The quality assurance process for the ARTSCAN head and neck study – A practical interactive approach for QA in 3DCRT and IMRT

Initial experience with introducing national guidelines for CT- and MRI-based delineation of organs at risk in radiotherapy

A fundamental problem in radiotherapy is the variation of organ at risk (OAR) volumes. Here we present our initial experience in engaging a large Radiation Oncology (RO) community to agree on national guidelines for OAR delineations. Our project builds on associated standardization initiatives and invites professionals from all radiotherapy departments nationwide. Presently, one guideline (rectum) has successfully been agreed on by a majority vote. Reaching out to all relevant parties in a timely manner and motivating funding agencies to support the work represented early challenges. Population-based data and a scalable methodological approach are major strengths of the proposed strategy.

Head and neck cancer management and cancer stem cells implication

Head and neck squamous cell carcinomas (HNSCCs) arise in the mucosal linings of the upper aerodigestive tract and are heterogeneous in nature. Risk factors for HNSCCs are smoking, excessive alcohol consumption, and the human papilloma virus. Conventional treatments are surgery, radiotherapy, chemotherapy, or a combined modality; however, no international standard mode of therapy exists. In contrast to the conventional model of clonal evolution in tumor development, there is a newly proposed theory based on the activity of cancer stem cells (CSCs) as the model for carcinogenesis. This “CSC hypothesis” may explain the high mortality rate, low response to treatments, and tendency to develop multiple tumors for HNSCC patients. We review current knowledge on HNSCC etiology and treatment, with a focus on CSCs, including their origins, identifications, and effects on therapeutic options.

A virtual dosimetry audit - Towards transferability of gamma index analysis between clinical trial QA groups

PURPOSE

Quality assurance (QA) for clinical trials is important. Lack of compliance can affect trial outcome. Clinical trial QA groups have different methods of dose distribution verification and analysis, all with the ultimate aim of ensuring trial compliance. The aim of this study was to gain a better understanding of different processes to inform future dosimetry audit reciprocity.

MATERIALS

Six clinical trial QA groups participated. Intensity modulated treatment plans were generated for three different cases. A range of 17 virtual 'measurements' were generated by introducing a variety of simulated perturbations (such as MLC position deviations, dose differences, gantry rotation errors, Gaussian noise) to three different treatment plan cases. Participants were blinded to the 'measured' data details. Each group analysed the datasets using their own gamma index (γ) technique and using standardised parameters for passing criteria, lower dose threshold, γ normalisation and global γ.

RESULTS

For the same virtual 'measured' datasets, different results were observed using local techniques. For the standardised γ, differences in the percentage of points passing with γ < 1 were also found, however these differences were less pronounced than for each clinical trial QA group's analysis. These variations may be due to different software implementations of γ.

CONCLUSIONS

This virtual dosimetry audit has been an informative step in understanding differences in the verification of measured dose distributions between different clinical trial QA groups. This work lays the foundations for audit reciprocity between groups, particularly with more clinical trials being open to international recruitment.

Dysphagia - Results from multivariable predictive modelling on aspiration from a subset of the ARTSCAN trial

PURPOSE

To establish predictive models for late objective aspiration and late patient-reported choking based on dose-volume parameters and baseline patient and treatment characteristics, for patients with head and neck cancer undergoing definitive radiotherapy (RT). The impact of electively treated volume on late aspiration was also investigated.

METHODS AND MATERIAL

This prospective cohort is a subsample of 124 survivors from the ARTSCAN study. Late aspiration was identified with videofluoroscopy, at a minimum of 25months after the start of RT. Patient-reported choking was analysed at 12 and 60months post RT using the EORTC Quality of Life Module for Head and Neck Cancer 35. Univariable and multivariable analyses were performed to describe the association between clinical factors and dose-volume descriptors for organs at risk (OARs) and late dysphagia.

RESULTS

Aspiration was found in 47% of the eligible patients. Mean dose to the middle pharyngeal constrictor (MPC), neck dissection post RT and age at randomisation in ARTSCAN were associated to late aspiration. Mean dose to the superior pharyngeal constrictor (SPC) and swallowing complaints at baseline were associated to patient reported choking at both time-points.

CONCLUSIONS

Three separate risk groups for late aspiration, and two risk groups for late patient-reported choking were identified based on number of risk factors. The size of the electively treated volume could be used as a surrogate for individual OARs predicting late aspiration.

