Creation of RTOG compliant patient CT-atlases for automated atlas based contouring of local regional breast and high-risk prostate cancers

Background

Increasing use of IMRT to treat breast and prostate cancers at high risk of regional nodal spread relies on accurate contouring of targets and organs at risk, which is subject to significant inter- and intra-observer variability. This study sought to evaluate the performance of an atlas based deformable registration algorithm to create multi-patient CT based atlases for automated contouring.

Methods

Breast and prostate multi-patient CT atlases (n = 50 and 14 respectively) were constructed to be consistent with RTOG consensus contouring guidelines. A commercially available software algorithm was evaluated by comparison of atlas-predicted contours against manual contours using Dice Similarity coefficients.

Results

High levels of agreement were demonstrated for prediction of OAR contours of lungs, heart, femurs, and minor editing required for the CTV breast/chest wall. CTVs generated for axillary nodes, supraclavicular nodes, prostate, and pelvic nodes demonstrated modest agreement. Small and highly variable structures, such as internal mammary nodes, lumpectomy cavity, rectum, penile bulb, and seminal vesicles had poor agreement.

Conclusions

A method to construct and validate performance of CT-based multi-patient atlases for automated atlas based auto-contouring has been demonstrated, and can be adopted for clinical use in planning of local regional breast and high-risk prostate radiotherapy.

Radiotherapy for intubated patients with malignant airway obstruction: Futile, or facilitating extubation?

e19120

Background: There is uncertainty as to the appropriate management of intubated patients with malignant airway obstruction (MAO). Radiotherapy (RT) may be delivered but requires substantial resources in this patient population. In the absence of evidence, it is unknown if radiotherapy facilitates extubation or prolongs ICU stays, resulting in a delay in the appropriate transition to end-of-life care. Methods: We performed a 10-year retrospective review of patients in the ICU treated with RT for MAO. Primary study endpoints were overall survival (OS) and extubation success (ES) defined as ≥48 hours without reintubation or death. Secondary endpoints included rates of discharge from the ICU and to home. Logistic regression and Cox regression analyses were performed to identify factors associated with ES and OS. Results: Twenty-six patients were eligible for analysis. Patients waited an average of 2.9 days (±4.5) from intubation and MV until receiving RT. Seven patients (27%) achieved ES, occurring between days 4 and 22 after RT initiation. All of these patients were discharged from the ICU, and most (n=6) were discharged home. There was a trend for a higher chance of ES in patients who received higher radiation doses (OR per 5 Gy increase: 0.63, p = 0.080). Median OS was only 0.36 months (range 0–113 months), and 6-months OS was 11%. On Cox regression analysis, increased radiation dose was predictive of improved OS (HR per 5 Gy increase: 0.74, p = 0.016). Conclusions: Although median survival is short, in a minority of intubated patients with MAO, RT is associated with ES. Survival beyond six months is uncommon, although improved OS is associated with higher delivered doses of RT.

Assessing fitness to drive in brain tumour patients: a grey matter of law, ethics, and medicine

BACKGROUND

Neurocognitive deficits from brain tumours may impair the ability to safely operate a motor vehicle. Although certain jurisdictions in Canada legally require that physicians report patients who are unfit to drive, criteria for determining fitness are not clearly defined for brain tumours.

METHODS

Patients receiving brain radiotherapy at our institution from January to June 2009 were identified using the Oncology Patient Information System. In addition to descriptive statistics, details of driving assessment were reviewed retrospectively. The Fisher exact test was used to determine factors predictive of reporting a patient to the Ontario Ministry of Transportation (mto) as unfit to drive. A logistic regression model was constructed to further determine factors predictive of reporting.

