Lymphocyte-Sparing Effect of Stereotactic Body Radiation Therapy in Patients With Unresectable Pancreatic Cancer

Journal Article · Tue Mar 01 04:00:00 EST 2016 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/J.IJROBP.2015.11.026· OSTI ID:22645107

Wild, Aaron T. ^[1]; Herman, Joseph M.; Dholakia, Avani S.; Moningi, Shalini ^[2]; Lu, Yao ^[3]; Rosati, Lauren M.; Hacker-Prietz, Amy; Assadi, Ryan K.; Saeed, Ali M. ^[2]; Pawlik, Timothy M. ^[4]; Jaffee, Elizabeth M.; Laheru, Daniel A. ^[5]; Tran, Phuoc T. ^[2]; Weiss, Matthew J.; Wolfgang, Christopher L. ^[4]; Ford, Eric ^[6]; Grossman, Stuart A. ^[5]; Ye, Xiaobu ^[3]

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1. Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States)
2. Department of Radiation Oncology, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States)
3. Department of Oncology Biostatistics, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States)
4. Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States)
5. Department of Medical Oncology, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States)
6. Department of Radiation Oncology, University of Washington School of Medicine, Seattle, Washington (United States)

Purpose: Radiation-induced lymphopenia (RIL) is associated with inferior survival in patients with glioblastoma, lung cancer, and pancreatic cancer. We asked whether stereotactic body radiation therapy (SBRT) decreases severity of RIL compared to conventional chemoradiation therapy (CRT) in locally advanced pancreatic cancer (LAPC). Methods and Materials: Serial total lymphocyte counts (TLCs) from patients enrolled in a prospective trial of SBRT for LAPC were compared to TLCs from an existing database of LAPC patients undergoing definitive CRT. SBRT patients received 33 Gy (6.6 Gy × 5 fractions). CRT patients received a median dose of 50.4 Gy (1.8 Gy × 28 fractions) with concurrent 5-fluorouracil (77%) or gemcitabine (23%) therapy. Univariate and multivariate analyses (MVA) were used to identify associations between clinical factors and post-treatment TLC and between TLC and survival. Results: Thirty-two patients received SBRT and 101 received CRT. Median planning target volume (PTV) was smaller in SBRT (88.7 cm{sup 3}) than in CRT (344.6 cm{sup 3}; P<.001); median tumor diameter was larger for SBRT (4.6 cm) than for CRT (3.6 cm; P=.01). SBRT and CRT groups had similar median baseline TLCs. One month after starting radiation, 71.7% of CRT patients had severe lymphopenia (ie, TLC <500 cells/mm{sup 3} vs 13.8% of SBRT patients; P<.001). At 2 months, 46.0% of CRT patients remained severely lymphopenic compared with 13.6% of SBRT patients (P=.007). MVA demonstrated that treatment technique and baseline TLCs were significantly associated with post-treatment TLC at 1 but not 2 months after treatment. Higher post-treatment TLC was associated with improved survival regardless of treatment technique (hazard ratio [HR] for death: 2.059; 95% confidence interval: 1.310-3.237; P=.002). Conclusions: SBRT is associated with significantly less severe RIL than CRT at 1 month in LAPC, suggesting that radiation technique affects RIL and supporting previous modeling studies. Given the association of severe RIL with survival in LAPC, further study of the effect of radiation technique on immune status is warranted.

• OSTI ID: 22645107
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Journal Name: International Journal of Radiation Oncology, Biology and Physics Journal Issue: 3 Vol. 94; ISSN IOBPD3; ISSN 0360-3016
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
CHEMOTHERAPY
FLUORINE COMPOUNDS
GY RANGE 01-10
GY RANGE 10-100
MULTIVARIATE ANALYSIS
NEOPLASMS
PANCREAS
PATIENTS
RADIOTHERAPY
THIN-LAYER CHROMATOGRAPHY