Donald M. Cannon

A multi-institution evaluation of deformable image registration algorithms for automatic organ delineation in adaptive head and neck radiotherapy

BackgroundAdaptive Radiotherapy aims to identify anatomical deviations during a radiotherapy course and modify the treatment plan to maintain treatment objectives. This requires regions of interest (ROIs) to be defined using the most recent imaging data. This study investigates the clinical utility of using deformable image registration (DIR) to automatically propagate ROIs.MethodsTarget (GTV) and organ-at-risk (OAR) ROIs were non-rigidly propagated from a planning CT scan to a per-treatment CT scan for 22 patients. Propagated ROIs were quantitatively compared with expert physician-drawn ROIs on the per-treatment scan using Dice scores and mean slicewise Hausdorff distances, and center of mass distances for GTVs. The propagated ROIs were qualitatively examined by experts and scored based on their clinical utility.ResultsGood agreement between the DIR-propagated ROIs and expert-drawn ROIs was observed based on the metrics used. 94% of all ROIs generated using DIR were scored as being clinically useful, requiring minimal or no edits. However, 27% (12/44) of the GTVs required major edits.ConclusionDIR was successfully used on 22 patients to propagate target and OAR structures for ART with good anatomical agreement for OARs. It is recommended that propagated target structures be thoroughly reviewed by the treating physician.

Increased local failure risk with prolonged radiation treatment time in head and neck cancer treated with concurrent chemotherapy

Prolonged radiation treatment time (RTT) in head and neck squamous cell carcinoma (HNSCC) is associated with inferior tumor control in patients treated with radiation therapy (RT) alone. However, the significance of prolonged RTT with concurrent chemotherapy is less clear.

Risk of Cerebrovascular Events in Elderly Patients After Radiation Therapy Versus Surgery for Early-Stage Glottic Cancer

PURPOSE Comprehensive neck radiation therapy (RT) has been shown to increase cerebrovascular disease (CVD) risk in advanced-stage head-and-neck cancer. We assessed whether more limited neck RT used for early-stage (T1-T2 N0) glottic cancer is associated with increased CVD risk, using the Surveillance, Epidemiology, and End Results (SEER)-Medicare linked database. METHODS AND MATERIALS We identified patients ≥66 years of age with early-stage glottic laryngeal cancer from SEER diagnosed from 1992 to 2007. Patients treated with combined surgery and RT were excluded. Medicare CPT codes for carotid interventions, Medicare ICD-9 codes for cerebrovascular events, and SEER data for stroke as the cause of death were collected. Similarly, Medicare CPT and ICD-9 codes for peripheral vascular disease (PVD) were assessed to serve as an internal control between treatment groups. RESULTS A total of 1413 assessable patients (RT, n=1055; surgery, n=358) were analyzed. The actuarial 10-year risk of CVD was 56.5% (95% confidence interval 51.5%-61.5%) for the RT cohort versus 48.7% (41.1%-56.3%) in the surgery cohort (P=.27). The actuarial 10-year risk of PVD did not differ between the RT (52.7% [48.1%-57.3%]) and surgery cohorts (52.6% [45.2%-60.0%]) (P=.89). Univariate analysis showed an increased association of CVD with more recent diagnosis (P=.001) and increasing age (P=.001). On multivariate Cox analysis, increasing age (P<.001) and recent diagnosis (P=.002) remained significantly associated with a higher CVD risk, whereas the association of RT and CVD remained not statistically significant (HR=1.11 [0.91-1.37,] P=.31). CONCLUSIONS Elderly patients with early-stage laryngeal cancer have a high burden of cerebrovascular events after surgical management or RT. RT and surgery are associated with comparable risk for subsequent CVD development after treatment in elderly patients.

Multi-institutional Quantitative Evaluation and Clinical Validation of Smart Probabilistic Image Contouring Engine (SPICE) Autosegmentation of Target Structures and Normal Tissues on Computer Tomography Images in the Head and Neck, Thorax, Liver, and Male Pelvis Areas

