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Acta Oncol. 2017 Nov;56(11):1507-1513. doi: 10.1080/0284186X.2017.1370130. Epub 2017 Sep 8.

Spatial rectal dose/volume metrics predict patient-reported gastro-intestinal symptoms after radiotherapy for prostate cancer.

Author information

1
a Department of Medical Physics , Aarhus University Hospital , Aarhus , Denmark.
2
b Department of Radiation, Medicine and Applied Sciences , University of California San Diego , San Diego , CA , USA.
3
c Department of Radiation Oncology , Aarhus University Hospital , Aarhus , Denmark.
4
d Danish Center for Particle Therapy , Aarhus University Hospital , Aarhus , Denmark.
5
e Department of Medical Physics , Memorial Sloan Kettering Cancer Center , New York City , NY , USA.

Abstract

BACKGROUND:

Gastro-intestinal (GI) toxicity after radiotherapy (RT) for prostate cancer reduces patient's quality of life. In this study, we explored associations between spatial rectal dose/volume metrics and patient-reported GI symptoms after RT for localized prostate cancer, and compared these with those of dose-surface/volume histogram (DSH/DVH) metrics.

MATERIAL AND METHODS:

Dose distributions and six GI symptoms (defecation urgency/emptying difficulties/fecal leakage, ≥Grade 2, median follow-up: 3.6 y) were extracted for 200 patients treated with image-guided RT in 2005-2007. Three hundred and nine metrics assessed from 2D rectal dose maps or DSHs/DVHs were subject to 50-times iterated five-fold cross-validated univariate and multivariate logistic regression analysis (UVA, MVA). Performance of the most frequently selected MVA models was evaluated by the area under the receiving-operating characteristics curve (AUC).

RESULTS:

The AUC increased for dose-map compared to DSH/DVH-based models (mean SD: 0.64 ± 0.03 vs. 0.61 ± 0.01), and significant relations were found for six versus four symptoms. Defecation urgency and faecal leakage were explained by high doses at the central/upper and central areas, respectively; while emptying difficulties were explained by longitudinal extensions of intermediate doses.

CONCLUSIONS:

Predictability of patient-reported GI toxicity increased using spatial metrics compared to DSH/DVH metrics. Novel associations were particularly identified for emptying difficulties using both approaches in which intermediate doses were emphasized.

PMID:
28885095
DOI:
10.1080/0284186X.2017.1370130
[Indexed for MEDLINE]

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