The ratio of weight loss to planning target volume significantly impacts setup errors in nasopharyngeal cancer patients undergoing helical tomotherapy with daily megavoltage computed tomography

In Silico Analysis of Adjuvant Head and Neck Online Adaptive Radiation Therapy

Purpose

Recently developed online adaptive radiation therapy (OnART) systems enable frequent treatment plan adaptation, but data supporting a dosimetric benefit in postoperative head and neck radiation therapy (RT) are sparse. We performed an in silico dosimetric study to assess the potential benefits of a single versus weekly OnART in the treatment of patients with head and neck squamous cell carcinoma in the adjuvant setting.

Methods and Materials

Twelve patients receiving conventionally fractionated RT over 6 weeks and 12 patients receiving hypofractionated RT over 3 weeks on a clinical trial were analyzed. The OnART emulator was used to virtually adapt either once midtreatment or weekly based on the patient's routinely performed cone beam computed tomography. The planning target volume (PTV) coverage, dose heterogeneity, and cumulative dose to the organs at risk for these 2 adaptive approaches were compared with the nonadapted plan.

Results

In total, 13, 8, and 3 patients had oral cavity, oropharynx, and larynx primaries, respectively. In the conventionally fractionated RT cohort, weekly OnART led to a significant improvement in PTV V100% coverage (6.2%), hot spot (-1.2 Gy), and maximum cord dose (-3.1 Gy), whereas the mean ipsilateral parotid dose increased modestly (1.8 Gy) versus the nonadapted plan. When adapting once midtreatment, PTV coverage improved with a smaller magnitude (0.2%-2.5%), whereas dose increased to the ipsilateral parotid (1.0-1.1 Gy) and mandible (0.2-0.7 Gy). For the hypofractionated RT cohort, similar benefit was observed with weekly OnART, including significant improvement in PTV coverage, hot spot, and maximum cord dose, whereas no consistent dosimetric advantage was seen when adapting once midtreatment.

Conclusions

For head and neck squamous cell carcinoma adjuvant RT, there was a limited benefit of single OnART, but weekly adaptations meaningfully improved the dosimetric criteria, predominantly PTV coverage and dose heterogeneity. A prospective study is ongoing to determine the clinical benefit of OnART in this setting.

The Impact of Weight Loss during Chemoradiotherapy for Unresectable Esophageal Cancer: Real-World Results

Weight loss is a common phenomenon presented in unresectable esophageal cancer (EC) patients during their definitive chemoradiotherapy (dCRT) treatment course. This study explored the prognostic value of weight changes during dCRT in unresectable EC patients. From 2009 to 2017, 69 cT4b thoracic EC patients undergoing complete curative dCRT without baseline malnutrition were included. Clinical factors were analyzed via the Cox proportional hazards model and survival was analyzed by the Kaplan−Meier method. During dCRT, the median weight loss percentage was 5.51% (IQR = 2.77−8.85%), and the lowest body weight was reached at 35 days (IQR = 23−43 days). Median OS of these patients was 13.5 months. Both univariate and multivariate analysis demonstrated that weight loss ≤ 4% during dCRT was significantly associated with superior OS with a hazard ratio of 2.61 (95% CI: 1.40−4.85, p = 0.002). The median OS for patients with weight loss ≤ 4% and >4% during dCRT was 59.6 months and 9.7 months, respectively (p = 0.001). Our study demonstrated that weight loss ≤ 4% during dCRT course is a favorable prognostic factor for cT4b EC patients. This index could serve as a nutrition support reference for unresectable EC patients receiving dCRT in the future.

Long-term monitoring and predictive factors of critical weight loss among patients with nasopharyngeal carcinoma in a curative treatment setting

PURPOSE

We aimed to determine weight change over time and identify risk factors of critical weight loss among patients with nasopharyngeal carcinoma (NPC).

MATERIALS AND METHODS

In this retrospective study, we investigated weight change over time in 445 patients with NPC who underwent curative treatment. Logistic regression analysis was used to identify possible predictors of critical weight loss.

