Long-Term Outcomes of Non-Vestibular Cranial Nerve Schwannomas Treated with Fractionated Stereotactic Radiotherapy and Stereotactic Radiosurgery

PURPOSE/OBJECTIVE(S)

Non-vestibular cranial nerve schwannomas (NVCNS) are rare tumors that account for approximately 10% of cranial nerve schwannomas. They are commonly treated with radiation therapy (XRT) due to their location often precluding safe resection. We examined the long-term outcomes of NVCNS treated with XRT as primary management and for post-operative salvage.

MATERIALS/METHODS

We conducted a retrospective review of patients with NVCNS treated with fractionated stereotactic radiation therapy (FSRT) or Gamma Knife Stereotactic Radiosurgery (GK-SRS) from 1996 to 2018 at our institution. We examined patient demographics, cranial nerve (CN) involvement, CN function pre-/post-XRT, treatment volume (TV), toxicity, surgery pre-XRT, and local control. Kaplan-Meier analysis was performed for evaluation of local control.

RESULTS

We identified 66 patients (38 female, 28 male) with NVCNS, a portion of whom had tumors involving more than one cranial nerve. Forty-six (69.7%) were treated with FSRT (median dose 50.4 Gy in 1.8 Gy/fraction; range 45-54 Gy), and 20 (30.3%) with GK-SRS (median dose 12 Gy; range 12-15 Gy). Median follow-up time was 92.5 months (5-306). Median Karnofsky Performance Status was 90 (70-100). Median age at start of XRT was 45 years old (15-92). Prior to XRT, 34.8% (23) of patients had surgical resection, with median time from surgery to XRT of 4.25 months (0.5-130 months). Median treatment volume was 4.72 cc (0.26-29). The cranial nerve most commonly involved was CN V (48.4%), followed by CN X (15.2%), CN VII (13.6%), CN VI (6.1%), CN XII (6.1%), CN III (6.1%), and CN IX (3%). Twenty-nine (43.9%) patients experienced grade 1 acute toxicity during treatment. Six (9%) patients experienced grade 1 chronic toxicity. No grade 2 or higher acute or chronic toxicity was observed. No significant difference in rates of acute or chronic toxicity was observed between patients treated with GK-SRS vs. FSRT. Post-XRT, 37 patients (56.1%) had improvement in CN function/symptom, 24 patients (36.3%) had stable function/symptoms, and 5 patients (7.6%) had worsening function/symptoms. Local control at one and five years was 100%. In-field recurrence was observed in one patient (1.5%), at 9 years post-XRT. For salvage this patient was treated with a second course of FSRT to the recurrent tumor.

CONCLUSION

Our large institutional series with long term follow up showed excellent local control of NVCNS treated with FSRT or GK-SRS both for primary management and post-operative salvage. Treatment is well tolerated, with high rates of preservation or improvement of CN function, and minimal acute and chronic toxicity.

Comprehensive Quality of Life Report from a Prospective Clinical Trial of 4DCT-Ventilation Functional Lung Avoidance Radiation Therapy

PURPOSE/OBJECTIVE(S)

Functional imaging has been developed that uses 4DCT images and image processing to generate lung ventilation maps (4DCT-ventilation). 4DCT-ventilation functional avoidance uses 4DCT-images to generate plans that avoid functional regions of the lung with the goal of reducing pulmonary toxicity. A 4DCT-ventilation functional avoidance, phase II, multi-center clinical trial was completed, and patient reported outcomes (PRO) measured. PROs are an essential measure of quality-of-life following radiotherapy. The purpose of this work is to quantify PRO changes for lung cancer patients treated with functional avoidance and to compare PROs against clinical pneumonitis.

MATERIALS/METHODS

Patients with locally advanced lung cancer receiving curative intent radiotherapy (prescriptions of 45-75 Gy) and chemotherapy were accrued. Each patient had a 4DCT-ventilation image generated using 4DCT data. Favorable arc geometry and optimization techniques were used to generate functional avoidance plans. PRO instruments included the Functional Assessment of Cancer Therapy Lung (FACT-L) questionnaire and the Visual Analog Scale (VAS) administered pre-treatment and 3-, 6-, and 12-months post-treatment to gather data on physical, social, emotional, functional, and pulmonary well-being. The percentage of patients with clinically significant decline was calculated using the FACT-TOI (Trial Outcome Index), FACT-LCS (Lung Cancer Subscale), and VAS instruments. To evaluate the correlation between PROs and clinical toxicity, the percentage of clinically significant FACT-LCS decline was compared (Chi-square test) for patients who did or did not experience grade 2+ pneumonitis.

RESULTS

Fifty-nine patients completed baseline PRO surveys. Median age was 65, 83% of patients had non-small-cell lung cancer, with 75% having stage III disease. Clinically significant FACT-TOI decline at, 3, 6, and 12 months was 46.3%, 38.5%, and 26.8%, respectively. The percentage of patients with clinically significant FACT-LCS decline was 33.3%, 33.3%, and 29.3%, at 3 months, 6 months, and 12 months, respectively. The percentage of patients with clinically significant VAS decline at 3, 6, and 12 months was 18.9%, 20.0%, and 18.6%, respectively. Patients who experienced grade 2+ pneumonitis had a greater percentage of clinically significant decline at all time-points with the results reaching significance (p = 0.045) at 6 months.

CONCLUSION

The study presents the first comprehensive evaluation of PROs for patients treated with 4DCT-ventilation functional avoidance. The data show that 20-40% of patients had clinically significant decline and that PROs had a strong correlation with pneumonitis. The PRO data demonstrate that functional avoidance results in low rates of patient reported outcome clinical decline and provide seminal results to be used in phase III studies.

In-drop thermal cycling of microcrystal assembly for senescence control (MASC) with minimal variation in efficacy

The secretome from mesenchymal stem cells (MSCs) has recently gained attention for new therapeutics. However, clinical application requires in vitro cell manufacturing to attain enough cells. Unfortunately, this process often drives MSCs into a senescent state that drastically changes cellular secretion activities. Antioxidants are used to reverse and prevent the propagation of senescence; however, their activity is short-lived. Polymer-stabilized crystallization of antioxidants has been shown to improve bioactivity, but the broad crystal size distribution (CSD) significantly increases the efficacy variation. Efforts were made to crystalize drugs in microdroplets to narrow the CSD, but the fraction of drops containing at least one crystal can be as low as 20%. To this end, this study demonstrates that in-drop thermal cycling of hyaluronic acid-modified antioxidant crystals, named microcrystal assembly for senescence control (MASC), can drive the fraction of microdrops containing crystals to >86% while achieving significantly narrower CSDs (13±3μm) than in bulk (35±11μm). Therefore, this approach considerably improves the practicality of CSD-control in drops. In addition to exhibiting uniform release, MASC made with antioxidizing N-acetylcysteine extended the release time by 40%. MASC further improves the restoration of reactive oxygen species homeostasis in MSCs, thus minimizing cellular senescence and preserving desired secretion activities. We propose that MASC is broadly useful to controlling senescence of a wide array of therapeutic cells during biomanufacturing.

Evaluating two steps in transcription using a fluorescence-based electrophoretic mobility shift assay

Transcription is the critical first step in expressing a gene, during which an RNA polymerase (RNAP) synthesizes an RNA copy of one strand of the DNA that encodes a gene. Here we describe a laboratory experiment that uses a single assay to probe two important steps in transcription: (1) RNAP binding to DNA, and (2) the transcriptional activity of the polymerase. Students probe both these steps in a single experiment using a fluorescence-based electrophoretic mobility shift assay (EMSA) and commercially available Escherichia coli RNAP. As an inquiry-driven component, students add the transcriptional inhibitor rifampicin to reactions and draw conclusions about its mechanism of inhibition by determining whether it blocks polymerase binding to DNA or transcriptional activity. Depending on the curriculum and learning goals of individual courses, this experimental module could be easily expanded to include additional experimentation that mimics a research environment more closely. After completing the experiment students understand basic principles of transcription, mechanisms of inhibition, and the use of EMSAs to probe protein/DNA interactions.

The Effect of Body Mass Index and Residence in Food Priority Areas on Patterns-of-Care and Cancer Outcomes in Patients With Stage III Non-Small Cell Lung Cancer

PURPOSE

Patients living in food priority areas (FPAs), where access to healthy meals is challenging, may be at greater risk of nutritional deficits, leading to poorer cancer outcomes. Currently, there are no published data analyzing how FPAs affect patterns-of-care or outcomes for patients with locally advanced non-small cell lung cancer (NSCLC). We aimed to analyze the effect of residing in an FPA on treatments rendered and cancer outcomes in patients with stage III NSCLC treated at a single institution.

