Cancer risk assessment in modern radiotherapy workflow with medical big data

Dosimetric and radiobiological comparison of simultaneous integrated boost radiotherapy for early stage right side breast cancer between three techniques: IMRT, hybrid IMRT and hybrid VMAT

Purpose

This study aimed at evaluating the clinical impact of full intensity-modulated radiotherapy (IMRT), hybrid IMRT (H-IMRT) and hybrid volumetric-modulated arc therapy (H-VMAT) for early-stage breast cancer with simultaneous integrated boost (SIB), in terms of plan quality and second cancer risk (SCR).

Methods

Three different plans were designed in full IMRT, hybrid IMRT, and hybrid VMAT for each of twenty patients with early-stage breast cancer. Target quality, organs at risk (OARs) sparing, and SCR were compared among the three plans for each case.

Results

In compared with H-IMRT, IMRT plans showed deterioration in terms of D_2% of SIB, V₁₀ of ipsilateral lung, and excess absolute risk (EAR) to contralateral lung (C-Lung) and esophagus. D_2% and the homogeneity index (HI) of SIB, V5 of ipsilateral lung (I-Lung), the D_mean of the esophagus, the EAR to C-Lung and the esophagus with hybrid VMAT dramatically increased by 0.63%, 10%, 17.99%, 149.27%, 230.41%, and 135.29%, respectively (p = 0.024; 0.025; 0.046; 0.011; 0.000; 0.014). D_mean of the heart, the EAR to contralateral breast (C-Breast) and C-Lung by full IMRT was significantly decreased in comparison to the H-VMAT (4.67%, p = 0.033, 26.76%, p = 0.018; 48.05%, p = 0.036).

Conclusion

The results confirmed that H-IMRT could achieve better target quality and OARs sparing than IMRT and H-VMAT for SIB radiotherapy of early-stage right breast cancer. H-IMRT was the best treatment option, while H-VMAT performed the worst among the three plans in terms of SCR to peripheral OARs.

Effectiveness of Image-Guided Radiotherapy in Adjuvant Radiotherapy on Survival for Localized Breast Cancer: A Population-Based Analysis

Purpose

Image-guided radiotherapy (IGRT) is an advanced radiotherapy technique to improve the radiotherapy delivery. We aimed to compare the overall survival (OS) for localized breast cancer (LBC) patient treated with adjuvant conventional fractionated radiotherapy (CFRT) using IGRT vs those without IGRT via a population-based analysis.

Patients and Methods

Eligible LBC patients diagnosed between 2011 and 2013 were identified via the Taiwan Cancer Registry. We used propensity score (PS) weighting to balance observable potential confounders between groups. The hazard ratio (HR) of death and other outcomes were compared between IGRT and non-IGRT. We also evaluated OS in various supplementary analyses.

Results

Our primary analysis included 6490 patients in whom covariates were well balanced after PS weighing. The HR for death when IGRT was compared with non-IGRT was 1.02 (95% confidence interval 0.80–1.31, P = 0.86). There were also no significant differences in the supplementary analyses.

Conclusion

We found that OS of LBC patients treated with adjuvant CFRT was not statistically different between those treated with IGRT versus without IGRT. This was the first study in this regard to our knowledge but randomized controlled trials were needed to confirm our finding.

Dose-time fractionation schedules of preoperative radiotherapy and timing to surgery for rectal cancer

Chemoradiotherapy (CRT) is extensively used prior to surgery for rectal cancer to provide significantly better local control, but the radiotherapy (RT), as the other component of CRT, has been subject to less interest than the drug component in recent years. With considerable developments in RT, the use of advanced techniques, such as intensity-modulated radiotherapy (IMRT) in rectal cancer, is garnering more attention nowadays. The radiation dose can be better conformed to the target volumes with possibilities for synchronous integrated boost without increased complications in normal tissue. Hopefully, both local recurrence and toxicities can be further reduced. Although those seem to be of interest, many issues remain unresolved. There is no international consensus regarding the radiation schedule for preoperative RT for rectal cancer. Moreover, an enormous disparity exists regarding the RT delivery. With the advent of IMRT, variations will likely increase. Moreover, time to surgery is also quite variable, as it depends upon the indication for RT/CRT in the clinical practices. In this review, we discuss the options and problems related to both the dose-time fractionation schedule and time to surgery; furthermore, it addresses the research questions that need answering in the future.

Clinical Impact of the Bolus in Intensity-Modulated Radiotherapy and Volumetric-Modulated Arc Therapy for Stage I-II Nasal Natural Killer/T-Cell Lymphoma

INTRODUCTION

To estimate the clinical impact of bolus in intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) for stage I-II nasal natural killer/T-cell lymphoma (NNKTCL), including target quality, organs at risk (OARs) sparing, and tumor control probability (TCP).

