Prostate cancer brachytherapy: SFRO guidelines 2021

Prostate brachytherapy techniques are described, concerning both permanent seed implant and high dose rate brachytherapy. The following guidelines are presented: brachytherapy indications, implant procedure for permanent low dose rate implants and high dose rate with source projector, as well as dose and dose-constraints objectives, immediate postoperative management, post-treatment evaluation, and long-term follow-up.

COVID-19-Associated Pneumonia: Radiobiological Insights

The evolution of SARS-CoV-2 pneumonia to acute respiratory distress syndrome is linked to a virus-induced “cytokine storm”, associated with systemic inflammation, coagulopathies, endothelial damage, thrombo-inflammation, immune system deregulation and disruption of angiotensin converting enzyme signaling pathways. To date, the most promising therapeutic approaches in COVID-19 pandemic are linked to the development of vaccines. However, the fight against COVID-19 pandemic in the short and mid-term cannot only rely on vaccines strategies, in particular given the growing proportion of more contagious and more lethal variants among exposed population (the English, South African and Brazilian variants). As long as collective immunity is still not acquired, some patients will have severe forms of the disease. Therapeutic perspectives also rely on the implementation of strategies for the prevention of secondary complications resulting from vascular endothelial damage and from immune system deregulation, which contributes to acute respiratory distress and potentially to long term irreversible tissue damage. While the anti-inflammatory effects of low dose irradiation have been exploited for a long time in the clinics, few recent physiopathological and experimental data suggested the possibility to modulate the inflammatory storm related to COVID-19 pulmonary infection by exposing patients to ionizing radiation at very low doses. Despite level of evidence is only preliminary, these preclinical findings open therapeutic perspectives and are discussed in this article.

Focal Brachytherapy for Localized Prostate Cancer: Midterm Outcomes

PURPOSE

Focal brachytherapy (F-BT) is a suitable technique for focal therapy in localized prostate cancer. It has the ability to adapt the seed implantation to the volume and location of the tumor. The aim of this study was to assess F-BT oncologic, functional, and toxicity midterm outcomes in men who underwent prostate cancer treatment.

METHODS AND MATERIALS

The study included 39 men with low- to intermediate-risk prostate cancer treated with F-BT between 2010 and 2015. The dose prescription was 145 Gy. Failure was defined as the presence of any residual prostate cancer in the treated area. The primary and secondary endpoints were the F-BT oncologic and functional outcomes, respectively. A 2-sided P value < .05 indicated statistical significance.

RESULTS

The mean follow-up time was 65 months (range, 43-104 months). After 24 months, 34 patients underwent control biopsies and 5 patients refused. The biopsies were negative in 27 cases (79%) and positive in 7 cases (21%), all outside the volume treated. Biochemical relapse-free survival at 5 years, disease-free survival, and overall survival were 96.8% ± 0.032%, 79.5% ± 0.076%, and 100%, respectively. The mean International Prostate Symptom Score at 2 months was significantly higher than initially (P = .0003), with no significant difference later. No late urinary, sexual, or rectal toxicity was observed. Salvage treatment was possible with good tolerance at 3.4 years of follow-up. Limitations of this study include the retrospective nature and lack of randomization.

CONCLUSIONS

F-BT is a safe and effective treatment for selected patients presenting with low- or intermediate-risk localized prostate cancer.

Is there any benefit to particles over photon radiotherapy?

Particle, essentially, proton radiotherapy (RT) could provide some benefits over photon RT, especially in reducing the side effects of RT. We performed a systematic review to identify the performed randomised clinical trials (RCTs) and ongoing RCTs comparing particle RT with photon therapy. So far, there are no results available from phase 3 RCTs comparing particle RT with photon therapy. Furthermore, the results on side effects comparing proton and carbon ion beam RT with photon RT do vary. The introduction of new techniques in photon RT, such as image-guided RT (IGRT), intensity-modulated RT (IMRT), volumetric arc therapy (VMAT) and stereotactic body RT (SBRT) was already effective in reducing side effects. At present, the lack of evidence limits the indications for proton and carbon ion beam RTs and makes the particle RT still experimental.

[Evaluation and results of ablative therapies in prostate cancer]

OBJECTIVE

To perform a state of the art about methods of evaluation and present results in ablative therapies for localized prostate cancer.

METHODS

A review of the scientific literature was performed in Medline database (http://www.ncbi.nlm.nih.gov) and Embase (http://www.embase.com) using different associations of keywords. Publications obtained were selected based on methodology, language and relevance. After selection, 102 articles were analysed.

RESULTS

Analyse the results of ablative therapies is presently difficult considering the heterogeneity of indications, techniques and follow-up. However, results from the most recent and homogeneous studies are encouraging. Oncologically, postoperative biopsies (the most important criteria) are negative (without any tumor cells in the treated area) in 75 to 95%. Functionally, urinary and sexual pre-operative status is spared (or recovered early) in more than 90% of the patients treated. More and more studies underline also the correlation between the results and the technique used considering the volume of the gland and, moreover, the "index lesion" localization.

CONCLUSION

The post-treatment pathological evaluation by biopsies (targeted with MRI or, perhaps in a near future, with innovative ultrasonography) is the corner stone of oncological evaluation of ablative therapies. Ongoing trials will allow to standardize the follow-up and determine the best indication and the best techniques in order to optimize oncological and functional results for each patient treated.

Risk of second cancers in the era of modern radiation therapy: does the risk/benefit analysis overcome theoretical models?

