Investigation of autosegmentation techniques on T2-weighted MRI for off-line dose reconstruction in MR-linac workflow for head and neck cancers

BACKGROUND

In order to accurately accumulate delivered dose for head and neck cancer patients treated with the Adapt to Position workflow on the 1.5T magnetic resonance imaging (MRI)-linear accelerator (MR-linac), the low-resolution T2-weighted MRIs used for daily setup must be segmented to enable reconstruction of the delivered dose at each fraction.

PURPOSE

In this pilot study, we evaluate various autosegmentation methods for head and neck organs at risk (OARs) on on-board setup MRIs from the MR-linac for off-line reconstruction of delivered dose.

METHODS

Seven OARs (parotid glands, submandibular glands, mandible, spinal cord, and brainstem) were contoured on 43 images by seven observers each. Ground truth contours were generated using a simultaneous truth and performance level estimation (STAPLE) algorithm. Twenty total autosegmentation methods were evaluated in ADMIRE: 1-9) atlas-based autosegmentation using a population atlas library (PAL) of 5/10/15 patients with STAPLE, patch fusion (PF), random forest (RF) for label fusion; 10-19) autosegmentation using images from a patient's 1-4 prior fractions (individualized patient prior [IPP]) using STAPLE/PF/RF; 20) deep learning (DL) (3D ResUNet trained on 43 ground truth structure sets plus 45 contoured by one observer). Execution time was measured for each method. Autosegmented structures were compared to ground truth structures using the Dice similarity coefficient, mean surface distance (MSD), Hausdorff distance (HD), and Jaccard index (JI). For each metric and OAR, performance was compared to the inter-observer variability using Dunn's test with control. Methods were compared pairwise using the Steel-Dwass test for each metric pooled across all OARs. Further dosimetric analysis was performed on three high-performing autosegmentation methods (DL, IPP with RF and 4 fractions [IPP_RF_4], IPP with 1 fraction [IPP_1]), and one low-performing (PAL with STAPLE and 5 atlases [PAL_ST_5]). For five patients, delivered doses from clinical plans were recalculated on setup images with ground truth and autosegmented structure sets. Differences in maximum and mean dose to each structure between the ground truth and autosegmented structures were calculated and correlated with geometric metrics.

RESULTS

DL and IPP methods performed best overall, all significantly outperforming inter-observer variability and with no significant difference between methods in pairwise comparison. PAL methods performed worst overall; most were not significantly different from the inter-observer variability or from each other. DL was the fastest method (33 s per case) and PAL methods the slowest (3.7-13.8 min per case). Execution time increased with a number of prior fractions/atlases for IPP and PAL. For DL, IPP_1, and IPP_RF_4, the majority (95%) of dose differences were within ± 250 cGy from ground truth, but outlier differences up to 785 cGy occurred. Dose differences were much higher for PAL_ST_5, with outlier differences up to 1920 cGy. Dose differences showed weak but significant correlations with all geometric metrics (R2 between 0.030 and 0.314).

CONCLUSIONS

The autosegmentation methods offering the best combination of performance and execution time are DL and IPP_1. Dose reconstruction on on-board T2-weighted MRIs is feasible with autosegmented structures with minimal dosimetric variation from ground truth, but contours should be visually inspected prior to dose reconstruction in an end-to-end dose accumulation workflow.

Safety and efficacy of salvage conventional re-irradiation following stereotactic radiosurgery for spine metastases

PURPOSE

There has been limited work assessing the use of re-irradiation (re-RT) for local failure following stereotactic spinal radiosurgery (SSRS). We reviewed our institutional experience of conventionally-fractionated external beam radiation (cEBRT) for salvage therapy following SSRS local failure.

MATERIALS AND METHODS

We performed a retrospective review of 54 patients that underwent salvage conventional re-RT at previously SSRS-treated sites. Local control following re-RT was defined as the absence of progression at the treated site as determined by magnetic resonance imaging.