Aspiration as a late complication after accelerated versus conventional radiotherapy in patients with head and neck cancer

Conclusion Neck dissection after radiotherapy increased the risk of aspiration as a late effect in a sub-sample of patients treated for head and neck cancer in the ARTSCAN study. Patients treated with accelerated fractionation (AF) developed aspiration, with or without coughing, more frequently than patients treated with conventional fractionation (CF). Objectives A long-term follow-up study was conducted to determine the frequency of aspiration as a late effect in patients with head and neck cancer treated with AF or CF. Method One-hundred and eight patients were recruited from two centres of the Swedish multi-centre study, ARTSCAN, where AF and CF were compared. Patients with positive lymph nodes were treated with neck dissection after completing radiotherapy. The follow-up was performed at a median of 65 months after initiation of radiotherapy and included an ENT and a videofluoroscopic examination. Results Aspiration was found in 51/108 (47%) and silent aspiration in 34/96 (35%) patients. Neck dissection (n = 47 patients) was significantly associated with both aspiration and silent aspiration. Aspiration was more common among patients treated with AF (34/61; 56%) compared to CF (17/47; 36%; p = 0.053). Silent aspiration was also more common after AF (24/54; 44%) than after CF (10/42; 24%; p = 0.052).

Mature results from a Swedish comparison study of conventional versus accelerated radiotherapy in head and neck squamous cell carcinoma - The ARTSCAN trial

BACKGROUND AND PURPOSE

This report contains the mature five-year data from the Swedish ARTSCAN trial including information on the influence of p16 positivity (p16+) for oropharyngeal cancers.

MATERIAL AND METHODS

Patients with previously untreated squamous cell carcinoma without distant metastases of the oral cavity, oropharynx, larynx (except T1-2, N0 glottic cancers) and hypopharynx were included. Patients were randomised between accelerated fractionation (AF) (1.1Gy+2Gy per day, 5days/week for 4.5weeks, total dose 68Gy) and conventional fractionation (CF) (2Gy per day, 5days/week for 7weeks, total dose 68Gy). Human papillomavirus (HPV)-associated p16-expression was assessed retrospectively in tumour tissues from patients with oropharyngeal carcinoma.

RESULTS

There was no significant difference in loco-regional control (LRC) between AF and CF (log-rank test p=0.75). LRC at 5years was 65.5% for AF and 64.9% for CF. Overall survival (OS) was similar in both arms (p=0.99). The estimated cancer specific survival (CSS) at 5years was 62.2% (AF) and 63.3% (CF) (p=0.99). 206 specimens were analysed for p16 with 153 specimens (74%) identified as p16+. P16 status did not discriminate for response to AF vs. CF with regard to LRC, OS or CSS. Patients with p16+ tumours had a statistically significant better overall prognosis compared with p16- tumours.

CONCLUSION

This update confirms the results of the 2-year report. We failed to identify a positive effect resulting from AF with regards to LRC, OS and CSS. The addition of information on the HPV-associated p16 overexpression did not explain this lack of effect.

Regional recurrence of oropharyngeal cancer after definitive radiotherapy: a case control study

Background

Elective treatment of lymph nodes in oropharyngeal cancer (OPC) has impact on both regional recurrences (RR) and risk of late side effects. This study was performed to quantify the dose-dependent impact on RR and overall survival (OS) in a prospectively collected cohort of OPC from the ARTSCAN study with emphasis on elective treatment.

Methods

ARTSCAN is a previously published prospective, randomized, multicentre study of altered radiotherapy (RT) fractionation in head and neck cancer. In ARTSCAN the elective treatment volume for node positive OPC varied significantly between centres due to local treatment principles. All patients with OPC in complete response after primary treatment were eligible for the present case–control study. Cases were patients with RR during five years follow-up. Patients with no recurrence were eligible as controls. Four controls per case were matched according to T- and N-stage. Mean (D_mean) and median (D_50%) dose for the lymph node level (LNL) of RR in the cases and the corresponding LNL in the controls were analysed with conditional logistic regression. OS was estimated with the Kaplan-Meier method and evaluated by multivariate Cox regression analysis.

Results

There was a dose-dependent risk reduction for D_50% in the interval that represented elective treatment (40–50 Gy) (OR = 0.18, p < 0.05) and a trend in the same dose interval for D_mean (OR = 0.19, p = 0.07). OS rates at five years were 0.39 (0.24-0.65) for cases and 0.70 (0.62–0.81) for controls (p < 0.001). The Kaplan-Meier and the Cox regression analysis for cases categorised by delivered dose showed an inverse relationship between dose and survival. The cases with RR in a LNL outside planning target volume (PTV) (D_mean < 40 Gy) had an OS rate comparable to that of all patients, and those with RR in a LNL in PTV_elective (D_mean 40–60 Gy) or PTV_tumour (D_mean >60 Gy) did significantly worse (p < 0.05). The same inverse relationship was also shown for a small subset of patient with known HPV-status, defined by over expression of p16 (p < 0.05).

