Clinical efficacy and safety of surface imaging guided radiosurgery (SIG-RS) in the treatment of benign skull base tumors

Frameless, surface imaging guided radiosurgery (SIG-RS) is a novel platform for stereotactic radiosurgery (SRS) wherein patient positioning is monitored in real-time through infra-red camera tracking of facial topography. Here we describe our initial clinical experience with SIG-RS for the treatment of benign neoplasms of the skull base. We identified 48 patients with benign skull base tumors consecutively treated with SIG-RS at a single institution between 2009 and 2011. Patients were diagnosed with meningioma (n = 22), vestibular schwannoma (n = 20), or nonfunctional pituitary adenoma (n = 6). Local control and treatment-related toxicity were retrospectively assessed. Median follow-up was 65 months (range 61-72 months). Prescription doses were 12-13 Gy in a single fraction (n = 18), 8 Gy × 3 fractions (n = 6), and 5 Gy × 5 fractions (n = 24). Actuarial tumor control rate at 5 years was 98%. No grade ≥3 treatment-related toxicity was observed. Grade ≤2 toxicity was associated with symptomatic lesions (p = 0.049) and single fraction treatment (p = 0.005). SIG-RS for benign skull base tumors produces clinical outcomes comparable to conventional frame-based SRS techniques while enhancing patient comfort.

Neurocognitive assessment following whole brain radiation therapy and radiosurgery for patients with cerebral metastases

The treatment of metastatic brain lesions remains a central challenge in oncology. Because most chemotherapeutic agents do not effectively cross the blood-brain barrier, it is widely accepted that radiation remains the primary modality of treatment. The mode by which radiation should be delivered has, however, become a source of intense controversy in recent years. The controversy involves whether patients with a limited number of brain metastases should undergo whole brain radiation therapy (WBRT) or stereotactic radiosurgery (SRS) delivered only to the radiographically visible tumours. Survival is comparable for patients treated with either modality. Instead, the controversy involves the neurocognitive function (NCF) of radiating cerebrum that appeared radiographically normal relative to effects of the growth from micro-metastatic foci. A fundamental question in this debate involves quantifying the effect of WBRT in patients with cerebral metastasis. To disentangle the effects of WBRT on neurocognition from the effects inherent to the underlying disease, we analysed the results from randomised controlled studies of prophylactic cranial irradiation in oncology patients as well as studies where patients with limited cerebral metastasis were randomised to SRS versus SRS+WBRT. In aggregate, these results suggest deleterious effects of WBRT in select neurocognitive domains. However, there are insufficient data to resolve the controversy of upfront WBRT versus SRS in the management of patients with limited cerebral metastases.

Frameless, Real-Time, Surface Imaging-Guided Radiosurgery

BACKGROUND:

Frameless stereotactic radiosurgery is commonly used to treat intracranial metastases, but mask-based immobilization can be uncomfortable for patients.

OBJECTIVE:

To describe the clinical outcomes using a novel real-time, frameless, surface imaging--guided radiosurgery (SIG-RS) technique to treat brain metastases.

METHODS:

Data were prospectively gathered for 44 consecutive patients totaling 115 intracranial metastases treated with SIG-RS in a median of 1 fraction (range, 1–5) to a median dose of 20 Gy (range, 15-30 Gy). Local control, regional control, and overall survival were estimated by the Kaplan-Meier method.

RESULTS:

Median follow-up for all patients was 6.0 months (range, 0.3-21.6 months), with 31 of 44 (70%) deceased at the time of analysis. The 35 patients (80%) with follow-up imaging totaled 88 lesions evaluable for local control. Actuarial 6- and 12-month local control was 90% (95% confidence interval, 82–98) and 76% (95% confidence interval, 60–91), respectively. Regional failure was observed in 16 patients (46%). The median actuarial overall survival was 7.7 months (95% confidence interval, 5.7-9.7). Analysis of the subset of 22 patients (55 lesions) who received SIG-RS alone (no prior treatment) in a single fraction yielded comparable clinical outcomes. Grade 3 or greater toxicity occurred in 4 patients (9%). The median treatment time from beam on to beam off was 15 minutes (range, 3-36 minutes).

CONCLUSION:

SIG-RS for treating intracranial metastases can produce clinical outcomes comparable to those with conventional frame-based and frameless stereotactic radiosurgery techniques while providing greater patient comfort with an open-faced mask and fast treatment times.

DNA damage response and repair: insights into strategies for radiation sensitization of gliomas

The incorporation of radiotherapy into multimodality treatment plans has led to significant improvements in glioma patient survival. However, local recurrence from glioma resistance to ionizing radiation remains a therapeutic challenge. The tumoricidal effect of radiation therapy is largely attributed to the induction of dsDNA breaks (DSBs). In the past decade, there have been tremendous strides in understanding the molecular mechanisms underlying DSB repair. The identification of gene products required for DSB repair has provided novel therapeutic targets. Recent studies revealed that many US FDA-approved cancer agents inhibit DSB repair by interacting with repair proteins. This article will aim to provide discussion of DSB repair mechanisms to provide molecular targets for radiation sensitization of gliomas and a discussion of FDA-approved cancer therapies that modulate DSB repair to highlight opportunities for combination therapy with radiotherapy for glioma therapy.

