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Lymphocyte-Sparing Effect of Stereotactic Body Radiation Therapy in Patients With Unresectable Pancreatic Cancer
- Source :
- International Journal of Radiation Oncology*Biology*Physics. 94:571-579
- Publication Year :
- 2016
- Publisher :
- Elsevier BV, 2016.
-
Abstract
- 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).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.Thirty-two patients received SBRT and 101 received CRT. Median planning target volume (PTV) was smaller in SBRT (88.7 cm(3)) than in CRT (344.6 cm(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, TLC500 cells/mm(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).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.
- Subjects :
- Male
0301 basic medicine
Antimetabolites, Antineoplastic
Cancer Research
medicine.medical_specialty
Stereotactic body radiation therapy
Lymphocyte
Urology
Adenocarcinoma
Radiosurgery
Deoxycytidine
Article
03 medical and health sciences
0302 clinical medicine
Lymphopenia
Pancreatic cancer
medicine
Humans
Radiology, Nuclear Medicine and imaging
In patient
Lymphocyte Count
Prospective Studies
Lung cancer
Aged
Radiation
business.industry
Hazard ratio
Chemoradiotherapy
Middle Aged
medicine.disease
Gemcitabine
Confidence interval
Pancreatic Neoplasms
030104 developmental biology
medicine.anatomical_structure
Oncology
030220 oncology & carcinogenesis
Female
Dose Fractionation, Radiation
Fluorouracil
business
Nuclear medicine
medicine.drug
Subjects
Details
- ISSN :
- 03603016
- Volume :
- 94
- Database :
- OpenAIRE
- Journal :
- International Journal of Radiation Oncology*Biology*Physics
- Accession number :
- edsair.doi.dedup.....68e045f4450e81141215dfcacf3c7d22