PURPOSE Clinical validation and quantitative evaluation of computed tomography (CT) image autosegmentation using Smart Probabilistic Image Contouring Engine (SPICE). METHODS AND MATERIALS CT images of 125 treated patients (32 head and neck [HN], 40 thorax, 23 liver, and 30 prostate) in 7 independent institutions were autosegmented using SPICE and computational times were recorded. The number of structures autocontoured were 25 for the HN, 7 for the thorax, 3 for the liver, and 6 for the male pelvis regions. Using the clinical contours as reference, autocontours of 22 selected structures were quantitatively evaluated using Dice Similarity Coefficient (DSC) and Mean Slice-wise Hausdorff Distance (MSHD). All 40 autocontours were evaluated by a radiation oncologist from the institution that treated the patients. RESULTS The mean computational times to autosegment all the structures using SPICE were 3.1 to 11.1 minutes per patient. For the HN region, the mean DSC was >0.70 for all evaluated structures, and the MSHD ranged from 3.2 to 10.0 mm. For the thorax region, the mean DSC was 0.95 for the lungs and 0.90 for the heart, and the MSHD ranged from 2.8 to 12.8 mm. For the liver region, the mean DSC was >0.92 for all structures, and the MSHD ranged from 5.2 to 15.9 mm. For the male pelvis region, the mean DSC was >0.76 for all structures, and the MSHD ranged from 4.8 to 10.5 mm. Out of the 40 autocontoured structures reviews by experts, 25 were scored useful as autocontoured or with minor edits for at least 90% of the patients and 33 were scored useful autocontoured or with minor edits for at least 80% of the patients. CONCLUSIONS Compared with manual contouring, autosegmentation using SPICE for the HN, thorax, liver, and male pelvis regions is efficient and shows significant promise for clinical utility.

Low Rates of Heterotopic Ossification After Resurfacing Hip Arthroplasty With Use of Prophylactic Radiotherapy in Select Patients

Recent reports have noted higher rates of heterotopic ossification (HO) with surface replacement arthroplasty (SRA) than with traditional total hip arthroplasty in the absence of postoperative HO prophylaxis. This study reports rates and grades of HO in 44 SRA patients with at least 1 year of follow-up. Heterotopic ossification prophylaxis was used in 32 (73%) of 44 cases. Heterotopic ossification prophylaxis consisted of radiotherapy (22/32), nonsteroidal anti-inflammatory drugs (8/32), or both (2/32). One case of clinically significant HO was documented in the no-prophylaxis group. This strategy of selective HO prophylaxis in patients felt by orthopedic surgeons to be at high risk of HO resulted in low rates of clinically relevant HO after SRA (1/44, 2.3%). Further study is needed to establish optimal selection criteria for HO prophylaxis after SRA.

Image-guided radiation therapy for liver tumors: gastrointestinal histology matters.

Objectives:To describe the safety and efficacy of single-fraction and hypofractionated image-guided radiotherapy techniques for the treatment of large liver tumors. Methods:Forty-six patients, with 50 tumors (10 primary liver tumors, 40 liver metastases) from March 2004 to March 2011 were reviewed. The maximal tumor diameter ranged from 1.2 to 11.3 cm (median, 4.2 cm). Eighty-seven percent of patients received prior systemic chemotherapy. Fifty-nine percent had prior invasive local therapy including surgery, ablation, or embolization. Twenty-five lesions were treated with hypofractionated therapy (24 to 30 Gy in 3 to 5 fractions), whereas 19 received a single fraction (18 or 24 Gy). Local control (LC) was calculated using competing risk analysis. Overall survival was calculated by the Kaplan-Meier method. Results:Median follow-up for all patients was 29.8 months (range, 3 to 46 mo). The median survival was 15.4 months. The 1- and 2-year LC rates were 78% and 75%, respectively. Dose and tumor size had no significant effect on tumor progression. The local progression at 1 and 2 years was 29% and 32% for gastrointestinal (GI) histologies versus 0% for non-GI histologies (P=0.02). Tumor volumes larger than 112 cm3 correlated with decreased survival (P=0.05). Three patients developed late grade 3 GI stricture or ulceration. Conclusions:Image-guided radiotherapy for liver tumors achieves good rates of LC with minimal toxicity at 1 and 2 years even in patients with large or recurrent disease that has been heavily pretreated. GI histology demonstrated decreased LC rates. Further management strategies should be considered in these patients.

Lung tumor segmentation using electric flow lines for graph cuts

Lung cancer is the most common cause of cancer-related death. A common treatment is radiotherapy where the lung tumors are irradiated with ionizing radiation. The treatment is typically fractionated, i.e. spread out over time, allowing healthy tissue to recover between treatments and allowing tumor cells to be hit in their most sensitive phase. Changes in tumors over the course of treatment allows for an adaptation of the radiotherapy plan based on 3D computer tomography imaging. This paper introduces a method for segmentation of lung tumors on consecutive computed tomography images. These images are normally only used for correction of movements. The method uses graphs based on electric flow lines. The method offers several advantages when trying to replicate manual segmentations. The method gave a dice coefficient of 0.85 and performed better than level set methods and deformable registration.

