Multi-Specialty Physician Performance in Predicting Radiographic Extranodal Extension in Nodal Metastases of Oropharyngeal Squamous Carcinoma

PURPOSE/OBJECTIVE(S)

The presence of extranodal extension (ENE) in oropharyngeal (OPC) cancer patients is an important prognostic factor and can be used to determine the optimal course of treatment; however, currently, the gold standard method for ENE assessment is performed pathologically, which can only be done in a post-hoc fashion after surgical treatment has already been performed. Anatomic imaging features are being explored as a possible method for the pre-therapeutic determination of ENE, but there is currently no objective standard for the assessment of ENE from radiographic images. In this study we recruited expert clinicians, including surgeons, radiation oncologists, and radiologists, across multiple institutions to individually evaluate the presence of ENE from CT scans in order to assess the performance of radiographic ENE evaluation in human experts across different specialties.

MATERIALS/METHODS

Pre-therapy contrast-enhanced CT scans were collected from 25 OPC patients with lymph node metastasis that were pathologically evaluated for ENE after surgical resection. 5 scans were randomly chosen to be duplicated and left/right inverted, resulting in a total of 30 scans of which 21 had pathologically-confirmed ENE. To hide the inversion, all images were cropped to only show the oropharynx region. 34 expert head and neck cancer physicians, comprised of 12 surgeons, 11 radiation oncologists, and 11 radiologists, then separately evaluated the 30 CT scans using 3D Slicer for ENE presence or absence with their prediction confidence. For each physician, discriminative performance metrics were measured by calculating the accuracy, sensitivity, specificity, area under the receiver-operating characteristic curve (AUC), and Brier score, a measure of the probabilistic prediction accuracy calculated from their confidence where a lower Brier score is better. Statistical tests were performed using the Mann Whitney U test.

RESULTS

The median (interquartile) study results are shown in Table 1. There was no statistically significant difference among groups for accuracy or AUC, but significant differences among groups for Brier score, sensitivity, and specificity.

CONCLUSION

In this study we provide evidence that expert physicians, regardless of specialty, show poor performance in assessing the presence of ENE from CT scans in OPC patients. These results agree with conclusions from previous literature, and suggest the need for further research in the automated analysis of radiographic ENE.

Pilot study of a Spanish language measure of financial toxicity in underserved Hispanic cancer patients with low English proficiency

Background

Financial toxicity (FT) reflects multi-dimensional personal economic hardships borne by cancer patients. It is unknown whether measures of FT-to date derived largely from English-speakers-adequately capture economic experiences and financial hardships of medically underserved low English proficiency US Hispanic cancer patients. We piloted a Spanish language FT instrument in this population.

Methods

We piloted a Spanish version of the Economic Strain and Resilience in Cancer (ENRICh) FT measure using qualitative cognitive interviews and surveys in un-/under-insured or medically underserved, low English proficiency, Spanish-speaking Hispanics (UN-Spanish, n = 23) receiving ambulatory oncology care at a public healthcare safety net hospital in the Houston metropolitan area. Exploratory analyses compared ENRICh FT scores amongst the UN-Spanish group to: (1) un-/under-insured English-speaking Hispanics (UN-English, n = 23) from the same public facility and (2) insured English-speaking Hispanics (INS-English, n = 31) from an academic comprehensive cancer center. Multivariable logistic models compared the outcome of severe FT (score > 6).

Results

UN-Spanish Hispanic participants reported high acceptability of the instrument (only 0% responded that the instrument was "very difficult to answer" and 4% that it was "very difficult to understand the questions"; 8% responded that it was "very difficult to remember resources used" and 8% that it was "very difficult to remember the burdens experienced"; and 4% responded that it was "very uncomfortable to respond"). Internal consistency of the FT measure was high (Cronbach's α = 0.906). In qualitative responses, UN-Spanish Hispanics frequently identified a total lack of credit, savings, or income and food insecurity as aspects contributing to FT. UN-Spanish and UN-English Hispanic patients were younger, had lower education and income, resided in socioeconomically deprived neighborhoods and had more advanced cancer vs. INS-English Hispanics. There was a higher likelihood of severe FT in UN-Spanish (OR = 2.73, 95% CI 0.77-9.70; p = 0.12) and UN-English (OR = 4.13, 95% CI 1.13-15.12; p = 0.03) vs. INS-English Hispanics. A higher likelihood of severely depleted FT coping resources occurred in UN-Spanish (OR = 4.00, 95% CI 1.07-14.92; p = 0.04) and UN-English (OR = 5.73, 95% CI 1.49-22.1; p = 0.01) vs. INS-English. The likelihood of FT did not differ between UN-Spanish and UN-English in both models (p = 0.59 and p = 0.62 respectively).

