The infused autograft absolute lymphocyte count (A-ALC) is an independent prognostic factor for survival after autologous hematopoietic stem cell transplant (AHSCT) in non-Hodgkin’s lymphoma (NHL). Previous studies have shown that A-ALC directly correlates with the peripheral blood absolute lymphocyte count (PC-ALC) at the time of apheresis collection. However, factors affecting the PC-ALC at apheresis remain undefined. We hypothesized that one possible factor impacting PC-ALC may be the time interval from last chemotherapy to stem cell collection (TILC). Data from 160 patients who underwent AHSCT for treatment of relapsed NHL at Mayo Clinic between 1993 and 2001 were collected and analyzed. The primary end point of this study was correlation between TILC and PC-ALC, and our analysis revealed a strong correlation (r = 0.67, p < 0.0001). Further analysis revealed higher PC-ALC numbers in patients with TILC ≥ 60 days versus TILC < 60 days (median of 7.44 x 109/L in the ≥ 60 day group versus 3.87 x 109/L in the < 60 day group, p < 0.0001). Both the median overall survival (figure below) and the progression-free survival were longer in the TILC ≥ 60 days group versus the TILC < 60 days group (76 versus 21 months, p < 0.0037; 76 versus 11 months, p < 0.018, respectively). These findings were independent of other prognostic indicators for relapsed NHL patients undergoing APHSCT. The data supports our hypothesis that TILC affects PC-ALC and survival post-AHSCT in NHL.

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