Rethinking the 10-pack-year rule for favorable human papillomavirus-associated oropharynx carcinoma: A multi-institution analysis.

BACKGROUND: De-intensified treatment strategies for early human papillomavirus-positive (HPV+) oropharynx cancer (OPC) rely on selecting patients with an excellent prognosis. The criterion for enrollment in current de-intensification trials is ≤10 pack-years. More nuance to the pack-year criteria may expand enrollment, improve patient outcomes, and prevent overtreatment. It was hypothesized that patients with more than 10 pack-years may experience favorable outcomes if smoking cessation has been achieved. METHODS: From an institutional review board-approved database, patients with HPV+ oropharyngeal squamous carcinoma treated definitively with radiation with or without chemotherapy were retrospectively identified. Patients with a history of smoking who were eligible for national de-intensification trials were included (cT1-2N1-2b or T3N0-2b [American Joint Committee on Cancer, seventh edition]). Cox regression with penalized smoothing splines was used to evaluate nonlinear effects of cessation. Recursive partitioning analysis (RPA) was used to objectively search for relationships between the 2 colinear variables (pack-years and time since cessation). RESULTS: Among 330 patients meeting the inclusion criteria, 130 (40%) were never smokers, 139 (42%) were former smokers, and 61 (18%) were current smokers. With standard therapy, all former smokers achieved a progression-free survival (PFS) rate higher than 91%, regardless of pack-year exposure. Nonlinear Cox regression demonstrated that more recent cessation was associated with significantly worse PFS even among those with ≤20 pack-years. RPA demonstrated that only current smokers experienced a 2-year PFS rate lower than 91%; former smokers, regardless of pack-years, experienced a 2-year PFS rate higher than 91%. CONCLUSIONS: The 10-pack-year rule may not apply to all early HPV+ OPCs, particularly for former smokers. Future randomized de-intensification trials should consider a broader and more nuanced approach until the predictive role of smoking status is established.

Use of surface-guided radiation therapy in combination with IGRT for setup and intrafraction motion monitoring during stereotactic body radiation therapy treatments of the lung and abdomen.

BACKGROUND AND PURPOSE: Multiple techniques can be used to assist with more accurate patient setup and monitoring during Stereotactic body radiation therapy (SBRT) treatment. This study analyzes the accuracy of 3D surface mapping with Surface-guided radiation therapy (SGRT) in detecting interfraction setup error and intrafraction motion during SBRT treatments of the lung and abdomen. MATERIALS AND METHODS: Seventy-one patients with 85 malignant thoracic or abdominal tumors treated with SBRT were analyzed. For initial patient setup, an alternating scheme of kV/kV imaging or SGRT was followed by cone beam computed tomography (CBCT) for more accurate tumor volumetric localization. The CBCT six degree shifts after initial setup with each method were recorded to assess interfraction setup error. Patients were then monitored continuously with SGRT during treatment. If an intrafractional shift in any direction >2 mm for longer than 2 sec was detected by SGRT, then CBCT was repeated and the recorded deltas were compared to those detected by SGRT. RESULTS: Interfractional shifts after SGRT setup and CBCT were small in all directions with mean values of <5 mm and < 0.5 degrees in all directions. Additionally, 25 patients had detected intrafraction motion by SGRT during a total of 34 fractions. This resulted in 25 (73.5%) additional shifts of at least 2 mm on subsequent CBCT. When comparing the average vector detected shift by SGRT to the resulting vector shift on subsequent CBCT, no significant difference was found between the two. CONCLUSIONS: Surface-guided radiation therapy provides initial setup within 5 mm for patients treated with SBRT and can be used in place of skin marks or planar kV imaging prior to CBCT. In addition, continuous monitoring with SGRT during treatment was valuable in detecting potentially clinically meaningful intrafraction motion and was comparable in magnitude to shifts from additional CBCT scans. PTV margin reduction may be feasible for SBRT in the lung and abdomen when using SGRT for continuous patient monitoring during treatment.

