Induction and repair of DNA double-strand breaks assessed by gamma-H2AX foci after irradiation with pulsed or continuous proton beams

In particle tumor therapy including beam scanning at accelerators, the dose per voxel is delivered within about 100 ms. In contrast, the new technology of laser plasma acceleration will produce ultimately shorter particle packages that deliver the dose within a nanosecond. Here, possible differences for relative biological effectiveness in creating DNA double-strand breaks in pulsed or continuous irradiation mode are studied. HeLa cells were irradiated with 1 or 5 Gy of 20-MeV protons at the Munich tandem accelerator, either at continuous mode (100 ms), or applying a single pulse of 1-ns duration. Cells were fixed 1 h after 1-Gy irradiation and 24 h after 5-Gy irradiation, respectively. A dose-effect curve based on five doses of X-rays was taken as reference. The total number of phosphorylated histone H2AX (gamma-H2AX) foci per cell was determined using a custom-made software macro for gamma-H2AX foci counting. For 1 h after 1-Gy 20-MeV proton exposures, values for the relative biological effectiveness (RBE) of 0.97 ± 0.19 for pulsed and 1.13 ± 0.21 for continuous irradiations were obtained in the first experiment 1.13 ± 0.09 and 1.16 ± 0.09 in the second experiment. After 5 Gy and 24 h, RBE values of 0.99 ± 0.29 and 0.91 ± 0.23 were calculated, respectively. Based on the gamma-H2AX foci numbers obtained, no significant differences in RBE between pulsed and continuous proton irradiation in HeLa cells were detected. These results are well in line with our data on micronucleus induction in HeLa cells.

Dose-escalated simultaneous integrated-boost treatment of prostate cancer patients via helical tomotherapy

PURPOSE

The goal of this work was to assess the feasibility of moderately hypofractionated simultaneous integrated-boost intensity-modulated radiotherapy (SIB-IMRT) with helical tomotherapy in patients with localized prostate cancer regarding acute side effects and dose-volume histogram data (DVH data).

METHODS

Acute side effects and DVH data were evaluated of the first 40 intermediate risk prostate cancer patients treated with a definitive daily image-guided SIB-IMRT protocol via helical tomotherapy in our department. The planning target volume including the prostate and the base of the seminal vesicles with safety margins was treated with 70 Gy in 35 fractions. The boost volume containing the prostate and 3 mm safety margins (5 mm craniocaudal) was treated as SIB to a total dose of 76 Gy (2.17 Gy per fraction). Planning constraints for the anterior rectal wall were set in order not to exceed the dose of 76 Gy prescribed to the boost volume. Acute toxicity was evaluated prospectively using a modified CTCAE (Common Terminology Criteria for Adverse Events) score.

RESULTS

SIB-IMRT allowed good rectal sparing, although the full boost dose was permitted to the anterior rectal wall. Median rectum dose was 38 Gy in all patients and the median volumes receiving at least 65 Gy (V65), 70 Gy (V70), and 75 Gy (V75) were 13.5%, 9%, and 3%, respectively. No grade 4 toxicity was observed. Acute grade 3 toxicity was observed in 20% of patients involving nocturia only. Grade 2 acute intestinal and urological side effects occurred in 25% and 57.5%, respectively. No correlation was found between acute toxicity and the DVH data.

CONCLUSION

This institutional SIB-IMRT protocol using daily image guidance as a precondition for smaller safety margins allows dose escalation to the prostate without increasing acute toxicity.

Radiotherapy in stage I-III follicular non-Hodgkin lymphoma. Retrospective analysis of a series of 50 patients

PURPOSE

The goal of this work was to analyze the response rate and outcome of patients with stage I-III follicular lymphoma (FL) treated with radiotherapy (RT) alone.

PATIENTS AND METHODS

The records of 50 consecutive patients with stage I-III FL treated with RT alone at our department from 1988-2009 were analyzed. The median age was 60 years (range 32-80 years) with a median follow-up duration of 8 years (range 4-11 years). Clinical staging was performed according to the Ann Arbor system. Stage I: 30 patients (60%), stage II: 15 patients (30%), stage III: 5 patients (10%). Thirty-two patients (64%) presented with nodal disease, 14 patients (28%) presented with disease in extranodal sites, and 4 patients (8%) had nodal and extranodal involvement. The RT field encompassed only the involved Ann Arbor nodal regions (involved-field RT) in 26 patients (52%), mantle and whole abdominopelvic fields in 6 patients (12%), mantle field in 10 patients (20%), whole abdominopelvic fields in 5 patients (10%), and a so-called mini-mantle in 3 patients (6%). The total RT dose ranged from 26-56 Gy (median 40 Gy) in daily fractions of 1.2-2.5 Gy.