METHODS AND MATERIALS

This is a retrospective study of 573 patients with locally advanced NSCLC consecutively treated from January 2000 to January 2020. χ² and Mann-Whitney U tests were performed to determine differences between select variables. Kaplan-Meier analysis and Cox proportional hazard models were used to analyze overall survival (OS) and freedom from recurrence. Cox regression with forward model selection was used for multivariate analysis.

RESULTS

Thirty-two percent of patients resided in an FPA (n = 183) and were more likely to self-identify as Black (P < .0001), single (P < .001), <60 years of age (P = .001), and uninsured (P < .0001), with a lower median income (P < .001). Patients in FPAs also had lower mean pre-chemoradiation (CRT) albumin (P = .002), lower pre-CRT body mass index (BMI) (P = .026), and were less likely to receive trimodality therapy (P ≤ .001) compared with patients not living in FPAs. There was no difference in OS or freedom from recurrence between the 2 cohorts. However, in patients with a normal BMI, either pre-CRT (median OS, 18.4 vs 25.0 months; P = .005) or after CRT (15.1 vs 28.1 months, P = .002), residing in an FPA resulted in an OS detriment.

CONCLUSIONS

We demonstrated a clear socioeconomic divide in our patient population with stage III NSCLC, where residing in FPAs was associated with less-aggressive therapy and an OS detriment for patients with a normal-weight BMI. We are currently conducting a prospective study characterizing the nutritional needs of patients, particularly those who live in FPAs.

Abstract 1173: Maintenance-phase Temozolomide as a lymphodepletion platform for intracranialadoptiveγδ T cell-basedtherapy in primary high-grade gliomas

Introduction: Lymphodepletion is a key factor for responses in both autologous and allogeneic cell therapies. We are currently evaluating in a Phase I trial, the combination of Temozolomide (TMZ) chemotherapy with methylguanine-DNA methyltransferase (MGMT) modified γδ T cells (Drug Resistant Immunotherapy, or DRI) during maintenance TMZ in patients receiving the Stupp protocol. In this report, we examine both DRI graft and circulating lymphocyte phenotype and function during the treatment phase.

Methods: Patients meeting enrollment criteria undergo tumor resection, placement of a Rickham catheter in the tumor cavity, and an apheresis collection immediately prior to standard chemoradiotherapy (CRT). DRI follows TMZ on Day 1 of maintenance and consists of 150mg/m2 IV TMZ and concurrent intracranial injection of 1.0 x 107 DRI γδT cells. Peripheral blood (PB) was collected at apheresis and immediately prior to the start of each 28-day maintenance cycle. Flow cytometric (FACS) analysis of PB and DRI grafts using antibodies to CD3, CD4, CD8, CD16/56, CD19, TCR-γδ, Vδ1, Vδ2, CD197, CD27, CD28, CD57, CD45RA, Th1/Th2/Th17 PB serum cytokines, and DRI cytotoxic graft function were obtained. When applicable, FFPE sections of recurrent resected GBM tissues were examined for immune infiltration.

Results: DRI grafts contained 74-93% activated γδ T cells with 0.3-0.5 MGMT copies/cell. Cytotoxicity against K562 ranged from 30% to 75% at 40:1 (E:T). Peripheral lymphodepletion was evident throughout TMZ treatment in the Stupp protocol. T cell counts fell precipitously after CRT and cycle 1 (1647+774 vs 609+214 cells/mL) and remained low throughout maintenance phase (range 214-1450 T cells/mL). NK counts remained normal and showed uneven recovery through the first three cycles but failed to recover for the remainder of maintenance phase. γδ T cells also recovered modestly through the first two cycles but failed to recover after additional cycles. Interestingly, CD45RA+CD27- effector T cells showed only slight increases for each patient throughout TMZ maintenance. Cytokine analysis did not show a clear trend except for consistent T cell expression of perforin and IP-10. One patient with recurrent GBM was successfully resected 110d following DRI. Histopathology revealed widespread necrosis with significant infiltration of CD4+ and CD8+ T cells and γδ T cells in the tumor parenchyma.

Conclusions: Standard of care TMZ is lymphodepleting and DRI therapy can be conducted in an environment favorable to T cell persistence and sustained immune response. One treated patient demonstrated infiltration of both αβ and γδ T cells 110 days following a single dose of DRI γδ T cells. TMZ maintenance during the Stupp regimen prolongs lymphodepletion, thereby presenting a favorable setting for adoptive cell therapy.

Citation Format: Lawrence S. Lamb, Lei Ding, Ryan C. Miller, Mariska ter Haak, Caitlyn Lucas, Becca Weekley, Samantha Youngblood, Cathy Langford, Guoling Chen, Louis B. Nabors. Maintenance-phase Temozolomide as a lymphodepletion platform for intracranialadoptiveγδ T cell-basedtherapy in primary high-grade gliomas [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1173.

A Pilot Trial Using Telemedicine in Radiation Oncology: The Future of Health Care Is Virtual

Background: Social determinants of health directly affect cancer survival. Driven by advances in technology and recent demands due to COVID-19, telemedicine has the ability to improve patient access to care, lower health care costs, and increase workflow efficiency. The role of telemedicine in radiation oncology is not established. Materials and Methods: We conducted an IRB-approved pilot trial using a telehealth platform for the first post-radiation visit in patients with any cancer diagnosis. The primary endpoint was feasibility of using telehealth defined by completion of five telehealth visits per month in a single department. Secondary endpoints included the ability to assess patients appropriately, patient and physician satisfaction. Physicians were surveyed again during the pandemic to determine whether viewpoints changed. Results: Between May 27, 2016 and August 1, 2018, 37 patients were enrolled in the Telehealth in Post-operative Radiation Therapy (TelePORT) trial, with 24 evaluable patients who completed their scheduled telehealth visit. On average, 1.4 patients were accrued per month. All patients were satisfied with their care, had enough time with their physician and 85.7% believed the telehealth communication was excellent. All physicians were able to accurately assess the patient's symptoms via telehealth, whereas 82.3% felt they could accurately assess treatment-related toxicity. Physicians assessing skin toxicity from breast radiation were those who did not feel they were able to assess toxicity. Discussion and Conclusions: Both health care providers and patients have identified telemedicine as a suitable platform for radiation oncology visits. Although there are limitations, telemedicine has significant potential for increasing access of cancer care delivery in radiation oncology.

Scalp-sparing radiation with concurrent temozolomide and tumor treating fields (SPARE) for patients with newly diagnosed glioblastoma

2056

Background: Standard of care for patients with newly diagnosed glioblastoma includes concurrent chemoradiation and maintenance temozolomide with Tumor Treating Fields (TTFields). Preclinical studies suggest TTFields and radiation treatment have synergistic effects. We report our clinical trial evaluating safety and tolerability of scalp-sparing radiation with concurrent temozolomide and TTFields. Methods: This is a single arm pilot study. Adult patients (age ≥ 18 years) with newly diagnosed glioblastoma and a KPS of ≥ 60 were eligible. All patients received concurrent scalp-sparing radiation (60 Gy in 30 fractions) with temozolomide (75 mg/m2 daily) and TTFields (200 kHz). Maintenance therapy included temozolomide and continuation of TTFields. Radiation treatment was delivered through TTFields arrays. The primary endpoint was safety and toxicity of TTFields concurrent with chemoradiation in patients with newly diagnosed glioblastoma. Results: A total of 30 patients were enrolled in the trial. Twenty were male and ten were female, with a median age of 58 years (range 19 to 77 years). Median KPS was 90 (range 70 to 100). Median follow-up was 8.9 months (range 1.6 to 21.4 months). Twenty (66.7%) patients had unmethylated MGMT promotor status and ten (33.3%) patients had methylated promoter status. Median time from surgery to radiation was 34 days (26 to 49 days). Scalp dose constraints were achieved for all patients, with the mean dose having a median value of 8.3 Gy (range 4.3 to 14.8 Gy), the D20cc median was 26.1 Gy (range 17.7 to 42.8 Gy), and the D30cc median was 23.5 Gy (range 14.8 to 35.4 Gy). Skin adverse events (AEs; erythema, dermatitis, irritation, folliculitis) were noted in 83.3% of patients, however, these were limited to Grade 1 or 2 events, which resolved spontaneously or with topical medications. No patient had radiation treatment interruption due to skin AEs. Other Grade 1 events included pruritus (33.3%), fatigue (30%), nausea (13.3%), headache (10%), dizziness (6.7%), and cognitive impairment (3.3%). Other Grade 2 events included headache (3.3%). Nineteen patients (63.3%) had progression, with a median PFS of 7.6 months (range 1.6 to 12.7 months). Overall survival was not reached. Conclusions: Concurrent TTFields (200 kHz) with scalp-sparing chemoradiation is a safe and feasible treatment option with limited toxicity. Future randomized prospective trials are warranted to define therapeutic advantages of concurrent TTFields with chemoradiation. Clinical trial information: NCT03477110.