External validity of two nomograms for predicting distant brain failure after radiosurgery for brain metastases in a bi-institutional independent patient cohort.

Patients treated with stereotactic radiosurgery (SRS) for brain metastases (BM) are at increased risk of distant brain failure (DBF). Two nomograms have been recently published to predict individualized risk of DBF after SRS. The goal of this study was to assess the external validity of these nomograms in an independent patient cohort. The records of consecutive patients with BM treated with SRS at Levine Cancer Institute and Emory University between 2005 and 2013 were reviewed. Three validation cohorts were generated based on the specific nomogram or recursive partitioning analysis (RPA) entry criteria: Wake Forest nomogram (n = 281), Canadian nomogram (n = 282), and Canadian RPA (n = 303) validation cohorts. Freedom from DBF at 1-year in the Wake Forest study was 30% compared with 50% in the validation cohort. The validation c-index for both the 6-month and 9-month freedom from DBF Wake Forest nomograms was 0.55, indicating poor discrimination ability, and the goodness-of-fit test for both nomograms was highly significant (p < 0.001), indicating poor calibration. The 1-year actuarial DBF in the Canadian nomogram study was 43.9% compared with 50.9% in the validation cohort. The validation c-index for the Canadian 1-year DBF nomogram was 0.56, and the goodness-of-fit test was also highly significant (p < 0.001). The validation accuracy and c-index of the Canadian RPA classification was 53% and 0.61, respectively. The Wake Forest and Canadian nomograms for predicting risk of DBF after SRS were found to have limited predictive ability in an independent bi-institutional validation cohort. These results reinforce the importance of validating predictive models in independent patient cohorts.

Receptor tyrosine kinase EphA5 is a functional molecular target in human lung cancer.

Lung cancer is often refractory to radiotherapy, but molecular mechanisms of tumor resistance remain poorly defined. Here we show that the receptor tyrosine kinase EphA5 is specifically overexpressed in lung cancer and is involved in regulating cellular responses to genotoxic insult. In the absence of EphA5, lung cancer cells displayed a defective G1/S cell cycle checkpoint, were unable to resolve DNA damage, and became radiosensitive. Upon irradiation, EphA5 was transported into the nucleus where it interacted with activated ATM (ataxia-telangiectasia mutated) at sites of DNA repair. Finally, we demonstrate that a new monoclonal antibody against human EphA5 sensitized lung cancer cells and human lung cancer xenografts to radiotherapy and significantly prolonged survival, thus suggesting the likelihood of translational applications.

Extent of pathologic extracapsular extension and outcomes in patients with nonoropharyngeal head and neck cancer treated with initial surgical resection.

BACKGROUND: Lymph node extracapsular extension (ECE) is a known adverse prognostic factor in head and neck cancer and is an indication for adjuvant chemoradiation (CRT). However, the extent of ECE may provide additional prognostic information in the setting of adjuvant CRT. METHODS: This study included 350 patients with oral cavity cancer (72.6%) or bulky/nonfunctional laryngeal cancer (27.4%) who underwent initial surgical resection. Extent of ECE was graded from 0 to 4 based on the scale established by Lewis and colleagues. Multivariable analyses (MVA) were adjusted for primary site, pathologic risk factors, and adjuvant therapy. RESULTS: In univariate failure-free survival (FFS) analysis, there was no significant difference in FFS for patients with lymph node-positive disease and no ECE (grade 0) versus patients with ECE grades 1 through 3. However, patients with ECE grade 4 had significantly worse FFS. In MVA for FFS, differences between ECE grades 0 through 3 and grade 4 did not remain significant. In MVA of overall survival, ECE grade 4 was significantly associated with higher risk of death compared with ECE grade 0 (hazard ratio, 0.46; P = .02) and ECE grades 1 through 3 (HR, 0.41; P = .01). CONCLUSIONS: Dichotomous evaluation of ECE is useful for determining appropriate adjuvant therapy but has limited additional prognostic value in the setting of adjuvant CRT. The detrimental effect of ECE grades 1 through 3 relative to no ECE is effectively mitigated with adjuvant CRT, but ECE grade 4 retains a poorer prognosis despite CRT with regard to overall survival. Patients with ECE grade 4 may be candidates for trials investigating novel methods of adjuvant therapy intensification.