RESULTS

Competing risk analysis for local failure was performed using a Fine-Gray model. The median follow-up time was 25 months and median overall survival (OS) was 16 months (95% confidence interval [CI], 10.8-24.9 months) following cEBRT re-RT. Multivariable Cox proportional-hazards analysis revealed Karnofsky performance score prior to re-RT (hazard ratio [HR] = 0.95; 95% CI, 0.93-0.98; p = 0.003) and time to local failure (HR = 0.97; 95% CI, 0.94-1.00; p = 0.04) were associated with longer OS, while male sex (HR = 3.92; 95% CI, 1.64-9.33; p = 0.002) was associated with shorter OS. Local control at 12 months was 81% (95% CI, 69.3-94.0). Competing risk multivariable regression revealed radioresistant tumors (subhazard ratio [subHR] = 0.36; 95% CI, 0.15-0.90; p = 0.028) and epidural disease (subHR = 0.31; 95% CI, 0.12-0.78; p =0.013) were associated with increased risk of local failure. At 12 months, 91% of patients maintained ambulatory function.

CONCLUSION

Our data suggest that cEBRT following SSRS local failure can be used safely and effectively. Further investigation is needed into optimal patient selection for cEBRT in the retreatment setting.

Feasibility of a novel non-invasive swab technique for serial whole-exome sequencing of cervical tumors during chemoradiation therapy

Background

Clinically relevant genetic predictors of radiation response for cervical cancer are understudied due to the morbidity of repeat invasive biopsies required to obtain genetic material. Thus, we aimed to demonstrate the feasibility of a novel noninvasive cervical swab technique to (1) collect tumor DNA with adequate throughput to (2) perform whole-exome sequencing (WES) at serial time points over the course of chemoradiation therapy (CRT).

Methods

Cervical cancer tumor samples from patients undergoing chemoradiation were collected at baseline, at week 1, week 3, and at the completion of CRT (week 5) using a noninvasive swab-based biopsy technique. Swab samples were analyzed with whole-exome sequencing (WES) with mutation calling using a custom pipeline optimized for shallow whole-exome sequencing with low tumor purity (TP). Tumor mutation changes over the course of treatment were profiled.

Results

216 samples were collected and successfully sequenced for 70 patients (94% of total number of tumor samples collected). A total of 33 patients had a complete set of samples at all four time points. The mean mapping rate was 98% for all samples, and the mean target coverage was 180. Estimated TP was greater than 5% for all samples. Overall mutation frequency decreased during CRT but mapping rate and mean target coverage remained at >98% and >180 reads at week 5.

Conclusion

This study demonstrates the feasibility and application of a noninvasive swab-based technique for WES analysis which may be applied to investigate dynamic tumor mutational changes during treatment to identify novel genes which confer radiation resistance.

Linguistic Biases in Letters of Recommendation for Radiation Oncology Residency Applicants from 2015 to 2019

We aimed to investigate whether implicit linguistic biases exist in letters of recommendation (LORs) for applicants to radiation oncology (RO) residency. LORs (n = 487) written for applicants (n = 125) invited to interview at a single RO residency program from the 2015 to 2019 application cycles were included for analysis. Linguistic Inquiry and Word Count (LIWC) software was used to evaluate LORs for length and a dictionary of predetermined themes. Language was evaluated for gender bias using a publicly available gender bias calculator. Non-parametric tests were used to compare linguistic domain scores. The median number of the LORs per applicant was 4 (range 3-5). No significant differences by applicant gender were detected in LIWC score domains or gender bias calculator (P > 0.05). However, LORs for applicants from racial/ethnic backgrounds underrepresented in medicine were less likely to include standout descriptors (P = 0.008). Male writers were less likely to describe applicant characteristics related to patient care (P < 0.0001) and agentic personality (P = 0.006). LORs written by RO were shorter (P < 0.0001) and included fewer standout descriptors (P = 0.014) but were also more likely to include statements regarding applicant desirability (P = 0.045) and research (P = 0.008). While language was globally male-biased, assistant professors were less likely than associate professors (P = 0.0064) and full professors (P = 0.023) to use male-biased language. Significant linguistic differences were observed in RO residency LORs, suggesting that implicit biases related to both applicants and letter writers may exist. Recognition, and ideally eradication, of such biases are crucial for fair and equitable evaluation of a diverse applicant pool of RO residency candidates.