Patterns of imaging failures in glioblastoma patients treated with chemoradiation: a retrospective study

Glioblastoma multiforme (GBM) is the most common primary brain tumor of adults and carries a poor prognosis. This study sought to investigate recurrence patterns of GBM treated with temozolomide-based chemoradiation. Records for 31 patients treated for newly diagnosed GBM between 2007 and 2009 were retrospectively analyzed. Ten patients received maximal surgical resection followed by conventionally fractionated radiation (CFR) to a median dose of 60 Gy with concurrent and planned adjuvant temozolomide. Twelve patients were treated with maximal surgical debulking, intracavitary brachytherapy (ICB), and external beam radiation therapy with concurrent and planned adjuvant temozolomide. The remaining 9 patients had unresectable disease and underwent biopsy followed by a hypofractionated course of radiation to a median dose of 60 Gy over 10 fractions. Tumor failure was classified as local, marginal, or distant according to whether the recurrence was completely inside, crossed, or completely outside the 100% isodose line. With a median follow-up of 12.6 months, 5 patients were lost to follow-up, while the remaining 26 patients (100%) developed recurrent disease. The first failures totaled 29 discrete lesions, of which 15 (52%), 6 (21%), and 8 (28%) were local, marginal, and distant failures at median times of 6.8, 10.1, and 7.9 months, respectively. Marginal or distant failure was more likely in ICB patients as compared to CFR patients. While local failure predominated, distant failures were not uncommon, particularly at later time points. As local control of GBM improves, further study is needed to identify and appropriately treat patients susceptible to distant failure.

Intensity modulated radiation therapy for retroperitoneal sarcoma: a case for dose escalation and organ at risk toxicity reduction

PURPOSE

Radiation therapy for retroperitoneal sarcoma remains challenging because of proximity to surrounding organs at risk (OAR). We report the use of intensity modulated radiation therapy (IMRT) in the treatment of retroperitoneal sarcomas to minimize dose to OAR while concurrently optimizing tumor dose coverage.

PATIENTS AND METHODS

From January 2000 to October 2002, 10 patients (average age 56 years) with retroperitoneal sarcoma and one with inguinal sarcoma were treated with radiation at Emory University. Prescription dose to the planning treatment volume (PTV) was commonly 50.4 at 1.8 Gy/fraction. CT simulation was used in each patient, three patients were treated with 3D-conformal treatment (3D-CRT), and the remaining eight received multi-leaf collimator-based (MLC) IMRT. IMRT treatment fields ranged from eight to 11 and average volume treated was 3498 cc. Optimal 3D-CRT plans were generated and compared with IMRT with respect to tumor coverage and OAR dose toxicity. Dose volume histograms were compared for both the 3D-CRT and IMRT plans.

RESULTS

Mean dose to small bowel decreased from 36 Gy with 3D-CRT to 27 Gy using IMRT, and tumor coverage (V95) increased from 95.3% with 3D-CRT to 98.6% using IMRT. Maximum and minimum doses delivered to the PTV were significantly increased by 6 and 22%, respectively (P = 0.011, P = 0.055). Volume of small bowel receiving > 30Gy was significantly decreased from 63.5 to 43.1% with IMRT compared with conventional treatment (P = 0.043). Seven patients developed grade 2 nausea, three developed grade 2 diarrhea, one had grade 2 skin toxicity, and one patient developed grade 3 liver toxicity (RTOG toxicity scale). No other delayed toxicities related to radiation were observed. At a median follow-up of 58 weeks, there were no local recurrences and only one patient developed disease progression with distant metastasis in the liver.

CONCLUSIONS

IMRT for retroperitoneal sarcoma allowed enhanced tumor coverage and better sparing of dose to critical normal structures such as small bowel, liver, and kidney. Escalation of dose has a positive impact on local control for retroperitoneal sarcoma; IMRT may be an effective method to achieve this goal. We are evaluating preoperative dose escalation to 59.4 Gy.

A survey of stereotactic body radiotherapy use in the United States

BACKGROUND

Stereotactic body radiotherapy (SBRT) is a technique used to deliver high, ablative doses of radiation in a limited number of fractions to ≥ 1 extracranial target(s). To the authors' knowledge, the prevalence of SBRT use among radiation oncologists in the United States is unknown.

METHODS

A random sample of 1600 American radiation oncologists was surveyed via e-mail and facsimile (fax) regarding SBRT usage, including year of adoption, motivations, disease sites treated, and common prescriptions used.

RESULTS

Of 1373 contactable physicians, 551 responses (40.1%) were received. The percentage of physicians using SBRT was 63.9% (95% confidence interval, 60%-68%), of whom nearly half adopted it in 2008 or later. The most commonly cited reasons for adopting SBRT were to allow the delivery of higher than conventional radiation doses (90.3%) and to allow retreatment (73.9%) in select patients. Academic physicians were more likely to report research as a motivation for SBRT adoption, whereas physicians in private practice were more likely to list competitive reasons. Among SBRT users, the most common disease sites treated were lung (89.3%), spine (67.5%), and liver (54.5%) tumors. Overall, 76.0% of current SBRT users planned to increase their use, whereas 66.5% of nonusers planned to adopt the technology in the future.

CONCLUSIONS

SBRT has rapidly become a widely adopted treatment approach among American radiation oncologists. Further research and prospective trials are necessary to assess the benefits and risks of this novel technology.

Observed magnetic resonance imaging changes in pediatric patients treated with stereotactic radiosurgery for intracranial tumors

PURPOSE

This study seeks to characterize magnetic resonance imaging (MRI) changes following stereotactic radiosurgery (SRS) of pediatric brain malignancies.

