HOUT-27. HEALTHCARE RESOURCE UTILIZATION OF LEPTOMENINGEAL CARCINOMATOSIS IN THE UNITED STATES

Abstract INTRODUCTION Leptomeningeal carcinomatosis (LC) represents a late complication of primary cancer spreading to the leptomeninges. METHODS The IBM MarketScan® Research databases were queried for adult patients diagnosed with LC between 2001 and 2015, secondary to four primary solid tumors (breast, lung, gastrointestinal, and melanoma). The primary outcome was overall healthcare resource utilization (HCRU) for each primary cancer subgroup, quantified as the total cost at baseline (1-year pre-LC diagnosis) and 30, 90, and 365 days post-LC diagnosis. The secondary outcome was interventional treatments for LC. RESULTS We identified 4,961 cases of LC (46% breast cancer, 35% lung cancer, 14% GI cancer, and 5% melanoma). The median baseline Elixhauser comorbidity index was lower for patients with LC secondary to breast cancer (19) relative to those with primary lung, GI, or melanoma (22). The overall median follow-up length was 66 days. The breast and lung cancer groups had the longest and shortest post-LC diagnosis follow-up at 84 and 51 days, respectively. Cost data demonstrated high baseline total costs for the year preceding LC diagnosis (median $117,219). Cumulative median service and medication costs at 365 days post-LC diagnosis were the highest for the GI subgroup ($167,768) and lowest for the lung cancer subgroup ($145,244). In the first 30 days post-diagnosis, 66.9% sought treatments of any kind: 40% radiotherapy, 28% therapeutic lumbar puncture (TLP), and 14% Ommaya insertion. Of the 747 (15%) patients surviving and continuously enrolled to 365 days post-diagnosis, 78.8% had at least one encounter for treatments: 58% radiotherapy, 30% TLP, and 15% Ommaya insertion. CONCLUSION In this large nationwide study of LC associated with four major primary cancers, breast cancer patients had the fewest comorbidities at baseline and the longest follow-up, while those with GI cancer had the highest cost both at baseline and one year after LC diagnosis.