Late-onset lymphopenia during radiation is associated with an increased
risk of tumor recurrence in newly-diagnosed pediatric medulloblastoma
Abstract
Background: Recent data found a correlation between lymphopenia
occurring early during craniospinal irradiation (CSI) and risk of
disease recurrence in newly-diagnosed childhood medulloblastoma.
1 However, the population included patients that
received myelosuppressive chemotherapy prior to or during RT. Here we
investigate the effect of lymphopenia during RT in patients with
newly-diagnosed pediatric medulloblastoma who did not receive
myelosuppressive chemotherapy with RT. Procedure: We analyzed
54 patients with newly-diagnosed medulloblastoma (ages 2-21 years)
treated between 1997-2013 with CSI. Log-rank tests were used to
determine survival differences, and Cox proportional hazards regression
was used to assess associations between patient characteristics and
lymphopenia with disease recurrence risk. Results: 78% of
patients (40/51) had grade ≥3 lymphopenia by RT week 3; 49% (23/47)
improved to grade ≤2 lymphopenia by week 5. Similarly, the lowest median
absolute lymphocyte count (ALC) occurred during RT week 3. Sixteen of 54
(30%) patients recurred an average of 30.2 months post-diagnosis. There
was higher risk of disease recurrence in patients with grade ≥3
lymphopenia during weeks 4 (log-rank p=0.015; Cox p=0.03) and 5
(log-rank p=0.0009; Cox p=0.004) of RT. Recurrence-free survival was
lower in patients with ALC Conclusions: Lymphopenia during RT weeks 4
and 5 correlates with increased risk of tumor recurrence in pediatric
patients with newly-diagnosed medulloblastoma. Future studies should
correlate baseline numbers of tumor-infiltrating lymphocytes with risks
of lymphopenia during RT and tumor recurrence.