RESULTS

Of the 158 patients available for analysis, 48 (30%) were reported to the mto, and 64 (41%) were advised to stop driving. With respect to the 53 patients with seizures, a report was submitted to the mto for 30 (57%), and a documented discussion about the implications of driving was held with 35 (66%). On univariate analysis, younger age, a central nervous system primary, higher brain radiotherapy dose, unifocal disease, and the presence of seizures were predictive of physician reporting (p < 0.05). On logistic regression modelling, the presence of seizures (odds ratio: 3.9) and a higher radiotherapy dose (odds ratio: 1.3) remained predictive of reporting.

INTERPRETATION

Physicians frequently do not discuss the implications of driving with brain tumour patients or are not properly documenting such advice (or both). Clear and concise reporting guidelines need to be drafted given the legal, medical, and ethical concerns surrounding this public health issue.

Multidisciplinary assessment of fitness to drive in brain tumour patients in southwestern Ontario: a grey matter

BACKGROUND

Neurocognitive impairments from brain tumours may interfere with the ability to drive safely. In 9 of 13 Canadian provinces and territories, physicians have a legal obligation to report patients who may be medically unfit to drive. To complicate matters, brain tumour patients are managed by a multidisciplinary team; the physician most responsible to make the report of unfitness is often not apparent. The objective of the present study was to determine the attitudes and reporting practices of physicians caring for these patients.

METHODS

A 17-question survey distributed to physicians managing brain tumour patients elicited Respondent demographicsKnowledge about legislative requirementsExperience of reportingBarriers and attitudes to reporting Fisher exact tests were performed to assess differences in responses between family physicians (fps) and specialists.

RESULTS

Of 467 physicians sent surveys, 194 responded (42%), among whom 81 (42%) were specialists and 113 (58%) were fps. Compared with the specialists, the fps were significantly less comfortable with reporting, less likely to consider reporting, less likely to have patients inquire about driving, and less likely to discuss driving implications. A lack of tools, concern for the patient-physician relationship, and a desire to preserve patient quality of life were the most commonly cited barriers in determining medical fitness of patients to drive.

CONCLUSIONS

Legal requirements to report medically unfit drivers put physicians in the difficult position of balancing patient autonomy and public safety. More comprehensive and definitive guidelines would be helpful in assisting physicians with this public health issue.

Assessment and improvement of radiation oncology trainee contouring ability utilizing consensus-based penalty metrics

INTRODUCTION

The objective of this study was to develop and assess the feasibility of utilizing consensus-based penalty metrics for the purpose of critical structure and organ at risk (OAR) contouring quality assurance and improvement.

METHODS

A Delphi study was conducted to obtain consensus on contouring penalty metrics to assess trainee-generated OAR contours. Voxel-based penalty metric equations were used to score regions of discordance between trainee and expert contour sets. The utility of these penalty metric scores for objective feedback on contouring quality was assessed by using cases prepared for weekly radiation oncology radiation oncology trainee treatment planning rounds.

RESULTS

In two Delphi rounds, six radiation oncology specialists reached agreement on clinical importance/impact and organ radiosensitivity as the two primary criteria for the creation of the Critical Structure Inter-comparison of Segmentation (CriSIS) penalty functions. Linear/quadratic penalty scoring functions (for over- and under-contouring) with one of four levels of severity (none, low, moderate and high) were assigned for each of 20 OARs in order to generate a CriSIS score when new OAR contours are compared with reference/expert standards. Six cases (central nervous system, head and neck, gastrointestinal, genitourinary, gynaecological and thoracic) then were used to validate 18 OAR metrics through comparison of trainee and expert contour sets using the consensus derived CriSIS functions. For 14 OARs, there was an improvement in CriSIS score post-educational intervention.

CONCLUSIONS

The use of consensus-based contouring penalty metrics to provide quantitative information for contouring improvement is feasible.