Outcomes After Breast Radiation Therapy in a Diverse Patient Cohort With a Germline BRCA1/2 Mutation

PURPOSE

BRCA1/2 pathogenic variant (PV) mutations confer radiation sensitivity preclinically, but there are limited data regarding breast cancer outcomes after radiation therapy (RT) among patients with documented BRCA1/2 PV mutations versus no PV mutations.

METHODS AND MATERIALS

This retrospective cohort study included women with clinical stage I-III breast cancer who received definitive surgery and RT and underwent BRCA1/2 genetic evaluation at the The University of Texas MD Anderson Cancer Center. Rates of locoregional recurrence (LRR), disease-specific death (DSD), toxicities, and second cancers were compared by BRCA1/2 PV status.

RESULTS

Of the 2213 women who underwent BRCA1/2 testing, 63% self-reported their race as White, 13.6% as Black/African American, 17.6% as Hispanic, and 5.8% as Asian/American Indian/Alaska Native; 124 had BRCA1 and 100 had BRCA2 mutations; and 1394 (63%) received regional nodal RT. The median follow-up time for all patients was 7.4 years (95% confidence interval [CI], 7.1-7.7 years). No differences were found between the groups with and without BRCA1/2 PV mutations in 10-year cumulative incidences of LRR (with mutations: 11.6% [95% CI, 7.0%-17.6%]; without mutations: 6.6% [95% CI, 5.3%-8.0%]; P = .466) and DSD (with mutations: 12.3% [95% CI, 8.0%-17.7%]; without mutations: 13.8% [95% CI, 12.0%-15.8%]; P = .716). On multivariable analysis, BRCA1/2 status was not associated with LRR or DSD, but Black/African American patients (P = .036) and Asians/American Indians/Alaska Native patients (P = .002) were at higher risk of LRR compared with White patients, and Black/African American patients were at higher risk of DSD versus White patients (P = .004). No in-field, nonbreast second cancers were observed in the BRCA1/2 PV group. Rates of acute and late grade ≥3 radiation-related toxicity in the BCRA1/2 PV group were 5.4% (n = 12) and 0.4% (n = 1), respectively.

CONCLUSIONS

Oncologic outcomes in a diverse cohort of patients with breast cancer who had a germline BRCA1/2 PV mutation and were treated with RT were similar to those of patients with no mutation, supporting the use of RT according to standard indications in patients with a germline BRCA1/2 PV mutation.

Breast Radiation Therapy-Related Treatment Outcomes in Patients With or Without Germline Mutations on Multigene Panel Testing

PURPOSE

Multigene panel testing has increased the detection of germline mutations in patients with breast cancer. The implications of using radiation therapy (RT) to treat patients with pathogenic variant (PV) mutations are not well understood and have been studied mostly in women with only BRCA1 or BRCA2 PVs. We analyzed oncologic outcomes and toxicity after adjuvant RT in a contemporary, diverse cohort of patients with breast cancer who underwent genetic panel testing.

METHODS AND MATERIALS

We retrospectively reviewed the records of 286 women with clinical stage I-III breast cancer diagnosed from 1995 to 2017 who underwent surgery, breast or chest wall RT with or without regional nodal irradiation, multigene panel testing, and evaluation at a large cancer center's genetic screening program. We evaluated rates of overall survival, locoregional recurrence, disease-specific death, and radiation-related toxicities in 3 groups: BRCA1/2 PV carriers, non-BRCA1/2 PV carriers, and patients without PV mutations.

RESULTS

PVs were detected in 25.2% of the cohort (12.6% BRCA1/2 and 12.6% non-BRCA1/2). The most commonly detected non-BRCA1/2 mutated genes were ATM, CHEK2, PALB2, CDH1, TP53, and PTEN. The median follow-up time for the entire cohort was 4.4 years (95% confidence interval, 3.8-4.9 years). No differences were found in overall survival, locoregional recurrence, or disease-specific death between groups (P > .1 for all). Acute and late toxicities were comparable across groups.