Weekly Versus Bolus Cisplatin Concurrent With Definitive Radiation Therapy for Squamous Carcinoma of the Head and Neck: A Systematic Review and Network Meta-Analysis.

PURPOSE: The schedule of cisplatin concurrent with definitive radiation for squamous carcinoma of the head and neck remains controversial. Most institutions deliver either a high-dose "bolus" schedule once every 3 weeks or a low-dose weekly schedule. We compared these 2 schedules via a simplified network meta-analysis with a common comparator. METHODS AND MATERIALS: We performed a PRISMA-concordant systematic review to identify randomized controlled trials comparing cisplatin with cetuximab for nonmetastatic, locoregionally advanced squamous carcinoma of the head and neck treated with definitive radiation. Trials incorporating primary surgery or induction therapy were excluded. Patient survival times were extracted on a per-event basis from the published curves using a digitizer and validated against published point estimates and hazard ratios (HRs). Survival was compared using random effects Cox regression under a frequentist framework. Toxicity and secondary endpoints were analyzed qualitatively. The Cochrane method assessed the risk of bias. The analysis plan was preregistered with the Open Science Foundation. RESULTS: Five randomized trials were identified, including 1678 patients. There was no statistical difference in overall survival between weekly and bolus regimens (HR, 0.90; 95% CI, 0.53-1.52, P = .345). This Cox model suggested that for the average patient in the cohort, the absolute difference in 5-year overall survival between weekly and bolus regimens was +1.2% (95% CI, -6.1%-+5.9%, P = .345). Secondary endpoints and toxicity were not obviously different by regimen, qualitatively. CONCLUSIONS: The cetuximab trials provide indirect data suggesting that the differences between cisplatin schedules are subtle.

Pleiotropic effects of HIF-1 blockade on tumor radiosensitivity.

We have previously shown that radiation increases HIF-1 activity in tumors, causing significant radioprotection of the tumor vasculature. The impact that HIF-1 activation has on overall tumor radiosensitivity, however, is unknown. We reveal here that HIF-1 plays an important role in determining tumor radioresponsiveness through regulating four distinct processes. By promoting ATP metabolism, proliferation, and p53 activation, HIF-1 has a radiosensitizing effect on tumors. Through stimulating endothelial cell survival, HIF-1 promotes tumor radioresistance. As a result, the net effect of HIF-1 blockade on tumor radioresponsiveness is highly dependent on treatment sequencing, with "radiation first" strategies being significantly more effective than the alternative. These data provide a strong rationale for pursuing sequence-specific combinations of HIF-1 blockade and conventional therapeutics.

Dosimetric Analysis of Intra-Fraction Motion Detected by Surface-Guided Radiation Therapy During Linac Stereotactic Radiosurgery.

Purpose: Stereotactic radiosurgery (SRS) immobilization with an open face mask is more comfortable and less invasive than frame based, but concerns about intrafraction motion must be addressed. Surface-guided radiation therapy (SGRT) is an attractive option for intrafraction patient monitoring because it is continuous, has submillimeter accuracy, and uses no ionizing radiation. The purpose of this study was to investigate the dosimetric consequences of uncorrected intrafraction patient motion detected during frameless linac-based SRS. Methods and Materials: Fifty-five SRS patients were monitored during treatment using SGRT between January 1, 2017, and September 30, 2020. If SGRT detected motion >1 mm, imaging was repeated and the necessary shifts were made before continuing treatment. For the 25 patients with intrafraction 3-dimensional vector shifts of ≥1 mm, we moved the isocenter in the planning system using the translational shifts from the repeat imaging and recalculated the plans to determine the dosimetric effect of the shifts. Planning target volume (PTV) coverage, minimum gross tumor volume (GTV) dose (relative and absolute), and normal brain V12 were evaluated. Wilcoxon signed rank tests were used to compare planned and simulated dosimetric parameters and median 2 sample tests were used to investigate these differences between cone and multileaf collimator (MLC) plans. Results: For simulated plans, V12 increased by a median of 0.01 cc (P = .006) and relative GTV minimum dose and PTV coverage decreased by a median of 15.8% (P < .001) and 10.2 % (P < .001), respectively. Absolute minimum GTV dose was found to be significantly lower in the simulated plans (P < .001). PTV coverage decreased more for simulated cone plans than for simulated MLC plans (11.6% vs 4.7%, P = .011) but median V12 differences were found to be significantly larger for MLC plans (-0.34 cc vs -0.01 cc, P = .011). Differences in GTV minimum dose between cone and MLC plans were not statistically significant. Conclusions: SGRT detected clinically meaningful intrafraction motion during frameless SRS, which could lead to large underdoses and increased normal brain dose if uncorrected.