In the era of modern radiation therapy, the compromise between the reductions in deterministic radiation-induced toxicities through highly conformal devices may be impacting the stochastic risk of second malignancies. We reviewed the clinical literature and evolving theoretical models evaluating the impact of intensity-modulated radiation therapy (IMRT) on the risk of second cancers, as a consequence of the increase in volumes of normal tissues receiving low doses. The risk increase (if any) is not as high as theoretical models have predicted in adults. Moreover, the increase in out-of-field radiation doses with IMRT could be counterbalanced by the decrease in volumes receiving high doses. Clinical studies with short follow-up have not corroborated the hypothesis that IMRT would drastically increase the incidence of second cancers. In children, the risk of radiation-induced carcinogenesis increases from low doses and consequently the relative risk of second cancers after IMRT could be higher than in adults, justifying current developments of proton therapy with priority given to this population. Although only longer follow-up will allow a true assessment of the real impact of these modern techniques on radiation-induced carcinogenesis, a comprehensive risk-adapted strategy will help minimize the probability of second cancers.

First-in-human phase I study of the DNA-repair inhibitor DT01 in combination with radiotherapy in patients with skin metastases from melanoma

BACKGROUND

DT01 is a DNA-repair inhibitor preventing recruitment of DNA-repair enzymes at damage sites. Safety, pharmacokinetics and preliminary efficacy through intratumoural and peritumoural injections of DT01 were evaluated in combination with radiotherapy in a first-in-human phase I trial in patients with unresectable skin metastases from melanoma.

METHODS

Twenty-three patients were included and received radiotherapy (30 Gy in 10 sessions) on all selected tumour lesions, comprising of two lesions injected with DT01 three times a week during the 2 weeks of radiotherapy. DT01 dose levels of 16, 32, 48, 64 and 96 mg were used, in a 3+3 dose escalation design, with an expansion cohort at 96 mg.

RESULTS

The median follow-up was 180 days. All patients were evaluable for safety and pharmacokinetics. No dose-limiting toxicity was observed and the maximum-tolerated dose was not reached. Most frequent adverse events were reversible grades 1 and 2 injection site reactions. Pharmacokinetic analyses demonstrated a systemic passage of DT01. Twenty-one patients were evaluable for efficacy on 76 lesions. Objective response was observed in 45 lesions (59%), including 23 complete responses (30%).

CONCLUSIONS

Intratumoural and peritumoural DT01 in combination with radiotherapy is safe and pharmacokinetic analyses suggest a systemic passage of DT01.

Focal brachytherapy for selected low-risk prostate cancers: a pilot study

PURPOSE

To evaluate the feasibility and the early toxicity of focal brachytherapy in highly selected localized prostate cancer patients.

METHODS AND MATERIALS

Twenty-one patients underwent a focal brachytherapy between February 2010 and March 2012, representing 3.7% of the cases treated by our group during this period. Patient selection was based on (at least) two series of prostate biopsies and a high-resolution MRI. Only patients with very limited and localized tumors, according to strict criteria, were selected for the procedure. The technique used a real-time procedure with the implantation of free (125)I seeds and dynamic dose calculation. The prescribed dose for the focal volume was 145Gy.

RESULTS

The treated volume corresponded to a mean value of 34% of the total prostatic volume (range, 20-48%). For the focal volume, the mean D90 and V100 was 183.2Gy (range, 176-188Gy) and 99.3% (range, 98.8-100%), respectively. The technique was performed in an hour and a half. When compared with a previous cohort treated by whole-prostate brachytherapy, urinary toxicity (International Prostate Symptom Score) was borderline reduced (p = 0.04) at 6 months only, whereas the recovery of the International Index of Erectile Function 5 was better (p = 0.014). The International Continence Score was nil in almost all cases as well as rectal toxicity.

CONCLUSION

Focal treatment by brachytherapy is easily feasible with little acute toxicity. Further investigation is needed to assess the results in terms of tumor control and long-term toxicity.

Morbidity of focal therapy in the treatment of localized prostate cancer

BACKGROUND

Focal therapy (FT) for prostate cancer (PCa) seems to be part of a natural evolution in the quest to improve the management of early organ-confined disease.

OBJECTIVE

To assess the morbidity of the initial experience of FT in a tertiary referral center for PCa management.

DESIGN, SETTING, AND PARTICIPANTS

From 2009 to 2011, a total of 1213 patients with clinically localized PCa were treated at our institution. Of these patients, 547 were considered to have indolent disease according to the D'Amico criteria for low-risk disease plus unilateral disease with a maximum of three positive biopsies. A total of 106 patients underwent FT using high-intensity focused ultrasonography (HIFU), brachytherapy, cryotherapy, or vascular-targeted photodynamic therapy (VTP).

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Complications were prospectively recorded and graded according to the Clavien-Dindo scale. Data were prospectively collected and retrospectively analyzed.

RESULTS AND LIMITATIONS

This study included 106 patients, median age 66.5 yr (interquartile range [IQR]): 61-73), who had a prostate hemiablation; 50 patients (47%) had cryotherapy, 23 patients (22%) had VTP, 21 patients (20%) received HIFU, and 12 patients (11%) had brachytherapy. The median prostate-specific antigen (PSA) level was 6.1 ng/ml (IQR: 5-8.1), all the patients had a biopsy Gleason score of 6, and the median prostate weight was 43 g (IQR: 33-55). The median International Prostate Symptom Score was 6 (IQR: 3-10), and the median International Index of Erectile Function score was 20 (IQR: 15-23). After treatment, the median PSA at 3, 6, and 12 mo was 3.1 2.9, and 2.7 ng/ml (IQR: 2-5.1, 1.1-4.7, and 1-4.4), respectively. Thirteen percent of the patients experienced treatment-related complications. There were 11 minor medical complications (10 grade 1 complications and 1 grade 2 complication), 2 grade 3 complications, and no grade 4 or higher complications.

CONCLUSIONS

FT for a highly selected population with PCa is feasible and had an acceptable morbidity with <2% major complications.