CONCLUSION

Oncologic and toxicity outcomes after RT in women with PV germline mutations detected by multigene pane testing are similar to those in patients without detectable mutations, supporting the use of adjuvant RT as a standard of care when indicated.

Expansion of Candidate HPV-Specific T Cells in the Tumor Microenvironment during Chemoradiotherapy Is Prognostic in HPV16+ Cancers

Human papillomavirus (HPV) infection causes 600,000 new cancers worldwide each year. HPV-related cancers express the oncogenic proteins E6 and E7, which could serve as tumor-specific antigens. It is not known whether immunity to E6 and E7 evolves during chemoradiotherapy or affects survival. Using T cells from 2 HPV16⁺ patients, we conducted functional T-cell assays to identify candidate HPV-specific T cells and common T-cell receptor motifs, which we then analyzed across 86 patients with HPV-related cancers. The HPV-specific clones and E7-related T-cell receptor motifs expanded in the tumor microenvironment over the course of treatment, whereas non-HPV-specific T cells did not. In HPV16⁺ patients, improved recurrence-free survival was associated with HPV-responsive T-cell expansion during chemoradiotherapy.

Use of specific duodenal dose constraints during treatment planning reduces toxicity after definitive para-aortic radiotherapy for cervical cancer

PURPOSE

To validate the safety of paraaortic nodal (PAN) radiation therapy (RT) for patients with cervical cancer when the duodenal dose is limited to V₅₅<15 cm³ and V₆₀<2 cm³.

METHODS AND MATERIALS

Ninety-seven patients who were treated with RT for cervical cancer between 2010 and 2018, received at least 56 Gy to grossly involved PANs. Patients were treated with concurrent chemoradiation (n=88, 91%), with 93% (n=90) receiving intensity-modulated RT (IMRT) to the initial PAN field, and 98% (n=95) receiving IMRT to a sequential PAN boost. V₅₅<15 cm³ and V₆₀ <2 cm³ criteria were implemented in 2014. Normal tissues were contoured on CT simulation datasets; the duodenum was contoured from the gastric outlet to the duodenojejunal flexure. Sixty-six patients (68%) had a resimulation scan after approximately 20 fractions. Composite duodenal doses were calculated using the initial CT for 50 patients (52%) and the resimulation CT for 47 patients (48%) depending on anatomic changes throughout treatment.

RESULTS

The median duodenal V₅₅ was 3.5 cm³ (interquartile range [IQR] 0.2-8.1 cm³) and the median V₆₀ was 0.3 cm³ (IQR 0.0-1.8). Constraints were exceeded in 18 patients, 16 (89%) of whom had been treated before 2014. Treatment for the 2 patients treated after 2014 had been complicated by significant weight loss and reduced anterior-posterior diameter, which likely overestimated the true dose on the composite plan. Only 1 patient experienced grade 3 duodenal toxicity (stricture requiring endoscopic balloon dilation 3 months after treatment); however, the stricture was outside the high-dose boost volume and the patient had a history of gastritis. Six patients (6%) had a first recurrence within the PAN region.

CONCLUSIONS

Limiting duodenal dose to V₅₅<15 cm³ and V₆₀<2 cm³ for patients with cervical cancer and PAN involvement is feasible and minimizes duodenal toxicity while maintaining acceptable local control rates.

Postoperative Radiotherapy for Locally Advanced NSCLC: Implications for Shifting to Conformal, High-Risk Fields

BACKGROUND

To examine the effect of radiotherapy field size on survival outcomes and patterns of recurrence in patients treated with postoperative radiotherapy (PORT) for non-small-cell lung cancer (NSCLC).

METHODS

We retrospectively reviewed the records of 216 patients with T1-4 N1-2 NSCLC following surgery and PORT using whole mediastinum (WM) or high-risk (HR) nodal fields from 1998 to 2015. Survival rates were calculated using the Kaplan-Meier method. Univariate and multivariable analyses were conducted using Cox proportional hazards modeling for outcomes and logistic regression analysis for treatment toxicities.