Conclusions

There was a significant risk reduction for RR of elective treatment. However the OS for patients with RR outside target volumes was not affected, with similar results for patients with HPV-positive OPC. This could be an argument for a prospective randomized study on limited elective target volumes in OPC.

Weight and body mass index in relation to irradiated volume and to overall survival in patients with oropharyngeal cancer: a retrospective cohort study

Background

Weight loss is a common problem in patients with Squamous Cell Carcinoma of the Head and Neck (SCCHN) treated with radiotherapy (RT). The aims of the present study were to determine if treated volume (TV), as a measure of the radiation dose burden, can predict weight loss in patients with oropharyngeal cancer and to analyze weight loss and body mass index (BMI) in the same patient group in relation to 5-year overall survival.

Methods

The ARTSCAN trial is a prospective, randomized, multicenter trial in patients with SCCHN. Nutritional data from the ARTSCAN trial were analyzed retrospectively using univariate and multivariate statistical methods based on information on percentage weight loss from the start of RT up to five months after the termination of RT (study cohort 1, n = 232) and information on patients’ BMI at the start of RT (study cohort 2, n = 203). TV was defined as the volume of the patient receiving at least 95% of the prescribed dose. TV_{64.6 Gy} encompasses macroscopic tumor and TV_{43.7 Gy} elective lymph nodes of the neck.

Results

TV_{64.6 Gy} and TV_{43.7 Gy} were both significantly correlated with higher weight loss up to five months after the termination of RT in study cohort 1 (p < 0.001 for both). BMI at the start of RT was shown to be a prognostic factor for 5-year overall survival in study cohort 2 but weight loss was not. The hazard ratios and 95% confidence intervals were 3.78 (1.46–9.75) and 2.57 (1.43–4.62) in patients with underweight and normal weight, respectively.

Conclusions

TV can predict weight loss during RT in patients with oropharyngeal cancer regardless of clinical stage. A high BMI (>25 kg/m²) at the start of RT is positively associated with survival in patients with oropharyngeal cancer.

Radiation-induced trismus in the ARTSCAN head and neck trial

Trismus, a well-known sequelae after treatment of head and neck cancer, decreases a patient's oral function and quality of life. The main objectives of this study were to: 1) investigate the long-term prevalence of radiation-induced trismus in patients treated for head and neck cancer according to two different fractionation schedules; and 2) model a dose-response relationship for trismus.

MATERIAL AND METHODS

Patients were recruited from the Swedish ARTSCAN trial, a prospective randomised multicentre study comparing conventional and accelerated fractionation. A total of 124 patients agreed to a clinical ENT examination 21-127 months (median 66 months) after beginning radiation therapy. Trismus-related scores were assessed using the EORTC H&N35 Quality of Life questionnaire. The TheraBite(®) range of motion scale was used to measure maximal interincisal distance. The dose-response relationship for structures important for mastication and the temporomandibular joints was investigated by normal tissue complication probability modelling.

RESULTS

No significant differences in patient-reported trismus or maximal interincisal distance were found between the two trial arms. Patient-reported moderate to high scores regarding trismus increased from 3% at the start of radiation therapy to 25% at the long-term follow-up. Maximal interincisal distance correlated significantly with patient-reported scores of trismus. The best dose-response fit to the endpoint data was found for the dose to the ipsilateral masseter.

CONCLUSIONS

Trismus is a persistent complication after radiotherapy with 3D-conformal radiation therapy. We found no difference between the severity and prevalence of trismus between conventional and accelerated fractionation, but a significant correlation between the absorbed dose to the mastication structures and opening of the mouth. Further prospective studies may determine whether a reduced dose to structures important for mastication using intensity-modulated radiation therapy will reduce problems with trismus.

Weight loss in patients with head and neck cancer during and after conventional and accelerated radiotherapy

Background

Weight loss is common among patients with squamous cell carcinoma of the head and neck (SCCHN) and is mainly due to tumor and treatment related factors. The aim of the present study was to evaluate weight loss in patients with SCCHN undergoing two different radiotherapy (RT) schedules.