Radiological protection in medicine: work of ICRP Committee 3

Committee 3 of the International Commission on Radiological Protection (ICRP) is concerned with protection in medicine, and develops recommendations and guidance on the protection of patients, staff, and the public against radiation exposure in medicine. This paper presents an overview of the work of Committee 3 over recent years, and the work in progress agreed at the last annual meeting in Bethesda, MD in October 2011. The reports published by ICRP dealing with radiological protection in medicine in the last 10 years cover topics on: education and training in radiological protection; preventing accidental exposures in radiation therapy; dose to patients from radiopharmaceuticals; radiation safety aspects of brachytherapy; release of patients after therapy with unsealed radionuclides; managing patient dose in digital radiology and computed tomography; avoidance of radiation injuries from medical interventional procedures; pregnancy and medical radiation; and diagnostic reference levels in medical imaging. Three new reports will be published in the coming months dealing with aspects of radiological protection in fluoroscopically guided procedures outside imaging departments; cardiology; and paediatric radiology. The work in progress agreed by Committee 3 is also described.

70 Gy versus 80 Gy in localized prostate cancer: 5-year results of GETUG 06 randomized trial

PURPOSE

To perform a randomized trial comparing 70 and 80 Gy radiotherapy for prostate cancer.

PATIENTS AND METHODS

A total of 306 patients with localized prostate cancer were randomized. No androgen deprivation was allowed. The primary endpoint was biochemical relapse according to the modified 1997-American Society for Therapeutic Radiology and Oncology and Phoenix definitions. Toxicity was graded using the Radiation Therapy Oncology Group 1991 criteria and the late effects on normal tissues-subjective, objective, management, analytic scales (LENT-SOMA) scales. The patients' quality of life was scored using the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire 30-item cancer-specific and 25-item prostate-specific modules.

RESULTS

The median follow-up was 61 months. According to the 1997-American Society for Therapeutic Radiology and Oncology definition, the 5-year biochemical relapse rate was 39% and 28% in the 70- and 80-Gy arms, respectively (p = .036). Using the Phoenix definition, the 5-year biochemical relapse rate was 32% and 23.5%, respectively (p = .09). The subgroup analysis showed a better biochemical outcome for the higher dose group with an initial prostate-specific antigen level >15 ng/mL. At the last follow-up date, 26 patients had died, 10 of their disease and none of toxicity, with no differences between the two arms. According to the Radiation Therapy Oncology Group scale, the Grade 2 or greater rectal toxicity rate was 14% and 19.5% for the 70- and 80-Gy arms (p = .22), respectively. The Grade 2 or greater urinary toxicity was 10% at 70 Gy and 17.5% at 80 Gy (p = .046). Similar results were observed using the LENT-SOMA scale. Bladder toxicity was more frequent at 80 Gy than at 70 Gy (p = .039). The quality-of-life questionnaire results before and 5 years after treatment were available for 103 patients with no differences found between the 70- and 80-Gy arms.

CONCLUSION

High-dose radiotherapy provided a better 5-year biochemical outcome with slightly greater toxicity.

ICRP publication 112. A report of preventing accidental exposures from new external beam radiation therapy technologies

Disseminating the knowledge and lessons learned from accidental exposures is crucial in preventing re-occurrence. This is particularly important in radiation therapy; the only application of radiation in which very high radiation doses are deliberately given to patients to achieve cure or palliation of disease. Lessons from accidental exposures are, therefore, an invaluable resource for revealing vulnerable aspects of the practice of radiotherapy, and for providing guidance for the prevention of future occurrences. These lessons have successfully been applied to avoid catastrophic events with conventional technologies and techniques. Recommendations, for example, include the independent verification of beam calibration and independent calculation of the treatment times and monitor units for external beam radiotherapy, and the monitoring of patients and their clothes immediately after brachytherapy. New technologies are meant to bring substantial improvement to radiation therapy. However, this is often achieved with a considerable increase in complexity, which in turn brings opportunities for new types of human error and problems with equipment. Dissemination of information on these errors or mistakes as soon as it becomes available is crucial in radiation therapy with new technologies. In addition, information on circumstances that almost resulted in serious consequences (near-misses) is also important, as the same type of events may occur elsewhere. Sharing information about near-misses is thus a complementary important aspect of prevention. Lessons from retrospective information are provided in Sections 2 and 4 of this report. Disseminating lessons learned for serious incidents is necessary but not sufficient when dealing with new technologies. It is of utmost importance to be proactive and continually strive to answer questions such as 'What else can go wrong', 'How likely is it?' and 'What kind of cost-effective choices do I have for prevention?'. These questions are addressed in Sections 3 and 5 of this report. Section 6 contains the conclusions and recommendations. This report is expected to be a valuable resource for radiation oncologists, hospital administrators, medical physicists, technologists, dosimetrists, maintenance engineers, radiation safety specialists, and regulators. While the report applies specifically to new external beam therapies, the general principles for prevention are applicable to the broad range of radiotherapy practices where mistakes could result in serious consequences for the patient and practitioner.

Molecular therapy in support to radiotherapy

Approximately half of all cancer patients are treated with radiation therapy. However, some tumor cells can escape the lethal effects of irradiation by hypoxia, deregulation of the cell cycle or apoptosis or by increasing their ability to repair the DNA damage induced, resulting in recurrence of disease. In order to overcome these resistance mechanisms, various strategies have been developed. Over the last decade, extensive progress in human genomics and genetic tools has been made. Several methods using DNA or RNA molecules have been developed to target angiogenesis or other cellular functions in order to restore sensitivity to irradiation. In this review, we focus on five classes of nucleic acid-based approaches, (i) gene transfer by recombinant plasmid or virus, (ii) immune-stimulating oligonucleotides, (iii) antisense oligonucleotides, (iv) siRNA and shRNA, and (v) siDNA (signal interfering DNA), which target specific proteins or pathways involved in radioresistance. We review the results of the preclinical studies and clinical trials conducted to date by combining nucleic acid-based molecular therapy and radiotherapy.

