Background: WD/ DD LPS is the most common LPS subtype, predominantly arising in the RP. Surgery is the primary treatment, but recurrences are frequent. CT is usually reserved for unresectable cases and the reported RECIST response rate (RR) is 12% (Italiano et al. 2012). However, in our experience, RECIST does not capture morphological changes consistent with response on imaging. Our objective was to review RR to CT and describe radiologic patterns of response. Methods: Search of the tumor registry for patients (pts) with RP WD/DD LPS who received CT at MD Anderson Cancer Center from 2003-2013 yielded 48 pts. The pathology database registered 316 new pts with RP WD/DD LPS in the same time frame. Data was collected from the electronic charts and the Social Security Death Index. Here we report the results for the first 48 pts; updated analysis with RECIST and imaging characteristics by an independent radiologist will be presented at the meeting. Results: Of 48 pts, 40 had WD/DD confirmed on pathology and were included; 2 had only WD LPS. Median age was 58 (48-65). Male/female ratio was 22/18. Nineteen pts received neoadjuvant CT (Group 1); 15 received CT for recurrent disease after upfront surgery (Group 2) and 6 received CT only (group 3). Based on the radiology report, response to first-line CT was: partial response (PR) 15/40, stable disease (SD) 19/40 and progression (PD) 6/40. Majority (36) received combination CT, mostly doxorubicin (A)-ifosfamide (I) (RR by CT regimen summarized in Table 1). In Group 1, 15/19 recurred after a follow-up of 30.4 months (m) (15.6-42). In groups 2 and 3, progression-free survival after starting CT was 5.4 m (2.1-9.0). One/two-year survival was: Group 1 100%/79%; Group 2 100%/93%; Group 3 77%/39%. Median survival was 50.5 m (29-194) for all patients. Conclusions: Combination CT yields a RR of 37% in WD/DD LPS. Analysis of the imaging characteristics will help us better understand response patterns in relation to RECIST.