Adenocarcinoma not otherwise specified on dorsum of tongue: case report and literature review

Primary adenocarcinoma of the oropharynx most often arises from the minor salivary glands, and primary squamous cell carcinoma is more commonly seen arising from the tongue. Few cases of adenocarcinoma not otherwise specified of the tongue have been reported in the literature, and none found on the dorsum of the tongue. Successful treatment strategies have therefore not been defined.We report a case of adenocarcinoma located on the dorsum of the posterior one third of the tongue adjacent to the circumvallate papillae in a woman presenting with globus sensation and mild dysphagia. Treatment consisted of transoral laser excision and postoperative external-beam radiotherapy, resulting in disease-free survival at her 5-year follow-up. The goals of this report are to present a case of adenocarcinoma arising from the minor salivary gland located on the dorsum of the tongue, to discuss previous reports of similar cases, and to suggest that surgery with or without radiotherapy be used as the mainstay of treatment.

Radiotherapy for steroid-resistant laryngeal Rosai-Dorfman disease

Rosai-Dorfman disease is a rare lymphoproliferative disorder that can have nodal and extranodal manifestations. In the absence of established guidelines for the management of this condition, various therapeutic modalities are used, including radiotherapy. Radiation dosages and fractionation schedules have not been reported in all instances. We present a case in which glottic and subglottic Rosai-Dorfman lesions causing airway obstruction in a frail steroid-refractory patient were put into complete remission using radiotherapy. The lesions responded transiently to a course of prednisone, but responded completely to external-beam radiation, with minimal side effects to the patient.

Fitness to drive in patients with brain tumours: the influence of mandatory reporting legislation on radiation oncologists in Canada

BACKGROUND

Certain jurisdictions in Canada legally require that physicians report unfit drivers. Physician attitudes and patterns of practice have yet to be evaluated in Canada for patients with brain tumours.

METHODS

We conducted a survey of 97 radiation oncologists, eliciting demographics, knowledge of reporting laws, and attitudes on reporting guidelines for unfit drivers. Eight scenarios with varying disability levels were presented to determine the likelihood of a patient being reported as unfit to drive. Statistical comparisons were made using the Fisher exact test.

RESULTS

Of physicians approached, 99% responded, and 97 physicians participated. Most respondents (87%) felt that laws in their province governing the reporting of medically unfit drivers were unclear. Of the responding physicians, 23 (24%) were unable to correctly identify whether their province had mandatory reporting legislation. Physicians from provinces without mandatory reporting legislation were significantly less likely to consider reporting patients to provincial authorities (p = 0.001), and for all clinical scenarios, the likelihood of reporting significantly depended on the physician's provincial legal obligations.

CONCLUSIONS

The presence of provincial legislation is of primary importance in determining whether physicians will report brain tumour patients to drivers' licensing authorities. In Canada, clear guidelines have to be developed to help in the assessment of whether brain tumour patients should drive.

Multidisciplinary assessment and reporting of fitness to drive in brain tumor patients: A gray matter

6130

Background: In some jurisdictions, there is a legal requirement for physicians to report medically unfit drivers. Objectives of this study are to determine physician knowledge and attitudes on reporting legislation and driving assessment, and review our institution’s experience in evaluating fitness to drive in brain tumour patients. Methods: Physicians caring for brain tumour patients in South-western Ontario were identified by public databases and surveyed by mail. Survey questions elicited demographics, opinions, and factors influencing the decision to report. Patients receiving brain radiotherapy at our institution between January and June 2009 were identified and details of driving assessment were extracted. Fisher’s exact test and a logistic regression model were used to determine differences in responses between specialists and family physicians and factors influencing reporting. Results: Surveys (n=467) were distributed with 198 (43%) responses. Most (76%) felt that reporting guidelines were unclear. Neurologists (43%) and Family Physicians (22%) were felt to be the most responsible to report unfit drivers. Compared to specialists, Family Physicians were less likely: to be comfortable with reporting (p=0.02), to consider reporting (p<0.001), or discuss the implications of driving (p<0.001). Perceived barriers in assessing fitness to drive included: lack of tools to assess (57%) and the impact on the patient-physician relationship (34%). 158 patients were retrospectively reviewed. Forty-eight patients (30%) were reported to the provincial licensing authority and 64 (41%) were advised not to drive. 53 patients experienced seizures, of which 36 (68%) had a documented discussion on driving. Only 30 (56%) of these patients were reported to the licensing authority despite legal requirements. Age, primary disease, previous neurosurgery and seizures were predictive of reporting (p<0.05). On logistic regression modeling, seizures (OR 12.4) and primary CNS disease (OR 15.5) remained predictive of reporting. Conclusions: Despite guidelines and laws, the assessment of fitness to drive in patients with brain tumours is not routinely conducted or documented in a multidisciplinary setting.