The Impact of Prostate Cancer Treatment on Quality of Life: A Narrative Review with a Focus on Randomized Data

Despite excellent oncologic outcomes, the management of localized prostate cancer remains complex and is dependent on multiple factors, including patient life expectancy, medical comorbidities, tumor characteristics, and genetic risk factors. Decades of iterative clinical trials have improved the optimization and utilization of surgical and radiation-based modalities, as well as their combinatorial use with anti-androgen and systemic therapies. While cure rates are high and converging on equivalent disease control should an upfront surgical or radiotherapeutic approach be optimized, the long-term side effects of surgical and radiation-based treatments can differ significantly in nature. Decisions regarding the selection of therapy are therefore best made in an informed and shared medical decision-making process between clinician and patient with respect to cancer control as well as adverse effects. We outline in this narrative review an understanding regarding implications of surgical and radiation treatment on quality of life after treatment, and how these data may be considered in the context of advising patients regarding the selection of therapy. This narrative review largely focuses on the quality of life data obtained from prospective randomized trials of men treated for prostate cancer. We believe this provides the best assessment of the quality of life and can be used to inform patients when making treatment decisions.

Treatment data and technical process challenges for practical big data efforts in radiation oncology

The term Big Data has come to encompass a number of concepts and uses within medicine. This paper lays out the relevance and application of large collections of data in the radiation oncology community. We describe the potential importance and uses in clinical practice. The important concepts are then described and how they have been or could be implemented are discussed. Impediments to progress in the collection and use of sufficient quantities of data are also described. Finally, recommendations for how the community can move forward to achieve the potential of big data in radiation oncology are provided.

Abstract 5008: The brain microenvironment mediates resistance in luminal breast cancer to PI3K inhibition through HER3 activation

Brain metastases represent a devastating progression of luminal breast cancer. While targeted therapies are often effective systemically, they fail to adequately control brain metastases. In preclinical models that faithfully recapitulate the disparate clinical responses in these microenvironments, we observed that brain metastases evade PI3K inhibition despite efficient drug delivery. In comparison to extracranial disease, there is increased HER3 expression and phosphorylation in the brain lesions. HER3 blockade overcomes the resistance of both HER2-amplified and/or PIK3CA-mutant breast cancer brain metastases to PI3K inhibitors, leading to striking tumor growth delay and significant improvement of mouse survival. Collectively, these data provide a mechanistic basis underlying therapeutic resistance in the brain microenvironment and identify rapidly translatable treatment strategiesfor HER2-amplified and/or PIK3CA-mutant breast cancer brain metastases.

Citation Format: Gino B. Ferraro, David P. Kodack, Vasileios Askoxylakis, Qing Sheng, Mark Badeaux, Shom Goel, Xiaolong Qi, Ram Shankaraiah, Alexander Z. Cao, Rakesh R. Ramjiawan, Divya Bezwada, Bhushankumar Patel, Youngchul Song, Carlotta Costa, Kamila Naxerova, Christina Wong, Jonas Kloepper, Rita Das, Angela Tam, Jantima Tanboon, Dan G. Duda, Ryan C. Miller, Marni B. Siegel, Carey K. Anders, Melinda Sanders, Valeria M. Estrada, Robert Schlegel, Carlos L. Arteaga, Elena Brachtel, Alan Huang, Dai Fukumura, Jeffrey A. Engelman, Rakesh K. Jain. The brain microenvironment mediates resistance in luminal breast cancer to PI3K inhibition through HER3 activation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5008. doi:10.1158/1538-7445.AM2017-5008

Esophageal self-expandable stent material and mesh grid density are the major determining factors of external beam radiation dose perturbation: results from a phantom model

BACKGROUND

Self-expandable esophageal stents are increasingly used for palliation or as an adjunct to chemoradiation for esophageal neoplasia. The optimal esophageal stent design and material to minimize dose perturbation with external beam radiation are unknown. We sought to quantify the deviation from intended radiation dose as a function of stent material and mesh density design.

METHODS

A laboratory dosimetric film model was used to quantify perturbation of intended radiation dose among 16 different esophageal stents with varying material and stent mesh density design.

RESULTS

Radiation dose enhancement due to stent backscatter ranged from 0 % to 7.3 %, collectively representing a standard difference from the intended mean radiation dose of 1.9 (95 % confidence interval [CI] 1.5 - 2.2). This enhancement was negligible for polymer-based stents and approached 0 % for the biodegradable stents. In contrast, all metal alloy stents had significant radiation backscatter; this was largely determined by the density of mesh design and not by the type of alloy used.

CONCLUSIONS

Stent characteristics should be considered when selecting the optimal stent for treatment and palliation of malignant esophageal strictures, especially when adjuvant or neo-adjuvant radiotherapy is planned.

Small cell carcinoma of the esophagus: a multicentre Rare Cancer Network study

Small cell carcinoma of the esophagus (SCCE) is a rare and aggressive malignant tumor with a poor prognosis. The aims of this retrospective study were to analyze the epidemiology, clinical characteristics, and treatment outcomes of these patients. Between 1994 and 2004, 24 patients with SCCE from several centers were reviewed for data on demographics, presenting symptoms, diagnosis, disease stage, type of treatment, and outcome. SCCE occurs in the sixth decade: median age (interquartile range [IQR]): 65 (59-69) years with a male predominance (63%). The most common complaining symptoms were rapidly progressive dysphagia (79%), weight loss (54%), and retrosternal/epigastric pain (46%). The tumor arises primarily in the middle (52%) or in the lower (35%) third of the esophagus. History of tobacco and alcohol exposure was present in 90% and 70% of case, respectively. Extensive disease was present in 13 cases (54%) at initial diagnosis. The overall median survival (IQR) was 11 (8-20) months for all 24 patients, and the 2-year overall survival was 25.1%. Four patients were alive more than 2 years after treatment. Chemotherapy increased the survival compared with symptomatic management in extensive disease (median survival [IQR]: 9.5 [6-14] vs. 6 [4-7] months, P= 0.05). In limited disease, concurrent chemo-radiotherapy was more effective than non-concurrent treatment (median survival [IQR]: 36 [14-93] vs. 11 [9-15] months, P= 0.04). Two patients were treated by surgery and chemoradiation therapy with a survival of 35 and 66 months. Chemotherapy is the cornerstone of treatment of SCCE in all stage. For limited disease SCCE, concurrent chemo-radiotherapy is the primary choice compared with sequential approach. The role of surgery was not assessable in our study.

Secretion of a bacterial cellulase by yeast

Gene fusions were constructed between a yeast expression plasmid and a Cellulomonas fimi DNA fragment encoding an endo-1,4-beta-D-glucanase or carboxymethylcellulase. Yeast transformed with the recombinant plasmids secreted carboxymethylcellulase activity. Secretion of active enzyme was greatly increased when the leader of a secreted yeast protein, the Kl toxin, was inserted immediately upstream of and in frame with the bacterial cellulase sequence. This is the first step in constructing a functional cellulase complex in Saccharomyces cerevisiae. It also provides an excellent system for the detailed examination of the determinants of protein secretion because of the ease with which secreted cellulase can be detected.

Expression in Escherichia coli of the Cellulomonas fimi Structural Gene for Endoglucanase B

Endoglucanase B (EB) of Cellulomonas fimi has an M(r) of 110,000 when it is produced in Escherichia coli. The level of expression of the cenB gene (encoding EB) was significantly increased by replacing its normal transcriptional and translational regulatory signals with those of the E. coli lac operon. EB was purified to homogeneity from the periplasmic fraction of E. coli in one step by affinity chromatography on microcrystalline cellulose (Avicel). Alignment of the NH(2)-terminal amino acid sequence with the partial nucleotide sequence of a fragment of C. fimi DNA showed that EB is preceded by a putative signal polypeptide of 33 amino acids. The signal peptide functions and is processed correctly in E. coli, even when its first 15 amino acids are replaced by the first 7 amino acids of beta-galactosidase. The intact EB polypeptide is not required for enzymatic activity. Active polypeptides with M(r)s of 95,000 and 82,000 also appear in E. coli, and a deletion mutant of cenB encodes an active polypeptide with an M(r) of 72,000.