METHODS

Serial MRI evaluations were performed on 21 lesions treated with SRS for either medulloblastoma (n=12), juvenile pilocytic astrocytoma (n=4), ependymoma (n=2), atypical rhabdoid teratoid tumor (n=2), or pineocytoma (n=1). Prescription doses ranged from 14 to 30 Gy in one to five fractions. Tumor response was qualified as complete (CR), partial (PR), stable disease (SD), or progressive disease (PD) according to the RECIST v1.1. Median radiographic follow-up after SRS was 17 months.

RESULTS

A total of 80 follow-up MRI scans were reviewed with a median of eight per patient. During serial MRI evaluation, eight lesions met criteria for PD at a median of 6 months. However, of these, three (37%) represented transient tumor edema with two lesions later developing a CR at a median of 15 months and one persisting as SD at 12 months. The remaining five lesions were true local failures. Of the 13 lesions that did not show evidence of PD, a CR was obtained in 11 lesions at a median of 3 months (range, 2-6), and SD was seen in the remaining two tumors at last follow-up.

CONCLUSION

Lesion enlargement following SRS for pediatric intracranial tumors is common, and a proportion of patients meeting requirements for PD at early radiographic follow-up may later develop complete resolution of their lesions. Physicians should be aware of these radiographic changes to avoid unwarranted medical and surgical interventions.

A survey of image-guided radiation therapy use in the United States

BACKGROUND

Image-guided radiation therapy (IGRT) is a novel array of in-room imaging modalities that are used for tumor localization and patient setup in radiation oncology. The prevalence of IGRT use among US radiation oncologists is unknown.

METHODS

A random sample of 1600 radiation oncologists was surveyed by Internet, e-mail and fax regarding the frequency of IGRT use, clinical applications, and future plans for use. The definition of IGRT included imaging technologies that are used for setup verification or tumor localization during treatment.

RESULTS

Of 1089 evaluable respondents, 393 responses (36.1%) were received. The proportion of radiation oncologists using IGRT was 93.5%. When the use of megavoltage (MV) portal imaging was excluded from the definition of IGRT, the proportion using IGRT was 82.3%. The majority used IGRT rarely (in <25% of their patients; 28.9%) or infrequently (in 25%-50% of their patients; 33.1%). The percentages using ultrasound, video, MV-planar, kilovoltage (kV)-planar, and volumetric technologies were 22.3%, 3.2%, 62.7%, 57.7%, and 58.8%, respectively. Among IGRT users, the most common disease sites treated were genitourinary (91.1%), head and neck (74.2%), central nervous system (71.9%), and lung (66.9%). Overall, 59.1% of IGRT users planned to increase use, and 71.4% of nonusers planned to adopt IGRT in the future.

CONCLUSIONS

IGRT is widely used among radiation oncologists. On the basis of prospective plans of responders, its use is expected to increase. Further research will be required to determine the safety, cost efficacy, and optimal applications of these technologies.

Frame-less and mask-less cranial stereotactic radiosurgery: a feasibility study

Currently, high-precision delivery in stereotactic radiosurgery (SRS) is achieved via high-precision target localization and rigid patient immobilization. Rigid patient immobilization can result in, however, patient discomfort, which is exacerbated by the long duration of SRS treatments and may induce patient movement. To address this issue, we developed a new SRS technique that is aimed to minimize patient discomfort while maintaining high-precision treatment, based on a less-rigid patient immobilization combined with continuous patient motion monitoring. In this paper, we examine the feasibility of this new technique. An anthropomorphic head phantom is used to check the accuracy of a 3D surface imaging system that provides the monitoring. Volunteers are used to study patient motion inside a new type of head mold that is used for minimal immobilization. Results show that for different couch angles, the difference between the phantom positions recorded by the surface imaging system and by an infrared optical tracking system was within 1 mm in displacements and 1 degrees in rotation. The motion detected by both systems during couch shifts is within 1 mm agreement. The average maximum volunteer head motion in the head mold during the 20 min interval in any direction was 0.7 mm (range: 0.4-1.1 mm). Patient motion due to couch motion was always less than 0.2 mm. We conclude that motion inside the minimally immobilizing head mold is small and can be accurately detected by real-time surface imaging.

Single-isocenter frameless intensity-modulated stereotactic radiosurgery for simultaneous treatment of multiple brain metastases: clinical experience

PURPOSE

To describe our clinical experience using a unique single-isocenter technique for frameless intensity-modulated stereotactic radiosurgery (IM-SRS) to treat multiple brain metastases.

METHODS AND MATERIALS

Twenty-six patients with a median of 5 metastases (range, 2-13) underwent optically guided frameless IM-SRS using a single, centrally located isocenter. Median prescription dose was 18 Gy (range, 14-25). Follow-up magnetic resonance imaging (MRI) and clinical examination occurred every 2-4 months.

RESULTS

Median follow-up for all patients was 3.3 months (range, 0.2-21.3), with 20 of 26 patients (77%) followed up until their death. For the remaining 6 patients alive at the time of analysis, median follow-up was 14.6 months (range, 9.3-18.0). Total treatment time ranged from 9.0 to 38.9 minutes (median, 21.0). Actuarial 6- and 12-month overall survivals were 50% (95% confidence interval [C.I.], 31-70%) and 38% (95% C.I., 19-56%), respectively. Actuarial 6- and 12-month local control (LC) rates were 97% (95% C.I., 93-100%) and 83% (95% C.I., 71-96%), respectively. Tumors <or=1.5 cm had a better 6-month LC than those >1.5 cm (98% vs. 90%, p = 0.008). New intracranial metastatic disease occurring outside of the treatment volume was observed in 7 patients. Grade >or=3 toxicity occurred in 2 patients (8%).

