Copenhagen, Denmark
Onsite/Online

ESTRO 2022

Session Item

Upper GI
6010
Poster (digital)
Clinical
Impacts and consequences of spleen irradiation after adjuvant chemoradiation for stomach cancer
Shing Fung Lee, Singapore
PO-1306

Abstract

Impacts and consequences of spleen irradiation after adjuvant chemoradiation for stomach cancer
Authors:

Shing Fung Lee1,2, Pui Lam Yip3, Aray Wong3, Francesca Ng2, Vicky Koh4, Lea Choung Wong4, Francis Ann Shing Lee2, Harvey Mamon5

1University of Hong Kong, Department of Clinical Oncology, Hong Kong, Hong Kong (SAR) China; 2Tuen Mun Hospital, Department of Clinical Oncology, Hong Kong, Hong Kong (SAR) China; 3Tuen Mun Hospital, Department of Clinical Oncology, Hong Kong, Hong Kong (SAR) China; 4National University Cancer Institute, Department of Radiation Oncology, Singapore, Singapore; 5Dana-Farber/Brigham and Women's Cancer Center, Harvard Medical School, Department of Radiation Oncology, Boston, Massachusetts, USA

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Purpose or Objective

To determine whether severity of lymphopenia is associated with the dose-volume histogram (DVH) parameters of the spleen irradiated unintentionally during adjuvant chemoradiation (CRT) in patients with gastric cancer.

Material and Methods

Patients who received adjuvant chemoradiation for gastric cancer from January 2015 to December 2020 were analyzed. The splenic DVH parameters were reported as mean splenic dose (MSD) and percentage of splenic volume receiving at least x Gray (Gy). Peripheral blood counts were recorded at baseline and after CRT. The development of severe post-CRT lymphopenia (absolute lymphocyte count [ALC] <0.5 K/μL) was assessed by multivariable logistic regression with use of patient and dosimetric factors. Overall survival (OS), recurrence-free survival (RFS), and cumulative incidence of infectious events were estimated and analyzed with the use of stepwise Cox model or competing risk analysis as appropriate. 

Results

We analyzed 84 patients, with median follow-up duration of 42 months. The median baseline ALC and post-CRT ALC were 1.9 K/μL (range, 0.7–2.8 K/μL) and 0.9 K/μL (range, 0.0–4.9 K/μL), respectively (P < 0.001). MSD > 40 Gy (odd ratio [OR], 3.81; 95% confidence interval [CI], 1.15–12.60; P = 0.028), high baseline neutrophil-to-lymphocyte ratio (OR per 1 unit increase, 2.13; 95% CI, 1.02–4.41; P = 0.043), and sex (OR for male to female, 0.34; 95% CI, 0.12–0.97; P = 0.043) were associated with the development of severe post-CRT lymphopenia, which was a risk factor for poorer OS (hazard ratio [HR], 2.27; 95% CI, 1.13–4.58; P = 0.022) and RFS (HR, 2.21; 95% CI, 1.13–4.32; P = 0.021). The cumulative incidence of infections was higher among patients with severe post-CRT lymphopenia (2.53, 95% CI, 1.03–6.23, P = 0.043).



Conclusion

Higher splenic radiation doses increase the odds of severe post-CRT lymphopenia, which is common and is an independent predictor of poorer OS and higher risks of recurrence and infections in gastric cancer patients receiving adjuvant CRT. Considering the spleen as an organ-at-risk and optimizing the splenic DVH parameters before plan evaluation may decrease the risk of severe post-CRT lymphopenia.