RESULTS

Complete remission (CR) and partial remission (PR) were observed in 39 (76%) and 9 (20%) patients, respectively. Only 2 of 8 patients (25%) with tumor bulk > 5 cm reached CR, whereas 37 of 42 patients (88%) with a maximum lymphoma diameter < 5 cm achieved CR (p = 0.0001). The median overall survival (OS) and median event-free survival (EFS) were 18 years (CI 95% 10-26 years) and 7 years (6-8 years), respectively. The 2-, 5-, and 10-year OS were 96 ± 3%, 90 ± 5%, and 70 ± 9%, respectively. The 2-, 5-, and 10-year EFS were 90 ± 5%, 70 ± 7%, and 38 ± 9%, respectively. Fifteen patients developed a recurrence outside the radiation field (30%) and 4 patients developed an in-field recurrence (8%). All in-field recurrences were observed in regions without clinical (macroscopic) involvement, which were irradiated with a dose of ≤ 26 Gy. Pretreatment maximum lymphoma diameter < 5 cm (p = 0.039) and complete remission after RT (p = 0.021) were significantly associated with a better OS in the univariate analysis.

CONCLUSION

RT is a curative option in the treatment of limited stage FL. If RT of microscopically uninvolved area is necessary, a reduction in the radiation dose should be carefully weighed against the risk of in-field recurrences.

Salvage radiotherapy in patients with recurrent esophageal carcinoma

PURPOSE

The feasibility and effectiveness of radiotherapy in the management of recurrent esophageal carcinoma (REC) is reported.

PATIENTS AND METHODS

A consecutive cohort of 54 patients with rcT1-4, rcN0-1, or cM0 recurrent esophageal carcinoma (69% squamous cell carcinoma, 31% adenocarcinoma) was treated between 1988 and 2010. The initial treatment for these patients was definitive radiochemotherapy, surgery alone, or neoadjuvant radiochemotherapy + surgical resection in 8 (15%), 33 (61%), and 13 (24%) patients, respectively. The median time to recurrence from initial treatment was 19 months (range 4-79 months). The site of the recurrence was anastomotic or local, nodal, or both in 63%, 30%, and 7% of patients, respectively. Salvage radio(chemo)therapy was carried out with a median dose of 45 Gy (range 30-68 Gy).

RESULTS

Median follow-up time for surviving patients from the start of R(C)T was 38 months (range 10-105 months). Relief of symptoms was achieved in 19 of 28 symptomatic patients (68%). The median survival time was 12 months (95% confidence interval (CI) 7-17 months) and the median recurrence-free interval was 8 months (95% CI 4-12 months). The survival rates at 1, 2, and 3 years were 55 ± 7%, 29 ± 6%, and 19 ± 5%, respectively. The recurrence-free survival rates at 1, 2, and 3 years were 44 ± 7%, 22 ± 6%, and 15 ± 5%, respectively. A radiation dose ≥ 45 Gy and conformal RT were associated with a better prognosis.

CONCLUSION

RT is feasible and effective in the management of recurrent esophageal carcinoma, especially for relief of symptoms. Toxicity is in an acceptable range. The outcome of REC is poor; however, long-term survival of patients with recurrent esophageal carcinoma after radiochemotherapy might be possible, even with a previous history of radiotherapy in the initial treatment. If re-irradiation of esophageal carcinoma is contemplated, three-dimensional conformal techniques and a minimum total dose of 45 Gy are recommended.