Conformal Radiotherapy Planning for Lung Cancer: Analysis of Set-Up Uncertainties

The objective of this study was to evaluate set-up uncertainties using a portal imaging system in a population of inoperable non-small cell lung cancer. Twenty-one patients were treated by a conformal radiotherapy technique with a personalized immobilization cast. The beam was verified by comparison with a corresponding digitally reconstructed radiograph by superimposition of anatomical structures. One thousand eight hundred eighty three images were analyzed. The mean intrafraction and interfraction errors (+/-SD) were 2.17 mm and 0.9 +/- 3.7 mm, 2.3 mm and 0.9 +/- 3.1 mm, 3 mm and 0.7 +/- 3 mm on the lateral (x), cranio-caudal (y) and anterior-posterior (z) axes, respectively. The mean systematic error was small, less than 1 mm, in all directions. The random errors were 2.5 mm, 2.4 mm, and 1.8 mm on the x, y, and z axes, respectively. No correlation between errors and the patient's height, weight, age, or sex was found. Set-up errors accuracy depending on practices, each institution should review their own treatments to quantify and reduce set-up errors in clinical practice.

Brachytherapy versus prostatectomy in localized prostate cancer: Results of a French multicenter prospective medico-economic study

PURPOSE

To prospectively compare health-related quality of life (HRQOL), patient-reported treatment-related symptoms, and costs of iodine-125 permanent implant interstitial brachytherapy (IB) with those of radical prostatectomy (RP) during the first 2 years after these treatments for localized prostate cancer.

METHODS AND MATERIALS

A total of 435 men with localized low-risk prostate cancer, from 11 French hospitals, treated with IB (308) or RP (127), were offered to complete the European Organization for Research and Treatment of Cancer core Quality of Life Questionnaire QLQ-C30 version 3 (EORTC QLQ-C30) and the prostate cancer specific EORTC QLQ-PR25 module before and at the end of treatment, 2, 6, 12, 18, and 24 months after treatment. Repeated measures analysis of variance and analysis of covariance were conducted on HRQOL changes. Comparative cost analysis covered initial treatment, hospital follow-up, outpatient and production loss costs.

RESULTS

Just after treatment, the decrease of global HRQOL was less pronounced in the IB than in the RP group, with a 13.5 points difference (p < 0.0001). A difference slightly in favor of RP was observed 6 months after treatment (-7.5 points, p = 0.0164) and was maintained at 24 months (-8.2 points, p = 0.0379). Impotence and urinary incontinence were more pronounced after RP, whereas urinary frequency, urgency, and urination pain were more frequent after IB. Mean societal costs did not differ between IB (8,019 euros at T24) and RP (8,715 euros at T24, p = 0.0843) regardless of the period.

CONCLUSIONS

This study suggests a similar cost profile in France for IB and RP but with different HRQOL and side effect profiles. Those findings may be used to tailor localized prostate cancer treatments to suit individual patients' needs.

Ionizing radiation to prevent arterial intimal hyperplasia at the edges of the stent: induces necrosis and fibrosis

BACKGROUND

Although ionizing radiation has been proposed for the prevention of intimal hyperplasia in coronary and peripheral arteries in multicenter clinical trials, information is lacking on how irradiation affects arterial histology after stenting and especially how it affects the edges of the stent. We investigated intimal hyperplasia recasting with histological changes in arterial wall at the edges of the stent after arterial stenting followed by adequate external radiation for the prevention of intimal hyperplasia in pigs.

MATERIALS AND METHODS

The aorta was experimentally stented in 30 pigs who were then assigned to two groups: irradiation with 20 Gy and a control group with no irradiation. The aorta was resected for morphometric and histological studies 6 weeks after procedure.

RESULTS

Intimal thickness was reduced and the intima/media ratio was significantly lower in irradiated groups than in control pigs. In the irradiated group histological examination at the edges of the stent showed thin neointimal proliferation with an intact endothelium. In all sections analyzed in the 20-Gy irradiated group the vascular media at 45 days contained necrotic areas and fibrosis with calcifications.

CONCLUSIONS

After arterial injury, adequate ionizing radiation effectively reduces neointimal thickening. Irradiation-induced histological changes include previously undetected recasting with necrosis and fibrosis at the arterial edges of the stent. The parietal recasting we observed in animal arteries irradiated at high doses is unclear and a cause of concern especially after clinical spontaneous dissection was recently reported. The use of ionizing radiation for the prevention of arterial restenosis awaits confirmation with a long-term follow-up including specific experimental histological analyses.

PSA bounce after permanent implant prostate brachytherapy may mimic a biochemical failure: A study of 295 patients with a minimum 3-year followup

PURPOSE

To assess the frequency and features of the PSA bounce phenomenon in a series of patients treated with permanent implant brachytherapy for prostate cancer, and to evaluate the percentage of cases in which this bounce could have mimicked a biochemical relapse according to the American Society for Therapeutic Radiology and Oncology consensus criteria.

METHODS AND MATERIALS

From January 1999 to December 2001, 295 patients were treated with a permanent prostate implantation (real-time technique, with free (125)I seeds) by the Paris Institut Curie/Hospital Cochin/Hospital Necker Paris group. Duration of followup is 40.3 months (9-66 months). PSA level was reported at intervals not exceeding 6 months. Bounce was defined by temporary elevation in PSA level, followed by a spontaneous decrease.

RESULTS

In our series, 161 patients (55%) showed a transitory PSA increase (bounce) of at least 0.1 ng/mL; 145 patients (49%) a bounce of 0.2 ng/mL; 93 patients (32%) a bounce of 0.4 ng/mL; and 43 patients (15%) a bounce of at least 1 ng/mL. Mean PSA bounce was 0.8 ng/mL (0.1-4.1), and mean time to bounce was 19 months. Thirty-two patients (11% of total) presented three successive PSA increases, and therefore were to be considered as experiencing a biochemical relapse according to the American Society for Therapeutic Radiology and Oncology (ASTRO) consensus criteria. Among those 32 patients, 18 (56%) subsequently showed, without any treatment, a complete normalization of their PSA. In multivariate analysis, age <70 (p<0.0001) and D90>200Gy (p<0.003) were identified as independent factors for a PSA bounce of at least 0.4 ng/mL.