Impact of a Contralateral Tumor Nodule on Survival in Non-Small-Cell Lung Cancer

Introduction: Contralateral lung tumors in non–small-cell lung cancer (NSCLC) are classified as stage M1a yet may represent hematogenous metastases or synchronous primary tumors. The impact of these tumors on overall survival (OS) is poorly understood. Here, we aim to determine whether NSCLC patients with M1a disease due only to a contralateral tumor nodule exhibit a favorable prognosis relative to other M1a or M1b patients. Methods: Retrospective evaluation of the impact of contralateral tumor nodules on OS in NSCLC stratified by primary tumor size and N stage attained from Surveillance, Epidemiology, and End Results database. Results: Of 173,640 patients, 5161 M1a-contra patients were identified. Median and 3-year OS for these patients exceeded that of patients with M1b (p < 0.0001) or other M1a disease (p < 0.0001). Primary tumor size and N stage were strongly associated with OS in M1a-contra patients. Three-year OS demonstrated a delayed convergence between M1a-contra and other M1a patients with primary tumors greater than or equal to 3 cm or mediastinal lymph node involvement. Proportional hazard modeling indicated that T1-2N0-1M1a-contra patients exhibit OS not significantly different (p = 0.258) from that predicted with comparable T and N stage disease plus a second early-stage primary. Conclusions: Contralateral tumors in NSCLC carry a more favorable prognosis than other M1a or M1b disease. Primary tumor size and N stage may help distinguish M1a-contra patients with hematogenous metastasis from those with a synchronous, second primary.

Lymph Node Yield in Therapeutic Neck Dissection: Impact of Dissection Levels and Prior Radiotherapy:

Objective: Lymph node yield in therapeutic neck dissection is clinically significant and incompletely studied. We quantified node yield based on extent of neck dissection and presence of preoperative radiation. We also evaluated factors affecting incidence of extracapsular spread (ECS). Methods: Retrospective review of 499 patients undergoing therapeutic neck dissection; 414 patients met inclusion criteria and were divided into 2 groups: neck dissection alone or before radiation (surgery first: 280 patients; 385 dissections) and primary radiation before surgery (radiation first: 134 patients; 157 dissections). Node yield relative to levels dissected and incidence of ECS were examined. Results: Dissection-specific node yield was greater in the surgery first group for dissection of levels I-V (31.1 ± 16.7 vs 24.0 ± 14.7, P < .001) and levels II-V (26.7 ± 14.4 vs 21.1 ± 10.7). Extracapsular spread incidence was 32.1% (98/305) in the surgery first group and 15.4% (23/149) in the radiation first group (P < .001). Conclusion: This study clarifies anticipated node yield based on number of levels dissected and presence of preoperative radiation. Node yield and incidence of ECS are lower in patients undergoing preoperative radiation.

Impact of Radiation on Lymph Node Counts and Incidence of Extracapsular-Spread in Neck Dissection Specimens

Objectives: 1) Analyze the impact of preoperative radiotherapy on total lymph node yield in neck dissection specimens. 2) Analyze the impact of preoperative radiotherapy on the presence of extracapsular-spread in neck dissection specimens. Methods: Historical cohort study. Setting: Academic medical center. Patients: 525 subjects who underwent neck dissection for a diagnosis of squamous cell carcinoma from 1990 to 2010 were analyzed. Subjects were divided into 2 groups; those who underwent neck dissection alone or had neck dissection before radiation (surgery first group), versus subjects who received radiation therapy before neck dissection (radiation first group). Outcome Measures: The total number of lymph nodes harvested as well as the incidence of extracapsular-spread was examined between these two groups. Results: A total of 366 patients in the surgery first group and 159 in the radiation first group were analyzed. The mean number of lymph nodes harvested in the surgery first group was 29.4, compared to 20.9 lymph nodes in the radiation first group (P < 0.001). Of 461 patients with available extracapsular-spread data, 106 (23.0%) had extracapsular-spread identified in their pathology report. Preoperative radiation significantly decreased the incidence of extracapsular-spread (OR=0.296, P < 0.001). The incidence of extracapsular-spread was 26.9% (84/312) in the surgery first group, and 14.8% (22/149) in the radiation first group. Conclusions: We identified a significantly decreased number of lymph nodes harvested and a decreased frequency of extracapsular-spread in the neck dissection specimens from patients who had undergone prior neck irradiation as compared to those without prior neck irradiation.