Absolute Lymphocyte Count Predicts Overall Survival in T Cell Lymphomas.

Background: Absolute lymphocyte count (ALC) recovery is an independent prognostic factor for survival for different hematological malignancies treated with autologous stem cell transplantation. Recently, we reported superior overall survival (OS) in patients with follicular lymphomas that presented with a higher ALC (ALC ≥ 1 x 10⁹/L) at diagnosis. The role of ALC at diagnosis on survival in T cell lymphomas is not known.

Methods: All patients evaluated at the Mayo Clinic for T cell lymphomas from October 1984 until April 2005 were analyzed in the study. The primary objective of the study was to assess the role of ALC at diagnosis and survival in T cell lymphomas. ALC at diagnosis was obtained from the standard complete blood cell count (CBC).

Results: 223 patients with T cell lymphomas were included in the study. The histology included: peripheral T-cell lymphoma-unspecified (40%), anaplastic large cell (13%), angioimmunoblastic (10%), angiocentric (4%), intestinal T-cell (2%), and other (31%). The median follow-up was 18.6 months (range: 1 month – 229 months [19 years]). The sample population included 60% male and 40% females with a median age of 60 years (15–90 years). The median ALC at diagnosis was 1.2 x 10⁹/L (range: 0.04–6.7 x 10⁹/L). ALC as a continuous variable was identified as predictor for OS in the univariate analysis (HR= 0.690, 95%CI: 0.542–0.862, p < 0.0006). ALC ≥ 1 x 10⁹/L was selected as the dichotomized value because it yielded the maximum difference in survival by c² analysis looking at different cut-point from 0.6 to 1.7 x 10⁹/L that were included between the 25% and 75% quartiles. Univariately, ALC ≥ 1 x 10⁹/L was also identified as a predictor for OS (HR = 0.682, 95%CL= 0.578–0.804, p < 0.0001). Patients (N = 122) with an ALC ≥ 1 x 10⁹/L experienced superior survival compared to patients (N = 101) with an ALC < 1 x 10⁹/L [median OS: 76.3 vs 10.6 months, respectively; and 5 years OS estimates of 53% vs 23%, respectively, p < 0.0001]. When ALC ≥ 1 x 10⁹/L was compared to the international prognostic index (IPI), ALC ≥ 1 x 10⁹/L remained an independent predictor for survival in the multivariate analysis (HR = 0.779, 95%CL: 0.655–0.925, p < 0.004).

Conclusion: This study demonstrates ALC as an independent predictor for OS in T cell lymphomas, suggesting that the host immune system affects survival in this group of patients.