CONCLUSIONS

The observed rate of 32% of patients showing a PSA bounce of at least 0.4 ng/mL in our series is in good agreement with what has been previously reported in the literature. Among 32 patients fulfilling the classical ASTRO criteria for a biochemical relapse, 18 (56%) subsequently showed a spontaneous PSA decrease, questioning the ASTRO consensus for the biochemical followup of patients undergoing permanent implant prostate brachytherapy.

Probability of mediastinal involvement in non–small-cell lung cancer: a statistical definition of the clinical target volume for 3-dimensional conformal radiotherapy?

PURPOSE

Conformal irradiation (3D-CRT) of non-small-cell lung carcinoma (NSCLC) is largely based on precise definition of the nodal clinical target volume (CTVn). A reduction of the number of nodal stations to be irradiated would facilitate tumor dose escalation. The aim of this study was to design a mathematical tool based on documented data to predict the risk of metastatic involvement for each nodal station.

METHODS AND MATERIALS

We reviewed the large surgical series published in the literature to identify the main pretreatment parameters that modify the risk of nodal invasion. The probability of involvement for the 17 nodal stations described by the American Thoracic Society (ATS) was computed from all these publications. Starting with the primary site of the tumor as the main characteristic, we built a probabilistic tree for each nodal station representing the risk distribution as a function of each tumor feature. Statistical analysis used the inversion of probability trees method described by Weinstein and Feinberg. Validation of the software based on 134 patients from two different populations was performed by receiver operator characteristic (ROC) curves and multivariate logistic regression.

RESULTS

Analysis of all of the various parameters of pretreatment staging relative to each level of the ATS map results in 20,000 different combinations. The first parameters included in the tree, depending on tumor site, were histologic classification, metastatic stage, nodal stage weighted as a function of the sensitivity and specificity of the diagnostic examination used (positron emission tomography scan, computed tomography scan), and tumor stage. Software is proposed to compute a predicted probability of involvement of each nodal station for any given clinical presentation. Double cross validation confirmed the methodology. A 10% cutoff point was calculated from ROC and logistic model giving the best prediction of mediastinal lymph node involvement.

CONCLUSION

To more accurately define the CTVn in NSCLC three-dimensional conformal radiotherapy, we propose a software that evaluates the risk of mediastinal lymph node involvement from easily accessible individual pretreatment parameters.

Irradiation du cancer du sein : incertitudes liées aux mouvements respiratoires et au repositionnement

Adjuvant Radiotherapy has been shown to significantly reduce locoregional recurrence but this advantage is associated with increased cardiovascular and pulmonary morbidities. All uncertainties inherent to conformal radiation therapy must be identified in order to increase the precision of treatment; misestimation of these uncertainties increases the potential risk of geometrical misses with, as a consequence, underdosage of the tumor and/or overdosage of healthy tissues. Geometric uncertainties due to respiratory movements or set-up errors are well known. Two strategies have been proposed to limit their effect: quantification of these uncertainties, which are then taken into account in the final calculation of safety margins and/or reduction of respiratory and set-up uncertainties by an efficient immobilization or gating systems. Measured on portal films with two tangential fields, CLD (central lung distance), defined as the distance between the deep field edge and the interior chest wall at the central axis, seems to be the best predictor of set-up uncertainties. Using CLD, estimated mean set-up errors from the literature are 3.8 and 3.2 mm for the systematic and random errors respectively. These depend partly on the type of immobilization device and could be reduced by the use of portal imaging systems. Furthermore, breast is mobile during respiration with motion amplitude as high as 0.8 to 10 mm in the anteroposterior direction. Respiratory gating techniques, currently on evaluation, have the potential to reduce effect of these movements. Each radiotherapy department should perform its own assessments and determine the geometric uncertainties with respect of the equipment used and its particular treatment practices. This paper is a review of the main geometric uncertainties in breast treatment, due to respiration and set-up, and solutions proposed to limit their impact.

Hypofractionnement en radiothérapie : le retour ?

Hypofractionation (i.e. the use of fewer higher fractional doses than usual) is not a new concept. It had actually been proposed in the early year of Radiotherapy by the German and Austrian specialists. In the seventy's, supported by the - wrong - hypotheses which gave birth to the NSD (Nominal Standard Dose), hypofractionation reappears. The consequential increase of late complications which was observed led the radiation oncologists to give up again using large doses per fraction, except for a few specific situations, such as palliative treatments. We are recently facing a new "come-back" of hypofractionation, in particular for breast and prostate cancers. In the case of breast cancer, the aim is clearly to look for more "convenience" for both the patients and the physicians, proposing shorter irradiation schedules including a lesser number of fractions. Some "modestly" hypofractionated schemes have been proposed and used, without apparently altering the efficacy/toxicity ratio, but these results have been seriously questioned. As for prostate cancer, the situation is different, since in that case new radiobiological data are at the origin of the newly proposed hypofractionation schedules. A number of papers actually strongly suggested that the fractionation sensitivity of prostate cancer could be higher than the one of the tissues responsible for late toxicity (i.e the exact opposite of the classical dogma). Based on those data, several hypofractionated schemes have been proposed, with a few preliminary results looking similar to the ones obtained by the classical schedules. However, no randomised study is available so far, and a few recent radiobiological data are now questioning the new dogma of the high fractionation sensitivity of prostate cancer. For those two - frequent - cancers, it seems therefore that prudence should prevail before altering classical irradiation schedules which have proven their efficacy, while staying open to new concepts and proposing well-designed randomised trials in specific cases.

Chronological Changes in Morphometry and Histology in the Rabbit Vascular Wall after External Radiation for the Prevention of Intimal Hyperplasia

BACKGROUND

Although ionizing radiation has been proposed for the prevention of intimal hyperplasia in coronary and peripheral arteries, information is lacking on how irradiation affects arterial histology and neointimal smooth-muscle cell proliferation-the hallmark of restenosis. We chronologically investigated early histological changes and quantitative changes in arterial wall cell proliferation after arterial injury followed by external radiation for the prevention of intimal hyperplasia in rabbits.

