Prognostic and predictive significance of smudge cell percentage on routine blood smear in chronic lymphocytic leukemia

Abstract

Introduction/background: Smudge cells are ruptured lymphocytes present on routine blood smears of chronic lymphocytic leukemia (CLL) patients. We evaluated prognostic and predictive significance of smudge cell percentage on a blood smear in CLL patients.

Materials and methods: We calculated smudge cell percentages (ratio of smudged to intact cells plus smudged lymphocytes) on archived blood smears of 222 untreated CLL patients registered at Institute Rotary Cancer Hospital, All India Institute of Medical Sciences, New Delhi over the past 12 years.

Results: The male:female ratio was 3:1, and median age 60 (range, 28-90) years. Median absolute lymphocyte count was 42 × 10(9)/L. The median smudge cell percentage was 29.6% (range, 4%-79%). We found no correlation of proportion of smudge cells with age, sex, lymphocyte count, organomegaly, or response to therapy, although there was a significant correlation with the Rai stage at diagnosis. Median smudge cell percentage in stage 0 and I was 33% (range, 12%-79%), in stage II 31% (range, 12%-61%), and stage III and IV 21% (range, 4%-51%) (P < .001). Patients with ≤ 30% smudge cells had a shorter median progression-free period (PFP) of 30 months compared with patients who had more than 30% smudge cells (PFP, 45 months; P = .01). The 5-year survival rate was 51% for patients with 30% or fewer smudge cells, and it was 81% for patients with more than 30% smudge cells (P < .001) at a median follow-up of 3.5 years.

Conclusion: Simple and inexpensive detection of smudge cells on routine blood smears seems useful in predicting progression-free and overall survival in CLL patients and might be beneficial in countries with limited resources.

Keywords: CLL; Prognosis; Smudge cell; Survival.