Conclusion

In medically underserved, uninsured Hispanic patients with cancer, comprehensive Spanish-language FT assessment in low English proficiency participants was feasible, acceptable, and internally consistent. Future studies employing tailored FT assessment and intervention should encompass the key privations and hardships in this population.

Auto-detection and segmentation of involved lymph nodes in HPV-associated oropharyngeal cancer using a convolutional deep learning neural network

•

Patients diagnosed with HPV-associated OPC are often found to have clinical evidence of lymph node involvement at the time of diagnosis.

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Manual segmentation of radiographically involved lymph nodes is an integral part of treatment planning for those patients dispositioned to definitive radiotherapy.

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We present a deep learning, convolutional neural network that can be used to automate the process of lymph node detection and segmentation and with potential to increase the efficiency to the radiotherapy workflow.

Purpose

Segmentation of involved lymph nodes on head and neck computed tomography (HN-CT) scans is necessary for the radiotherapy planning of early-stage human papilloma virus (HPV) associated oropharynx cancers (OPC). We aimed to train a deep learning convolutional neural network (DL-CNN) to segment involved lymph nodes on HN-CT scans.

Methods

Ground-truth segmentation of involved nodes was performed on pre-surgical HN-CT scans for 90 patients who underwent levels II-IV neck dissection for node-positive HPV-OPC (training/validation [n = 70] and testing [n = 20]). A 5-fold cross validation approach was used to train 5 DL-CNN sub-models based on a residual U-net architecture. Validation and testing segmentation masks were compared to ground-truth masks using predetermined metrics. A lymph auto-detection model to discriminate between “node-positive” and “node-negative” HN-CT scans was developed by thresholding segmentation model outputs and evaluated using the area under the receiver operating characteristic curve (AUC).

Results

In the DL-CNN validation phase, all sub-models yielded segmentation masks with median Dice ≥ 0.90 and median volume similarity score of ≥ 0.95. In the testing phase, the DL-CNN produced consensus segmentation masks with median Dice of 0.92 (IQR, 0.89–0.95), median volume similarity of 0.97 (IQR, 0.94–0.99), and median Hausdorff distance of 4.52 mm (IQR, 1.22–8.38). The detection model achieved an AUC of 0.98.

Conclusion

The results from this single-institution study demonstrate the successful automation of lymph node segmentation for patients with HPV-OPC using a DL-CNN. Future studies, including validation with an external dataset, are necessary to clarify its role in the larger radiation oncology treatment planning workflow.

Benchmarking Outcomes for Definitive Treatment of Young-Onset, Locally Advanced Rectal Cancer

PURPOSE

There has been an increase in the incidence of rectal cancer diagnosed in young adults (age < 50 years). We evaluated outcomes among young adults treated with pre-operative long course chemoradiation (CRT) and total mesorectal excision (TME).

METHODS

The medical records of 219 patients, age 18-49, with non-metastatic, cT3-4, or cN1-2 rectal adenocarcinoma treated from 2000 to 2017 were reviewed for demographic and treatment characteristics, as well as pathologic and oncologic outcomes. The Kaplan-Meier test, log-rank test, and Cox regression analysis were used to evaluate survival outcomes.

RESULTS

The median age at diagnosis was 44 years. CRT followed by TME and post-operative chemotherapy was the most frequent treatment sequence (n = 196), with FOLFOX (n = 115) as the predominant adjuvant chemotherapy. There was no difference in sex, stage, MSS/pMMR, or pCR by age (< 45 years [n = 111] vs. ≥ 45 years [n = 108]). The 5-year rates of DFS were 77.2% for all patients, 69.8% for age < 45 years and 84.7% for age ≥ 45 years (P = .01). The 5-year rates of OS were 89.6% for all patients, 85.1% for patients with age < 45 years and 94.3% for patients with age ≥ 45 years (P = .03). Age ≥ 45 years was associated with a lower risk of disease recurrence or death on multivariable Cox regression analysis (HR = 0.55, 95% CI 0.31-0.97, P = .04).

CONCLUSION

Among young adults, patients with age < 45 years had lower rates of DFS and OS, compared to those with age ≥ 45 years. These outcomes could serve as a benchmark by which to evaluate newer treatment approaches.