A multiphase validation of atlas-based automatic and semiautomatic segmentation strategies for prostate MRI

PURPOSE

To perform a rigorous technological assessment and statistical validation of a software technology for anatomic delineations of the prostate on MRI datasets.

METHODS AND MATERIALS

A 3-phase validation strategy was used. Phase I consisted of anatomic atlas building using 100 prostate cancer MRI data sets to provide training data sets for the segmentation algorithms. In phase II, 2 experts contoured 15 new MRI prostate cancer cases using 3 approaches (manual, N points, and region of interest). In phase III, 5 new physicians with variable MRI prostate contouring experience segmented the same 15 phase II datasets using 3 approaches: manual, N points with no editing, and full autosegmentation with user editing allowed. Statistical analyses for time and accuracy (using Dice similarity coefficient) endpoints used traditional descriptive statistics, analysis of variance, analysis of covariance, and pooled Student t test.

RESULTS

In phase I, average (SD) total and per slice contouring time for the 2 physicians was 228 (75), 17 (3.5), 209 (65), and 15 seconds (3.9), respectively. In phase II, statistically significant differences in physician contouring time were observed based on physician, type of contouring, and case sequence. The N points strategy resulted in superior segmentation accuracy when initial autosegmented contours were compared with final contours. In phase III, statistically significant differences in contouring time were observed based on physician, type of contouring, and case sequence again. The average relative timesaving for N points and autosegmentation were 49% and 27%, respectively, compared with manual contouring. The N points and autosegmentation strategies resulted in average Dice values of 0.89 and 0.88, respectively. Pre- and postedited autosegmented contours demonstrated a higher average Dice similarity coefficient of 0.94.

CONCLUSION

The software provided robust contours with minimal editing required. Observed time savings were seen for all physicians irrespective of experience level and baseline manual contouring speed.

Inter- and intrafraction uncertainty in prostate bed image-guided radiotherapy

PURPOSE

The goals of this study were to measure inter- and intrafraction setup error and prostate bed motion (PBM) in patients undergoing post-prostatectomy image-guided radiotherapy (IGRT) and to propose appropriate population-based three-dimensional clinical target volume to planning target volume (CTV-PTV) margins in both non-IGRT and IGRT scenarios.

METHODS AND MATERIALS

In this prospective study, 14 patients underwent adjuvant or salvage radiotherapy to the prostate bed under image guidance using linac-based kilovoltage cone-beam CT (kV-CBCT). Inter- and intrafraction uncertainty/motion was assessed by offline analysis of three consecutive daily kV-CBCT images of each patient: (1) after initial setup to skin marks, (2) after correction for positional error/immediately before radiation treatment, and (3) immediately after treatment.

RESULTS

The magnitude of interfraction PBM was 2.1 mm, and intrafraction PBM was 0.4 mm. The maximum inter- and intrafraction prostate bed motion was primarily in the anterior-posterior direction. Margins of at least 3-5 mm with IGRT and 4-7 mm without IGRT (aligning to skin marks) will ensure 95% of the prescribed dose to the clinical target volume in 90% of patients.

CONCLUSIONS

PBM is a predominant source of intrafraction error compared with setup error and has implications for appropriate PTV margins. Based on inter- and estimated intrafraction motion of the prostate bed using pre- and post-kV-CBCT images, CBCT IGRT to correct for day-to-day variances can potentially reduce CTV-PTV margins by 1-2 mm. CTV-PTV margins for prostate bed treatment in the IGRT and non-IGRT scenarios are proposed; however, in cases with more uncertainty of target delineation and image guidance accuracy, larger margins are recommended.