CONCLUSION

Frameless IM-SRS using a single-isocenter approach for treating multiple intracranial metastases can produce clinical outcomes that compare favorably with those of conventional SRS in a much shorter treatment time (<40 minutes). Given its faster treatment time, this technique is appealing to both patients and personnel in busy clinics.

Utilization of advanced imaging technologies for target delineation in radiation oncology

PURPOSE

The aim of this study was to evaluate the utilization of advanced imaging technologies for target delineation among radiation oncologists in the United States.

METHODS

A random sample of 1,600 radiation oncologists was contacted by Internet, e-mail, and fax and questioned regarding the use of advanced imaging technologies, clinical applications, and future plans for use. Advanced imaging technologies were defined as any of the following that were directly incorporated into radiation therapy planning: MRI, PET, single-photon emission CT, 4-D CT, functional MRI, and MR spectroscopy.

RESULTS

Of 1,089 contactable physicians, 394 (36%) responded. Of respondents, 65% were in private practice and 35% were in academic practice. The proportion using any advanced imaging technology for target delineation was 95%. However, the majority reported only rare (in <25% of their patients; 46.6%) or infrequent (in 25%-50% of their patients; 26.0%) utilization. The most commonly used technologies were 2-[(18)F]fluoro-2-deoxyglucose PET (76%), MRI (72%), and 4-D CT (44%). The most common cancers treated using image-guided target delineation were those of the lung (83%), central nervous system (79%), and head and neck (79%). Among users of advanced imaging technologies, 66% planned to increase use; 30% of nonusers planned to adopt these technologies in the future.

CONCLUSIONS

Advanced imaging technologies are widely used by US radiation oncologists for target delineation. Although the majority of respondents used them in <50% of their patients, the frequency of utilization is expected to increase. Studies determining the optimal application of these technologies in radiation therapy planning are needed.

Dosimetric comparison of intensity-modulated radiosurgery and helical tomotherapy for the treatment of multiple intracranial metastases

The purpose of this study was to evaluate the dosimetry of single fraction, single-isocenter intensity-modulated radiosurgery (IMRS) plans for multiple intracranial metastases and to compare Helical Tomotherapy (HT). Ten treatment plans with 3-6 brain metastases treated with IMRS were re-planned with HT. The mean number of lesions was 5 and mean PTV 22 cm(3). The prescribed dose was 16-20 Gy. The mean V100% was similar for IMRS and HT, and the mean conformity index was 1.4, mean Paddick confirmity index was 0.7, and mean MDPD was 1.1 for both. The mean gradient index was similar for both. The mean 50% _isodose volume was 179.2 cm(3) for IMRS and 277.0 cm(3) for HT (p=0.01). The mean maximum doses to organs at risk were lower for IMRS except brainstem and right optic nerve. For brain, the integral dose was 5.1 and 6.8 Gy-kg (p<0.001) and mean dose 4.0 and 5.4 Gy (p<0.001) for IMRS and HT, respectively. The mean treatment times were 23 (IMRS) and 41 (HT) minutes. Conformity and homogeneity indices were equivalent and sparing of the organs at risk was clinically acceptable for both IMRS and HT. Though the gradient index was similar for IMRS and HT, the mean 50% isodose volume and integral dose to normal brain were lower for IMRS as was treatment time.

Optically-guided frameless linac-based radiosurgery for brain metastases: clinical experience

The purpose of this study was to describe our clinical experience using optically-guided linear accelerator (linac)-based frameless stereotactic radiosurgery (SRS) for the treatment of brain metastases. Sixty-five patients (204 lesions) were treated between 2005 and 2008 with frameless SRS using an optically-guided bite-block system. Patients had a median of 2 lesions (range, 1-13). Prescription dose ranged from 14 to 22 Gy (median, 18 Gy) and was given in a single fraction. Clinical and radiographic evaluation occurred every 2-4 months following treatment. At a median follow-up of 6.2 months, actuarial survival at 12 months was 40% [95% confidence interval (CI), 28-52). Of 135 lesions that were evaluable for local control (LC), 119 lesions (88%) did not show evidence of progression. Actuarial 12 month LC was 76% (95% CI, 66-86). Tumors <or=2 cm in size had a better 12 month LC rate (81% vs. 36%, P = 0.017) than those >2 cm. Adverse events occurred in three patients (5%). Optically-guided linac-based frameless SRS can produce clinical outcomes that compare favorably to frame-based techniques. As this technique is convenient to use and allows for the uncomplicated delivery of hypofractionated radiotherapy, frameless SRS will likely have an increasingly important role in the management of brain metastases.

Percutaneous feeding tubes in patients with head and neck cancer: rethinking prophylactic placement for patients undergoing chemoradiation

OBJECTIVES

Although intensified therapy has contributed to improved outcomes for patients with head and neck cancer, acute toxicity has increased as well. To lessen the severity of nutritional compromise in these patients, our institutional protocol has been to routinely place feeding tubes before the initiation of therapy. This investigation details the toxicities associated with feeding tube placement and predictors for duration of tube dependence.

