Survival outcomes in primary cutaneous diffuse large B-cell lymphoma, leg type.

e19074 Background: Primary cutaneous diffuse large B-cell lymphoma (PCDLBCL-LT) is an uncommon type of lymphoma predominantly affects elderly patients and is associated with poor outcome. Large-scale studies describing and evaluating the effect of different type of treatments on survival outcome are lacking. Methods: The National Cancer Database (NCDB) was queried for patients diagnosed with PCDLBCL-LT between 2004 and 2020. All patients aged ≥18 years diagnosed with PCDLBL-LT were included. We excluded patients with unknown chemotherapy and radiation therapy status or lost to follow-up (unknown vital status of last contact). Kaplan-Meier and multivariate Cox regression were used in the analyses. Results: The total cohort consisted of 967 patients with PCDLBCL-LT. Out of whom 516 (53%) were females, 841 (87%) were White non-Hispanic, 41 (4%) were White Hispanic and 37 (4%) were African Americans. 276 (29%) received chemotherapy, 203 (21%) received radiation only, 293 (30%) received chemoradiation, 147 (15%) did not receive any treatment and 48 (5%) had unknown treatment status. The median age at diagnosis was 78 years (range 23-90). The median follow-up time was 87 months (95% CI 74-99), the median overall survival (mOS) for the whole cohort was 42 months (95%CI 37-47). Among patients with known treatment status and vital status of last contact (N=841), patient who received chemoradiation had significantly better mOS compared to patients who received chemotherapy only, radiation only and no treatment (64 vs 41, 39 and 9 months, respectively P<0.001). Patient who received chemotherapy only and radiation only as first line therapy had significantly better mOS compared to patients who received no treatment (41 and 39 vs 9 months, respectively P<0.001), but there was no statistically significant difference in the mOS between chemotherapy only and radiation only (41 vs 39 months, P=0.359). On multivariate analysis, older age, male gender, and Charlson-Deyo score 2 and ≥3 were associated with worse OS (HR 1.061 95%CI 1.050-1.072; P<0.001, HR 1.241 95%CI 1.093-1.482; P=0.017, HR 1.396 95%CI 1.004-1.941; P=0.047 and HR 2.454 95%CI 1.619-3.719; P<0.001 respectively), all type of treatments including chemotherapy only, chemoradiation, and radiation only were associated with better OS (HR 0.576 95% CI 0.443-0.749; P<0.001, HR 0.379 95%CI 0.290-0.495; P<0.001 and HR 0.443 95%CI 0.339-0.578; P<0.001, respectively). Conclusions: This large real-world analysis shows a survival benefit with combined treatment of chemoradiation in this uncommon type of lymphoma compared to single treatment modality.