Material and methods

Nutritional data were analyzed from the ARTSCAN study, a controlled randomized prospective Swedish multicenter study conducted with the aim of comparing conventional fractionation (2.0 Gy per day, total 68 Gy during 7 weeks) and accelerated fractionation (1.1 + 2.0 Gy per day, total 68 Gy during 4.5 weeks). Seven hundred and fifty patients were randomized and 712 patients were followed from the start of RT in the present nutritional study.

Results

The patients had a weight loss of 11.3% (± 8.6%) during the acute phase (start of RT up to five months after the termination of RT). No difference in weight loss was seen between the two RT fractionation schedules (p = 0.839). Three factors were significantly predictive for weight loss during the acute phase, i.e. tumor site, overweight/obesity or lack of tube feeding at the start of RT. Moreover, the nadir point of weight loss occurred at five months after the termination of RT.

Conclusion

The results of the present study showed no difference in weight loss between the two RT fractionation schedules and also highlight that weight loss in SCCHN is a multifactorial problem. Moreover, the nadir of weight loss occurred at five months after the termination of treatment which calls for more intense nutritional interventions during the period after treatment.

Implementation of remote 3-dimensional image guided radiation therapy quality assurance for radiation therapy oncology group clinical trials

PURPOSE

To report the process and initial experience of remote credentialing of three-dimensional (3D) image guided radiation therapy (IGRT) as part of the quality assurance (QA) of submitted data for Radiation Therapy Oncology Group (RTOG) clinical trials; and to identify major issues resulting from this process and analyze the review results on patient positioning shifts.

METHODS AND MATERIALS

Image guided radiation therapy datasets including in-room positioning CT scans and daily shifts applied were submitted through the Image Guided Therapy QA Center from institutions for the IGRT credentialing process, as required by various RTOG trials. A centralized virtual environment is established at the RTOG Core Laboratory, containing analysis tools and database infrastructure for remote review by the Physics Principal Investigators of each protocol. The appropriateness of IGRT technique and volumetric image registration accuracy were evaluated. Registration accuracy was verified by repeat registration with a third-party registration software system. With the accumulated review results, registration differences between those obtained by the Physics Principal Investigators and from the institutions were analyzed for different imaging sites, shift directions, and imaging modalities.

RESULTS

The remote review process was successfully carried out for 87 3D cases (out of 137 total cases, including 2-dimensional and 3D) during 2010. Frequent errors in submitted IGRT data and challenges in the review of image registration for some special cases were identified. Workarounds for these issues were developed. The average differences of registration results between reviewers and institutions ranged between 2 mm and 3 mm. Large discrepancies in the superior-inferior direction were found for megavoltage CT cases, owing to low spatial resolution in this direction for most megavoltage CT cases.

CONCLUSION

This first experience indicated that remote review for 3D IGRT as part of QA for RTOG clinical trials is feasible and effective. The magnitude of registration discrepancy between institution and reviewer was presented, and the major issues were investigated to further improve this remote evaluation process.

Do we need fractionation-corrected doses in sequential two-phase treatments? A quantification of dose differences between non-corrected and corrected combined non-uniform dose distributions in normal tissue

BACKGROUND

For many tumour sites, external beam radiation therapy (EBRT) is delivered with a sequential two-phase treatment regime. Yet, there is a lack of consensus of how to add two different non-uniform dose distributions in order to evaluate the late radiation effect for normal tissue. The purpose of this novel investigation is to quantify the dose differences between non-corrected and fractionation-corrected combined non-uniform dose distributions.

MATERIAL AND METHODS

We used a model of an organ at risk (OAR) located in six different positions relative the treated volume giving 16 clinically representative two-phase treatment situations (46 Gy + 22 Gy). The linear-quadratic model was applied to correct for fractionation effects in each voxel before the doses were added. Dose differences were quantified using mean and maximum doses with corresponding fractionation-corrected doses as reference.

RESULTS

Non-corrected doses were higher than fractionation-corrected doses in all treatment situations (mean dose: p<0.001; maximum dose: p=0.003). With the OAR outside the treated volume, non-corrected doses were 3-6 Gy higher representing 10-50% of the reference dose (10-25 Gy); with the OAR included in the treated volume, 1-6 Gy higher representing 1-15% (30-60 Gy). Mean dose differences were generally larger than maximum dose differences.

CONCLUSION

Substantial dose differences were present in all of the simulated treatment situations but more apparent when the OAR was located outside the treated volume in both phases. Our findings require verification in clinical cases but nevertheless indicate a need for fractionation-corrected doses in two-phase treatments both in the daily clinical routine as well as in the modelling of late radiation effects. Our data suggest that adjusting for fractionation effects would lead to lower tolerance doses than currently suggested, in particular for OARs with parallel tissue architecture.