Does Unintentional Splenic Radiation Predict Outcomes After Pancreatic Cancer Radiation Therapy?

Journal Article · Wed Feb 01 04:00:00 EST 2017 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/J.IJROBP.2016.10.046· OSTI ID:22645770

Chadha, Awalpreet S.; Liu, Guan ^[1]; Chen, Hsiang-Chun ^[2]; Das, Prajnan; Minsky, Bruce D.; Mahmood, Usama; Delclos, Marc E. ^[1]; Suh, Yelin ^[3]; Sawakuchi, Gabriel O. ^[3]; Beddar, Sam ^[3]; Katz, Matthew H.; Fleming, Jason B. ^[4]; Javle, Milind M.; Varadhachary, Gauri R.; Wolff, Robert A. ^[5]; Crane, Christopher H. ^[1]; Wang, Xuemei ^[2]; Thames, Howard ^[1]; Krishnan, Sunil ^[1]

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1. Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States)
2. Department of Biostatistics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States)
3. Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States)
4. Department of Surgical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States)
5. Department of Gastrointestinal Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States)

Purpose: To determine whether severity of lymphopenia is dependent on radiation dose and fractional volume of spleen irradiated unintentionally during definitive chemoradiation (CRT) in patients with locally advanced pancreatic cancer (LAPC). Methods: 177 patients with LAPC received induction chemotherapy (mainly gemcitabine-based regimens) followed by CRT (median 50.4 Gy with concurrent capecitabine) from January 2006 to December 2012. Absolute lymphocyte count (ALC) was recorded at baseline, before CRT, and 2 to 10 weeks after CRT. Splenic dose-volume histogram (DVH) parameters were reported as mean splenic dose (MSD) and percentage of splenic volume receiving at least 5- (V5), 10- (V10), 15- (V15), and 20-Gy (V20) dose. Overall survival (OS) was analyzed with use of the Cox model, and development of post-CRT severe lymphopenia (ALC <0.5 K/UL) was assessed by multivariate logistic regression with use of baseline and treatment factors. Results: The median post-CRT ALC (0.68 K/UL; range, 0.13-2.72) was significantly lower than both baseline ALC (1.42 K/UL; range, 0.34-3.97; P<.0001) and pre-CRT ALC (1.32 K/UL, range 0.36-4.82; P<.0001). Post-CRT ALC <0.5 K/UL was associated with inferior OS on univariate analysis (median, 11.1 vs 15.3 months; P=.01) and multivariate analysis (hazard ratio = 1.66, P=.01). MSD (9.8 vs 6 Gy, P=.03), median V10 (32.6 vs 16%, P=.04), V15 (23.2 vs 9.5%, P=.03), and V20 (15.4 vs 4.6%, P=.02) were significantly higher in patients with severe lymphopenia than in those without. On multivariate analysis, postinduction lymphopenia (P<.001; odds ratio [OR] = 5.25) and MSD (P=.002; OR= 3.42) were independent predictors for the development of severe post-CRT lymphopenia. Conclusion: Severe post-CRT lymphopenia is an independent predictor of poor OS in LAPC patients receiving CRT. Higher splenic doses increase the risk for the development of severe post-CRT lymphopenia. When clinically indicated, assessment of splenic DVHs before the acceptance of treatment plans may minimize the risk of severe post-CRT lymphopenia.

• OSTI ID: 22645770
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Journal Name: International Journal of Radiation Oncology, Biology and Physics Journal Issue: 2 Vol. 97; ISSN IOBPD3; ISSN 0360-3016
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
CHEMOTHERAPY
GY RANGE 01-10
GY RANGE 10-100
LYMPHOPENIA
MULTIVARIATE ANALYSIS
NEOPLASMS
PANCREAS
PATIENTS
RADIATION DOSES
RADIOTHERAPY