Lymphopaenia and accidental splenic doses: Do they have any prognostic value for locally advanced gastric cancer patients treated with radiochemotherapy?

Aim of the study
To determine the effect of chemoradiotherapy (CRT)-induced lymphopaenia, and irradiated splenic volume and splenic doses on oncological outcomes in patients with locally advanced gastric cancer (LAGC).

Material and methods
A consecutive cohort of 52 patients with LAGC treated between 2005 and December 2016 was included. The absolute neutrophil, lymphocyte, and platelet counts were recorded prior to any treatment (baseline), just after the completion of CRT, and 2–6 weeks after the completion of CRT (control evaluation).

Results
The median follow-up time was 30 months (range, 8–130). The incidence of severe lymphopaenia was only 1% at control evaluation, but it was 93% after CRT (p < 0.001). Both in univariate and multivariate analyses, stage 3 disease (p < 0.001 and p = 0.041, respectively) and metastatic to dissected lymph node (MDLN) ratio > 20% (p < 0.001 and p = 0.032) had a negative effect on OS. Mean splenic dose ≥ 35 Gy was a significant poor prognostic factor for OS and recurrence-free survival (RFS) (p = 0.042 and p = 0.50, respectively). Maximum splenic dose ≥ 58 Gy effected OS unfavourably (p = 0.050). Volumetric modulated arc therapy (VMAT), intravenous CT, and age ≥ 65 years were significant predictors for subsequent severe lymphopaenia.

Conclusions
Severe lymphopaenia could not be accepted as a predictive or prognostic factor for LAGC. Mean and maximum splenic doses should be kept on mind while evaluating the treatment dose-volume histograms (DVHs). Patient age, IV usage of concomitant CT agent, and RT technique can influence the ALC. Disease-related factors such as stage and MDLN ratio were the most important factors.