RESULTS

Median follow-up was 28 months (interquartile range [IQR] 13-75 months) and 38 months (IQR 19-73 months) for WM (n = 131) and HR (n = 84) groups, respectively. Overall survival (OS) was not significantly different between groups (median OS: HR 49 vs. WM 32 months; P = .08). There was no difference in progression-free survival (PFS), freedom from locoregional recurrence (LRR), or freedom from distant metastasis (P > .2 for all). Field size was not associated with OS, PFS, or LRR (P > .40 for all). LRR rates were 20% for HR and 26% for WM groups (P = .30). There was no significant difference in patterns of initial site of LRR between groups (P > .1). WM fields (OR 3.73, P = .001) and concurrent chemotherapy (odds ratio 3.62, P = .001) were associated with grade ≥2 toxicity.

CONCLUSIONS

Locoregional control and survival rates were similar between PORT groups; an improved toxicity profile was observed in the HR group. Results from an ongoing prospective randomized clinical trial will provide further insight into the consequences of HR PORT fields.

Gut microbiome diversity is an independent predictor of survival in cervical cancer patients receiving chemoradiation

Diversity of the gut microbiome is associated with higher response rates for cancer patients receiving immunotherapy but has not been investigated in patients receiving radiation therapy. Additionally, current studies investigating the gut microbiome and outcomes in cancer patients may not have adjusted for established risk factors. Here, we sought to determine if diversity and composition of the gut microbiome was independently associated with survival in cervical cancer patients receiving chemoradiation. Our study demonstrates that the diversity of gut microbiota is associated with a favorable response to chemoradiation. Additionally, compositional variation among patients correlated with short term and long-term survival. Short term survivor fecal samples were significantly enriched in Porphyromonas, Porphyromonadaceae, and Dialister, whereas long term survivor samples were significantly enriched in Escherichia Shigella, Enterobacteriaceae, and Enterobacteriales. Moreover, analysis of immune cells from cervical tumor brush samples by flow cytometry revealed that patients with a high microbiome diversity had increased tumor infiltration of CD4+ lymphocytes as well as activated subsets of CD4 cells expressing ki67+ and CD69+ over the course of radiation therapy. Modulation of the gut microbiota before chemoradiation might provide an alternative way to enhance treatment efficacy and improve treatment outcomes in cervical cancer patients.

Single Institution Experience of Proton and Photon-based Postoperative Radiation Therapy for Non-small-cell Lung Cancer

INTRODUCTION

Postoperative radiation therapy (PORT) for non-small-cell lung cancer remains controversial with studies showing no overall survival (OS) benefit in the setting of excessive cardiopulmonary toxicity. Proton beam therapy (PBT) can potentially reduce toxicity with improved organ-at-risk sparing. We evaluated outcomes of PORT patients treated with PBT and intensity-modulated radiation therapy (IMRT).

MATERIALS AND METHODS

This is a retrospective review of 136 PORT patients (61 PBT, 75 IMRT) treated from 2003 to 2016. A Kaplan-Meier analysis was performed to assess oncologic outcomes. A Cox regression was conducted to identify associated factors. Total toxicity burden (TTB) was defined as grade ≥ 2 pneumonitis, cardiac, or esophageal toxicity.

RESULTS

Median OS was 76 and 46 months for PBT and IMRT with corresponding 1- and 5-year OS of 85.3%, 50.9% and 89.3%, 37.2% (P = .38), respectively. V30 Gy heart (odds ratio [OR], 144.9; 95% confidence interval [CI], 2.91-7214; P = .013) and V5 Gy lung (OR, 15.8; 95% CI, 1.22-202.7; P = .03) were predictive of OS. Organ-at-risk sparing was improved with PBT versus IMRT; mean heart 2.0 versus 7.4 Gy (P < .01), V30 Gy heart 2.6% versus 10.7% (P < .01), mean lung 7.9 versus 10.4 Gy (P = .042), V5 Gy lung 23.4% versus 42.1% (P < .01), and V10 Gy lung 20.4% versus 29.6% (P < .01). TTB was reduced with PBT (OR, 0.35; 95% CI, 0.15-0.83; P = .017). Rates of cardiac toxicity were 14.7% IMRT and 4.9% PBT (P = .09). Rates of ≥ grade 2 pneumonitis were 17.0% IMRT and 4.9% PBT (P = .104).