RESULTS

The incidence of critical weight loss was 67.87%. The long-term monitoring demonstrated a rapid weight loss, especially in the first 2 months of treatment, which continued up to 5 months. Patients with critical weight loss did not regain weight until 3 years. Univariate analysis showed that the following factors were significantly associated with critical weight loss: lower pretreatment body mass index (BMI), tumor stage, subjective global assessment score, Eastern Cooperative Oncology Group (ECOG) score, and enteral tube feeding. Multivariate analysis showed four factors that were associated with a lower critical weight loss: pretreatment BMI < 18.5 kg/m² (p < 0.001, 95% confidence interval [CI] = 0.25 [0.12-0.52]), early tumor stage (p = 0.004, 95% CI = 0.46 [0.27-0.79]), ECOG grade II (p = 0.006, 95% CI = 0.15 [0.04-0.51]), and early prophylactic percutaneous gastrostomy (PEG) tube feeding (p = 0.001, 95% CI = 0.26 [0.12-0.59]).

CONCLUSION

Patients having NPC with critical weight loss showed a significantly rapid decline in their weight in the first 2 months; the weight was persistently less than the baseline value during a 36-month follow-up period. Patients with lower BMI, early-stage cancer, and early prophylactic PEG tube feeding had a significantly lower critical weight loss than those without the abovementioned characteristics.

Practical aspects of the application of helical tomotherapy for craniospinal irradiation

We investigated the practical aspects of the application of craniospinal irradiation using helical tomotherapy (HT-CSI) by evaluating interfractional setup errors and intrafractional movement during each treatment in 83 patients undergoing HT-CSI between January 2014 and December 2018. Interfractional setup errors in each axis (mediolateral; ML, craniocaudal; CC, and anteroposterior; AP) were assessed as differences between pre-treatment megavoltage computed tomography (MVCT) images scanned (zygomatic arch to the C4 spine) and planning CT images. Intrafractional movements were evaluated as the difference between pre-treatment and post-treatment MVCT (T12–L4 spine) images at each fraction. Median interfractional setup error was acceptable in every axis (ML: 1.6 mm, CC: 1.9 mm, AP: 3.1 mm). Seven patients (8.4%) experienced significant intrafractional displacement from 1 to 10 fractions (0.34% for ML, 0.74% for CC, 1.21% for AP). Weight loss grade 1+ during treatment (p = 0.016) was an independent risk factor for significant intrafractional displacement. The risk factor for significant intrafractional movement in pediatric patients was weight loss grade 1+ (p = 0.020), while there was no factor in adults. HT-CSI could be a feasible treatment modality with acceptable setup verification. Inter- and intrafractional errors were acceptable; paying attention to weight loss during treatment is necessary, especially in pediatric patients.

Weight Change Trajectory in Patients With Locally Advanced Nasopharyngeal Carcinoma During the Peri-Radiation Therapy Period

OBJECTIVES

To analyze the weight change trajectory in patients with locally advanced nasopharyngeal carcinoma (LANPC) before, during, and after radiation therapy for a time span of 40 weeks.

SAMPLE & SETTING

147 patients from a university-affiliated medical center in China were included.

METHODS & VARIABLES

Body weight was measured weekly during intensive treatment and biweekly after radiation therapy.

RESULTS

All 147 patients experienced critical weight loss during the peri-radiation therapy period. Overall, body weight remained basically unchanged during induction chemotherapy, followed by a sharp and severe decrease during radiation therapy. At 20 weeks after radiation therapy, body weight had increased only slightly from the lowest point.

IMPLICATIONS FOR NURSING

A time-tailored intervention based on the weight change trajectory is necessary for patients with LANPC. According to the weight change trajectory, relevant interventions for maintaining body weight should be initiated as early as the second week of radiation therapy and no later than the fourth week of radiation therapy, and these interventions should continue for at least four weeks after radiation therapy.

Radiotherapy for Head and Neck Cancer: Evaluation of Triggered Adaptive Replanning in Routine Practice

Purpose and Objective

A proportion of patients receiving radiotherapy for head and neck squamous cell carcinoma (HNSCC) require ad hoc treatment re-planning. The aim of this retrospective study is to analyze the patients who required ad hoc re-planning and to identify factors, which may predict need for re-planning.