Expression and Secretion of a Cellulomonas fimi Exoglucanase in Saccharomyces cerevisiae

We used the yeast MEL1 gene for secreted alpha-galactosidase to construct cartridges for the regulated expression of foreign proteins from Saccharomyces cerevisiae. The gene for a Cellulomonas fimi beta-1,4-exoglucanase was inserted into one cartridge to create a fusion of the alpha-galactosidase signal peptide to the exoglucanase. Yeast transformed with plasmids containing this construction produced active extracellular exoglucanase when grown under conditions appropriate to MEL1 promoter function. The cells also produced active intracellular enzyme. The secreted exoglucanase was N-glycosylated and was produced continuously during culture growth. It hydrolyzed xylan, carboxymethyl cellulose, 4-methylumbelliferyl-beta-d-cellobiose, and p-nitrophenyl-beta-d-cellobiose. A comparison of the recombinant S. cerevisiae enzyme with the native C. fimi enzyme showed the yeast version to have an identical K(m) and pH optimum but to be more thermostable.

The cellulose-binding domain (CBD(Cex)) of an exoglucanase from Cellulomonas fimi: production in Escherichia coli and characterization of the polypeptide

The gene fragment encoding the cellulose-binding domain (CBD) of an exoglucanase (Cex) from Cellulomonas fimi was subcloned and expressed in Escherichia coli. Transcription from the lac promoter coupled with translation from a consensus prokaryotic ribosome binding site led to the production of large quantities of CBD(Cex) (up to 25% total soluble cell protein). The polypeptide leaked into the culture supernatant (up to 50 mg . L(-1)), facilitating one-step purification by affinity chromatography on cellulose. The 11-kDa polypeptide reacted with Cex antiserum. Absence of free thiols indicated that the two Cys residues of CBD(Cex) form a disulfide bridge. It had the same N-terminal amino acid sequence as CBD(Cex) prepared from Cex by proteolysis, plus two additional N-terminal amino acid residues (Ala and Ser) encoded by the Nhel site introduced during plasmid construction. CBD(Cex) bound to a variety of beta-1, 4-glycans with different affinities and saturation levels. Adsorption to bacterial microcrystalline cellulose was dependent on the temperature, but not on the pH.

Non-traumatic vertebral fractures in patients with locally advanced esophageal cancer: a previously unreported, unrecognized problem

Recent studies suggest cancer therapy may compromise bone integrity. What is the rate of vertebral fractures among patients who have received trimodality therapy (radiation, chemotherapy, and surgery) for locally advanced esophageal cancer? This single-institution, retrospective study attempted to answer this question, focusing on 337 patients who had received trimodality therapy for locally advanced esophageal cancer between 1996 and 2005. Reports of serial radiographs were reviewed to identify vertebral fractures. Duration of follow-up was gathered for all esophageal cancer patients with the intention of calculating fracture incidence rates. Fracture-related symptoms, types of intervention and fracture recurrence were also gleaned from the clinical records. First-time fractures were identified in 47 patients, and 45 of these were new since the cancer diagnosis. Thus, the first-time fracture incidence rate from the time of cancer diagnosis was 12 fractures per 100 patient years. The median time from cancer diagnosis to fracture was 9 months. Fifteen (33%) patients were symptomatic. Acknowledging that a retrospective study can inadvertently result in information omission, we report that pain medications were started in only seven patients (16%), and osteoporosis medication in only six (13%). Two patients were hospitalized, and two underwent vertebroplasty. The median survival after fracture diagnosis was 36 months. This report describes a seemingly high fracture incidence rate that requires confirmation. If confirmed, future studies should focus on identifying risk factors and optimal strategies for the prevention and treatment of vertebral fractures in patients with esophageal cancer.

Curing patients with locally advanced esophageal cancer: an update on multimodality therapy

Combining different treatment modalities--such as surgery, radiation, and chemotherapy--is often utilized to treat patients with locally advanced esophageal cancer. However, it remains controversial how best to combine these modalities to provide patients with the greatest chance of cure. This review discusses recent studies in this field and outlines promising versus less promising therapeutic strategies.

Intraoperative radiotherapy for treatment of locally advanced and recurrent esophageal and gastric adenocarcinomas

Intraoperative radiotherapy (IORT) allows delivery of radiotherapy doses in excess of those typically deliverable with conventional external beam radiotherapy. IORT has potential utility in clinical situations, such as treatment of esophageal and gastric malignancies, in which the radiation tolerance of normal organs limits the dose that can be given with conventional radiotherapy techniques. We reviewed the records of 50 patients who received IORT for locally advanced primary or recurrent gastric or esophageal adenocarcinomas deemed unresectable for cure. IORT was given as a single fraction of electron beam radiotherapy (10-25 Gy) after maximal tumor resection: R0 in 42%, R1 in 46%, and R2 in 12%. Forty-eight patients also received external beam radiotherapy (8-55 Gy), 46 received radiosensitizing chemotherapy, and nine received systemic chemotherapy after radiotherapy. Outcomes were estimated with Kaplan-Meier analysis. Median survival was 1.6 years. Overall survival at 1, 2, and 3 years was 70%, 40%, and 27%. Of 42 patients who died, 37 died from cancer progression and three from multifactorial treatment toxicity. Median survival for patients with recurrent disease versus primary disease was 3.0 years versus 1.3 years (P < 0.05), with a delay of metastatic failure in patients with recurrent tumors (P = 0.06). At 3 years, distant metastatic failure was 79%, local failure was 10%, and regional failure was 15%. IORT for locally advanced primary or recurrent gastric malignancies effectively decreases the risk of local failure. For patients with isolated local recurrences, IORT may be effective salvage therapy. However, more effective systemic therapy is needed as a component of treatment.

Ovulation detection methods for urinary hormones: precision, daily and intermittent sampling and a combined hierarchical method

BACKGROUND

We evaluate the performance of ovulation detection methods and present new approaches, including evaluation of methods for precision, combining multiple markers into a hierarchical system and using ovulation markers in intermittent sampling designs.

METHODS

With serum LH peak day as the 'gold standard' of ovulation, we estimated accuracy and precision of ovulation day algorithms using 30 ovulatory menstrual cycles with daily urinary and serum hormones and transvaginal ultrasound. Sensitivity and specificity for estimating the presence of ovulation were tested using visually assessed ovulatory (30) and anovulatory (22) cycles.

RESULTS

Sensitivity and specificity ranged from 70 to 100% for estimating presence of ovulation with twice-per-cycle, weekly, twice weekly, every-other-day and daily specimens. A combined hierarchical method estimated ovulation day using daily specimens within +/-2 days of the gold standard in 93% of cases. Accuracy of estimating ovulation day within +/-2 days using intermittent sampling ranged from 40% (weekly sampling) to 97% (every-other-day).

CONCLUSIONS

A combined hierarchical algorithm using precise and accurate markers allows maximal use of available data for efficient and objective identification of ovulation using daily specimens. In intermittent sampling designs, the presence and the timing of ovulation can be estimated with good sensitivity, specificity and accuracy.

A Canadian high-energy neutron spectrometry system for measurements in space

Bubble Technology Industries Inc. (BTI), with the support of the Canadian Space Agency, has finished the construction of the Canadian High-Energy Neutron Spectrometry System (CHENSS). This spectrometer is intended to measure the high energy neutron spectrum (approximately 1-100 MeV) encountered in spacecraft in low earth orbit. CHENSS is designed to fly aboard a US space shuttle and its scientific results should facilitate the prediction of neutron dose to astronauts in space from readings of different types of radiation dosimeters that are being used in various missions.

Routine screening mammography: how important is the radiation-risk side of the benefit-risk equation?

The potential radiation hazards associated with routine screening mammography, in terms of breast cancer induction, are discussed in the context of the potential benefits. The very low energy X-rays used in screening mammography (26-30 kVp) are expected to be more hazardous, per unit dose, than high-energy X- or gamma-rays, such as those to which A-bomb survivors (from which radiation risk estimates are derived) were exposed. Based on in vitro studies using oncogenic transformation and chromosome aberration end-points, as well as theoretical estimates, it seems likely that low doses of low-energy X-rays produce an increased risk per unit dose (compared with high energy photons) of about a factor of 2. Because of the low doses involved in screening mammography, the benefit-risk ratio for older women would still be expected to be large, though for younger women the increase in the estimated radiation risk suggests a somewhat later age than currently recommended--by about 5-10 years--at which to commence routine breast screening.