CONCLUSION

PBT improved cardiac and lung sparing and reduced toxicity compared with IMRT. Considering the impact of cardiopulmonary toxicity on PORT outcomes, PBT warrants prospective evaluation.

Quantitative 3-Dimensional Photographic Assessment of Breast Cosmesis After Whole Breast Irradiation for Early Stage Breast Cancer: A Secondary Analysis of a Randomized Clinical Trial

Purpose

Our purpose was to use 3-dimensional (3D) surface photography to quantitatively measure breast cosmesis within the framework of a randomized clinical trial of conventionally fractionated (CF) and hypofractionated (HF) whole breast irradiation (WBI); to identify how 3D measurements are associated with patient- and physician-reported cosmesis; and to determine whether objective measures of breast symmetry varied by WBI treatment arm or transforming growth factor β 1 (TGFβ1) status.

Methods and Materials

From 2011 to 2014, 287 women age ≥40 with ductal carcinoma in situ or early-stage invasive breast cancer were enrolled in a multicenter trial and randomized to HF-WBI or CF-WBI with a boost. Three-dimensional surface photography was performed at 3 years posttreatment. Patient-reported cosmetic outcomes were recorded with the Breast Cancer Treatment Outcome Scale. Physician-reported cosmetic outcomes were assessed by the Radiation Therapy Oncology Group scale. Volume ratios and 6 quantitative measures of breast symmetry, termed F1-6C, were calculated using the breast contour and fiducial points assessed on 3D surface images. Associations between all metrics, patient- and physician-reported cosmesis, treatment arm, and TGFβ1 genotype were performed using the Kruskal-Wallis test and multivariable logistic regression models.

Results

Among 77 (39 CF-WBI and 38 HF-WBI) evaluable patients, both patient- and physician-reported cosmetic outcomes were significantly associated with the F1C vertical symmetry measure (both P < .05). Higher dichotomized F1C and volumetric symmetry measures were associated with improved patient- and physician-reported cosmesis on multivariable logistic regression (both P ≤ .05). There were no statistically significant differences in vertical symmetry or volume measures between treatment arms. Increased F6C horizontal symmetry was observed in the CF-WBI arm (P = .05). Patients with the TGFβ1 C-509T variant allele had lower F2C vertical symmetry measures (P = .02).

Conclusions

Quantitative 3D image-derived measures revealed comparable cosmetic outcomes with HF-WBI compared with CF-WBI. Our findings suggest that 3D surface imaging may be a more sensitive method for measuring subtle cosmetic changes than global patient- or physician-reported assessments.

Estimating PTV Margins in Head and Neck Stereotactic Ablative Radiation Therapy (SABR) Through Target Site Analysis of Positioning and Intrafractional Accuracy

PURPOSE

Recurrent or previously irradiated head and neck cancers (HNC) are therapeutically challenging and may benefit from high-dose, highly accurate radiation techniques, such as stereotactic ablative radiation therapy (SABR). Here, we compare set-up and positioning accuracy across HNC subsites to further optimize the treatment process and planning target volume (PTV) margin recommendations for head and neck SABR.

METHODS AND MATERIALS

We prospectively collected data on 405 treatment fractions across 79 patients treated with SABR for recurrent/previously irradiated HNC. First, interfractional error was determined by comparing ExacTrac x-ray to the treatment plan. Patients were then shifted and residual error was measured with repeat x-ray. Next, cone beam computed tomography (CBCT) was compared with ExacTrac for positioning agreement, and final shifts were applied. Lastly, intrafractional error was measured with x-ray before each arc. Results were stratified by treatment site into skull base, neck/parotid, and mucosal.

