Prognostic and predictive significance of smudge cell percentage on routine blood smear in chronic lymphocytic leukemia patients: A single center study from northern India.

Abstract

6593 Background: Smudge cells are ruptured lymphocytes seen on routine blood smears of chronic lymphocytic leukemia (CLL) patients. We evaluated prognostic and predictive significance of smudge cells percentage on a blood smear in CLL patients. Methods: We calculated smudge cell percentages (ratio of smudged to intact cells plus smudged lymphocyte) on archived blood smears of 185 untreated CLL patients registered at I.R.C.H, AIIMS, New Delhi over a period of 11 years. Results: There were 135 males and 50 females. The median age was 60 years (28-89). Median absolute lymphocyte count was 42 X109/L. Clinical Rai stage distribution was: stage 0 - 10%, stage I - 15%, stage II - 40%, stage III -15 % and stage IV - 20%. The median smudge cells percentage was 27% (4% to 76%). There was no correlation of proportion of smudge cells with age, sex, lymphocyte count, organomegaly, ZAP 70 + or CD 38 + CLL patients, but there was significant correlation with stage of disease. Median smudge cell percentage in stage 0 & I -33% (12-76), stage II- 31% (12-61) and stage III&IV-21% (4-51) [ p=<0.001]. One third of early stage (0, I &II) patients required treatment during follow up, at the end of 5 years of follow up 55% required treatment with smudge cell < 30%, against 24% patients requiring treatment with smudge cells > 30% [p=0.01]. The percentage of smudge cells as a continuous variable correlated with OS [HR 0.96, p< 0.001]. The 5-year survival rate was 51% for patients with 30% or less smudge cells compared with 81% for patients with more than 30% of smudge cells. Thirty percent of patients died during follow up. Median OS was 5 years with median follow up period of 3.9 years. Smudge cells percentage (<30% vs. >30%) had significant association with OS [HR 0.47, 95%CI (0.32-0.71), p=0.001)]. Conclusions: Simple and inexpensive detection of smudge cells on blood smears on routine diagnostic test useful in predicting progression free and OS in CLL patients and may be beneficial in countries with limited recourses.