A novel long chain polyunsaturated fatty acid, beta-Oxa 21:3n-3, inhibits T lymphocyte proliferation, cytokine production, delayed-type hypersensitivity, and carrageenan-induced paw reaction and selectively targets intracellular signals

A novel polyunsaturated fatty acid (PUFA), beta-oxa 21:3n-3, containing an oxygen atom in the beta position, was chemically synthesized, and found to have more selective biological activity than the n-3 PUFA, docosahexaenoic acid (22:6n-3) on cells of the immune system. Although beta-oxa 21:3n-3 was very poor compared with 22:6n-3 at stimulating oxygen radical production in neutrophils, it was more effective at inhibiting human T lymphocyte proliferation (IC(50) of 1.9 vs 5.2 microM, respectively). beta-Oxa 21:3n-3 also inhibited the production of TNF-beta, IFN-gamma, and IL-2 by purified human T lymphocytes stimulated with PHA plus PMA, anti-CD3 plus anti-CD28 mAbs, or PMA plus A23187. Metabolism of beta-oxa 21:3n-3 via the cyclooxygenase and lipoxygenase pathways was not required for its inhibitory effects. Consistent with its ability to suppress T lymphocyte function, beta-oxa 21:3n-3 significantly inhibited the delayed-type hypersensitivity response and carrageenan-induced paw edema in mice. In T lymphocytes, beta-oxa 21:3n-3 inhibited the agonist-stimulated translocation of protein kinase C-betaI and -epsilon, but not -alpha, -betaII, or -theta to a particulate fraction, and also inhibited the activation of the extracellular signal-regulated protein kinase, but not c-Jun NH(2)-terminal kinase and p38. In contrast, 22:6n-3 had no effects on these protein kinase C isozymes. The increase in antiinflammatory activity and loss of unwanted bioaction through the generation of a novel synthetic 22:6n-3 analogue provides evidence for a novel strategy in the development of anti-inflammatory agents by chemically engineering PUFA.

Measurement of chemopreventive efficacy in skin biopsies

OBJECTIVE

To explore methods suitable for quantitative assessment of the efficacy of chemopreventive intervention.

STUDY DESIGN

High-resolution imagery of nuclei from the suprabasal and basal cell layers of sun-damaged skin were recorded. There were 10 cases. A shave biopsy was taken from an area of clearly evident solar keratosis before and after treatment with 2-difluoromethyl-dlornithine (DFMO) and from the colateral forearm, treated with a placebo. A number of karyometric variables were computed and combined to derive marker features that provided a numeric measure of the degree of nuclear deviation from normal.

RESULTS

DFMO treatment was effective overall in reducing the degree of nuclear abnormality seen in the biopsies; in 8 of the 10 cases there was a significant improvement. The placebo-treated arm did not show a statistically different abnormality from the untreated arm.

CONCLUSION

Karyometric analysis can provide numeric measures that allow documentation of statistically significant regression of actinic keratotic lesions following treatment with DFMO.

Long-term efficacy of intracoronary irradiation in inhibiting in-stent restenosis

BACKGROUND

Intracoronary irradiation is a promising modality for inhibition of in-stent restenosis. Results of randomized clinical trials at 6 months after gamma ray irradiation are highly encouraging. The first results at 3 years after irradiation, while still showing benefit, have shown significant late loss. The probable mechanism of the radiation is to inactivate (prevent from dividing) most cells that otherwise could proliferate to produce neointimal formation. We measured the proportion of cells that survive with their clonogenic potential intact after the doses and dose rates used in the randomized trials, and we then modeled the subsequent repopulation of the surviving cells that might cause late restenosis.

METHODS AND RESULTS

Human aortic smooth muscle cells were irradiated with gamma rays, including the doses and dose rates used in current trials, and clonogenic surviving fractions were measured. The subsequent repopulation of the surviving cells was modeled with the assumption that the repopulation kinetics were similar to those in unirradiated cells. The radiation is expected to delay the time to restenosis by factors of approximately 6 to 8, depending on the dose, shifting the delay from a median of 6 months (for no irradiation) to median values from 36 months (for a nominal 13 Gy) to 43 months (for a nominal 15 Gy).

CONCLUSIONS

These results and predictions are quantitatively consistent with clinical results and suggest that clonogenic inactivation (prevention of cellular division) is the dominant mechanism of radiation action in the delay of restenosis. Intracoronary radiotherapy is a very promising modality for significantly delaying, although probably not preventing, in-stent restenosis.

Structure-activity relationships of neurokinin A (4-10) at the human tachykinin NK(2) receptor: the role of natural residues and their chirality

A structure-activity study of neurokinin A (NKA) (4-10) was performed to investigate the importance of residue and chirality for affinity and efficacy at the NK(2) receptor in human colon circular muscle. Two series of NKA(4-10) analogues were produced with either L-alanine or the D-enantiomer substituted. Their activities were determined in vitro by means of radioligand binding and isolated smooth muscle pharmacology. NKA was more potent than NKA(4-10) at the human, unlike the rabbit, NK(2) receptor. The contractile response of NKA(4-10) was unaffected by N-terminal acetylation. L-Ala substitution of Asp(4), Val(7), Leu(9), and Met(10) caused an 8- to 80-fold decrease, and substitution of Phe(6) caused a 5000-fold decrease in binding affinity (P < 0.01). Positions Ser(5) and Gly(8) were not significantly affected. In functional studies, a similar pattern was observed. The replacement of residues with their respective D-enantiomer drastically reduced binding affinity and functional potency, particularly at positions 6 and 7 (P < 0.05). NKA(4-10) analogues L-Ala(6), L-Ala(8), D-Phe(6), D-Val(7), and D-Met(10) were partial agonists. An excellent correlation was observed between binding and functional data (r = 0.95). A retro-inverso analogue of NKA(4-10) was inactive. In conclusion, the side chains of Asp(4), Phe(6), Val(7), Leu(9), and Met(10) are structurally important features of NKA(4-10) for agonist activity, and changes in amino acid chirality are detrimental to binding affinity and functional activity. Overall, our data are broadly similar to those of previous studies in the rat. However, at the human NK(2) receptor, unlike the rat, [Ala(8)]NKA(4-10) was an antagonist.

Oncogenic transformation in C3H10T1/2 cells by low-energy neutrons

PURPOSE

Occupational exposure to neutrons typically includes significant doses of low-energy neutrons, with energies below 100 keV. In addition, the normal-tissue dose from boron neutron capture therapy will largely be from low-energy neutrons. Microdosimetric theory predicts decreasing biological effectiveness for neutrons with energies below about 350 keV compared with that for higher-energy neutrons; based on such considerations, and limited biological data, the current radiation weighting factor (quality factor) for neutrons with energies from 10 keV to 100 keV is less than that for higher-energy neutrons. By contrast, some reports have suggested that the biological effectiveness of low-energy neutrons is similar to that of fast neutrons. The purpose of the current work is to assess the relative biological effectiveness of low-energy neutrons for an endpoint of relevance to carcinogenesis: in vitro oncogenic transformation.

METHODS

Oncogenic transformation induction frequencies were determined for C3H10T1/2 cells exposed to two low-energy neutron beams, respectively, with dose-averaged energies of 40 and 70 keV, and the results were compared with those for higher-energy neutrons and X-rays.

RESULTS

These results for oncogenic transformation provide evidence for a significant decrease in biological effectiveness for 40 keV neutrons compared with 350 keV neutrons. The 70 keV neutrons were intermediate in effectiveness between the 70 and 350 keV beams.

CONCLUSIONS

A decrease in biological effectiveness for low-energy neutrons is in agreement with most (but not all) earlier biological studies, as well as microdosimetric considerations. The results for oncogenic transformation were consistent with the currently recommended decreased values for low-energy neutron radiation weighting factors compared with fast neutrons.