Evaluation of deep learning-based multiparametric MRI oropharyngeal primary tumor auto-segmentation and investigation of input channel effects: Results from a prospective imaging registry

BACKGROUND/PURPOSE

Oropharyngeal cancer (OPC) primary gross tumor volume (GTVp) segmentation is crucial for radiotherapy. Multiparametric MRI (mpMRI) is increasingly used for OPC adaptive radiotherapy but relies on manual segmentation. Therefore, we constructed mpMRI deep learning (DL) OPC GTVp auto-segmentation models and determined the impact of input channels on segmentation performance.

MATERIALS/METHODS

GTVp ground truth segmentations were manually generated for 30 OPC patients from a clinical trial. We evaluated five mpMRI input channels (T2, T1, ADC, Ktrans, Ve). 3D Residual U-net models were developed and assessed using leave-one-out cross-validation. A baseline T2 model was compared to mpMRI models (T2 + T1, T2 + ADC, T2 + Ktrans, T2 + Ve, all five channels [ALL]) primarily using the Dice similarity coefficient (DSC). False-negative DSC (FND), false-positive DSC, sensitivity, positive predictive value, surface DSC, Hausdorff distance (HD), 95% HD, and mean surface distance were also assessed. For the best model, ground truth and DL-generated segmentations were compared through a blinded Turing test using three physician observers.

RESULTS

Models yielded mean DSCs from 0.71 ± 0.12 (ALL) to 0.73 ± 0.12 (T2 + T1). Compared to the T2 model, performance was significantly improved for FND, sensitivity, surface DSC, HD, and 95% HD for the T2 + T1 model (p < 0.05) and for FND for the T2 + Ve and ALL models (p < 0.05). No model demonstrated significant correlations between tumor size and DSC (p > 0.05). Most models demonstrated significant correlations between tumor size and HD or Surface DSC (p < 0.05), except those that included ADC or Ve as input channels (p > 0.05). On average, there were no significant differences between ground truth and DL-generated segmentations for all observers (p > 0.05).

CONCLUSION

DL using mpMRI provides reasonably accurate segmentations of OPC GTVp that may be comparable to ground truth segmentations generated by clinical experts. Incorporating additional mpMRI channels may increase the performance of FND, sensitivity, surface DSC, HD, and 95% HD, and improve model robustness to tumor size.

Advances in Imaging for HPV-Related Oropharyngeal Cancer: Applications to Radiation Oncology

While there has been an overall decline of tobacco and alcohol-related head and neck cancer in recent decades, there has been an increased incidence of HPV-associated oropharyngeal cancer (OPC). Recent research studies and clinical trials have revealed that the cancer biology and clinical progression of HPV-positive OPC is unique relative to its HPV-negative counterparts. HPV-positive OPC is associated with higher rates of disease control following definitive treatment when compared to HPV-negative OPC. Thus, these conditions should be considered unique diseases with regards to treatment strategies and survival. In order to sufficiently characterize HPV-positive OPC and guide treatment strategies, there has been a considerable effort to diagnose, prognose, and track the treatment response of HPV-associated OPC through advanced imaging research. Furthermore, HPV-positive OPC patients are prime candidates for radiation de-escalation protocols, which will ideally reduce toxicities associated with radiation therapy and has prompted additional imaging research to detect radiation-induced changes in organs at risk. This manuscript reviews the various imaging modalities and current strategies for tackling these challenges as well as provides commentary on the potential successes and suggested improvements for the optimal treatment of these tumors.

Precision association of lymphatic disease spread with radiation-associated toxicity in oropharyngeal squamous carcinomas

PURPOSE

To determine whether patient similarity in terms of head and neck cancer spread through lymph nodes correlates significantly with radiation-associated toxicity.

MATERIALS AND METHODS

582 head and neck cancer patients received radiotherapy for oropharyngeal cancer (OPC) and had non-metastatic affected lymph nodes in the head and neck. Affected lymph nodes were segmented from pretreatment contrast-enhanced tomography scans and categorized according to consensus guidelines. Similar patients were clustered into 4 groups according to a graph-based representation of disease spread through affected lymph nodes. Correlation between dysphagia-associated symptoms and patient groups was calculated.

RESULTS

Out of 582 patients, 26% (152) experienced toxicity during a follow up evaluation 6 months after completion of radiotherapy treatment. Patient groups identified by our approach were significantly correlated with dysphagia, feeding tube, and aspiration toxicity (p < .0005).

DISCUSSION

Our results suggest that structural geometry-aware characterization of affected lymph nodes can be used to better predict radiation-associated dysphagia at time of diagnosis, and better inform treatment guidelines.

CONCLUSION

Our work successfully stratified a patient cohort into similar groups using a structural geometry, graph-encoding of affected lymph nodes in oropharyngeal cancer patients, that were predictive of late radiation-associated dysphagia and toxicity.

