toxicity is currently being collected; these will be correlated with the CGA components and presented at the 2014 ASCO Genitourinary Cancers Symposium. Conclusions: These data demonstrate that many older men with localised prostate cancer are vulnerable according to a CGA. Correlations observed between radiotherapy toxicity and CGA scores would have important implications for therapeutic decisions.