Neutron-energy-dependent cell survival and oncogenic transformation

Both cell lethality and neoplastic transformation were assessed for C3H10T1/2 cells exposed to neutrons with energies from 0.040 to 13.7 MeV. Monoenergetic neutrons with energies from 0.23 to 13.7 MeV and two neutron energy spectra with average energies of 0.040 and 0.070 MeV were produced with a Van de Graaff accelerator at the Radiological Research Accelerator Facility (RARAF) in the Center for Radiological Research of Columbia University. For determination of relative biological effectiveness (RBE), cells were exposed to 250 kVp X rays. With exposures to 250 kVp X rays, both cell survival and radiation-induced oncogenic transformation were curvilinear. Irradiation of cells with neutrons at all energies resulted in linear responses as a function of dose for both biological endpoints. Results indicate a complex relationship between RBEm and neutron energy. For both survival and transformation, RBEm was greatest for cells exposed to 0.35 MeV neutrons. RBEm was significantly less at energies above or below 0.35 MeV. These results are consistent with microdosimetric expectation. These results are also compatible with current assessments of neutron radiation weighting factors for radiation protection purposes. Based on calculations of dose-averaged LET, 0.35 MeV neutrons have the greatest LET and therefore would be expected to be more biologically effective than neutrons of greater or lesser energies.

Investigation of hypersensitivity to fractionated low-dose radiation exposure

PURPOSE

Hypersensitivity to cell killing of exponentially growing cells exposed to X-rays and gamma rays has been reported for doses below about 0.5 Gy. The reported results have been interpreted to suggest that a dose of 0.5 Gy or less is not sufficient to trigger an inducible repair mechanism. The purpose of this study was to examine this suggested hypersensitivity after multiple low doses (0.3 Gy) of gamma rays where a) the effect would be expected to be significantly magnified, and b) the effect might be of clinical relevance.

METHODS AND MATERIALS

C3H 10T1/2 mouse embryo cells were grown to confluence in culture vessels. While in plateau phase of growth, cells were exposed to 6 Gy of gamma rays, delivered in either 6 Gy, 3 Gy, 2 Gy, 1 Gy, or 0.3 Gy well-separated fractions. Corresponding experiments were performed with V-79 and C3H 10T1/2 cells in exponential growth. Cells were replated at low density and assayed for clonogenicity.

RESULTS

The results of this study were not inconsistent with some hypersensitivity at low doses, in that 20 fractions each of 0.3 Gy produced a slightly lower (though nonsignificant) surviving fraction compared with the same dose given in 2-Gy fractions. However, the results of the 20 x 0.3 Gy exposures also agreed well with the standard linear-quadratic (LQ) model predictions based on high dose per fraction (1-6 Gy) data. In addition, effects of cellular redistribution were seen which were explained quantitatively with an extended version of the LQ model.

CONCLUSIONS

These experiments were specifically designed to magnify and probe possible clinical implications of proposed "low-dose hypersensitivity" effects, in which significant deviations at low doses from the LQ model have been suggested. In fact, the results at low doses per fraction were consistent with LQ predictions based on higher dose per fraction data. This finding is in agreement with the well-documented utility of the LQ approach in estimating isoeffect doses for alternative fractionation schemes, and for brachytherapy.

Multiple courses of betamethasone to enhance fetal lung maturation do not suppress neonatal adrenal response

OBJECTIVE

Our purpose was to evaluate the neonatal adrenal gland by provocative testing in neonates of mothers who had received multiple courses of betamethasone to enhance fetal lung maturity.

STUDY DESIGN

Infants of mothers who had received >/=3 courses of betamethasone for fetal lung maturation were enrolled in the study. Twenty-four hours after delivery a baseline serum cortisol concentration was obtained. A synthetic adrenocorticotropic hormone (Cortrosyn) was administered (0.25 mg/1.73 m2). Two hours later a second serum cortisol concentration was obtained. An increase in serum cortisol in response to Cortrosyn was considered a positive test result. Nominal data were compared by means of the Student t test.

RESULTS

There were 9 infants enrolled in the study. The mean number of betamethasone treatment cycles was 4.8 +/- 1.09. The mean baseline cortisol level was 2.23 +/- 0.52 microgram/dL, and the mean post-adrenocorticotropic hormone cortisol level was 9.86 +/- 1.70 microgram/dL. All neonates had a positive adrenocorticotropic hormone test result. Stepwise linear regression showed no association between the number of courses of betamethasone treatment cycles and the post-adrenocorticotropic hormone cortisol concentration.

CONCLUSION

Multiple weekly treatment cycles of betamethasone for fetal lung maturity administered between 24 and 34 weeks' gestation do not appear to cause adrenal suppression.

Decrease in cranial nerve complications after radiosurgery for acoustic neuromas: a prospective study of dose and volume

PURPOSE

To determine whether tumor control can be maintained, and cranial nerve complications decreased by reducing the radiosurgical dose to acoustic neuromas.

METHODS AND MATERIALS

Forty-two consecutive patients with acoustic neuromas were treated prospectively using an initial standard-dose protocol in which the tumor-margin dose (50% isodose) was 20, 18, and 16 Gy for tumor diameters < or =2 cm, 2.1-3 cm, and 3.1-4 cm, respectively. After analysis of tumor control and complications, the next 40 patients were treated using a reduced-dose protocol in which the tumor-margin dose was 16, 14, and 12 Gy for tumor volumes < or =4.2 cm3, 4.2-14.1 cm3, and > or =14.1 cm3, respectively.

RESULTS

Median follow-up was 2.3 years (range 0.1-6) for 80 of 82 patients. The actuarial incidence (Kaplan-Meier) of facial neuropathy at 2 years was 38% (95% confidence interval [CI], 23-53%) for the standard-dose protocol and 8% (95% CI, 0-17%) for the reduced-dose protocol (p = 0.006). Univariate analysis revealed an association between risk of facial neuropathy and use of CT planning, higher radiosurgical dose, and neurofibromatosis, type 2. Multivariate analysis revealed that the only factor associated with increased risk of post-treatment facial neuropathy was a tumor margin dose > or =18 Gy. The incidence of trigeminal neuropathy at 2 years was 29% (95% CI, 15-43%) for the standard-dose protocol and 15% (95% CI, 3-27%) for the reduced-dose protocol (p = 0.17). Univariate analysis revealed an association between maximal tumor diameter and increased risk of trigeminal neuropathy; multivariate analysis revealed no additional statistically significant associations between tumor and dosimetric and patient characteristics and risk of trigeminal neuropathy. Two tumors in the standard-dose protocol required salvage surgery for progression. To date, no tumor in the reduced-dose protocol has shown progression.

CONCLUSION

Our analysis suggests that a tumor margin dose of > or =18 Gy is the most significant risk factor for facial nerve complications after acoustic neuroma radiosurgery. Patients receiving a minimal tumor dose of < or =16 Gy are at significantly lower risk for permanent facial neuropathy after radiosurgery. Longer follow-up is required before definitive conclusions can be made about the ultimate rate of tumor control using reduced radiosurgical doses.

The oncogenic transforming potential of the passage of single alpha particles through mammalian cell nuclei

Domestic, low-level exposure to radon gas is considered a major environmental lung-cancer hazard involving DNA damage to bronchial cells by alpha particles from radon progeny. At domestic exposure levels, the relevant bronchial cells are very rarely traversed by more than one alpha particle, whereas at higher radon levels-at which epidemiological studies in uranium miners allow lung-cancer risks to be quantified with reasonable precision-these bronchial cells are frequently exposed to multiple alpha-particle traversals. Measuring the oncogenic transforming effects of exactly one alpha particle without the confounding effects of multiple traversals has hitherto been unfeasible, resulting in uncertainty in extrapolations of risk from high to domestic radon levels. A technique to assess the effects of single alpha particles uses a charged-particle microbeam, which irradiates individual cells or cell nuclei with predefined exact numbers of particles. Although previously too slow to assess the relevant small oncogenic risks, recent improvements in throughput now permit microbeam irradiation of large cell numbers, allowing the first oncogenic risk measurements for the traversal of exactly one alpha particle through a cell nucleus. Given positive controls to ensure that the dosimetry and biological controls were comparable, the measured oncogenicity from exactly one alpha particle was significantly lower than for a Poisson-distributed mean of one alpha particle, implying that cells traversed by multiple alpha particles contribute most of the risk. If this result applies generally, extrapolation from high-level radon risks (involving cellular traversal by multiple alpha particles) may overestimate low-level (involving only single alpha particles) radon risks.

Impact of genetic counseling on primary and preventive care in obstetrics and gynecology

OBJECTIVE

To evaluate the utility of the prenatal three-generation pedigree in assessment of the obstetric patient's primary medical risks.

STUDY DESIGN

In a case series, 250 charts of patients referred for amniocentesis on the basis of advanced maternal age were reviewed for a significant genetic risk of a primary care disorder.

