Long-term survival in chronic lymphocytic leukemia after first primary malignancy in the United States.

Abstract

e18090 Background: There has been significant improvement in survival among patients with primary Chronic Lymphocytic Leukemia (CLL) in recent years but, not much is known about survival among CLL developed after a first primary malignancy. Methods: SEER 18 database, 2015 submission, was used to calculate 5 and 10 year relative survival (RS) by period survival modeling method for 1993 to 2012, with division of the period into 4 cohorts of 5 years each. SEER*Stat software from National Cancer Institute was used to calculate relative survival (RS) for 4 different periods of 5 years duration. The trend in survival for cases with CLL as second primary cancer (CLLSPC) was evaluated using COX proportional hazard method using Cansurv software and also compared with that of primary CLL cases. Results: A total of 8731 patients with CLLSPC were included in the study, which represents 14.5% of all cases of CLL. The median age at diagnosis was 75 years. Median time to diagnosis of CLL was 50 months after diagnosis of first primary malignancy. Prostate cancer, breast cancer and colorectal cancer were 3most common primary cancers. 5-year and 10-year RS improved significantly in the year 2008-2012 compared to 1993-1997 (59.3% to 70.2%,P 0.044 and 40.1% to 50.6%, p 0.045). In subgroup analysis, significant improvement in 5-year and 10-year RS was seen in females and ≥ 80 years age group but no significant improvement was observed in males and age group 60-79 years. Survival among CLLSPC was significant worse compared to first primary CLL in all periods, even after adjusting for age and sex. Conclusions: CLLSPC represents about 14.5% of all CLL cases. Relative survival among patients with CLLSPC is gradually improving but still lags behind that of CLL as first primary cancer.