METHODS

Two different treatment plans were designed in IMRT and VMAT for 10 stage I-II NNKTCL patients. The clinical plans added bolus perfectly contacting the nose skin, similar to common clinical planning design practices. The edited bolus plans resulted from dose recalculation with the edited bolus, which simulated the actual shape of a commercial flat bolus during treatment. All the plans were with no beam passing through the couch avoiding beam attenuation caused by the couch. Differences between both types of plans in target quality, OARs sparing, and TCP were evaluated.

RESULTS

Compared with clinical plans, the D98%, D2%, Dmean, and TCP of edited bolus plans with IMRT slightly decreased (p = 0.002, 0.015, 0.000, and 0.000), the homogeneity index increased 8.33% (p = 0.024), and the doses to a small number of OARs slightly changed. Similar results were obtained for VMAT.

CONCLUSION

The bolus deformation in practical clinical treatment resulted clinically in tiny changes with respect to the target coverage, OARs sparing, and TCP in both IMRT and VMAT for stage I-II NNKTCL. This implied that the clinical impact of the boluscan be negligible when utilizing it to increase the dose to irregularly shaped tumors in the nasal area.

Estimation of radiotherapy modalities for patients with stage I-II nasal natural killer T-Cell lymphoma

Purpose

The objective of this study is to estimate radiotherapy (RT) modalities for patients with stage I-II nasal natural killer T-Cell lymphoma (NNKTCL), including plan quality, radiation delivery efficiency, cost of RT and excess absolute risk (EAR).

Materials and methods

Twenty-four representative patients with stage I-II NNKTCL treated with fix-field intensity-modulated radiotherapy (FF-IMRT) were re-planned for volumetric modulated arc therapy (VMAT), TomoDirect (TD) and TomoHelical (TH) on the TomoHDA system, respectively. Plan characteristics, cost of RT and EAR were compared.

Results

Compared with IMRT, TD and TH showed significant improvement in terms of D_98%, D_2%, cold spot volume and homogeneity index (HI) of planning target volume (PTV), while achieving worse D_mean and conformity index (CI). The mean dose of oropharynx, thyroid and left salivary, and the maximum dose of right salivary by TD (249.20%, p=0.000; 52.94%, p=0.000; 160.23%, p=0.022; 122.67%, p=0.027), VMAT (15.76%, p=0.000; 23.53%, p=0.000; 34.09%, p=0.000; 31.33%, p=0.000) and TH (250.32%, p=0.000; 58.82%, p=0.000; 120.45%, p=0.020; 117.33%, p=0.032) increased significantly compared to IMRT. VMAT reduced treatment time (p=0.000; 0.000; 0.000) and monitor units (MUs) (p=0.000; 0.000; 0.000) obviously compared with IMRT, TD and TH. The cost of RT for TD and TH increased 150% compared with IMRT and VMAT. IMRT obtained the lowest EAR to oropharynx, thyroid, left and right salivary gland in the four treatment modalities.

Conclusion

The results show that both TD and TH can achieve higher conformal target quality while getting worse organs at risk (OARs) sparing and EAR to some organs than IMRT for patients with stage I-II NNKTCL. IMRT delivers the lowest dose to most OARs, VMAT requires the lower cost of RT and shortest delivery time, and TH obtained the optimal target coverage. The results could provide direction for selecting proper RT modalities for different cases.

Effectiveness of image-guided radiotherapy for rectal cancer patients treated with neoadjuvant concurrent chemoradiotherapy: A population-based propensity score-matched analysis

AIM

The effects of image-guided radiotherapy (IGRT, an advanced RT technology) have been debated in the literature. We compared the outcomes of locally advanced rectal cancer (LARC) patients treated with neoadjuvant concurrent chemoradiotherapy (NCCRT; with vs without IGRT) in a large population-based propensity score (PS)-matched analysis.

METHODS

We identified LARC patients diagnosed between 2007 and 2015 via the Taiwan cancer registry (TCR) and constructed a PS-matched cohort to balance observable potential confounders. Outcomes (R0 resection, overall survival, incidence of local regional recurrence [ILRR], rectal cancer mortality [IRCM], other cancer mortality [IOCM] and cardiovascular mortality [ICVM]) were obtained from TCR and the national death registry. We compared the hazard ratio (HR) of death and other endpoints between IGRT and non-IGRT groups. We performed supplementary analysis (SA) to evaluate the robustness of these results in a subgroup, taking an additional potential confounder into account.

RESULTS

Our study population comprised of 586 patients that were balanced with regard to observed covariables. There was no significant difference in HR for death (0.99; 95% confidence interval 0.70-1.39; P = 0.94) between IGRT and non-IGRT groups. There were also no significant differences in R0 resection, ILRR, IRCM, IOCM or ICVM. The results of our SA were consistent with these findings.

CONCLUSION

For LARC patients treated with NCCRT, the treatment outcome was not significantly different among patients treated with and without IGRT. Further study is needed to clarify these results with consideration to additional potential confounding factors and toxicity profiles at endpoints.