Radiation therapy for cT1-2 carcinoma of the palatine tonsil diagnosed via a simple tonsillectomy: Dosimetry and patterns of care in the IMRT era.

OBJECTIVE: Small carcinomas of the palatine tonsil are often diagnosed via simple tonsillectomy, a maneuver with non-therapeutic intent. Herein, practice patterns for this unique situation are evaluated. PATIENTS AND METHODS: A retrospective review was performed across 10 facilities to identify patients with cT1-2 squamous carcinomas of the tonsil diagnosed by simple tonsillectomy between 2010 and 2018. Patients who received curative-intent intensity modulated radiotherapy (IMRT) without additional surgery were included. Target volumes were reviewed, and cumulative incidences of local failure and severe late dysphagia were calculated. RESULTS: From 638 oropharyngeal patients, 91 were diagnosed via simple tonsillectomy. Definitive IMRT with no additional surgery to the primary site was utilized in 57, and three with gross residual disease were excluded, leaving 54 for analysis. Margins were negative in 13%, close (<5 mm) in 13%, microscopically positive in 61%, and not reported in 13%. Doses typically delivered to gross disease (68-70.2 Gy in 33-35 fx or 66 Gy/30 fx) were prescribed to the tonsil bed in 37 (69%). Sixteen patients (29%) received doses from 60 to 66 Gy (≤2 Gy/fx) and one received 50 Gy (2 Gy/fx). No local failures were observed. One late oropharyngeal soft tissue ulcer occurred, treated conservatively (grade 2). At five years, the cumulative incidence of severe late dysphagia was 17.4% (95% CI 6.1-28.8%). CONCLUSION: Small tonsil carcinomas diagnosed by simple tonsillectomy represent a niche subset with favorable oncologic outcomes. Regardless, radiation oncologists tend to deliver full-dose to the tonsil bed. The necessity of this routine could be questioned in the modern era.

Radiation activates HIF-1 to regulate vascular radiosensitivity in tumors: role of reoxygenation, free radicals, and stress granules.

Through a poorly understood mechanism, tumors respond to radiation by secreting cytokines capable of inhibiting apoptosis in endothelial cells, thereby diminishing treatment response by minimizing vascular damage. We reveal here that this pathway is governed by a major angiogenesis regulator, HIF-1. Following radiotherapy, tumor reoxygenation leads to: (1) nuclear accumulation of HIF-1 in response to reactive oxygen, and (2) enhanced translation of HIF-1-regulated transcripts secondary to stress granule depolymerization. The resulting increase in HIF-1-regulated cytokines enhances endothelial cell radioresistance. Inhibiting postradiation HIF-1 activation significantly increases tumor radiosensitivity as a result of enhanced vascular destruction. These data describe novel pathways contributing significantly to our understanding of HIF-1 regulation which may be major determinants of tumor radiosensitivity, potentially having high clinical relevance.

Oncologists' Perspective on Dental Care Around the Treatment of Head and Neck Cancer: A Pattern of Practice Survey.