External Beam Radiotherapy in Western Africa: 1969-2019

AIMS

We describe the absolute and per capita numbers of megavoltage radiotherapy machines (MVMs) in Western Africa from 1969 to 2019.

MATERIALS AND METHODS

Western Africa was defined in accordance with the United Nations' delineation and inclusive of 16 countries. A literature search for publications detailing the number of cobalt-60 machines (COs) and linear accelerators (LINACs) in radiotherapy centres was carried out. Population data from the World Bank Group and crude cancer rates from the International Agency for Research on Cancer were used to calculate ratios of million persons per MVM and MVMs per 1000 cancer cases.

RESULTS

The numbers of MVMs in Western Africa in 1969, 1979, 1989, 1999 and 2009 were zero, two, three, six and nine, respectively. In 2019 there were 22 MVMs distributed across Ghana (five), Côte d'Ivoire (two), Mali (one), Mauritania (two), Nigeria (nine) and Senegal (three). Nine countries (56.3%) had no history of external beam radiotherapy (EBRT). The largest increase in absolute EBRT capacity occurred from 2017 to 2019, during which 13 MVMs were commissioned. The largest decrease in EBRT capacity occurred from 2015 to 2017, during which four LINACs and three COs were rendered non-operational. The ratio of million persons per MVM improved from 67.0 in 1979 to 17.8 in 2019. As of 2019, there was 0.09 MVM per 1000 cancer cases.

CONCLUSIONS

Western African nations have experienced an increase in the absolute number of MVMs and per capita radiotherapy capacity during the last 50 years, especially in the last decade. As non-functional LINACs contributed to a temporary decline in the EBRT infrastructure, dual use of CO/LINAC technologies may act to promote the availability of EBRT treatment in centres with capacity for multiple MVMs.

Clinical outcomes following definitive treatment of young-onset, locally advanced rectal cancer: A single institution experience

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Background: We evaluated demographic, treatment, and survival outcomes of adults age 18 to 49 years treated at our institution with long course chemoradiotherapy (CRT) followed by total mesorectal excision (TME) for locally advanced rectal cancer. Additionally, we compared outcomes between those age < 45 vs. > 45 years. Methods: The records of 219 patients diagnosed with non-metastatic, clinical T3, T4, or node positive rectal adenocarcinoma and treated between April 2000 and November 2017 were reviewed for age, sex, and presenting symptoms; clinical stage and microsatellite stable (MSS)/DNA mismatch repair (MMR) proficiency status; treatments delivered and sequence; pathologic response to pre-operative therapies; and the development of locoregional recurrence (LRR), distant metastasis (DM), and secondary pelvic malignancy. The Kaplan-Meier method and Log-Rank test were used to calculate and compare disease-free survival (DFS) and overall survival (OS) rates from the date of TME. Results: The median age at diagnosis was 44 years (range 19-49) and there was no sex predominance. Rectal bleeding was the most common presenting symptom (91%), with a median time to diagnosis of 5 months. Clinical tumor/nodal categories were T1-2 in 4%, T3 in 87%, T4 in 7%, N0 in 17%, and N1–2 in 80% of patients. MSS/MMR proficient disease was identified in 95% of tumors with status reported (n = 170). CRT followed by TME and post-operative chemotherapy was the most frequent treatment sequence (n = 196), with capecitabine (n = 176) and FOLFOX (n = 115) as the predominant concurrent and post-operative chemotherapies, respectively. Pathologic complete response at both primary and nodal sites occurred in 15% of all cases and 16% of MSS/MMR proficient cases. There was no difference in sex, tumor category, nodal category, MSS/MMR proficiency status, or pathologic complete response, by age ( < 45 years [n = 111] vs. > 45 years [n = 108]). At a median DFS follow-up time of 5.0 years, there were 11 LRR, 40 DM (including 11 DM detected prior to/at time of TME), and 1 synchronous presentation of LRR and DM. The 5-year rate of DFS was 70.4% for age < 45 years and 85.3% for age > 45 years ( P = 0.02). At an OS median follow-up time of 7.5 years, there were 38 deaths. The 5-year rate of OS was 87.7% for age < 45 years and 94.4% for age > 45 years ( P = 0.126). Two patients developed non-rectal pelvic malignancies. Conclusions: The outcomes reported here from one of the largest single-institution series for young-onset, locally advanced rectal cancer could serve as a benchmark to evaluate newer treatment approaches. Rectal bleeding was the leading presenting symptom, with approximately half-year delay from development of symptoms to diagnosis. Most tumors were MSS/MMR proficient. At 5 years’ follow-up time, the DFS rate was lower for patients age < 45 years when compared to those > 45 years. Secondary pelvic malignancies were a rare occurrence.