Alpha particles induce different F values in monocellular layers of settled and attached human lymphocytes

There is rapidly increasing information on the issue of three-dimensional nuclear architecture, according to which chromosomes are organized in localized territories and chromosome arms in exclusive domains within a given territory. The aim of the present study was to investigate the impact of different cell exposure conditions on cytogenetic damage induced by high-LET radiation. To this end the yield ratio of dicentrics to centric rings (F value) induced by (241)Am α particles was analyzed in monolayer cultures of human lymphocytes that were either settled or attached to foils, simulating a rounded or spread out cellular geometry, respectively. Monolayers were exposed in special irradiation chambers to 0.1 and 1.0 Gy and subsequently analyzed for chromosome aberrations. Independent of these different dose levels, significantly different F values of 10.07 ± 1.73 and 4.27 ± 0.44 have been determined in attached and settled lymphocytes, respectively. Since the diameter of nuclei vertically traversed by α particles in attached cells is about one-half that in settled cells, these F values support the postulate that proximity effects regarding the chromatin geometry in flattened or spherical human lymphocytes influence the formation of high-LET radiation-induced dicentrics and centric rings. A comparison with our earlier data sets obtained for both in vitro and in vivo exposure of human lymphocytes to α particles or (137)Cs γ rays supports the notion that the F value depends on the radiation quality when investigations are confined to spherical human lymphocytes. Thus the F value should not be ruled out as a practical chromosomal "fingerprint" for past exposure to high-LET radiation.

PET-guided treatment in locally advanced adenocarcinoma of the esophagogastric junction (AEG): The MUNICON-II study

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Background: Previous studies demonstrated that fluorodeoxyglucose (FDG)-PET can help to detect response early during neoadjuvant chemotherapy. The prognosis of metabolic non-responders is poor. Therefore, we initiated the prospective MUNICON-II study to determine the value of salvage neoadjuvant chemoradiation in early PET nonresponders.

Methods: 56 patients (pts) with locally advanced AEG type I and II (cT3/4 Nx M0) were included. Tumor glucose uptake was assessed by FDG-PET before and 14 days after initiation of chemotherapy. PET nonresponse was defined as a decrease of the tumor FDG standard uptake value < 35%. Nonresponders received salvage preoperative chemoradiation consisting of external beam radiation 32 Gy (1.6 Gy/fr x 2/day) plus daily cisplatin 6mg/m2 and then proceeded to surgery. Metabolic responders continued with chemotherapy (platin/5-FU-based) for 3 months.

Results: 33 pts had a PET response, 23 had a PET nonresponse. Resection was performed on 54 pts. R0 was achieved in 27 (82%) PET responders versus 16 (70%) nonresponders (p = 0.51). Major histologic remissions (< 10% residual tumor) were observed in 12 PET responders (36%) and 6 PET non responders (26%). After a median follow-up time of 38.0 mon, the median event-free survival (EFS) and the median overall survival (OS) were not yet reached in the PET responders, while EFS was 15.4 mon and OS was 18.3 mon in nonresponders.

Conclusions: This study confirms the prognostic value of early metabolic response evaluation during neoadjuvant chemotherapy. Histopathologic responses were observed after salvage chemoradiation, but the clinical outcome of early PET non-responders to chemotherapy remains poor, indicating a dismal tumor biology in this group of pts.

No significant financial relationships to disclose.

Imaging of tumor physiology: impacts on clinical radiation oncology

As the metabolic microenvironment markedly influences the therapeutic response of malignant tumors, imaging of the microenvironment is one of the goals researcher have been aiming at for years. Several methods such as positron emission tomography, functional magnetic resonance imaging (MRI) or contrast enhanced MRI/CT are now available. For radiation oncology, tumor oxygenation and perfusion are the most important (patho-) physiological parameters that might be included in radiotherapy regimens and treatment planning. In order to overcome resistance of tumor cells resulting from hypoxia, positron emission tomography (PET) using nitroimidazole tracers is the most advanced technique at this time. Since reproducibility of the PET signal/tracer distribution, thresholding and exact quantification are not thoroughly understood and further investigation is needed before including it into radiotherapy regimens. To image tumor perfusion, dynamic contrast enhanced computed tomography (DCE-CT) or dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) are the most suitable techniques. Co-investigation of tumor oxygenation and perfusion should be performed in order to investigate their interaction and consequences for radiooncology.

Prediction of short survival in patients with brain metastases based on three different scores: a role for 'triple-negative' status?

AIMS

To evaluate models predicting short survival in patients with brain metastases treated with whole-brain radiotherapy (WBRT).