PURPOSE: Patients with head and neck cancer are at risk of long-term dental complications. Proper dental assessment pre- and post-treatment can improve outcomes but is logistically challenging. We surveyed oncologists to better understand their perspectives surrounding dental care in this unique population. METHODS: We surveyed oncologists at institutions associated with an ongoing national study of oral health after treatment of head and neck cancer. Seventeen questions were used to assess provider characteristics, patterns of practice, patterns of referral, barriers to referral, and willingness to apply fluoride varnish in the oncology clinic. RESULTS: Ninety-seven oncologists were invited from six institutions, of whom 40 (41%) responded. Surgeons represented 45% of the sample, followed by radiation oncologists (40%) and medical oncologists (15%). Both generalists and subspecialists were included. All practiced in a metropolitan area with an academic dental practice, and many felt that this improved access to care. Despite this, most oncologists thought that financial factors were a significant barrier to obtaining timely dental care. Most oncologists performed a dental assessment during visits. Oncologists felt qualified to identify the most significant complications of treatment, such as exposed bone, but felt underqualified to identify early changes in need of intervention. When asked if the oncology clinic could apply fluoride varnish during follow-ups, most stated that this seemed feasible but would require education and financial support. CONCLUSION: Oncologists often perform limited dental evaluations during their routine visits. Given the challenges associated with access to proper dental care for this population, these oncology visits may provide a window for preventative intervention.

The economic impact of circulating tumor-tissue modified HPV DNA for the post-treatment surveillance of HPV-driven oropharyngeal cancer: A simulation.

PURPOSE: Following treatment of HPV-driven oropharynx cancer, surveillance nasopharyngoscopy and imaging are often performed but are expensive and frequently ineffective. A novel plasma circulating tumor-tissue modified viral HPV DNA (TTMV-HPV-DNA) assay accurately detects recurrences. We modeled the cost of the new assay. METHODS: We designed and validated a partitioned survival model which replicated the results of the RTOG 1016 study and calculated cumulative surveillance costs from the payer's perspective. Two strategies were considered: a standard of routine endoscopy with imaging as needed and an alternative strategy which omitted scopes and imaging but obtained serial TTMV-HPV-DNA samples. No difference in effectiveness (QALY or LY) was assumed in the base case. A 5-year horizon was used, costs were reported in 2020 U.S. dollars discounted by 3%. Seven scenarios tested model assumptions and practice variation. Deterministic and probabilistic sensitivity analyses assessed parameter uncertainty. RESULTS: In the base case, at the list TTMV-HPV-DNA price, the cumulative cost of surveillance was $11,674 for the standard strategy and $20,756 for the TTMV-HPV-DNA strategy (+$9082 over 5 years). Probabilistic sensitivity analysis demonstrated the cost difference ranged from $4917-$12,047. The TTMV-HPV-DNA strategy was most likely to be either cost saving or cost-effective if future data demonstrate small improvements in quality or quantity of life (approximately 33 quality-adjusted life-days), if the assay reduces utilization of imaging, and if the periodicity of TTMV-HPV-DNA draws could be reduced from that on clinical trials. CONCLUSIONS: This data informs providers seeking to design more accurate, accessible, and economical post-treatment surveillance strategies.

Defining targets to improve care delivery for T4 larynx squamous cell carcinoma.