MATERIALS AND METHODS

The records of the Radiation Oncology Department at Emory Clinic were reviewed for patients receiving definitive radiotherapy between 6/1/2003 and 6/1/2006. The records of the subset of patients with feeding tube placement before the initiation of therapy were then reviewed for toxicities as well as length of time of tube dependence.

RESULTS

There were 102 eligible patients. Radiotherapy was delivered with concomitant chemotherapy in all. Median time with feeding tube in place for all patients was 4.4 months (range, 0.2-28.9 months). For 82 patients with eventual tube removal, the median time of tube dependence was 3.8 months (range, 1.4-28.9 months). Risk factors for prolonged tube dependence are analyzed; on multivariate analysis, patient age, T stage, and nodal status remained significant. The most common complication was tube replacement, with 11.8% of all tubes requiring replacement. Infection and pain occurred in 8.8% and 5.9% of patients, respectively.

CONCLUSION

Feeding tubes are required for more than 2 months after combined modality treatment of head and neck cancer. They are generally well tolerated, but toxicities are not trivial: more than 10% require replacement and more than 8% of patients develop infection at the insertion site. We are assessing their routine placement in light of these data.

Early clinical results from chemoradiation with 5-fluorouracil and oxaliplatin for locally advanced rectal cancer

PURPOSE

Preoperative chemoradiation with 5-fluorouracil (5-FU) has improved local control and resectability in patients with locally advanced rectal adenocarcinoma. The possible benefit of adding oxaliplatin is being investigated. We present background on the use of oxaliplatin as well as institutional experience assessing treatment tolerability and early outcome data.

PATIENTS AND METHODS

From August 2001 to August 2006, 15 patients were treated with concurrent 5-FU, oxaliplatin, and radiation. Each had locally advanced rectal carcinoma with staging as follows: T3 (10 patients), T4 (5 patients), N1 (3 patients), and M1 (1 patient). Three patients were treated for local recurrence; 2 had received previous radiation therapy. All patients received continuous-infusion 5-FU at 225 mg/m2 per day. The oxaliplatin dose was 70 mg/m2 in 1 patient and 85 mg/m2 in the others, administered every other week x 3 weeks starting on day 1 of radiation. Resection followed completion of radiation by 6 weeks.

RESULTS

The treatment was tolerable, with the most frequent hematologic toxicity being grade 1/2 anemia. Twelve patients were evaluable, with 11 treated preoperatively. All were able to undergo resection with negative margins, with T stage at resection as follows: T4 (2 patients, 1 with 5% viable tumor), T3 (4 patients), T2 (1 patient), T1 (2 patients); there were pathologic complete responses in 4 patients. At resection, 2 patients had N2 disease; 1 of these was also found to have a peritoneal metastasis. Two patients with clinical N1 disease initially were N0 at resection. With median follow-up of 13 months (range, 4-36 months), 9 patients have clinically no evidence of disease. There have been no local recurrences and 1 death from disease.

CONCLUSION

We present tolerability and early clinical efficacy data for patients treated with concurrent 5-FU and oxaliplatin chemoradiation. The oxaliplatin-based regimen was tolerable. All patients were able to undergo resection with negative margins, with encouraging downstaging, local control, and survival.

Early clinical experience with kilovoltage image-guided radiation therapy for interfraction motion management

Interest in image-guided radiation therapy (IGRT) reflects the desire to minimize interfraction positioning variability. Using a kilovoltage (kV) imaging unit mounted to a traditional LINAC allows daily matching of kV images to planning digitally reconstructed radiographs (DRRs). We quantify and evaluate the significance of calculated deviation from the intended isocenter. Since September 2004, 117 patients with various malignancies were treated using the On-Board Imaging (OBI) system, with 2088 treatment sessions. Patients were positioned by the treating therapist; orthogonal images were then obtained with the OBI unit. Couch shifts were made, aligning bony anatomy to the initial simulation image. Routine port films were performed weekly (after that day's OBI session). Ninety percent of all lateral, longitudinal, and vertical shifts were less than 0.8 cm, 0.6 cm, and 0.7 cm, respectively. The median vector shift for each anatomic site was: 0.42 cm for head and neck, 0.40 cm for CNS, 0.59 cm for GU/prostate, and 0.73 cm for breast; shift magnitude did not change with successive OBI sessions. The use of OBI effectively corrects setup variability. These shifts are typically small and random. The use of OBI likely can replace weekly port films for isocenter verification; however, OBI does not provide field shape verification.

Concurrent platinum-based chemotherapy and simultaneous modulated accelerated radiation therapy for locally advanced squamous cell carcinoma of the tongue base

BACKGROUND

Randomized data support use of chemotherapy concurrently with radiation in treatment of advanced squamous cell carcinoma (SCC) of the oropharynx. Intensity modulated radiation therapy (IMRT) is increasingly being used to deliver such radiotherapy; no published reports specifically describe results of chemotherapy with IMRT for SCC of the base of tongue (BOT). We present outcomes data using simultaneous modulated accelerated radiation therapy (SMART) combined with platinum-based chemotherapy in treatment of locally advanced SCC of the BOT METHODS: The records of the Otolaryngology/Head and Neck Surgery Department of Emory University were screened for patients undergoing definitive chemoradiotherapy for SCC of the BOT. Radiation Oncology records were reviewed for dosimetry and prescription data. Hospital and clinic records were reviewed for control and toxicity data. All patients were treated definitively with platinum-based chemotherapy and once-daily RT. Median dose and dose per fraction to sites of gross primary or nodal disease, clinically involved neck, and clinically uninvolved neck were 70.29 Gy (2.13 Gy/fx), 63.03 Gy (1.91 Gy/fx), and 57.75 Gy (1.75 Gy/fx), respectively.