Materials and Methods

A single center evaluation of all patients receiving radical or adjuvant (chemo)radiotherapy (CRT) for HNSCC between January and December 2016 was undertaken. Patients who underwent ad hoc re-planning during the treatment were identified in electronic records. Reasons for re-planning were categorized as: weight loss, tumor shrinkage, changes in patient position and immobilization-related factors. Potential trigger factors for adaptive radiotherapy such as patient characteristics, primary tumor site, stage, concomitant chemotherapy, weight loss ratios, radical/adjuvant treatment, and nutritional interventions were investigated.

Results

31/290 (10.6%) HNSCC patients who underwent radical/adjuvant radiotherapy required re-planning. The adaptive radiotherapy (ART) was performed at a mean fraction of 15. The most common documented reasons for re-planning were tumor shrinkage (35.5%) and weight loss (35.5%). Among the patient/tumor/treatment factors, nasopharyngeal primary site (p = 0.013) and use of concurrent chemotherapy with radiotherapy (p = 0.034) were found to be significantly correlated with the need for re-planning.

Conclusion

Effective on-treatment verification schedules and close follow up of patients especially with NPC primary and/or treated with concurrent chemoradiotherapy are crucial to identify patients requiring ART. We suggest an individualized triggered approach to ART rather than scheduled strategies as it is likely to be more feasible in terms of utilization of workload and resources.

Perspective: Do Fasting, Caloric Restriction, and Diets Increase Sensitivity to Radiotherapy? A Literature Review

Caloric starvation, as well as various diets, has been proposed to increase the oxidative DNA damage induced by radiotherapy (RT). However, some diets could have dual effects, sometimes promoting cancer growth, whereas proposing caloric restriction may appear counterproductive during RT considering that the maintenance of weight is a major factor for the success of this therapy. A systematic review was performed via a PubMed search on RT and fasting, or caloric restriction, ketogenic diet (>75% of fat-derived energy intake), protein starvation, amino acid restriction, as well as the Warburg effect. Twenty-six eligible original articles (17 preclinical studies and 9 clinical noncontrolled studies on low-carbohydrate, high-fat diets popularized as ketogenic diets, representing a total of 77 patients) were included. Preclinical experiments suggest that a short period of fasting prior to radiation, and/or transient caloric restriction during treatment course, can increase tumor responsiveness. These regimens promote accumulation of oxidative lesions and insufficient repair, subsequently leading to cancer cell death. Due to their more flexible metabolism, healthy cells should be less sensitive, shifting their metabolism to support survival and repair. Interestingly, these regimens might stimulate an acute anticancer immune response, and may be of particular interest in tumors with high glucose uptake on positron emission tomography scan, a phenotype associated with poor survival and resistance to RT. Preclinical studies with ketogenic diets yielded more conflicting results, perhaps because cancer cells can sometimes metabolize fatty acids and/or ketone bodies. Randomized trials are awaited to specify the role of each strategy according to the clinical setting, although more stringent definitions of proposed diet, nutritional status, and consensual criteria for tumor response assessment are needed. In conclusion, dietary interventions during RT could be a simple and medically economical and inexpensive method that may deserve to be tested to improve efficiency of radiation.

Prospective assessment of inter- or intra-fractional variation according to body weight or volume change in patients with head and neck cancer undergoing radiotherapy

This study aimed to prospectively investigate the association between body weight (ΔBW) or body volume variations (ΔBV) and inter- or intra-fractional variations (Δ(inter) or Δ(intra)) in patients with head and neck cancer (HNC) undergoing radiotherapy (RT). This study enrolled patients with HNC from December 2015 to December 2017. All patients underwent curative intensity-modulated RT (IMRT) either as definitive or adjuvant treatment. Six-dimensional inter- and intra-fractional variations (Δ(inter) and Δ(intra)) were obtained with ExacTrac (BrainLAB, Feldkirchen, Germany) system. BV was measured 7.5 cm cranio-caudally from the centre using cone beam computed tomography. The BW, BV, and Δ(inter) were calculated based on the value obtained on the first treatment day after each simulation. Both Δ(inter) and Δ(intra) were considered in calculating the optimal margins for planning target volume (PTV), which was calculated using van Herk’s formula. In total, 678 fractions with 39 simulations in 22 patients were analysed. The average ΔBW and ΔBV was -0.43±1.90 kg (range, -7.3 to 5.0) and -24.34±69.0 cc (range, -247.15 to 214.88), respectively. In correlation analysis, Δ(intra) was more associated with ΔBW or ΔBV than Δ(inter). Receiver operating characteristic analysis showed Δ(intra) could differentiate ΔBW from ΔBV, while Δ(inter) could not. The optimal margins for PTV considering both Δ(inter) and Δ(intra) were 3.70 mm, 4.52 mm, and 5.12 mm for the right-left, superior-inferior, and anterior-posterior directions, respectively. In conclusion, the PTV margin of 6 mm for anterior-posterior direction and 5 mm for the other directions were needed. ΔBW or ΔBV correlated with Δ(intra) rather than Δ(inter). Therefore, ΔBW or ΔBV should be assessed for accurate IMRT in patients with HNC.