MATERIALS AND METHODS

This was a retrospective analysis of 312 patients. Each patient was assigned to three different four-tiered prognostic scores: the Basic Score for Brain Metastases (BSBM), the Graded Prognostic Assessment (GPA) and the score developed by Rades et al. In addition, a 'triple-negative' cohort was evaluated (all three scores predicted unfavourable prognosis, n=30).

RESULTS

No statistically significant survival differences were found between the most unfavourable BSBM, GPA, Rades et al. and 'triple-negative' groups. The BSBM best predicted short survival: patients classified in the unfavourable group (Karnofsky performance status <80, uncontrolled primary tumour and presence of extracranial metastases) had a 12.5% survival at 4 months and a 0% 1-year survival. Patients in this group who survived for 4 months or more had simultaneously detected cancer and brain metastases, were treatment naive, and received systemic therapy in addition to WBRT. Excluding this type of patient from the analysis resulted in survival figures that were indistinguishable from those obtained with best supportive care without WBRT in other studies.

CONCLUSIONS

Although continuous research is necessary to identify patients who can be managed safely and palliated without WBRT, we feel that a model of the BSBM unfavourable group (Karnofsky performance status <80, uncontrolled primary tumour and presence of extracranial metastases) and no intent to treat systemically might form a basis for validation in other large databases. The triple-negativity criterion was not superior for predicting poor prognosis.

Limited resection and free jejunal graft interposition for squamous cell carcinoma of the cervical oesophagus

BACKGROUND

Therapeutic strategies for cervical oesophageal squamous cell carcinoma (SCC) are controversial. Treatment options range from definitive radiotherapy to multimodal treatment. Outcome after limited resection and reconstruction with a free jejunal graft interposition was evaluated retrospectively.

METHODS

Patients with clinical T1-4 Nx M0 tumours treated between 1986 and 2006 were included.

RESULTS

Of 109 patients, 94 underwent preoperative chemoradiotherapy and 15 had a primary resection. Complete or partial preservation of the larynx was achieved in 93 patients (85.3 per cent). Minor and major complications occurred in 74.3 per cent, with 44.0 per cent of all patients having more than one complication. Reoperation was necessary in 29.4 per cent. The 30-day mortality rate was 1.8 per cent, and the in-hospital mortality rate 2.8 per cent. The complete R0 resection rate was 72.5 per cent. Median overall survival was 34.3 months; 1-, 3- and 5-year survival rates were 83.8, 47.0 and 47.0 per cent respectively. Survival was not influenced by complications (P = 0.401) or reoperation (P = 0.428).

CONCLUSION

Despite high complication and reoperation rates, the mortality rate was low, even after preoperative chemoradiation. This complex surgical strategy is a treatment option for cervical SCC in oncological centres with an infrastructure providing multidisciplinary management.

Neoadjuvant continuous infusion of weekly 5-fluorouracil and escalating doses of oxaliplatin plus concurrent radiation in locally advanced oesophageal squamous cell carcinoma: results of a phase I/II trial

Oxaliplatin and 5-fluorouracil have a significant activity in locally advanced oesophageal squamous cell cancer (OSCC). However, their optimal dosage and efficacy when combined with concurrent radiotherapy as neoadjuvant treatment are unknown. This non-randomised, phase I/II study aimed to define the maximum tolerated dose (MTD) and assessed the histopathological tumour response rate to neoadjuvant oxaliplatin in weekly escalating doses (40, 45, 50 mg m⁻²) and continuous infusional 5-fluorouracil (CI-5FU; 225 mg m⁻²) plus concurrent radiotherapy. Patients had resectable OSCC. Resection was scheduled for 4–6 weeks after chemoradiotherapy. During phase I (dose escalation; n=19), weekly oxaliplatin 45 mg m⁻² plus CI-5FU 225 mg m⁻² was established as the MTD and was the recommended dosage for phase II. Oesophageal mucositis was the dose-limiting toxicity at higher doses. During phase II, histopathological responses (<10% residual tumour cells within the specimen) were observed in 10 of 16 patients (63%; 95% confidence interval: 39–82%). Overall, 16 of the 25 patients (64%) who underwent resection had a histopathological response; tumour-free resection (R0) was achieved in 80%. Neoadjuvant weekly oxaliplatin 45 mg m⁻² plus CI-5FU 225 mg m⁻² with concurrent radiotherapy provides promising histological response rates and R0 resection rates in locally advanced OSCC.