Association Between Facility Volume and Overall Survival for Patients with Grade II Meningioma after Gross Total Resection

BACKGROUND

The role of adjuvant radiation after gross total resection (GTR) for grade II meningioma is evolving, prompting further evaluation in NRG-BN003, a phase 3 national trial. Furthermore, the relationship between facility volume and outcomes in patients with grade II meningioma after GTR has not been examined at a national level. We aim to assess overall survival (OS) of patients with grade II meningioma after GTR by surgical case volume and OS by receipt of adjuvant radiation.

METHODS

We used the National Cancer Database to identity 2823 patients diagnosed with grade II meningioma who underwent GTR. Propensity score matching was applied to balance covariates in patients with grade II meningioma after GTR stratified by adjuvant radiation status. Multivariable logistic regression was used to assess factors associated with radiation receipt. Kaplan-Meier and log-rank tests were used to assess OS by facility volume.

RESULTS

As facility volume increased, OS increased, with a 5-year OS of 72.8% for facilities with GTR grade II meningioma volumes of ≤8 cases per decade and 87.5% for >8 cases per decade (P < 0.0001). There was no difference in 5-year OS between GTR alone and GTR with adjuvant radiation (84.8% vs. 86.4%; P = 0.151). Covariates significantly associated with radiation receipt included facility location, facility volume, distance, and tumor size.

CONCLUSIONS

Treatment at higher surgical case volume facilities is associated with improved OS for GTR grade II meningioma. These facilities also have more patients receiving adjuvant radiation. However, we observed no difference in OS between adjuvant radiation and surgery alone.

Modeling Complex Deformations of the Sigmoid Colon Between External Beam Radiation Therapy and Brachytherapy Images of Cervical Cancer

PURPOSE

In this study, we investigated registration methods for estimating the large interfractional sigmoid deformations that occur between external beam radiation therapy (EBRT) and brachytherapy (BT) for cervical cancer.

METHODS AND MATERIALS

Sixty-three patients were retrospectively analyzed. The sigmoid colon was delineated on 2 computed tomography images acquired during EBRT (without applicator) and BT (with applicator) for each patient. Five registration approaches were compared to propagate the contour of the sigmoid from BT to EBRT anatomies: rigid registration, commercial hybrid (ANAtomically CONstrained Deformation Algorithm), controlling ROI surface projection of RayStation, and the classical and constrained symmetrical thin-plate spline robust point matching (sTPS-RPM) methods. Deformation of the sigmoid due to insertion of the BT applicator was reported. Registration performance was compared by using the Dice similarity coefficient (DSC), distance to agreement, and Hausdorff distance. The 2 sTPS-RPM methods were compared by using surface triangle quality criteria between deformed surfaces. Using the deformable approaches, the BT dose of the sigmoid was deformed toward the EBRT anatomy. The displacement and discrepancy between the deformable methods to propagate the planned D1cm³ and D2cm³ of the sigmoid from BT to EBRT anatomies were reported for 55 patients.

RESULTS

Large and complex deformations of the sigmoid were observed for each patient. Rigid registration resulted in poor sigmoid alignment with a mean DSC of 0.26. Using the contour to drive the deformation, ANAtomically CONstrained Deformation Algorithm was able to slightly improve the alignment of the sigmoid with a mean DSC of 0.57. Using only the sigmoid surface as controlling ROI, the mean DSC was improved to 0.79. The classical and constrained sTPS-RPM methods provided mean DSCs of 0.95 and 0.96, respectively, with an average inverse consistency error <1 mm. The constrained sTPS-RPM provided more realistic deformations and better surface topology of the deformed sigmoids. The planned mean (range) D1cm³ and D2cm³ of the sigmoid were 13.4 Gy (1-24.1) and 12.2 Gy (1-21.5) on the BT anatomy, respectively. Using the constrained sTPS-RPM to deform the sigmoid from BT to EBRT anatomies, these hotspots had a mean (range) displacement of 27.1 mm (6.8-81).

CONCLUSIONS

Large deformations of the sigmoid were observed between the EBRT and BT anatomies, suggesting that the D1cm³ and D2cm³ of the sigmoid would unlikely to be at the same position throughout treatment. The proposed constrained sTPS-RPM seems to be the preferred approach to manage the large deformation due to BT applicator insertion. Such an approach could be used to map the EBRT dose to the BT anatomy for personalized BT planning optimization.