RESULTS

Between January 2003 and August 2005, 34 patients underwent definitive therapy for SCC of the BOT using SMART and chemotherapy. Follow-up was documented in all cases (median, 20.1 months). There have been 3 distant failures and 3 locoregional failures.

CONCLUSION

With moderate follow-up, chemotherapy and SMART contributes to excellent results, with 24-month actuarial overall survival and local control of 90% and 92%, respectively. Toxicity may be increased, however, with 15% of patients developing esophageal stricture or stenosis. .

Frequency of esophageal stenosis after simultaneous modulated accelerated radiation therapy and chemotherapy for head and neck cancer

BACKGROUND

Chronic esophageal toxicity after radiotherapy alone for cancer of the head and neck (HNCa) is rare: 2.6% for strictures and 0.8% for stenosis after a 60-Gy dose. With combined modality therapy, stricture rates of 22% to 37% have been reported. We report the frequency of esophageal toxicity after simultaneous modulated accelerated radiation therapy (SMART) with chemotherapy for HNCa.

METHODS

The records of the otolaryngology/head and neck surgery department of Emory University, Atlanta, GA, were screened for patients undergoing combined modality therapy using SMART for HNCa. Radiation Oncology records were reviewed for target and critical normal structure dosimetry, with detailed analysis of esophageal and supraglottic laryngeal dosimetry. Hospital and clinic records were reviewed for evidence of esophageal toxicity.

RESULTS

From January 2003 to August 2005, 99 patients underwent definitive therapy for squamous cell HNCa using SMART and chemotherapy. Follow-up was documented in all cases. Median dose to sites of gross primary or nodal disease was 70.29 Gy, at 2.13 Gy per fraction. Median dose to the ipsilateral neck was 63.03 Gy at 1.91 Gy per fraction. Median dose to the contralateral neck in 97 patients treated was 57.75 Gy at 1.75 Gy per fraction. Thirteen (13%) patients developed esophageal strictures. Five (5%) patients had complete esophageal stenosis. Four (14%) of the 29 patients with either a hypopharyngeal primary or a N2c nodal disease developed complete stenosis. A statistically larger esophageal volume of esophagus reactivity > or = 60 Gy (V(60)) was found in patients who developed stenosis/stricture when compared with a randomly selected population of N2a/b patients who did not develop those toxicities. Esophageal stenosis/stricture was also numerically more common in patients receiving taxane-based chemotherapy, developing in 23%, as opposed to 9% in patients treated with platinum-based chemotherapy.

CONCLUSION

The risk of esophageal stenosis may increase with SMART and chemotherapy for HNCa. Potential mechanisms to reduce this include (a) contouring the esophagus as a dose-limiting structure; (b) early flexible examination posttreatment, with early intervention with dilation; (c) improved therapy for mucositis.

Quantitative evaluation of a cone-beam computed tomography-planning computed tomography deformable image registration method for adaptive radiation therapy

Deformable (non‐rigid) registration is an essential tool in both adaptive radiation therapy and image‐guided radiation therapy to account for soft‐tissue changes during the course of treatment. The evaluation method most commonly used to assess the accuracy of deformable image registration is qualitative human evaluation. Here, we propose a method for systematically measuring the accuracy of an algorithm in recovering artificially introduced deformations in cases of rigid geometry, and we use that method to quantify the ability of a modified basis spline (B‐Spline) registration algorithm to recover artificially introduced deformations. The evaluation method is entirely computer‐driven and eliminates biased interpretation associated with human evaluation; it can be applied to any chosen method of image registration.

Our method involves using planning computed tomography (PCT) images acquired with a conventional CT simulator and cone‐beam computed tomography (CBCT) images acquired daily by a linear accelerator–mounted kilovoltage image system in the treatment delivery room. The deformation that occurs between the PCT and daily CBCT images is obtained using a modified version of the B‐Spline deformable model designed to overcome the low soft‐tissue contrast and the artifacts and distortions observed in CBCT images. Clinical CBCT images and contours of phantom and central nervous system cases were deformed (warped) with known random deformations. In registering the deformed with the non‐deformed image sets, we tracked the algorithm's ability to recover the original, non‐deformed set. Registration error was measured as the mean and maximum difference between the original and the registered surface contours from outlined structures. Using this approach, two sets of tests can be devised. To measure the residual error related to the optimizer's convergence performance, the warped CBCT image is registered to the unwarped version of itself, eliminating unknown factors such as noise and positioning errors. To study additional errors introduced by artifacts and noise in the CBCT image, the warped CBCT image is registered to the original PCT image.

Using a B‐Spline deformable image registration algorithm, mean residual error introduced by the algorithm's performance on noise‐free images was less than 1 mm, with a maximum of 2 mm. The chosen deformable image registration model was capable of accommodating significant variability in structures over time, because the artificially introduced deformation magnitude did not significantly influence the residual error. On the second type of test, noise and artifacts reduced registration accuracy to a mean of 1.33 mm and a maximum of 4.86 mm.