Objective: United States oncology trends consistently demonstrate that nearly half of T4a larynx carcinoma patients are treated with larynx preservation, despite national guidelines favoring laryngectomy. This study identifies clinical decision-making drivers and defines patient subsets that should become targets for care improvement. Methods: Retrospective analysis of patients with cT4 squamous cell carcinoma of the larynx from US National Cancer Database 2005-2016. Demographic data and survival rates between clinical pathways were compared. Survival was estimated by Kaplan-Meier method with statistical comparisons assessed by log-rank test. Results: Of 11,556 patients with cT4 disease, laryngectomy (TL) was the initial treatment for 4627 (40%) patients. Larynx preservation via chemoradiation (CRT) occurred for 4307 patients. TL and CRT patients had similar Charlson-Deyo comorbidity indices and insurance status. TL patients had higher total tumor size, lower N3 rates and were more often seen at academic institutions (p < .0001). N0 surgery patients with adjuvant treatment demonstrated superior median survival (MS) compared to CRT (surgery + radiation MS: 69 months, surgery + chemoradiation MS: 66, CRT MS: 37.7), p < .0001. MS for N1/N2 disease patients was 56.5 months for surgery + radiation and 35.5 months for surgery + CRT, superior to CRT, MS 30.8 months, p < .0001. Tri-modality N3 patients with up front surgery had similar MS compared to CRT (surgery + chemoradiation 21.3 months vs. CRT 16.1), p = .95. Conclusion: National quality improvement initiatives are needed to promote guideline adherence and improve survival in advanced larynx cancer. Targets for such initiatives should be patients with limited or no nodal disease burden, that meet clear T4a imaging criteria. Level of Evidence: Level IV, non-randomized controlled cohort.

The type III TGF-beta receptor suppresses breast cancer progression.

The TGF-beta signaling pathway has a complex role in regulating mammary carcinogenesis. Here we demonstrate that the type III TGF-beta receptor (TbetaRIII, or betaglycan), a ubiquitously expressed TGF-beta coreceptor, regulated breast cancer progression and metastasis. Most human breast cancers lost TbetaRIII expression, with loss of heterozygosity of the TGFBR3 gene locus correlating with decreased TbetaRIII expression. TbetaRIII expression decreased during breast cancer progression, and low TbetaRIII levels predicted decreased recurrence-free survival in breast cancer patients. Restoring TbetaRIII expression in breast cancer cells dramatically inhibited tumor invasiveness in vitro and tumor invasion, angiogenesis, and metastasis in vivo. TbetaRIII appeared to inhibit tumor invasion by undergoing ectodomain shedding and producing soluble TbetaRIII, which binds and sequesters TGF-beta to decrease TGF-beta signaling and reduce breast cancer cell invasion and tumor-induced angiogenesis. Our results indicate that loss of TbetaRIII through allelic imbalance is a frequent genetic event during human breast cancer development that increases metastatic potential.

Leveraging molecular heterogeneity of the vascular endothelium for targeted drug delivery and imaging.

Patterns of luminal vascular protein expression vary according to tissue of origin, and these so-called vascular zip codes play an important role in the maintenance of normal physiological processes in multiorgan species. These zip codes are also often modified in response to pathology and play a critical role in the response to and recovery from disease. These differentially expressed proteins offer opportunities for organ- and disease-specific ligand-targeted molecular delivery, offering clear pharmacologic advantages to traditional systemic drug delivery. However, this approach depends on the availability of frequently elusive targets. Combinatorial screening is a valuable tool for identifying optimal ligands for targeted delivery to the vasculature, especially when adapted for in vivo selection. Here we discuss molecular heterogeneity of the vascular endothelium and the use of phage display as a combinatorial screening method to exploit this heterogeneity for tissue or disease-specific vascular targeting. We also highlight applications of this approach for both drug delivery and molecular imaging.

Spectral imaging facilitates visualization and measurements of unstable and abnormal microvascular oxygen transport in tumors.

Abnormal microvasculature contributes to the pathophysiologic microenvironment of tumors. Understanding microvascular tumor oxygen transport is necessary to comprehend the factors that influence tumor biology, physiology, and therapy. Previously, we described an in vivo spectral imaging microscopy system for measurements of microvessel hemoglobin saturation (HbSat). We measure temporal fluctuations and spatial gradients in tumor microvessel oxygenation and identify instances of anastomoses between vessels with significantly different oxygenations. Slow periodic fluctuations in HbSat <0.2 cycles per minute were observed. These measurements are consistent with microelectrode measurements of fluctuating tumor oxygenation. Gradients in HbSat along individual tumor microvessels were measured that were larger in magnitude than normal tissue microvessels. Images were captured of anastomoses of tumor microvessels with diameters 20%). Shunting of inspired oxygen, presumably due to arteriovenous anastomoses, from tumor feeding arterioles to adjacent venules was imaged. This effect was confined to a region around the tumor and was not observed in nearby normal microvessels. Imaging measurements of tumor microvessel oxygen transport may offer insight to current questions regarding oxygen-related tumor biology and treatment responses, and spectral imaging may be a useful research tool in this regard.

