Incidence and Risk Factors for Severe Thrombocytopenia in Lymphoma Patients Receiving Chemotherapy.

Background: Severe thrombocytopenia (TCP) can be a serious complication of chemotherapy (CT) in lymphoma patients (pts), however the exact incidence with the current regimens and risk factors for TCP are not well known.

Methods: A retrospective cohort study was conducted to determine the incidence of TCP, and logistic regression analysis were performed to identify the clinical and laboratory features correlated with severe TCP in lymphoma. Medical records of 538 consecutive pts out of the 1050 lymphoma pts, who were newly referred to MDACC in 2003, were reviewed.

Results: 202 pts who received > 1 cycle of treatment were included in the analysis. The total number of CT cycles (with PLT counts) for the 202 pts was 985 (median 6, range, 1–20). Grade (gr) 4 TCP (PLT nadir < 25x10³/μL) was observed in 39% (79/202) of pts and 20% (196/985) of cycles. The median cycle in which gr 4 TCP occurred was 2 (range, 1 to 11), and median PLT nadir count for gr 4 TCP was 12x10³/μL (3 to 24x10³/μL). The regimens most commonly associated with gr 4 TCP were Hyper-CVAD/ Ara-c/Mtx (31/35=89%), ESHAP (6/7=86%), ASHAP (3/4=75%), and ICE (5/7=71%) + rituxan, and the most common histological subtypes were MCL (15/19=79%), Burkitts lymphoma (7/9=78%), T cell lymphoma (10/17=58%), and LCL (31/64=48%). Thirty two of 79 (41%) gr 4 TCP pts had bleeding as compared to 8 of 123 (7%) pts with higher PLT counts (p=0.0001). Overall, the incidence of bleeding was 20% (40/202) by pts and 6% (60/985) by cycles; however, the most incidents [95% (57/60)] were minor. 80% (63/79) of Grade 4 TCP pts received PLT transfusions, as compared to only 2% (2/123) of the rest (p<0.0001). Using multivariate logistic regression, histological gr, (highly aggressive or aggressive vs indolent: OR=10.402, 95% CI, 3.991 to 27.107, p<0.0001), baseline PLT count (≤150 vs >150x10³/μL: OR=4.610, 95% CI, 1.366 to 15.560, p=0.0138), prior therapy (yes vs. no: OR=2.575, 95% CI, 1.337 to 4.961, p=0.0047), Beta2 Microglobulin (B2M) (≥2 vs <2mg/L: OR=2.846, 95% CI, 1.401 to 5.783, p=0.0038), age (>60 vs. ≤60 yrs: OR=0.479, 95% CI, 0.241 to 0.952, p=0.0356) were the most important risk factors for grade 3 or 4 TCP.

Conclusions: The incidence of severe TCP in this population is high. Baseline pt characteristics including histological gr, PLT counts, prior therapy, age and serum B2M were found to be significant risk factors predictive for chemotherapy-induced TCP (CIT). These findings could be useful to identify high risk pts for consideration of treatment approaches for prevention and treatment of CIT.