RESULTS

Most patients (66.7%) were treated to 45 Gy in 5 fractions (range, 21-47.5 Gy in 3-5 fractions). The initial mean ± standard deviation interfractional errors were -0.2 ± 1.4 mm (anteroposterior), 0.2 ± 1.8 mm (craniocaudal), and -0.1 ± 1.7 mm (left-right). Interfractional 3-dimensional vector error was 2.48 ± 1.44, with skull base significantly lower than other sites (2.22 vs 2.77; P = .0016). All interfractional errors were corrected to within 1.3 mm and 1.8°. CBCT agreed with ExacTrac to within 3.6 mm and 3.4°. CBCT disagreements and intrafractional errors of >1 mm or >1° occurred at significantly lower rates in skull base sites (CBCT: 16.4% vs 50.0% neck, 52.0% mucosal, P < .0001; intrafractional: 22.0% vs 48.7% all others, P < .0001). Final PTVs were 1.5 mm (skull base), 2.0 mm (neck/parotid), and 1.8 mm (mucosal).

CONCLUSIONS

Head and neck SABR PTV margins should be optimized by target site. PTV margins of 1.5 to 2 mm may be sufficient in the skull base, whereas 2 to 2.5 mm may be necessary for neck and mucosal targets. When using ExacTrac, skull base sites show significantly fewer uncertainties throughout the treatment process, but neck/mucosal targets may require the addition of CBCT to account for positioning errors and internal organ motion.

Spine Stereotactic Radiosurgery for Metastatic Pheochromocytoma

Purpose: Despite aggressive primary treatment, up to 13.5% of patients diagnosed with pheochromocytoma may develop metastases, most often affecting the axial skeleton. Given that systemic therapy options are often inadequate, local therapy remains the cornerstone of palliation for these patients. Historically poor responses to standard fractionated radiotherapy have led to the consideration of stereotactic radiosurgery as an option to overcome potential radioresistance and provide durable local control of these tumors. Here we report our institutional experience in treating spine metastases from pheochromocytoma with spine stereotactic radiosurgery (SSRS).

Methods and materials: Our clinical databases were retrospectively reviewed for patients with metastatic pheochromocytoma treated with SSRS from 2000-2017. Seven patients with 16 treated metastatic spinal lesions were identified. Local control was evaluated using magnetic resonance imaging (MRI). Pain and symptom data were assessed to evaluate toxicity using Common Terminology Criteria for Adverse Events (CTCAE) v4.03. The Kaplan-Meier method was used to assess local control and overall survival (OS).

Results: Median follow-up for treated lesions was 11 months (range 2.2 - 70.8). Most lesions were treated to a dose of 27 Gy in three fractions (62.5%). Other fractionation schemes included 24 Gy in one fraction (25%), 16 Gy in one fraction (6.3%), and 18 Gy in three fractions (6.3%). Treatment sites included the cervical spine (18.8%), thoracic spine (37.5%), lumbar spine (31.3%), and sacrum (12.5%). The crude local control rate was 93.7%, with one thoracic spine lesion progressing 20.7 months after treatment with 24 Gy in one fraction. Kaplan-Meier OS rates at 1 and 2 years after SSRS were 71.4% and 42.9%, respectively. Most common toxicities included acute grade 1-2 pain and fatigue. There was one case of vertebral fracture in a cervical spine lesion treated to 27 Gy in three fractions, which was managed non-surgically.

Conclusion: Very few studies have explored the use of SSRS in metastatic pheochromocytoma. Our data suggest this modern radiation modality is effective, safe, and provides durable local control to palliate symptoms and potentially limit further metastatic seeding. Larger patient numbers and longer follow-up will further define the role of SSRS as a treatment option in these patients.

MicroRNA-363 targets myosin 1B to reduce cellular migration in head and neck cancer

Background

Squamous cell carcinoma of the head and neck (SCCHN) remains a prevalent and devastating disease. Recently, there has been an increase in SCCHN cases that are associated with high-risk human papillomavirus (HPV) infection. The clinical characteristics of HPV-positive and HPV-negative SCCHN are known to be different but their molecular features are only recently beginning to emerge. MicroRNAs (miRNAs, miRs) are small, non-coding RNAs that are likely to play significant roles in cancer initiation and progression where they may act as oncogenes or tumor suppressors. Previous studies in our laboratory showed that miR-363 is overexpressed in HPV-positive compared to HPV-negative SCCHN cell lines, and the HPV type 16-E6 oncoprotein upregulates miR-363 in SCCHN cell lines. However, the functional role of miR-363 in SCCHN in the context of HPV infection remains to be elucidated.