Preoperative stereotactic radiosurgery before planned resection of brain metastases: updated analysis of efficacy and toxicity of a novel treatment paradigm.

OBJECTIVEPreoperative stereotactic radiosurgery (SRS) is a feasible alternative to postoperative SRS and may lower the risk of radiation necrosis (RN) and leptomeningeal disease (LMD) recurrence. The study goal was to report the efficacy and toxicity of preoperative SRS in an expanded patient cohort with longer follow-up period relative to prior reports.METHODSThe records for patients with brain metastases treated with preoperative SRS and planned resection were reviewed. Patients with classically radiosensitive tumors, planned adjuvant whole brain radiotherapy, or no cranial imaging at least 1 month after surgery were excluded. Preoperative SRS dose was based on lesion size and was reduced approximately 10-20% from standard dosing. Surgery generally followed within 48 hours.RESULTSThe study cohort consisted of 117 patients with 125 lesions treated with single-fraction preoperative SRS and planned resection. Of the 117 patients, 24 patients were enrolled in an initial prospective trial; the remaining 93 cases were consecutively treated patients who were retrospectively reviewed. Most patients had a single brain metastasis (70.1%); 42.7% had non-small cell lung cancer, 18.8% had breast cancer, 15.4% had melanoma, and 11.1% had renal cell carcinoma. Gross total resection was performed in 95.2% of lesions. The median time from SRS to surgery was 2 days, the median SRS dose was 15 Gy, and the median gross tumor volume was 8.3 cm3. Event cumulative incidence at 2 years was as follows: cavity local recurrence (LR), 25.1%; distant brain failure, 60.2%; LMD, 4.3%; and symptomatic RN, 4.8%. The median overall survival (OS) and 2-year OS rate were 17.2 months and 36.7%, respectively. Subtotal resection (STR, n = 6) was significantly associated with increased risk of cavity LR (hazard ratio [HR] 6.67, p = 0.008) and worsened OS (HR 2.63, p = 0.05) in multivariable analyses.CONCLUSIONSThis expanded and updated analysis confirms that single-fraction preoperative SRS confers excellent cavity local control with very low risk of RN or LMD. Preoperative SRS has several potential advantages compared to postoperative SRS, including reduced risk of RN due to smaller irradiated volume without need for cavity margin expansion and reduced risk of LMD due to sterilization of tumor cells prior to spillage at the time of surgery. Subtotal resection, though infrequent, is associated with significantly worse cavity LR and OS. Based on these results, a randomized trial of preoperative versus postoperative SRS is being designed.

Radiation and a metalloporphyrin radioprotectant in a mouse prostate tumor model.

BACKGROUND: Antioxidants have the potential to protect normal tissues against radiation-induced damage, but must not protect tumor cells during radiotherapy. The major objectives were to determine whether a metalloporphyrin antioxidant affects prostate tumor response to radiation and identify possible mechanisms of interaction. MATERIALS AND METHODS: C57BL/6 mice with RM-9 tumor were treated with manganese (III) meso-tetrakis (1,3-diethylimidazolium-2-yl) porphyrin (MnTDE-2-ImP) and 10 gray (Gy) radiation. Tumor volume was quantified and a subset/group was evaluated for hypoxia-inducible factor-1alpha (HIF-1alpha), bone marrow-derived cell populations and cytokines. RESULTS: The addition of MnTDE-2-ImP transiently increased tumor response compared to radiation alone. The group receiving drug plus radiation had reduced intratumoral HIF-1alpha and decreased capacity to secrete TNF-alpha, whereas production of IL-4 was increased. There were no toxicities associated with combination treatment. CONCLUSION: The results demonstrate that MnTDE-2-ImP did not protect the RM-9 prostate tumor against radiation; instead, radiation effectiveness was modestly increased. Possible mechanisms include reduction of radiation-induced HIF-1alpha and an altered cytokine profile.