Patient positioning in head and neck cancer : Setup variations and safety margins in helical tomotherapy

OBJECTIVE

To evaluate the interfractional variations of patient positioning during intensity-modulated radiotherapy (IMRT) with helical tomotherapy in head and neck cancer and to calculate the required safety margins (sm) for bony landmarks resulting from the necessary table adjustments.

MATERIALS AND METHODS

In all, 15 patients with head and neck cancer were irradiated using the Hi-Art II tomotherapy system between April and September 2016. Before therapy sessions, patient position was frequently checked by megavolt computed tomography (MV-CT). Necessary table adjustments (ta) in the right-left (rl), superior-inferior (si) and anterior-posterior (ap) directions were recorded for four anatomical points: second, fourth and sixth cervical vertebral body (CVB), anterior nasal spine (ANS). Based upon these data sm were calculated for non-image-guided radiotherapy, image-guided radiotherapy (IGRT) and image guidance limited to a shortened area (CVB 2).

RESULTS

Based upon planning CT the actual treatment required ta from -0.05 ± 1.31 mm for CVB 2 (ap) up to 2.63 ± 2.39 mm for ANS (rl). Considering the performed ta resulting from image control (MV-CT) we detected remaining ta from -0.10 ± 1.09 mm for CVB 4 (rl) up to 1.97 ± 1.64 mm for ANS (si). After theoretical adjustment of patients position to CVB 2 the resulting ta ranged from -0.11 ± 2.44 mm for CVB6 (ap) to 2.37 ± 2.17 mm for ANS (si). These data imply safety margins: uncorrected patient position: 3.63-9.95 mm, corrected positioning based upon the whole target volume (IGRT): 1.85-6.63 mm, corrected positioning based upon CVB 2 (IGRT): 3.13-6.66 mm.

CONCLUSIONS

The calculated safety margins differ between anatomic regions. Repetitive and frequent image control of patient positioning is necessary that, however, possibly may be focussed on a limited region.

Effect of body thickness on helical and direct treatment delivery modes: a phantom study

Objective: Chemoradiation therapy is among the standard treatments for cancer, which often causes a decrease in appetite and subsequent weight loss. When weight loss occurs during treatment, the external body contour changes from that indicated during initial planning, causing changes in dose distribution to the target tumor regions and organs at risk (OARs). This study aimed to examine the dose changes to both the target regions and OARs, based on the dose-volume histogram (DVH).

Methods: We established a 60 mm-diameter planning target volume (PTV) and a 30 mm-diameter rectum region of interest (OAR), using a phantom; this was followed by a 50 Gy/25 fraction irradiation to the target region that was measured using a two-dimensional-array ion chamber device. The measurement was conducted by varying the bolus thickness from 0 to −25 mm, in 5 mm decrements. In addition, the maximum dose for both PTV and OAR were evaluated based on the DVH, created using the Adaptive software.

Results: The gamma analysis showed that the pass rate was less than 95% when the bolus thickness was altered by −25 mm for the helical delivery mode and by −10 mm for the direct delivery mode, resulting in a dose error greater than 3%. Results of the DVH evaluation revealed that the maximum dose of PTV increased by 5.18% when the bolus thickness was −25 mm for helical delivery, whereas a 9.95% increase was noted for the direct delivery mode compared with the dose at the reference level of 0 mm bolus thickness.

Discussion: Our results suggest that it is necessary to formulate a new treatment plan owing to increased dose error, if the body thickness decreases by more than 20 mm and 10 mm for the helical and direct delivery modes, respectively. The results also demonstrate that helical delivery is less affected by changes in body thickness than direct delivery.