RESULTS

A total of 40 patients (16%) were at significantly increased risk for a primary care disorder. Thirty-eight patients (15.2%) were at increased risk for medical conditions for which early screening, detection and/or intervention are established.

CONCLUSION

For the advanced maternal age population, formal genetic risk assessment performed prior to amniocentesis can be beneficial in primary care risk assessment.

Radiobiological principles in intravascular irradiation

BACKGROUND

There is wide interest in the use of intravascular irradiation to control restenosis following balloon angioplasty. Part of the mechanism of restenosis appears to be the proliferation of smooth muscle cells (SMCs), triggered to divide by the damage caused by the angioplasty, and this proliferation can be inhibited by irradiation with y-rays or beta-rays.

METHODS

In vitro data for the survival of smooth muscle cells exposed to radiation was used to model the likely control of restenosis by radiation. Physical and biological data were used to estimate differences in biological effectiveness of gamma-rays and beta3-rays, as well as the effect on cell killing of extending the exposure time.

RESULTS

Based on the radiosensitivity of SMCs, measured in vitro, and the limited proliferative potential of these normal somatic cells, it is possible to understand and to model quantitatively how a single acute gamma-ray dose in the range of 15-20 Gy can inhibit restenosis. The few successful trials carried out to date where radiation has been shown to inhibit restenosis have all involved the gamma-emitter Iridium-192. The use of this radionuclide involves radiation safety problems and an inconveniently long treatment time. Consequently, there is much interest in developing a beta-emitting source that would solve both problems, and a number of different possibilities are being pursued. This development introduces two new problems discussed in this paper. First, beta-rays in the megavoltage range are less effective biologically than gamma-rays in the kilovoltage range, but the magnitude of the difference is not well known. Second, in the case of a single large dose, such as that proposed to inhibit restenosis, the biological effect will vary substantially as the exposure time varies from 1 to 20 min. If the clinical data are to be compared between centers using a variety of beta and y-emitting radionuclides, these factors will need to be taken into account.

CONCLUSIONS

Doses of > 15 Gy are unlikely to result in elimination of the restenosis problem but should delay onset of restenosis for a significant period; the larger the dose, the longer the delay. Successful trials of endovascular radiation completed to date involve y-rays, while many systems being developed are based on beta-emitting radionuclides. Experimental data are urgently needed so that allowances can be made for the difference in dose-rate and radiation quality between gamma and beta-emitting radionuclides.

Cytokine mRNA profiles in contused spinal cord and axotomized facial nucleus suggest a beneficial role for inflammation and gliosis

We have studied temporal mRNA expression patterns for interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), macrophage colony stimulating factor (M-CSF), and transforming growth factor-beta1 (TGF-beta1) in two rat injury paradigms with very different cellular inflammatory reactions: contussion of the spinal cord and axotomy of the facial nerve. Our comparative analyses using semiquantitative reverse transcription polymerase chain reaction (RT-PCR) show an early and robust upregulation of IL-1beta, TNF-alpha, IL-6, and M-CSF mRNAs in spinal cord after contusion injury. Peak expression of these mRNAs was transient and returned to control levels by 24 h postinjury. In contrast, expression of IL-1beta and TNF-alpha mRNAs in the axotomized facial nucleus was minimal and delayed, and levels of M-CSF mRNA remained unaltered. Similar to injured spinal cord, the axotomized nucleus showed a dramatic and early upregulation of IL-6 mRNA, but unlike spinal cord, IL-6 mRNA levels subsided only gradually. Both injury paradigms showed gradually increasing levels of TGF-beta1 mRNA which were maximal at 7 days postinjury. RT-PCR analyses were also performed on isolated blood-borne mononuclear cells and neutrophils. The results showed that these cells contain high levels of IL-1beta and M-CSF mRNAs, moderate levels of TGF-beta and TNF-alpha mRNAs, and minimal levels of IL-6 mRNA. The RT-PCR analyses together with histological observations indicate that expression of the proinflammatory cytokines IL-1beta, TNF-alpha, and IL-6 is short-lived and self-limited after contusion injury, and that it occurs primarily within endogenous glial cells. Transient expression of these molecules likely triggers secondary events which may be beneficial to wound repair and regeneration.

Impact of beam energy and field margin on penumbra at lung tumor-lung parenchyma interfaces

PURPOSE

To determine the characteristics of the penumbra in the region of the lung tumor-lung parenchyma interfaces for various radiation beam energies and various field margins.

METHODS AND MATERIALS

A phantom simulating the thoracic cavity with a tumor arising within the lung parenchyma was irradiated with opposed 6-, 10-, and 18-MV photon beams. Beam profiles were obtained at the tumor's surface and midplane using radiographic film. The field edge varied from 0.0 to 3.5 cm from the gross tumor volume. The effective penumbra (distance from 80 to 20% dose) and beam fringe (distance from 90 to 50% dose) were measured. Clinically acceptable beam profiles were defined as those in which no point of the planning target volume (gross tumor volume plus a 1-cm margin) received less than 95% of the central tumor dose.

RESULTS

Mean effective penumbra and beam fringe were found to differ in a statistically significant manner with respect to energy, but not with distance from field edge to gross tumor volume. With the field edge < or = 1.5 cm from the gross tumor volume, no energy provided an acceptable dose distribution, as defined above. With the field edge 2 cm from the gross tumor volume, 6 and 10 MV provided acceptable dose distributions, but 18 MV did not. With the field edge > or = 2.5 cm from the gross tumor volume, all energies provided acceptable dose distributions.

CONCLUSION

For irradiation of lung carcinomas in which the planning target volume includes a margin of normal lung tissue, 6- and 10-MV opposed beams yield a superior dose distribution with respect to penumbra at the tumor's surface and midplane, with the field edge placed 2 cm from the gross tumor volume. To achieve an equivalent distribution with 18-MV photons, a distance of 2.5 cm from field edge to the gross tumor volume is necessary, leading to an increase in normal lung tissue irradiated.

Acute treatment-related diarrhea during postoperative adjuvant therapy for high-risk rectal carcinoma

PURPOSE

The combination of pelvic radiotherapy and 5-fluorouracil-based chemotherapy is associated with an increase in acute gastrointestinal toxicity during rectal adjuvant therapy, most notably an increased incidence of diarrhea. Previous randomized, prospective studies have limited their analysis to presenting rates of severe and life-threatening diarrhea (Grade 3 or greater), and few data are available detailing the extent of mild to moderate diarrhea. To provide baseline data for future studies, we conducted a detailed analysis of diarrhea from a prior clinical trial of adjuvant therapy for rectal cancer.

METHODS AND MATERIALS

In a multiinstitutional clinical trial, 204 eligible patients with rectal carcinoma that either was deeply invasive (T3-T4) or involved regional lymph nodes were randomized to receive either postoperative pelvic radiotherapy alone (45 to 50.4 Gy) or pelvic radiotherapy and bolus 5-fluorouracil-based chemotherapy. Toxicity was assessed prospectively.

RESULTS

For the 99 eligible patients who received pelvic radiotherapy alone, rates of Grades 0, 1, 2, 3, and 4 diarrhea during treatment were 59, 20, 17, 4, and 0%, respectively. For the 96 eligible patients who received radiotherapy and 5-fluorouracil, the overall rates of grades 0, 1, 2, 3, and 4 diarrhea were 21, 34, 23, 20, and 2%, respectively. The increased rates of diarrhea during adjuvant rectal therapy were manifested across all toxicity levels for patients receiving chemotherapy and pelvic radiotherapy. Of primary clinical importance is the substantial increase in severe or life-threatening diarrhea (Grade 3 or more) (22 vs. 4%,p = 0.001) Additionally, increased rates of any diarrhea and also severe or life-threatening diarrhea were observed in patients who had a low anterior resection compared with those who had an abdominoperineal resection (p < 0.001 and p = 0.006, respectively).

CONCLUSION

These results will be of value as a baseline for investigators who want to use treatment toxicity as an end point in cancer control or cancer therapy trials utilizing similar treatment techniques. Patients receiving 5-fluorouracil and pelvic radiotherapy compared with patients receiving pelvic radiotherapy alone and patients with a prior history of a low anterior resection compared with patients who had a prior history of an abdominoperineal resection experienced increased rates of Grades 1 through 4 acute treatment-related diarrhea, and the most important increase occurred as Grade 3 toxicity.

