Volumetric image-guided conformal radiotherapy for localized prostate cancer: Analysis of dosimetric and clinical factors affecting acute and late toxicity

Ingrosso, Gianluca; Carosi, Alessandra; Cristino, Daniela di; Ponti, Elisabetta; Lancia, Andrea; Bottero, Marta Carla; Cancelli, Alessandro; Murgia, Alessandra; Turturici, Irene; Santoni, Riccardo

doi:10.1016/j.rpor.2018.07.010

Cited by 3 publications

(1 citation statement)

References 30 publications

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“…The physical proximity of the two organs often makes it a challenge to deliver high doses of radiation to the prostate without giving injury inducing doses to the rectum. Since rectal dose is well‐established as a cause of radiation induced rectal injury, early identification of patients unlikely to meet rectal dose constraints may help with selective use of rectal sparing devices (RSD). Rectal sparing devices such as hydrogel spacers offer the prospect of increased space between the prostate and rectum, causing reduced rectal dose and potentially reduced injury .…”

Section: Introductionmentioning

confidence: 99%

Comparison of statistical machine learning models for rectal protocol compliance in prostate external beam radiation therapy

et al. 2020

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Purpose: Limiting the dose to the rectum can be one of the most challenging aspects of creating a dosimetric external beam radiation therapy (EBRT) plan for prostate cancer treatment. Rectal sparing devices such as hydrogel spacers offer the prospect of increased space between the prostate and rectum, causing reduced rectal dose and potentially reduced injury. This study sought to help identify patients at higher risk of developing rectal injury based on estimated rectal dosimetry compliance prior to the EBRT simulation and planning procedure. Three statistical machine learning methods were compared for their ability to predict rectal dose outcomes with varied classification thresholds applied. Methods: Prostate cancer patients treated with conventionally fractionated EBRT to a reference dose of 74-78 Gy were invited to participate in the study. The dose volume histogram data from each dosimetric plan was used to quantify planned rectal volume receiving 50%, 83% 96%, and 102% of the reference dose. Patients were classified into two groups for each of these dose levels: either meeting tolerance by having a rectal volume less than a clinically acceptable threshold for the dose level (Y) or violating the tolerance by having a rectal volume greater than the threshold for the dose level (N). Logistic regression, classification and regression tree, and random forest models were compared for their ability to discriminate between class outcomes. Performance metrics included area under the receiver operator characteristic curve (AUC), sensitivity, specificity, positive predictive value and negative predictive value. Finally, three classification threshold levels were evaluated for their impact on model performance. Results: A total of 176 eligible participants were recruited. Variable importance differed between model methods. Area under the receiver operator characteristic curve performance varied greatly across the different rectal dose levels and between models. Logistic regression performed best at the 83% reference dose level with an AUC value of 0.844, while random forest demonstrated best discrimination at the 96% reference dose level with an AUC value of 0.733. In addition to the standard classification probability threshold of 50%, the clinically representative threshold of 10%, and the best threshold from each AUC plot was applied to compare metrics. This showed that using a 50% threshold and the best threshold from the AUC plots yields similar results. Conversely, applying the more conservative clinical threshold of 10% maximized the sensitivity at V83_RD and V96_RD for all model types. Based on the combination of the metrics, logistic regression would be the recommendation for rectal protocol compliance prediction at the 83% reference dose level, and random forest for the 96% reference dose level, particularly when using the clinical probability threshold of 10%. Conclusions: This study demonstrated the efficacy of statistical machine learning models on rectal protocol compliance prediction for prostate cancer...

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Section: Introductionmentioning

confidence: 99%

Comparison of statistical machine learning models for rectal protocol compliance in prostate external beam radiation therapy

et al. 2020

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Comparison of Outcomes and Toxicity Between Extreme and Moderate Radiation Therapy Hypofractionation in Localized Prostate Cancer: A Propensity Score Analysis

Marvaso

Ciardo

Gandini

et al. 2019

International Journal of Radiation Oncology*Biology*Physics

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Toxicity reduction required for MRI-guided radiotherapy to be cost-effective in the treatment of localized prostate cancer

Schumacher

Pra

Hoffe

et al. 2020

The British Journal of Radiology

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Objective: To determine the toxicity reduction required to justify the added costs of MRI-guided radiotherapy (MR-IGRT) over CT-based image guided radiotherapy (CT-IGRT) for the treatment of localized prostate cancer. Methods: The costs of delivering prostate cancer radiotherapy with MR-IGRT and CT-IGRT in conventional 39 fractions and stereotactic body radiotherapy (SBRT) 5 fractions schedules were determined using literature values and cost accounting from two institutions. Gastrointestinal and genitourinary toxicity rates associated with CT-IGRT were summarized from 20 studies. Toxicity-related costs and utilities were obtained from literature values and cost databases. Markov modeling was used to determine the savings per patient for every 1% relative reduction in acute and chronic toxicities by MR-IGRT over 15 years. The costs and quality adjusted life years (QALYs) saved with toxicity reduction were juxtaposed with the cost increase of MR-IGRT to determine toxicity reduction thresholds for cost-effectiveness. One way sensitivity analyses were performed. Standard $100,000 and $50,000 per QALY ratios were used. Results: The added cost of MR-IGRT was $1,459 per course of SBRT and $10,129 per course of conventionally fractionated radiotherapy. Relative toxicity reductions of 7 and 14% are required for SBRT to be cost-effective using $100,000 and $50,000 per QALY, respectively. Conventional radiotherapy requires relative toxicity reductions of 50 and 94% to be cost-effective. Conclusion: From a healthcare perspective, MR-IGRT can reasonably be expected to be cost-effective. Hypofractionated schedules, such a five fraction SBRT, are most likely to be cost-effective as they require only slight reductions in toxicity (7–14%). Advances in knowledge: This is the first detailed economic assessment of MR-IGRT, and it suggests that MR-IGRT can be cost-effective for prostate cancer treatment through toxicity reduction alone.

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Volumetric image-guided conformal radiotherapy for localized prostate cancer: Analysis of dosimetric and clinical factors affecting acute and late toxicity

Cited by 3 publications

References 30 publications

Comparison of statistical machine learning models for rectal protocol compliance in prostate external beam radiation therapy

Comparison of statistical machine learning models for rectal protocol compliance in prostate external beam radiation therapy

Comparison of Outcomes and Toxicity Between Extreme and Moderate Radiation Therapy Hypofractionation in Localized Prostate Cancer: A Propensity Score Analysis

Toxicity reduction required for MRI-guided radiotherapy to be cost-effective in the treatment of localized prostate cancer

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