Outcomes and toxicities following stereotactic ablative radiotherapy for pulmonary metastases in patients with primary head and neck cancer

BACKGROUND

Metastatic head and neck cancers (HNCs) predominantly affect the lungs and have a two-year overall survival (OS) of 15% to 50%, if amenable for pulmonary metastasectomy.

METHODS

Retrospective review of the two-year local control (LC), local-regional control (LRC) within the same lobe, OS, and toxicity rates in consecutive patients with metastatic pulmonary HNC who underwent stereotactic ablative radiotherapy (SABR) January 2007 to May 2018.

RESULTS

Evaluated 82 patients with 107 lung lesions, most commonly squamous cell carcinoma (SCC; 64%). Median follow-up was 20 months (range: 9.0-97.6). Systemic therapy administered in 34%. LC, LRC, and OS rates were 94%, 90%, and 62%. Patients with oligometastatic disease had a higher OS than polymetastatic disease, 72% vs 44% (HR = 0.30, 95% CI: 0.14-0.64; P = .008). OS in oligometastatic non-SCC and SCC were 100% and 66% (P = .03). There were no grade ≥3 toxicities.

CONCLUSIONS

Metastatic pulmonary HNCs after SABR have a two-year OS rate comparable to pulmonary metastasectomy.

Spine stereotactic radiosurgery for metastatic thyroid cancer: a single-institution experience

OBJECTIVE

Patients with metastatic thyroid cancer have prolonged survival compared to those with other primary tumors. The spine is the most common site of osseous involvement in cases of metastatic thyroid cancer. As a result, obtaining durable local control (LC) in the spine is crucial. This study aimed to evaluate the efficacy of spine stereotactic radiosurgery (SSRS) in patients with metastatic thyroid cancer.

METHODS

Information on patients with metastatic thyroid cancer treated with SSRS for spinal metastases was retrospectively evaluated. SSRS was delivered with a simultaneous integrated boost technique using single- or multiple-fraction treatments. LC, defined as stable or reduced disease volume, was evaluated by examining posttreatment MRI, CT, and PET studies.

RESULTS

A total of 133 lesions were treated in 67 patients. The median follow-up duration was 31 months. Dose regimens for SSRS included 18 Gy in 1 fraction, 27 Gy in 3 fractions, and 30 Gy in 5 fractions. The histology distribution was 36% follicular, 33% papillary, 15% medullary, 13% Hurthle cell, and 3% anaplastic. The 1-, 2-, and 5-year LC rates were 96%, 89%, and 82%, respectively. The median overall survival (OS) was 43 months, with 1-, 2-, and 5-year survival rates of 86%, 74%, and 44%, respectively. There was no correlation between the absolute biological equivalent dose (BED) and OS or LC. Patients with effective LC had a trend toward improved OS when compared to patients who had local failure: 68 versus 28 months (p = 0.07). In terms of toxicity, 5 vertebral compression fractures (2.8%) occurred, and only 1 case (0.6%) of greater than or equal to grade 3 toxicity (esophageal stenosis) was reported.

CONCLUSIONS

SSRS is a safe and effective treatment option with excellent LC and minimal toxicity for patients with metastatic thyroid cancer. No association with increased radiation dose or BED was found, suggesting that such patients can be effectively treated with reduced dose regimens.

RapidPlan development of VMAT plans for cervical cancer patients in low- and middle-income countries

Cervical cancer has a high incidence and mortality rate in low- and middle-income countries (LMICs) largely due to limited resources and insufficient staffing. Knowledge-based planning (KBP) could alleviate understaffing issues by streamlining the radiotherapy treatment planning process. Varian's KBP system (RapidPlan) was used to develop a model capable of producing volumetric modulated arc therapy (VMAT) plans for cervical cancer patients. Plan data from 46 patients previously treated at MD Anderson Cancer Center (MDACC) were used to create and train the model which was then applied to 32 patients excluded from the training process. Dose volume histogram (DVH) values for the planning target volume (PTV_High), bladder, rectum, and bowel were evaluated for the validation plans and found to have satisfied the required PTV coverage and organ-at-risk (OAR) dose constraints. The average value for PTV_High D_95.0% was 48.0 Gy (sd = 3.0 Gy) for existing clinical plans and 48.4 Gy (sd = 2.6 Gy) for the validation plans. The mean dose for the bladder, rectum, and bowel was 39.8 Gy (sd = 3.9 Gy), 41.6 Gy (sd = 5.2 Gy), and 21.6 Gy (sd = 5.0 Gy) for existing clinical plans and 38.9 Gy (sd = 4.0 Gy), 40.3 Gy (sd = 4.8 Gy), and 21.5 Gy (sd = 4.6 Gy) for validation plans, respectively. A TOST test showed that the p values for the PTV_High D_95.0% (p < 0.001), rectum V_30Gy (p = 0.039), and mean dose to the bladder (p = 0.0014), rectum (p = 0.025), and bowel (p = 0.006) were statistically significant within a 5% equivalence margin of the clinical value thereby providing strong evidence of equivalence. Based on this statistical analysis, it was determined that the model was capable of generating treatable VMAT plans for cervical cancer patients.