MATERIALS AND METHODS

The aorta was experimentally injured in 26 rabbits who were then assigned to two groups: irradiation with 20 Gy and a control group with no irradiation. The aorta was resected for morphometric and histological studies at 3, 7, 15, 30, and 45 days after experimental injury.

RESULTS

Intimal thickness was reduced and the intima/media ratio was significantly lower in irradiated groups than in control rabbits. In the irradiated group histological examination showed delayed neointimal proliferation with an intact endothelium. In the 20-Gy irradiated group the vascular media at 7 days contained necrotic areas and delayed fibrosis with calcifications. There was no statistical difference between the number of proliferating cells in the irradiated groups and the control group. Proliferating cells reached maximum numbers later in irradiated groups than in control rabbits (45 days versus 3 days).

CONCLUSION

After arterial injury, external irradiation at 20 Gy effectively reduced aortic neointimal thickening. Irradiation-induced histological changes include recasting with rapid necrosis and delayed fibrosis. Radiation-induced parietal recasting with necrosis, fibrosis, and calcifications might worsen in time. Although irradiation after arterial injury leaves proliferative smooth-muscle cells within the arterial wall quantitatively unchanged in the early days after the procedure, it then induces a delayed reaction (observed over 45 days in our study). Whether neointimal hyperplasia is merely delayed or will ultimately develop causing restenosis awaits confirmation from experimental and clinical studies with a long-term follow-up.

[Respiratory gated radiotherapy: the 4D radiotherapy]

Respiration-gated radiotherapy offers a significant potential for improvement in the irradiation of tumor sites affected by respiratory motion such as lung, breast and liver tumors. An increased conformality of irradiation fields leading to decreased complications rates of organs at risk (lung, heart...) is expected. Respiratory gating is in line with the need for improved precision required by radiotherapy techniques such as 3D conformal radiotherapy or intensity modulated radiotherapy. Reduction of respiratory motion can be achieved by using either breath hold techniques or respiration synchronized gating techniques. Breath hold techniques can be achieved with active, in which airflow of the patient is temporarily blocked by a valve, or passive techniques, in which the patient voluntarily breath-hold. Synchronized gating techniques use external devices (CCD camera for the GEMS/Varian system tested at Curie Institute) to predict the phase of the respiration cycle while the patient breaths freely. A new strategy is currently developed: the 4D Respiration correlated CT. It consists of retrospectively reconstruct CT slices at different phases of the breathing cycle allowing to measure residual movements and to choose the optimal patient's breathing phase where tumor movements are lower. These techniques presently investigated in several medical centers worldwide. The first results are very promising.

Choix des contraintes et amélioration dosimétrique d’une radiothérapie conformationnelle du cancer de la prostate modulée en intensité pendant une partie du traitement

PURPOSE

Intensity modulated radiation therapy (IMRT) is based on a methodology called inverse planning. Starting from dosimetric objectives, constraints of optimization are fixed and given to the inverse planning system, which in turn calculates the modulated intensity to apply to each beam. Since the algorithms allow the constraints to be violated, the results of optimization may differ from the initial dosimetric objectives. Consequently, the user is compelled to adapt the choice of the constraints according to the type of modulation and until satisfactory results are found. The purpose of this work is to present our experience in the choice of these constraints for prostate cancer treatments, as we moved from conformal radiotherapy to IMRT. Treatments were performed with a Varian 23EX linac and calculations were realized with the Varian CadPlan-Helios planning system.

PATIENTS AND METHODS

The approach used for the first 12 patients treated at institut Curie with IMRT from June 2002 was analysed. The treatment always consisted of a combination of conformal radiotherapy with and without intensity modulation.

RESULTS AND CONCLUSION

Results showed that, a larger fraction of the treatment performed with IMRT induced a better sparing of the organs at risk for the same homogeneous dose distribution to the target volume. Apart from the dose-volume constraint for the rectum, a fixed set of constraints, slightly more restrictive than the dosimetric objectives, could be used for all patients. Compared with conformal radiotherapy, the conformation factor for IMRT increased up to 16%. A specific study was undertaken in view of treatments completely performed with IMRT. The optimal technique consisted in performing separated IMRT plans for the two target volumes, the prostate volume and the prostate plus seminal vesicles volume respectively. Another satisfactory possibility was to define new constraints on two separated planning target volumes, prostate and seminal vesicles. This last approach is now routinely implemented for our IMRT patients.

[Radiation toxicity to the heart: physiopathology and clinical data]

Irradiation of the heart begets different complications in which pericardial disease is the most common manifestation. Thoracic irradiation of lymphoma, Hodgkin's disease, lung and breast cancer could be complicated by adverse effects to every structure of the heart. Potential injury of mediastinal irradiation can include acute and late pericarditis, cardiomyopathy, valvular disease and conduction abnormalities. The pathophysiology of these various syndromes is probably similar, starting by prior microvascular injury that leads to subsequent myocardium ischemia, all of which cause late fibrous scars. Acute pericarditis is often asymptomatic and clear spontaneously. Late pericarditis affects approximately 5% of the patients when the irradiation dose exceeds 40 Gy. At this dose, the mortality rate is below than 1%. Cardiomyopathy is rare and often asymptomatic. A long time unrecognized, coronary artery disease, diagnosed in 5 to 10% of the patients, begets multifarious sequelae like myocardial infarction, valvular abnormalities and cardiac rhythm changes. This coronary artery disease is more likely to occur if the patient was young at the time of the irradiation (< or = 21 years) and/or if other cardiovascular risk factors are associated. Incidence and mortality rates of valvular defects are about 20 and 0.5%, respectively. Conduction dysfunctions can also be seen in 5% of the patients. Radiation-induced heart complications seem to be related to total dose (> 30 Gy), irradiated tissue volume and fraction size. Since cardiac complications appear months to years following incidental irradiation of the heart, appropriate screening and long-term cardiac follow-up of these patients is essential.

