Background: Few population studies have examined the frequencies and durations of specific CT treatment regimens in MPC. Methods: We assessed 3,796 consecutive MPC pts who received CT between Jan 2005 and Aug 2013 at academic, private and community hospital-based practices participating in a US-wide CT order entry system that captures pt, provider and treatment data. Multivariate analyses of prospectively recorded pt and provider characteristics identified predictors of specific therapeutic approaches. Results: Among all pts, median age was 70; 55% male. In 1^st-line CT, 48% of pts received gemcitabine (GEM) monotherapy, 16% received a GEM-based doublet (incl. GEM + nab-paclitaxel [NAB-P]), 9% received fluoropyrimidine (FU) + oxaliplatin (OX) + irinotecan (FOLFIRINOX), 9% received FU monotherapy, and 5% received FU + OX (FOLFOX). The remaining 13% received other regimens. GEM monotherapy use peaked at 58% in 2009 but declined to 28% in 2013. FOLFIRINOX use emerged in 2010 with 4% usage and peaked at 23% in 2012. Since 2012, GEM + NAB-P use has risen substantially, representing 20% of first-line therapy in 2013. GEM + cisplatin use declined steadily from 2010 (9%) to 2013 (3%). Pts under age 60 and those treated at academic centers were more likely to receive first-line FOLFIRINOX and less likely to receive GEM monotherapy (both p<0.05). Mean duration of all 1^st-line treatments was 87 days. 31% of all pts received 2^nd-line treatment, 13% third-line, and 5% fourth-line. Second-line CTs included GEM monotherapy (28%), FOLFOX (14%), FOLFIRINOX (7%) and GEM + NAB-P (6%). 37% of pts who received second-line GEM + NAB-P received 1st-line FOLFIRINOX. Conclusions: This population-based study provides insight into US MPC treatment patterns. Treatments vary significantly according to patient and practice characteristics.

†Through Aug 31 (data through Dec 31, 2013 will be presented at the meeting). ‡Not including GEM + NAB-P.