Deformable image registration for dose mapping between external beam radiotherapy and brachytherapy images of cervical cancer

For locally advanced cervical cancer (LACC), anatomy correspondence with and without BT applicator needs to be quantified to merge the delivered doses of external beam radiation therapy (EBRT) and brachytherapy (BT). This study proposed and evaluated different deformable image registration (DIR) methods for this application. Twenty patients who underwent EBRT and BT for LACC were retrospectively analyzed. Each patient had a pre-BT CT at EBRT boost (without applicator) and a CT and MRI at BT (with applicator). The evaluated DIR methods were the diffeomorphic Demons, commercial intensity and hybrid methods, and three different biomechanical models. The biomechanical models considered different boundary conditions (BCs). The impact of the BT devices insertion on the anatomy was quantified. DIR method performances were quantified using geometric criteria between the original and deformed contours. The BT dose was deformed toward the pre-CT BT by each DIR method. The impact of boundary conditions to drive the biomechanical model was evaluated based on the deformation vector field and dose differences. The GEC-ESTRO guideline dose indices were reported. Large organ displacements, deformations, and volume variations were observed between the pre-BT and BT anatomies. Rigid registration and intensity-based DIR resulted in poor geometric accuracy with mean Dice similarity coefficient (DSC) inferior to 0.57, 0.63, 0.42, 0.32, and 0.43 for the rectum, bladder, vagina, cervix and uterus, respectively. Biomechanical models provided a mean DSC of 0.96 for all the organs. By considering the cervix-uterus as one single structure, biomechanical models provided a mean DSC of 0.88 and 0.94 for the cervix and uterus, respectively. The deformed doses were represented for each DIR method. Caution should be used when performing DIR for this application as standard techniques may have unacceptable results. The biomechanical model with the cervix-uterus as one structure provided the most realistic deformations to propagate the BT dose toward the EBRT boost anatomy.

Prevalence, Predictors, and Implications for Appropriate Use of Active Surveillance Management Among Black Men Diagnosed With Low-risk Prostate Cancer

BACKGROUND

Consensus guidelines recommend that active surveillance (AS) be considered in the management of men with low-risk prostate cancer (LRPC). The objective was to evaluate the prevalence and predictors of an AS approach in black men (BM) diagnosed with LRPC after inclusion of AS in LRPC consensus guidelines.

MATERIALS AND METHODS

BM and white men (WM) diagnosed with LRPC (prostate-specific antigen ≤10 ng/mL, Gleason score [GS] ≤6, clinical stage T1-T2a) between 2010 and 2013 were identified from the National Cancer Database. Logistic regression models were used to assess the likelihood of AS over time and to examine associations between sociodemographic characteristics (SDCs) and the receipt of AS. A subanalysis was performed to assess the likelihood of GS upgrading on prostatectomy specimens for cases that received definitive treatment with radical prostatectomy.

RESULTS

Overall, 9% of BM (N=15,242) with LRPC were managed with AS. The likelihood of BM undergoing AS increased from 2010 and for all subsequent years of the study period (P<0.001). Uninsured BM were twice as likely as those with private insurance to undergo AS (odds ratio [OR]=1.97; 95% confidence interval [CI], 1.51-2.58; P<0.001). BM were less likely than WM (N=86,655) to receive AS (OR=0.82; 95% CI, 0.77-0.87; P<0.001). However, on multivariate analysis adjusted for SDCs, there was no significant difference in AS utilization between the 2 race groups. Nearly half of BM (47.5%) treated with radical prostatectomy had a postprostatectomy GS≥7, and BM were 17% more likely to experience postprostatectomy upgrading to GS≥7 when compared with WM (OR=1.17; 95% CI, 1.08-1.26; P<0.001).

CONCLUSIONS

The utilization of AS for BM with LRPC seems to be increasing, is influenced by SDCs, and may not differ from AS utilization among WM. Careful consideration of prostate biopsy technique and sampling as well as SDCs at time of treatment planning may be necessary to ensure adequate evaluation of prostatic disease and appropriate disease management for BM with LRPC.