The accuracy of deformable image registration can be easily and consistently measured by evaluating the algorithm's ability to recover artificially introduced deformations in rigid cases in which the true solution is known a priori. The method is completely automated, applicable to any chosen registration algorithm, and does not require user interaction of any kind.

PACS numbers: 87.57.Gg, 87.57.Ce, 87.62.+n

Chemoradiotherapy for gastrointestinal cancers

New combinations of chemotherapy with radiotherapy for gastrointestinal cancers are showing evidence that improved outcomes may result from toxicity profiles associated with "targeted" systemic radiosensitizing agents. These new agents are also clinically attractive owing to such factors as oral bioavailability and patient dosing schedules, making them practical and convenient compared with older intravenous administration requirements. Several new classes of radiosensitizing agents are discussed here and underscore aspects of molecular activation in tumors rather than normal tissues because of differences in pathways of metabolism or based on the process of tumor-associated angiogenesis.

Intrinsically disordered protein

Proteins can exist in a trinity of structures: the ordered state, the molten globule, and the random coil. The five following examples suggest that native protein structure can correspond to any of the three states (not just the ordered state) and that protein function can arise from any of the three states and their transitions. (1) In a process that likely mimics infection, fd phage converts from the ordered into the disordered molten globular state. (2) Nucleosome hyperacetylation is crucial to DNA replication and transcription; this chemical modification greatly increases the net negative charge of the nucleosome core particle. We propose that the increased charge imbalance promotes its conversion to a much less rigid form. (3) Clusterin contains an ordered domain and also a native molten globular region. The molten globular domain likely functions as a proteinaceous detergent for cell remodeling and removal of apoptotic debris. (4) In a critical signaling event, a helix in calcineurin becomes bound and surrounded by calmodulin, thereby turning on calcineurin's serine/threonine phosphatase activity. Locating the calcineurin helix within a region of disorder is essential for enabling calmodulin to surround its target upon binding. (5) Calsequestrin regulates calcium levels in the sarcoplasmic reticulum by binding approximately 50 ions/molecule. Disordered polyanion tails at the carboxy terminus bind many of these calcium ions, perhaps without adopting a unique structure. In addition to these examples, we will discuss 16 more proteins with native disorder. These disordered regions include molecular recognition domains, protein folding inhibitors, flexible linkers, entropic springs, entropic clocks, and entropic bristles. Motivated by such examples of intrinsic disorder, we are studying the relationships between amino acid sequence and order/disorder, and from this information we are predicting intrinsic order/disorder from amino acid sequence. The sequence-structure relationships indicate that disorder is an encoded property, and the predictions strongly suggest that proteins in nature are much richer in intrinsic disorder than are those in the Protein Data Bank. Recent predictions on 29 genomes indicate that proteins from eucaryotes apparently have more intrinsic disorder than those from either bacteria or archaea, with typically > 30% of eucaryotic proteins having disordered regions of length > or = 50 consecutive residues.

Isolation of chloroform-resistant mutants of filamentous phage: localization in models of phage structure

Interaction of fd or M13 filamentous phage with a chloroform/water interface induces morphological change, contracting the filaments sequentially into shortened rods (I-forms), and then into spheroidal particles (S-forms). To further investigate this phage contraction, 34 and 26 chloroform-resistant isolates of fd and M13, respectively, were selected after chloroform treatment of wild-type phages at pH 8. 2 and 4 degrees C. DNA sequencing of gene VIII of the 34 fd isolates revealed five different mutants: these were D5H, M28L, V31L, I37T, and S50T. All 26 M13 isolates were I37T. These mutants exhibited variable sensitivity to chloroform, but all contracted much more slowly than wild-type phage during treatment at 4 degrees C. They all contracted like wild-type phage at 37 degrees C. Site-directed mutagenesis showed that the indicated single mutations carried the chloroform resistance. In structural models of the phage, the D5H locus is on the outside and the S50T locus is on the inside. The M28L and I37T loci are buried in a mostly hydrophobic region in the middle. Although these four mutants are spread out radially, they are localized in the axial direction into a thin disk in the model. The last mutant locus, V31L, is out of this disk, but this locus is proximal to the M28L and I37T loci and also in contact with the surface via a deep hydrophobic hole or depression. These five mutants, their locations, and their variable affects on contraction suggest that chloroform-induced contraction involves a specific mechanism rather than a generalized solvent-induced denaturation and that the critical structural changes occur in a localized level in the phage. These results add weight to suggestions that the sequential contraction of filaments-->I-forms-->S-forms mimic corresponding steps in phage penetration, and, in the reverse order, for phage assembly.

Guidelines for managing low back pain: a policy checklist

Back injuries devour one-third of health care benefits and workers' compensation, yet corporate strategies vary widely in their approach to back pain prevention, treatment and rehabilitation. These recommendations provide a benchmark for evaluation policies on low back pain. They emphasize a sports medicine approach, focused on returning workers to activity as soon as possible.