'Best clinical practice': assessment of processes of care and of outcomes in the US Military Health Services System

The National Quality Management Program of the Military Health Services System of the United States has undertaken a series of projects whose objective is the active, on-going monitoring and improvement of the effectiveness and efficiency of the care provided to a broad population that encompasses troops on active duty, retirees and dependents. The analytic activities consist of (1) identification by clinical panels of conditions and procedures of interest; (2) collection of data from electronic repositories and from charts to characterize the patients, how they are managed, the clinical outcomes they experience, the resource costs their care entails, and, from questionnaires, their functional status and level of satisfaction, and (3) generation of 'report cards' that inform organizational units down to the level of the hospital of the characteristics of their patients, their practices, and the risk-adjusted outcomes they achieve. The patterns of care employed by the hospitals that obtain the best risk-adjusted outcomes and resource utilization ('best clinical practice') are identified and made known. In addition, (4) a systematic process of developing outcomes-based practice guidelines has been devised. It intent is to serve as a decision-support tool for clinicians. Initial estimates have been obtained of the probable consequences of the application of this tool to operative interventions in childbirth. Use of the tool would result in a higher occurrence of elective Caesarean sections, a reduced rate of emergency Caesarean sections and much lower use of forceps, with an overall improvement in outcomes and lower resource costs. This program is currently in the early phases of implementation. The two principal requirements for the immediate future are (1) education of the clinical and administrative communities in the use of the data and the decision-support tools and (2) evaluation of the consequences of the use of the data by the clinical and administrative communities.

Spinal cord localization in the treatment of lung cancer: use of radiographic landmarks

PURPOSE

In the treatment of thoracic malignancies with radiotherapy, the critical dose-limiting structure is the spinal cord. Oblique fields typically are designed to exclude the spinal cord, and by convention, the field edge that shields the spinal cord is placed at the anterior border of the vertebral pedicles. Thus, the purpose of our study was to estimate the distance between the field edge and spinal cord in oblique fields that were designed by using the vertebral pedicle as a radiographic landmark.

METHODS AND MATERIALS

The spinal cord of a cadaver was wrapped in wire, and oblique fields were simulated at 15 degree intervals. The distance from the spinal cord to a field edge placed at the anterior border of the pedicle was measured. In the second investigation, a three-dimensional treatment planning system was used to simulate hypothetical fields using actual patient data from computed tomography (n = 10), and measurements identical to those in the anatomical model were made (n = 1,100).

RESULTS

The results of the anatomical and computed tomographic models were in close agreement (mean difference, 0.6 mm). The computed tomographic model predicted a mean field edge to spinal cord distance of 8.7 mm (95% confidence interval, 5.6-11.8 mm) for 30 degree/150 degree oblique fields and 8.0 mm (95% confidence interval, 4.7-11.7 mm) for 45 degree/135 degree oblique fields. This distance was greatest at levels T-1, T-2, and T-11 (8 to 20% greater).

CONCLUSIONS

The mean distance from a field edge placed at the anterior border of a vertebral pedicle to the spinal cord for commonly used oblique angles constitutes a sufficient margin to account for expected differences in daily positional variations and mechanical uncertainties.

Effect of track structure and radioprotectors on the induction of oncogenic transformation in murine fibroblasts by heavy ions

The oncogenic potential of high-energy 56Fe particles (1 GeV/nucleon) accelerated with the Alternating Gradient Synchrotron at the Brookhaven National Laboratory was examined utilizing the mouse C3H 10T1/2 cell model. The dose-averaged LET for high-energy 56Fe is estimated to be 143 keV/micrometer with the exposure conditions used in this study. For 56Fe ions, the maximum relative biological effectiveness (RBEmax) values for cell survival and oncogenic transformation were 7.71 and 16.5 respectively. Compared to 150 keV/micrometer 4He nuclei, high-energy 56Fe nuclei were significantly less effective in cell killing and oncogenic induction. The prostaglandin E1 analog misoprostol, an effective oncoprotector of C3H 10T1/2 cells exposed to X rays, was evaluated for its potential as a radioprotector of oncogenic transformation with high-energy 56Fe. Exposure of cells to misoprostol did not alter 56Fe cytotoxicity or the rate of 56Fe-induced oncogenic transformation.

Aspirated safety pin requiring thoracotomy: report of a case and review

Foreign body aspirations in children are relatively uncommon occurrences, but they can be a serious events, causing respiratory distress, atelectasis, chronic pulmonary infections, or death. Safety pins are not commonly aspirated objects and account for less than 3% of all foreign bodies found in the tracheobronchial tree. Fewer than 2% of patients require thoracotomy, and most aspirated materials can be removed by bronchoscopy, with low morbidity and mortality. A discussion of airway foreign bodies follows the presentation of a case of an older child who aspirated a safety pin, which required open thoracostomy for removal.

The role of stereotactic radiosurgery in the treatment of malignant skull base tumors

PURPOSE

To determine the efficacy and toxicity of stereotactic radiosurgery in the treatment of malignant skull base tumors.

METHODS AND MATERIALS

Thirty-two patients with 35 newly diagnosed or recurrent malignant skull base tumors < or = 33.5 cm3 were treated using the Leksell Gamma unit. Tumor histologies included: adenoid cystic carcinoma [12], basal cell carcinoma [1], chondrosarcoma [1], chordoma [8], nasopharyngeal carcinoma [3], osteogenic sarcoma [2], and squamous cell carcinoma [8].

RESULTS

After a median follow-up of 2.3 years, 83% +/- 15% (+/-95% confidence interval) of patients experienced a symptomatic response to treatment. Local control at the skull base was 95 +/- 9% at 2 years and 78 +/- 23% at 3 years. Local-regional control above the clavicles was 75 +/- 15% at 1 year and 51 +/- 20% at 2 years. Overall and cause specific survival were identical, 82 +/- 13% at 1 year, 76 +/- 14% at 2 years, and 72 +/- 16% at 3 years. One patient developed a radiation-induced optic neuropathy 12 months after radiosurgery.

CONCLUSION

Stereotactic radiosurgery using the Leksell Gamma Unit can provide durable tumor control and symptomatic relief with acceptable toxicity in the majority of patients with malignant tumors 4 cm or less in size involving the skull base. Further evaluation of more patients with longer follow-up is warranted.

Neonatal effects and serum cortisol levels after multiple courses of maternal corticosteroids

OBJECTIVE

To determine the effects of multiple courses of maternal betamethasone for fetal lung maturation on neonatal serum cortisol levels and clinical Cushing syndrome.

METHODS

Seventy-nine mother-infant pairs delivered between 24 and 36 weeks' gestation were enrolled in the study. They were grouped according to the number of courses of betamethasone received between 24 and 34 weeks' gestation for fetal lung maturation: those receiving no courses, one course, and two or more courses. Physical examinations were performed and serum glucose, electrolyte, and cortisol levels were measured on days 1 and 3 of life.

RESULTS

For those receiving multiple courses of betamethasone (n = 43), the mean (+/- standard error of the mean [SEM]) number of courses was 5.3 +/- 0.4, with a mean (+/-SEM) total dose of 125.0 +/- 10.7 mg. No neonates had findings suggestive of Cushing syndrome. Day 1 cortisol levels (pooled mean +/- SEM) were 12.6 +/- 2.4, 5.3 +/- 3.2, and 4.4 +/- 1.8 microg/dL in those receiving no courses, one course, and two or more courses, respectively (P = .03; no courses versus two or more courses, P = .03), but the differences were not significant when corrected for multiple variables. Differences among day 3 cortisol levels (pooled mean +/- SEM) were not significant: 8.3 +/- 1.6, 5.8 +/- 1.4, and 5.8 +/- 0.9 microg/dL in those receiving no courses, one course, and two or more courses, respectively. None of the neonates in the group receiving no courses of betamethasone had day 1 cortisol levels lower than normal, whereas 22% and 11% of the neonates receiving one and two or more courses, respectively, had day 1 levels lower than normal. On day 3, 15% of those receiving one course and 10% of those receiving two or more courses had serum cortisol levels lower than normal, whereas none of those who received no courses had a low cortisol level. Multivariate regression analysis could show no association between the number of courses or total dose of betamethasone and the day 1 or day 3 cortisol values. The day 1 cortisol level (log10) was most associated with the severity of respiratory distress syndrome (RDS) and day 3 cortisol level (log10) with race and severity of RDS. Only in neonates with absent or mild RDS did number of courses correlate with day 3 cortisol levels (log10), but this was a positive correlation.

CONCLUSION

Serum cortisol levels either were independent of the number of courses or total dose of corticosteroids given or, in a subpopulation, were associated with increasing levels with increasing doses, suggesting that there is no suppressive effect with repeated dosing.