Tumor burden (TB) as a prognostic indicator in patients with metastatic colorectal cancer (mCRC).

572 Background: At initial diagnosis of mCRC, accurate assessment of patient prognosis is critical to defining the optimal initial treatment strategy. While performance status (PS) and number of metastatic sites are presumed surrogates of TB, to date TB assessment has not been formally examined as a potential prognostic marker in mCRC, despite supportive evidence in other malignancies. Methods: We developed a CT-based scoring system for TB on mCRC patients from the TRACC (Treatment of Recurrent and Advanced Colon Cancer) database. Objective (size and number of metastases) and subjective (clinical judgment) scoring systems were used to separate patients into high, moderate, or low TB subsets. Subjective scoring was repeated by a blinded second assessor on a subset of cases. Clinicopathologic correlates with TB were then assessed, along with survival outcomes for each subset. Results: 151 patients were assessed, median age was 68 years and 51% were male. Using subjective scoring, 55 (36%), 33 (22%), and 63 ...