Homologous veins as an arterial substitute: long-term results

From 1968 through 1982, 129 homologous vein grafts were used in 91 patients in the following positions: 75 in the femoropopliteal, tibial, or peroneal artery; 38 in the aortocoronary artery; 13 in the aortopulmonary artery; and one each in the atrioventricular fistula, carotid-subclavian artery, and brachial-radial artery. In the lower extremity patency ranged from 0 to 121 months (mean 22.4 +/- 4.4 months). All grafts were performed for limb salvage, and 75% of the patients had undergone previous operations. Cumulative patency by the life-table method showed that while 50% of grafts occluded by 1 year, 60% of the remaining grafts continued to be functional for more than 5 years. Fifty percent of the aortocoronary bypass grafts studied were occluded at 1 year. Eight of the 13 systemic pulmonary artery shunts were patent at time of death, revision, or total correction. Multiple revisions and thrombectomies are required to maintain patency of homograft veins. The outcome is variable and unpredictable. The inconsistency is due to the antigenicity of the graft. If one is committed to the necessary efforts required to ensure long-term patency, the homologous saphenous vein is a suitable substitute when autogenous tissue is unavailable.

Median arcuate ligament syndrome with severe two-vessel involvement

Intestinal angina is an unusual condition caused by decreased blood supply to the abdominal viscera. It has been hypothesized that at least two of the three vessels supplying the viscera need to be compromised to cause ischemia. On the other hand, compression of the celiac axis by the medium arcuate ligament, causing symptoms, has been reported. We described a severely symptomatic patient in whom this ligament completely occluded the celiac axis and severely narrowed the superior mesenteric artery. The condition was cured by division of the ligament.

Three simple solutions for renal flush and preservation

The harvesting of kidneys at small hospitals where standard flush solutions are not available has led to the use of several flush solutions that can be made from readily available materials. Mongrel dogs (15) had bilateral nephrectomy after receiving intravenously a mixture of Ringer's lactate, furosemide (Lasix), mannitol, and chlorpromazine (Thorazine). One kidney was perfused with iced Collins' solution and stored for 24 hours, submerged in the perfusate at 4 C. Five dogs each had the contralateral kidney perfused with a solution of either (1) Ringer's lactate, salt-poor albumin, and heparin; (2) 6% dextran 70 and Fenwall buffered heparin solution; or (3) Ringer's lactate, mannitol, and heparin, and were stored in their respective perfusate. After 24 hours' storage the kidneys were transplanted into the neck, and creatinine clearance (Crcl) was determined on days 1, 2, 3, 5, and 7. The dogs were sacrificed on day 7 and biopsy specimens were obtained from each kidney for pathologic examination. The kidneys perfused with Collins' solution had immediate function after transplantation with an average Crcl of 10.5 at 25 hours and 20.2 at seven days. The kidneys perfused with Ringer's lactate and albumin had minimal function immediately after transplantation and were anuric within 24 hours. The kidneys perfused with dextran solution and Ringer's lactate and mannitol solution had immediate function but output remained low, and by seven days the average Crcl was only 3.0 and 4.5 respectively. All solutions except the Ringer's lactate and albumin were hyperosmolar, thus helping to prevent the "no reflow" phenomenon. These results indicate that the solutions tested do not result in the adequate preservation to warrant clinical use.

Resection of abdominal aortic aneurysms in the over-80 age group

We reviewed the risk of resecting an abdominal aortic aneurysm in 38 patients aged 80 years or older. The operative mortality for an elective aneurysm was 5.2%, for symptomatic but nonruptured aneurysm 26.6%, and for ruptured aneurysm 66.7%. The preoperative risk factors were essentially the same for the elective and ruptured group. Several of the patients with ruptured aneurysm had been followed up with their aneurysm for several years by nonsurgeons. To better understand why these patients were not being referred for elective repair, 100 nonsurgeons were sent a questionnaire concerning abdominal aortic aneurysms in octogenarians. The results showed that 81% overestimated the elective operative mortality and as a result did not recommend elective resection.

Revascularization of the poorly functioning kidney

The effect of renal vascularization on renal function in kidneys with poor preoperative excretory function is summarized in this report. Twenty-five patients with kidneys having preoperative creatinine clearance of less than 30 ml/min, as determined during split renal function studies (SRFS), which were revascularized for treatment of secondary renovascular hypertension and then were reevaluated by repeat SRFS form the basis of this report. There were 13 male and 12 female patients. The type of renal artery lesion was atherosclerotic in 21 patients and fibromuscular dysplastic in four patients. Eight individuals had total renal artery occlusion. Significant contralateral renal artery disease was present in 15 patients (60%). Preoperative creatinine clearances in the affected kidneys ranged from 0.27 ml/min (mean, 16 +/- 9 ml/min). after operation, creatinine clearances ranged from 0 to 72 ml/min (mean, 32 +/- 16 ml/mn). Fifteen of the 16 kidneys with preoperative creatinine clearances less than 20 ml/min had improvement in renal function following revascularization (P less than 0.01). Improvement (60%) or cure (36%) in hypertension followed revascularization in 24 of the 25 patients. The most dependable predictor of successful management of both hypertension and retrieval of renal function in these patients was the arteriographic demonstration of a patent distal vessel without evidence of severe intrarenal stenoses. These results support an aggressive attitude toward the use of revascularization in the operative treatment of such patients with renovascular hypertension, even when the residual excretory function is minimal or absent.

Hypertension secondary to complete occlusion of the renal artery

In summary, we feel the results of this study support an aggressive approach toward the diagnostic evaluation and operative management of patients with renovascular hypertension secondary to complete occlusion of the renal artery. Further, the frequent presence of contralateral disease and the progressive nature of renal artery occlusions represent a significant threat to renal function. Since renal function is frequently compromised but potentially retrievable by revascularization, nephrectomy should be employed only when hypertension is difficult to control, revascularization is impossible, and excretory function in the affected kidney is minimal.