TH-A-BRB-03: Tumor Control Probability Models for Hypofractionated Therapy: Known Unknowns, Unknown Unknowns, and Comparison with Data

2012 ◽  
Vol 39 (6Part29) ◽  
pp. 3982-3983
Author(s):  
J Deasy ◽  
J Jeong
Keyword(s):  
Tumor Control ◽  
Tumor Control Probability ◽  
Probability Models ◽  
Known Unknowns ◽  
Hypofractionated Therapy

scholarly journals The Impact of Different Timing Schedules on Prostate HDR-Mono-Brachytherapy. A TCP Modeling Investigation

Cancers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 4899
Author(s):  
Pavel Stavrev ◽  
Nadejda Stavreva ◽  
Boriana Genova ◽  
Ruggero Ruggieri ◽  
Filippo Alongi ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Clinical Data ◽  
Prolonged Treatment ◽  
Tumor Control ◽  
High Dose ◽  
Treatment Schedule ◽  
Tumor Control Probability ◽  
Probability Models ◽  
Radio Sensitivity ◽  
The Impact

Background: Mechanistic TCP (tumor control probability) models exist that account for possible re-sensitization of an initially hypoxic tumor during treatment. This phenomenon potentially explains the better outcome of a 28-day vs 14-day treatment schedule of HDR (high dose rate) brachytherapy of low- to intermediate-risk prostate cancer as recently reported. Methods: A TCP model accounting for tumor re-sensitization developed earlier is used to analyze the reported clinical data. In order to analyze clinical data using individual TCP model, TCP distributions are constructed assuming inter-individual spread in radio-sensitivity. Results: Population radio-sensitivity parameter values are found that result in TCP population values which are close to the reported ones. Using the estimated population parameters, two hypothetical regimens are investigated that are shorter than the ones used clinically. The impact of the re-sensitization rate on the calculated treatment outcome is also investigated as is the anti-hypothesis that there is no re-sensitization during treatment. Conclusions: The carried out investigation shows that the observed clinical data cannot be described without assuming an initially hypoxic state of the tumor followed by re-oxygenation and, hence, re-sensitization. This phenomenon explains the better outcome of the prolonged treatment schedule compared to shorter regimens based on the fact that prostate cancer is a slowly repopulating tumor.

Self-consistent tumor control probability and normal tissue complication probability models based on generalized EUDa)

2007 ◽  
Vol 34 (7) ◽  
pp. 2807-2815 ◽  
Author(s):  
Su-Min Zhou ◽  
Shiva K. Das ◽  
Zhiheng Wang ◽  
Xuejun Sun ◽  
Mark Dewhirst ◽  
...  
Keyword(s):  
Normal Tissue ◽  
Normal Tissue Complication Probability ◽  
Tumor Control ◽  
Tumor Control Probability ◽  
Probability Models ◽  
Self Consistent

scholarly journals Automated Non-Coplanar VMAT for Dose Escalation in Recurrent Head and Neck Cancer Patients

Cancers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1910
Author(s):  
Kaley Woods ◽  
Robert K. Chin ◽  
Kiri A. Cook ◽  
Ke Sheng ◽  
Amar U. Kishan ◽  
...  
Keyword(s):  
Head And Neck Cancer ◽  
Head And Neck ◽  
Neck Cancer ◽  
Dose Escalation ◽  
Volumetric Modulated Arc Therapy ◽  
Normal Tissue Complication Probability ◽  
Tumor Control ◽  
Tumor Control Probability ◽  
Increased Risk ◽  
Recurrent Head

This study evaluates the potential for tumor dose escalation in recurrent head and neck cancer (rHNC) patients with automated non-coplanar volumetric modulated arc therapy (VMAT) stereotactic body radiation therapy (SBRT) planning (HyperArc). Twenty rHNC patients are planned with conventional VMAT SBRT to 40 Gy while minimizing organ-at-risk (OAR) doses. They are then re-planned with the HyperArc technique to match these minimal OAR doses while escalating the target dose as high as possible. Then, we compare the dosimetry, tumor control probability (TCP), and normal tissue complication probability (NTCP) for the two plan types. Our results show that the HyperArc technique significantly increases the mean planning target volume (PTV) and gross tumor volume (GTV) doses by 10.8 ± 4.4 Gy (25%) and 11.5 ± 5.1 Gy (26%) on average, respectively. There are no clinically significant differences in OAR doses, with maximum dose differences of <2 Gy on average. The average TCP is 23% (± 21%) higher for HyperArc than conventional plans, with no significant differences in NTCP for the brainstem, cord, mandible, or larynx. HyperArc can achieve significant tumor dose escalation while maintaining minimal OAR doses in the head and neck—potentially enabling improved local control for rHNC SBRT patients without increased risk of treatment-related toxicities.

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