Prevalence and predictors of active surveillance management for black males diagnosed with low risk prostate cancer

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Background: Consensus guidelines recommend that active surveillance (AS) be considered in the management of men with low risk prostate cancer (LRPC). The evidence supporting this recommendation is largely derived from studies in which men of African descent were underrepresented; thus, the appropriate implementation of AS in this population remains controversial. The objective of our study was to evaluate the prevalence and clinical predictors of an AS approach in black men (BM) diagnosed with LRPC following the 2010 inclusion of AS in LRPC management consensus guidelines. Methods: BM (N = 15,242) and non-Hispanic white men (WM) (N = 86,655) diagnosed with LRPC (as defined by PSA ≤ 10 ng/ml, Gleason score ≤ 6, clinical stage T1 – T2a) between 2010 and 2013 were identified from the National Cancer Database. Logistic regression models were used to assess the likelihood of pursuing an AS strategy over time, as well as to examine associations between sociodemographic characteristics (SDCs) and the receipt of AS. Results: Overall, 9% of BM with LRPC were managed with AS. On univariate analysis, the likelihood of BM undergoing AS increased from 2010 and was statistically significant ( p < 0.001) for all subsequent years (2011: OR = 1.54, 95% CI 1.30-1.82; 2012: OR = 2.19, 95% CI 1.82-2.60; 2013: OR = 2.55, 95% CI 2.15-3.02). Uninsured BM were twice as likely as those with private insurance to pursue AS (OR 1.97, 95% CI 1.51-2.58, p < 0.001). BM seen at academic cancer programs were also more likely to be managed with AS, when compared to those seen at community cancer centers (OR 1.47, 95% CI 1.37-1.60, p < 0.001). BM were less likely than WM to receive AS (OR = 0.82, 95% CI 0.77 to 0.87, p < 0.001). On multivariate analysis adjusted for SDCs, there was no significant difference in AS utilization between the two ethnic groups. Conclusions: The utilization of AS for BM with LRPC appears to be increasing, may be influenced by SDCs, and may not differ from the AS utilization for WM with LRPC. Given the observed elevated rates of post-prostatectomy adverse pathologic features among BM, further evaluation of the determinants of AS utilization and scrutinous consideration of the appropriateness of AS in this population is warranted.

The use of 11carbon methionine positron emission tomography (PET) imaging to enhance radiotherapy planning in the treatment of a giant, invasive pituitary adenoma

A 54-year-old male presented with visual loss owing to a giant, infiltrative pituitary adenoma. Following decompressive trans-sphenoidal surgery, the patient was referred for adjuvant radiotherapy. We describe the potential utility of ¹¹carbon methionine positron emission tomography imaging in confirming the true extent of tumour infiltration, which included the cavernous sinuses and the bones of the skull base. The co-registration of positron emission tomography imaging to planning MR and CT imaging provided assurance of complete radiotherapy coverage of the target volume and assisted with the minimisation of collateral radiation dose to adjacent organs at risk.

Time Dependence of Radiation-induced Hypothalamic-Pituitary Axis Dysfunction in Adults Treated for Non-pituitary, Intracranial Neoplasms

AIMS

Hypothalamic-pituitary axis (HPA) dysfunction is a sequela of cranial radiotherapy. The purpose of this study was to use endocrine data from existing publications to characterise the baseline endocrine status, the effects of radiotherapy on the HPA during the first follow-up year and the time dependence of radiation-induced HPA dysfunction in patients treated with radiotherapy for non-pituitary intracranial neoplasms.

MATERIALS AND METHODS

A systematic search of databases was carried out for articles that reported the results of endocrine testing for patients aged 16 years and older who were treated with neurosurgery for non-pituitary intracranial neoplasms or radiotherapy for nasopharyngeal neoplasms. To analyse the radiotherapy-related changes in hormone levels over time, long-term prospective endocrine data from nasopharyngeal studies were normalised to baseline hormone data and fitted to an exponential decay model. This process was repeated with normalisation to year 1 hormone data.

RESULTS

Eight unique articles met eligibility criteria. HPA dysfunction occurred in 21.6-64.7% of patients who were assessed for endocrinopathies following neurosurgery. Studies on the early effects of radiotherapy on nasopharyngeal patients showed statistically significant changes in growth hormone, luteinizing hormone and follicle stimulating hormone levels during the first year of follow-up. Time dependence modelling showed that normalisation to year 1 hormone levels yield exponential equations with stronger measures of goodness of fit.

CONCLUSION

HPA dysfunction in patients treated for non-pituitary intracranial neoplasms is probably a result of both neurosurgery and radiotherapy treatments. Although statistically significant endocrine changes can occur during this first year of follow-up, those documented at year 1 may be more predictive of subsequent HPA dysfunction.