By Dr. Khurram Shehzad
Abstract:
Introduction
Radiation-induced lymphopenia (RIL) has been identified as a
prognostically adverse factor in several cancers. The impact of
this condition on head and neck cancers, particularly
nasopharyngeal carcinoma (NPC) is not well-defined.
This retrospective analysis was done to evaluate the incidence
and severity of RIL in patients with nasopharyngeal carcinoma
(NPC) undergoing definitive radiotherapy. Also to identify
patient, clinical, and treatment-related factors associated with
lymphopenia (Grades 3-4) during radiotherapy, and to explore
the relationship between RIL and outcomes in terms of overall
survival (OS), recurrence-free survival (RFS) and distant
metastasis-free survival (MFS).
Methods
Records of 107 patients between 2012 and 2018 at our
institution were reviewed.
All patients had induction chemotherapy followed by
concurrent chemoradiotherapy using tomotherapy, with a total dose of 70 Gy delivered in 33 fractions.
Absolute lymphocyte counts were collected at three time
points: pre-treatment, weekly during treatment, and 12 weeks
post-treatment.
Patient-related, tumor-related, and treatment-related
characteristics, as well as clinical outcomes and lymphocyte
counts during radiotherapy, were recorded.
Descriptive statistics were used to summarize categorical
variables. The severity of lymphopenia was classified
according to CTCAE v4.0, and patients were grouped into
those with mild lymphopenia (Grades 0-2) and severe
lymphopenia (Grades 3-4).
Relationships between lymphopenia severity (Grades 0-2 vs.
Grades 3-4) and clinical variables were examined using
appropriate statistical tests. Survival outcomes (OS, RFS,
MFS) were analyzed using Kaplan-Meier curves and compared
with log-rank tests. Cox proportional hazards models were
used to identify independent predictors of survival, with
p-values < 0.05 considered significant.
Results
There was a statistically significant difference in lymphopenia
severity based on sex (p = 0.029). All female patients
developed severe lymphopenia (G3-G4), while 84% of males
also experienced severe lymphopenia, with 16% having mild
lymphopenia (G0-G2).
A significant association was also found between N stage and
lymphopenia severity (p = 0.049).
Patients with severe lymphopenia had consistently lower
lymphocyte counts compared to those with mild lymphopenia.
This difference was significant from baseline (p < 0.001) and
persisted through treatment and follow-up (p < 0.001 at most
time points).
Conclusion
Lymphopenia severity did not significantly affect overall
survival (OS), recurrence-free survival (RFS), or
metastasis-free survival (MFS).