[The recommendations of the International Commission on Radiological Protection (ICRP) for high-dose-rate brachytherapy and for permanent prostatic implants]

ICRP (International Commission for Radiological Protection) Committee 3 ("Radioprotection in medicine") is currently finalizing two recommendations about Brachytherapy. The first text, from Task Group (TG) 53, is focussing on the prevention of high-dose-rate brachytherapy accidents. It reminds the reader of the 500 accidents/incidents which have been reported so far in the literature, and reports in details on some representative accidents. Building on those data, the text gives general and specific recommendations, aiming at reducing both the frequency and the severity of those accidents. The second text, from Task Group 57, considers the radiation safety aspects of brachytherapy for prostate cancer using permanently implanted sources. For this topic, no severe accident has never been reported so far. However, some radioprotection problems arose, due to the dose received from the patients, to migrating seeds and to cremation. The text presents recommendations specifically addressing those issues.

Prostate cancer brachytherapy: is real-time ultrasound-based dosimetry predictive of subsequent CT-based dose distribution calculation? a study of 450 patients by the Institut Curie/Hospital Cochin (Paris) Group

PURPOSE

Real-time ultrasound (US)-based dosimetry performed during (125)I loose seed implantation provides the radiation oncologist with an estimation of the dose distribution at seed insertion. However, for a number of reasons, this distribution may not reflect the real (reference) dosimetry as determined by subsequent CT, usually performed 1-2 months after implantation. The present study compared the two dosimetry data sets (US and CT) to evaluate how predictive extemporaneous US-based dosimetry can be of the real dose distribution.

METHODS AND MATERIALS

A total of 450 patients with prostate cancer were treated with loose (125)I seed implantation between June 1999 and October 2002 by the Institut Curie/Hospital Cochin (Paris) Group. The mean patient age was 65 years. Most patients (74%) had Stage T1c; the stage did not exceed T2b for the others. All patients had a prostate-specific antigen level of <15 ng/mL and was <10 ng/mL for 72%; 84% had a Gleason score of < or =6 and did not exceed 7 for the others; and 56% were treated with neoadjuvant hormonal therapy for a mean of 4.3 months. All patients were treated with loose seed implantation. Real-time US-based dosimetry was performed intraoperatively for all patients. CT-based dosimetry was performed 2 months after implantation, using the VariSeed software. The minimal dose to 90% of the outlined volume (D(90)) and percentage of volume receiving at least 100% of the prescribed dose (V(100)) were calculated with the two methods and compared for all patients.

RESULTS

On CT-based dosimetry, the D(90) was found to be > or =145 Gy (range, 115-240 Gy) in all patients except one. A large majority (86%) of patients showed a CT-based V(100) of >95%, and 48% had a V(100) of >98%. The mean CT-based D(90)/US-based D(90) ratio was 1.0 (range, 0.66-1.33). For 89% of the patients, the difference between the two values was <20% and for 62% was <10%. The mean CT-based V(100)/US-based V(100) ratio was 0.98 (range, 0-1.02), with 89% of patients showing a difference of <5%.

CONCLUSION

Our results indicate that the D(90) and V(100) values obtained intraoperatively with our real-time US-based dosimetry are in reasonable agreement with the subsequent values obtained with CT-based dosimetry performed 2 months after implantation. Recent innovations in our dose planning software allowed better control of the longitudinal seed position and could still improve the correlation between real-time US-based dosimetry and the subsequent CT-based dose distribution.

POST-BRACHYTHERAPY TRANSURETHRAL RESECTION OF THE PROSTATE IN PATIENTS WITH LOCALIZED PROSTATE CANCER

PURPOSE

We assessed the rate and results of transurethral resection of the prostate (TURP) in patients previously treated with brachytherapy as monotherapy for localized prostate cancer.

MATERIALS AND METHODS

From May 1998 to May 2003, 600 patients with localized prostate cancer were treated with brachytherapy at our institution. Brachytherapy was performed as monotherapy with curative intent for clinically localized prostate cancer without adjuvant treatment in patients with clinical stages T1c (68.4%) or T2a (31.6%) disease. -Iodine and palladium implants were used in 583 and 7 patients, respectively. A real-time interactive implantation technique was used in all but the first 17 patients, who were treated using a preplanned technique.

RESULTS

Of the 600 patients 19 (3.1%) underwent TURP after brachytherapy. Among the patients with acute urinary retention the median interval between prostate brachytherapy and urinary retention was 2 months (range 0.5 to 32). No TURP was done within 6 months after implant. The median interval between prostate brachytherapy and TURP was 7 months (range 6 to 41) and median prostate specific antigen (PSA) before TURP was 0.5 ng/ml (range 0.04 to 3.4). In the 19 patients the median weight of resected prostatic tissue was 8 gm (range 2 to 19) and 1 to 11 seeds were removed (median 5). The perioperative and postoperative courses were uneventful. There was no TURP related incontinence. With a median followup of 28 months after brachytherapy (range 7 to 48) no patient had clinical or biochemical evidence of disease progression, and for the group of 19 patients who underwent TURP median serum PSA at the end of followup was 0.38 ng/ml (range 0.03 to 3.4).

CONCLUSIONS

After brachytherapy as monotherapy, TURP can be done safely if indicated. In our experience the resection of prostatic tissue along with a limited number of seeds at least 6 months after implantation did not impair PSA based biological and clinical results of brachy-therapy.

Morphometric and histological changes in the vascular wall after external radiation for the prevention of intimal hyperplasia

BACKGROUND

Recent reports describe spontaneous dissections and aneurysms after coronary and peripheral artery irradiation for the prevention of intimal hyperplasia. We investigated histological changes and the vasomotor reaction in the vascular wall after external radiation for the prevention of intimal hyperplasia in rabbits.