Histopathological response after preoperative radiochemotherapy in rectal carcinoma is associated with improved overall survival

BACKGROUND

Recent studies showed improved local control after preoperative radiochemotherapy (RCTX) in patients with locally advanced rectal carcinoma, but failed to demonstrate a survival benefit. Our aims were to determine outcome and impact of histopathological response after preoperative RCTX.

METHODS

One hundred four patients with uT3 rectal carcinoma were treated with preoperative RCTX of 45 Gy and continuous 5-FU infusion between 1997 and 2001 (group I). Histopathological response was evaluated in all specimens after tumor resection. Group II consisted of 114 patients with uT3 rectal carcinoma treated with postoperative RCTX between 1988 and 1997.

RESULTS

Group I showed a 6.1% 5-year local recurrence rate compared to 15.3% in group II (P = 0.023). Overall survival rates did not differ significantly between both groups (P = 0.225). Histopathological responders had a significantly improved 5-year overall survival with 89.1 (7.8)% compared to 68.7 (6.7)% of the non-responders (P = 0.008) and were identified as an independent prognostic factor.

CONCLUSIONS

Significant improvement of overall survival was observed for histopathological tumor responders after neoadjuvant radiochemotherapy. Our protocol of preoperative radiochemotherapy confirms the results of the multi-center studies in regard to local control and overall survival.

Informatics and medicine--from molecules to populations

OBJECTIVES

To clarify challenges and research topics for informatics in health and to describe new approaches for interdisciplinary collaboration and education.

METHODS

Research challenges and possible solutions were elaborated by scientists of two universities using an interdisciplinary approach, in a series of meetings over several months.

RESULTS AND CONCLUSION

In order to translate scientific results from bench to bedside and further into an evidence-based and efficient health system, intensive collaboration is needed between experts from medicine, biology, informatics, engineering, public health, as well as social and economic sciences. Research challenges can be attributed to four areas: bioinformatics and systems biology, biomedical engineering and informatics, health informatics and individual healthcare, and public health informatics. In order to bridge existing gaps between different disciplines and cultures, we suggest focusing on interdisciplinary education, taking an integrative approach and starting interdisciplinary practice at early stages of education.

Ten-year data on 138 patients with endometrial carcinoma and postoperative vaginal brachytherapy alone: No need for external-beam radiotherapy in low and intermediate risk patients

OBJECTIVE

To evaluate long-term outcome, risk factors, and causes of death in stage I-IIIA endometrial carcinoma (EC) patients treated only with adjuvant vaginal brachytherapy (VB) and to clarify for which subgroups of patients it is safe to omit external-beam radiotherapy (EBRT).

METHODS

Out of 224 EC patients receiving postoperative radiotherapy between 1990 and 2002, 138 had VB alone in curative intent (FIGO [2002]: 85%I, 12%II, 3%IIIA; 18 low risk [IA G1-2, IB G1], 103 intermediate risk [IB G2-3, IC G1-2, IIA-B G1-2], 17 high risk [IC G3, IIIA]). After surgery+/-lymphadenectomy, HDR-brachytherapy prescription (in 95.7% of patients) was 3x10 Gy to the surface or 3x5 Gy at 5 mm tissue depths.

RESULTS

Median follow-up was 107 months (range 3-185). Three intermediate and 7 high risk-patients relapsed. The 10-year vaginal control was 99.2%, locoregional control was 95.2% (low/intermediate/high risk: 100%/98.9%/68.8%), and disease-free survival (DFS) was 91.7% (100%/96.8%/55.2%). Risk factors for poor DFS were lymphovascular space invasion, > or = 50% myometrial invasion (univariate, p<0.05), pathological FIGO-stage, and grade 3 (uni-/multivariate, p<0.05). Leading causes of deaths (n=41) were cardiovascular disease (29%) and other malignancies (24%) ahead of EC (19.5%). The 10-year overall survival was 68.5% and the disease-specific survival was 92.4%. Thirty-five secondary tumors in 31 patients led to a higher actuarial death rate (10-year 9.9%, 15-year 17.7%) than EC (7.6%).

CONCLUSIONS

Restricting adjuvant therapy to VB alone seems to be safe in low and intermediate risk EC and can be recommended. As death rarely relates to early-stage EC, value of adjuvant therapy is probably better reflected by DFS rather than by overall survival.