Methods

We analyzed miR-363 levels in SCCHN tumors with known HPV-status from The Cancer Genome Atlas (TCGA) and an independent cohort from our institution. Cell migration studies were conducted following the overexpression of miR-363 in HPV-negative cell lines. Bioinformatic tools and a luciferase reporter assay were utilized to confirm that miR-363 targets the 3’-UTR of myosin 1B (MYO1B). MYO1B mRNA and protein expression levels were evaluated following miR-363 overexpression in HPV-negative SCCHN cell lines. Small interfering RNA (siRNA) knockdown of MYO1B was performed to assess the phenotypic implication of reduced MYO1B expression in SCCHN cell lines.

Results

MiR-363 was found to be overexpressed in HPV-16-positive compared to the HPV-negative SCCHN tumors. Luciferase reporter assays performed in HPV-negative JHU028 cells confirmed that miR-363 targets one of its two potential binding sites in the 3’UTR of MYO1B. MYO1B mRNA and protein levels were reduced upon miR-363 overexpression in four HPV-negative SCCHN cell lines. Increased miR-363 expression or siRNA knockdown of MYO1B expression reduced Transwell migration of SCCHN cell lines, indicating that the miR-363-induced migration attenuation of SCCHN cells may act through MYO1B downregulation.

Conclusions

These findings demonstrate that the overexpression of miR-363 reduces cellular migration in head and neck cancer and reveal the biological relationship between miR-363, myosin 1b, and HPV-positive SCCHN.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1888-3) contains supplementary material, which is available to authorized users.

Clinical Pathways: A Catalyst for the Adoption of Hypofractionation for Early-Stage Breast Cancer

PURPOSE

Hypofractionated whole-breast irradiation (HF-WBI) remains underutilized in the United States despite support by multiple clinical trials. We evaluated the success of iterative modifications of our breast cancer clinical pathway on the adoption of HF-WBI in a large, integrated radiation oncology network.

METHODS AND MATERIALS

The breast clinical pathway was modified in January 2011 (Amendment 1) to recommend HF-WBI as the first option for women ≥70 of age with stages 0 to IIA, while maintaining conventional fractionation (CF) as a pathway-concordant secondary option. In January 2013 (Amendment 2), the pathway's HF-WBI recommendation was extended to women ≥50 years of age. In January 2014 (Amendment 3), the pathway mandated HF-WBI as the only pathway-concordant option in women ≥50 years of age, and all pathway-discordant plans were subject to peer review and justification. Women ≥50 years of age with ductal carcinoma in situ or invasive breast cancer who underwent breast conserving surgery and adjuvant WBI were included in this analysis.

RESULTS

We identified 5112 patients from 2009 to 2014 who met inclusion criteria. From 2009 to 2012, the overall HF-WBI use rate was 8.3%. Following Amendments 2 and 3 (2013 and 2014, respectively), HF-WBI use significantly increased to 21.8% (17.3% in the community, 39.7% at academic sites) and 76.7% (75.5% in the community, 81.4% at academic sites), respectively (P<.001). Compared to 2009 to 2012, the relative risk of using HF-WBI was 7.9 (95% confidence interval: 7.1-8.6, P<.001) and 10.7 (95% CI: 10.3-11.0, P<.001), respectively, after Amendments 2 and 3, respectively. Age ≥70 and treatment at an academic site increased the likelihood of receiving HF-WBI in 2009 to 2012 and following Amendment 2 (P<.001).

CONCLUSIONS

This study demonstrates the transformative effect of a clinical pathway on patterns of care for breast radiation therapy. Although our initial HF-WBI use rate was low (8%-22%) and consistent with national rates, the clinical pathway approach dramatically increased adoption rate to >75%. In contrast to passive guidelines, clinical pathways serve as active tools to promote current best practices.