In:
Journal of Clinical Oncology, American Society of Clinical Oncology (ASCO), Vol. 33, No. 3_suppl ( 2015-01-20), p. 380-380
Abstract:
380 Background: When tumors are near organs at risk such as bowel or heart, this results in partial underdosing relative to prescribed dose. We hypothesized that equivalent uniform dose (EUD) may better capture the biologic effect than other dose metrics. Methods: In this IRB-approved retrospective study, 257 primary and metastatic liver tumors from 168 patients treated with SBRT at the University of Michigan Health System between 2005 and 2014 were identified. Univariate analysis and multivariate Cox regression models were used to correlate patient, tumor, and treatment characteristics with rates of LC. Results: 1 and 2 year LC were 93% and 75% for all. Of the 156 primary liver tumors, 1 and 2 year LC were 94% and 76%, compared to 83% and 61%, for patients with colorectal metastases (CRM). 22 tumors locally progressed in 17 patients of which 9 were CRM, 5 hepatocellular carcinomas (HCC), and 3 other. Tumors that locally progressed received a median prescribed dose of 50 Gy (24 - 60), GTV EUD (a=-10) 49 Gy (23 - 72), and PTV EUD 46 Gy (17 - 69). Median gross tumor volume (GTV) was 21 cc (1-103). Tumors that did not locally progress received a median prescribed dose of 50 Gy (19 - 60), GTV EUD (a=-10) 52 Gy (17 - 86), and PTV EUD 47 Gy (7 - 76). Median GTV was 10 cc (0.2 - 2092). On univariate analysis, CRM (p = 0.005) was correlated with higher progression, while high GTV and PTV EUD (a=-10) (p = 0.01, 0.05) were correlated with lower progression. HCC (p = 0.06) was borderline for low progression. Age, gender, primary or metastatic, prescribed dose, biologically equivalent dose (BED), minimum GTV or PTV dose and GTV did not predict for progression. In a multivariable model including age, gender, histology, prescribed dose, BED, GTV EUD and GTV size, only GTV EUD predicted for LC, HR = 0.947, 95% CI = 0.901 - 0.996, p = 0.036. Every 1 Gy increase in EUD decreased the risk of local failure by 5%. Conclusions: EUD was predictive of local progression even when accounting for histology, size, and dose as measured by prescribed dose and BED. GTV EUD (a=-10) over 47.64 Gy yielded a 〉 95% local control. EUD may be the preferred dose metric in future tumor control studies.
Type of Medium:
Online Resource
ISSN:
0732-183X
,
1527-7755
DOI:
10.1200/jco.2015.33.3_suppl.380
Language:
English
Publisher:
American Society of Clinical Oncology (ASCO)
Publication Date:
2015
detail.hit.zdb_id:
2005181-5
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