Observation of incipient tumor angiogenesis that is independent of hypoxia and hypoxia inducible factor-1 activation.

It is well established that hypoxia potently stimulates tumor angiogenesis by activating hypoxia inducible factor-1 (HIF-1)-induced proangiogenic factors, such as vascular endothelial growth factor. However, very little is known about the role of hypoxia in incipient angiogenesis in avascular tumors during their early stages of growth. To noninvasively investigate the functional significance of hypoxia and HIF-1 activation in incipient tumor angiogenesis, we genetically engineered HCT116 human colon carcinoma cells and 4T1 mouse mammary carcinoma cells with constitutively expressed red fluorescence protein as a tumor marker and green fluorescence protein (GFP) as a reporter for hypoxia and HIF-1 activation. The accuracy of GFP fluorescence in reporting hypoxia was confirmed by flow cytometry analysis and by immunohistochemical comparison with pimonidazole, a well-established hypoxia marker drug. Mouse dorsal skin-fold window chambers showed that incipient angiogenesis preceded a detectable level of hypoxia. The detectable levels of hypoxia were spatially and temporally related with more intensive secondary angiogenesis following the initial onset of new vessel formation. Selective killing of hypoxic cells by tirapazamine efficiently eliminated or delayed the detection of hypoxic cells, but it did not significantly delay the onset of incipient angiogenesis. These findings provide the first in vivo evidence that incipient tumor angiogenesis may not depend on hypoxia or HIF-1 activation. This is in contrast to the clear role of hypoxia in driving angiogenesis once initial tumor microvessel formation has occurred.

Single-Fraction Stereotactic Radiosurgery (SRS) Alone Versus Surgical Resection and SRS for Large Brain Metastases: A Multi-institutional Analysis.

PURPOSE: Stereotactic radiosurgery (SRS) dose is limited by brain metastasis (BM) size. The study goal was to retrospectively determine whether there is a benefit for intracranial outcomes and overall survival (OS) for gross total resection with single-fraction SRS versus SRS alone for patients with large BMs. METHODS AND MATERIALS: A large BM was defined as ≥4 cm3 (2 cm in diameter) prior to the study. We reviewed the records of consecutive patients treated with single-fraction SRS alone or surgery with preoperative or postoperative SRS between 2005 and 2013 from 2 institutions. RESULTS: Overall, 213 patients with 223 treated large BMs were included; 66 BMs (30%) were treated with SRS alone and 157 (70%) with surgery and SRS (63 preoperatively and 94 postoperatively). The groups (SRS vs surgery and SRS) were well balanced except regarding lesion volume (median, 5.9 cm3 vs 9.6 cm3; P<.001), median number of BMs (1.5 vs 1, P=.002), median SRS dose (18 Gy vs 15 Gy, P<.001), and prior whole-brain radiation therapy (33% vs 5%, P<.001). The local recurrence (LR) rate was significantly lower with surgery and SRS (1-year LR rate, 36.7% vs 20.5%; P=.007). There was no difference in radiation necrosis (RN) by resection status, but there was a significantly increased RN rate with postoperative SRS versus with preoperative SRS and with SRS alone (1-year RN rate, 22.6% vs 5% and 12.3%, respectively; P<.001). OS was significantly higher with surgery and SRS (2-year OS rate, 38.9% vs 19.8%; P=.01). Both multivariate adjusted analyses and propensity score-matched analyses demonstrated similar results. CONCLUSIONS: In this retrospective study, gross total resection with SRS was associated with significantly reduced LR compared with SRS alone for patients with large BMs. Postoperative SRS was associated with the highest rate of RN. Surgical resection with SRS may improve outcomes in patients with a limited number of large BMs compared with SRS alone. Further studies are warranted.