P3-16-11: Prospective Evaluation of Radiation Pneumonitis in Neoadjuvant Concurrent Docetaxel and Radiation Therapy for Locally Advanced Breast Cancer

Background: Taxanes are known to have radiosensitizing properties, by causing cell arrest in the G2 and M phases of the cell cycle. As taxanes have become integrated into routine oncologic use, concerns have arisen over the association between taxanes and radiation toxicities such as pneumonitis. Pneumonitis has been reported to occur both with taxane administration alone or, more commonly, with concurrent or sequential radiation. The purpose of this study is to evaluate radiation pneumonitis from our institutional phase I/II protocol of neoadjuvant FEC chemotherapy followed by weekly docetaxel concurrent with radiotherapy in the treatment of locally advanced breast cancer (LABC).

Materials and Methods: Since August 2009, thirty-two LABC patients with stage IIB, IIIA, IIIB, or IIIC invasive breast cancer were enrolled to receive protocol based treatment consisting of 3 cycles of intravenous (IV) fluorouracil 500 mg/m2, epirubicin 100 mg/m2, and cyclophosphamide 500 mg/m2 (FEC) every 3 weeks. Following this, weekly IV docetaxel 35 mg/m2 was administered concurrently with locoregional external beam radiotherapy to a total dose of 45 Gy in 25 fractions followed by a boost of 5.4-9 Gy in 3–5 fractions to gross residual disease. Adverse events were scored using the National Cancer Institute Common Terminology Criteria for Adverse Events v3.0. A linear regression model was built used to evaluate potential parameters predictive of clinical pneumonitis (grade ≥2).

Results: Of the 32 patients enrolled on this prospective protocol, 7 were excluded from analysis (n = 6, follow-up &lt; 4 weeks; n = 1, converted to palliative radiotherapy due to metastatic disease). Twenty-five patients remained for analysis. The median age was 48 years (range 26 to 64). Thirteen patients were treated with intensity modulated radiation therapy while 12 were treated using 3D conformal radiotherapy. In total 13 patients (52%) experienced clinical pneumonitis with 6 of these patients (24%) transiently requiring supportive oxygen (grade 3). On linear regression modeling, the use of IMRT (p = 0.08), grade 3 skin toxicity (p = 0.08), and baseline left ventricular ejection fraction (LVEF, p = 0.05) were potentially predictive of symptomatic pneumonitis. Conversely, various heart and lung dose-volume histogram parameters, trastuzumab use, bolus use, disease laterality, total docetaxel dose, were not predictive of symptomatic pneumonitis (p &gt; 0.10). In multivariable modeling, the use of IMRT (p = 0.05) and baseline LVEF (0 = 0.03) remained predictive of symptomatic pneumonitis.

Conclusion: The use of concurrent weekly docetaxel-based chemoradiotherapy in LABC is associated with significant symptomatic pneumonitis and may be related to low baseline LVEF and the use of IMRT. However, conventional parameters of low dose volumes of lung and heart irradiated were not predictive of pneumonitis. The relationship of the use of IMRT and taxanes in the development of pnemonitis is likely complex and warrants further investigation.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-16-11.

Systematic review of the cost-effectiveness of positron-emission tomography in staging of non--small-cell lung cancer and management of solitary pulmonary nodules

Implementation of positron-emission tomography (PET) is variable depending on jurisdiction in part due to uncertainty about cost-effectiveness. Our objective was to perform a systematic review describing cost-effectiveness of PET in staging of non-small-cell lung cancer (NSCLC) and management of solitary pulmonary nodules (SPN). Systematic literature searches were conducted using separate search strategies for multiple databases. Our validity criteria included measurement of study quality by means of the validated Quality of Health Economic Studies (QHES) instrument. Metrics such as mean PET costs, median average cost savings per patient, incremental cost-effectiveness ratio based on life years saved and quality-adjusted life years were calculated. Eighteen studies met our inclusion criteria with average QHES scores > 75. Studies were primarily based on the national health insurance payer perspective from 10 different countries. Cost-effectiveness was assessed primarily using decision-tree modeling and sensitivity analysis to determine the effects of changing variables on expected cost and life expectancy. After adjusting for currency exchange rates and inflation to 2010 United States dollars, the mean cost of PET was $1478. The cost-effectiveness metrics used in these studies were variable depending on sensitivity and specificity of diagnostic tests used in the models, probability of malignancy, and baseline strategy. Despite observed study heterogeneity, the consensus of these studies conclude that the additional information gained from PET imaging in the staging of NSCLC and diagnosis of SPNs is worth the cost in context of proper medical indications.

Withholding stereotactic radiotherapy in elderly patients with stage I non-small cell lung cancer and co-existing COPD is not justified: outcomes of a Markov model analysis

BACKGROUND AND PURPOSE

To model outcomes of SBRT versus best supportive care (BSC) in elderly COPD patients with stage I NSCLC.

MATERIAL AND METHODS

A Markov model was constructed to simulate the quality-adjusted and overall survival (OS) in patients ⩾75years undergoing either SBRT or BSC for a five-year timeframe. SBRT rates of local, regional and distant recurrences were obtained from 247 patients treated at the VUMC, Amsterdam. Recurrence rates were converted into transition probabilities and stratified into four groups according to T stage (1, 2) and COPD GOLD score (I-II, III-IV). Data for untreated patients were obtained from the California Cancer Registry. Tumor stage and GOLD score utilities were adapted from the literature.

RESULTS

Our model correlated closely with the source OS data for SBRT treated and untreated patients. After SBRT, our model predicted for 6.8-47.2% five-year OS and 14.9-27.4 quality adjusted life months (QALMs). The model predicted for 9.0% and 2.8% five-year OS, and 10.1 and 6.1 QALMs for untreated T1 and T2 patients, respectively. The benefit of SBRT was the least for T2, GOLD III-IV patients.

CONCLUSION

Our model indicates that SBRT should be considered in elderly stage I NSCLC patients with COPD.

Potential utility of BimS as a novel apoptotic therapeutic molecule

We have previously demonstrated a 1000-fold induction of gene expression exclusive to Epstein-Barr virus (EBV)-positive nasopharyngeal carcinoma (NPC) cells using an adenoviral vector (ad5.oriP). This platform allows us to explore tumor-specific gene therapy with BimS (ad5.oriP.BimS), a potent proapoptotic Bcl-2 family member. Ad5.oriP.BimS (25 infectious units (ifu)/cell) reduced C666-1 viability in a time- and dose-dependent manner to 15% survival. The effect was enhanced with radiation (6 Gy). Three days after infection, the proportion of apoptotic cells increased from 3.5% (control) to 47.5% (25 ifu/cell). Confocal microscopy demonstrated Bim colocalization to the mitochondria within 18 h of ad5.oriP.BimS infection. Ad5.oriP.BimS induced a 2.8-, 2.1-, and 1.85-fold increase in caspase-3, -8, and -9 activities, respectively. When C666-1 cells were infected with ad5.oriP.BimS (20 ifu/cell), no tumors formed in 7/9 mice followed for 100 days. Six intratumoral injections of ad5.oriP.BimS (1.5 x 10(9) ifu/dose) in combination with radiation were sufficient to cause almost complete disappearance of established C666-1 or C15 xenograft tumors. Intravenous injections of ad5.oriP.BimS (10(9) ifu) induced mild perturbation in liver function tests, associated with hepatocyte apoptoses and mitoses. This vector appears to be safe and effectively cytotoxic to EBV-positive NPC cells both in vitro and in vivo, mediated primarily through the induction of apoptosis.