MATERIALS AND METHODS

The aorta was experimentally injured in 34 rabbits who were then assigned to one of three groups: irradiation with 20 Gy; with 25 Gy; and a control group with no irradiation. Before the arterial injury and 45 days later, vasomotor function was assessed with an intravascular ultrasound catheter. The aorta was resected for morphometric and histological studies.

RESULTS

After injury and irradiation, vasomotor responses were significantly lower in the two irradiated groups (P < 0.05). Intimal thickness and the intima/media ratio were significantly lower in irradiated groups. In the irradiated group histological examination showed reduced intimal proliferation with an intact endothelium. In the 20-Gy irradiated group the vascular media contained necrotic areas, and in the 25-Gy irradiated group, severe fibrosis.

CONCLUSION

After arterial injury, external irradiation at 20 and 25 Gy effectively reduces aortic intimal and medial thickening. Histological changes include recasting with necrosis and fibrosis causing a decreased vasomotor response. Further investigations are needed to confirm medial necrosis and replacement with fibrosis. Because the irradiation doses in this study match those currently used and also recommended for experimental and clinical use, if confirmed in humans parietal recasting might possibly explain the reported spontaneous dissections and aneurysm formation after irradiation.

External beam ionizing radiation for inhibition of myointimal hyperplasia after dilatation and anastomoses: experimental models and results

In recent years there has been intensive research on the use of ionizing radiation for inhibition of intimal hyperplasia (IH). Results have clearly established that beta ionizing radiation delivered from an endoluminal source after angioplasty inhibits intimal restenosis. This effect has been confirmed by recent multicenter clinical trials in patients undergoing coronary dilatation. The purpose of this study was to determine if gamma radiation therapy delivered superficially from an external source also reduced smooth muscle cell proliferation in two animals models-the first involving experimentally induced restenosis and the second involving anastomosis between a prosthesis and artery. Ultimately we hope to develop a therapeutic application for patients undergoing peripheral anastomoses, especially in the lower extremities. Two different animal models were used in this two-stage study. The first-stage rabbit model (model 1) involved balloon injury of the aorta to validate the dose effect of external beam irradiation. The second-stage porcine model (model 2) involved aortic bypass followed by external beam irradiation of the distal anastomosis site. In model 1 a total of 56 rabbits were studied. They were divided into five groups including one control group in which external radiation was not applied after balloon injury and four test groups in which external radiation was applied in a single fraction on day 0 at four different doses: 10 grays, 15 grays, 20 grays, and 25 grays. In model 2, a total of 24 pigs underwent aortic bypass with a 6-mm PTFE graft followed by irradiation of the distal end-to-side anastomosis at a dose of 20 grays on day 0. In both models specimens were harvested after 6 weeks and studied histologically after staining with HES and orcein, histomorphometrically by measuring intimal hyperplasia, and immunohistochemically using actin and factor VIII/von Willebrand factor (F VIII/vWF). The zones of study on the anastomosis were separated into base of the artery to the tip and heel of the anastomosis and the edge of the arteriotomy. Measurements were compared using the Mann Whitney test. In the first-stage model designed to study IH in rabbits, mean intimal and medial thickness values and the intima-to-media ratio showed no difference between the control group and the groups irradiated at doses of 10 grays and 15 grays (p = 0.111, p = 0.405, and p = 0.14); (p = 0.301, p = 0.206, and p = 0.199). Conversely, there was a significant difference between the control group and the groups irradiated at 20 grays and 25 grays (p < 0.0001, p = 0.107 and p = 0.008; p = 0.008, p = 0.155, and p = 0.008). Histological examination demonstrated extensive changes in the wall with high-grade fibrosis after application of ionizing radiation. In the second-stage swine model, irradiation significantly inhibited development of IH at the level of anastomosis both at the base of the artery (p < 0.01) (tip 0.06 vs. 0.27 mm and heel 0.04 vs. 0.36) and at the level of the arteriotomy at the suture site (p < 0.001) (0.13 vs. 0.86 mm). Immunochemical analysis of the thickened zones showed a positive reaction of endothelial cells to smooth muscle actin and F VII/vWF. Like irradiation applied using an endoluminal source, superficial gamma ionizing radiation from an external source inhibits IH. Analysis of the dose effect showed that the overall dose must be between 15 and 20 grays. External radiation also reduces overall IH at the anastomosis between a prosthesis and artery. Although these experimental data are promising, further study will probably be necessary before attempting to undertake clinical trials using external beam radiation therapy for patients undergoing peripheral anastomoses.

[External ionizing radiation on the prosthesis-arterial anastomosis for the prevention of intimal hyperplasia and study of biomechanical resistance. Experiments and results]

PURPOSE

To evaluate the use of external ionizing radiation for the prevention of intimal hyperplasia in anastomosis between PTFE and artery.

METHODS

Bypass using a 6 mm PTFE was performed on a swine subrenal aorta with a distal conventional anastomosis (N = 35) associated (test group; N = 17) or not (control group; N = 18) with post-operative external radiation (20 Gy) on this anastomosis. At 45 days, histological studies and morphometric studies were performed on the aorta receiving the anastomosis. Two protocols were performed, the first protocol with standard analysis and the animals were randomly assigned to either group (test group; N = 11 and control group; N = 13) and the second protocol with test of extraction comparing the biomechanical resistance between the irradiated group (N = 6) and the control group (N = 5).

RESULTS

Twenty-one animals survived the procedure in the first protocol, 11 in the second. The endothelium was restored in either group. Histological recasting was observed in the media after radiation with fibrosis and areas of necrosis. Intimal thickness was significantly lower after irradiation in the heel (P < 0.01), the head (P < 0.01) and the suture line (P < 0.001) of the artery in the first protocol. The intimal thickness was also significantly lower in the second protocol after radiation in the heel (P < 0.05) and the head of the artery (P < 0.05). There was no difference between the two groups comparing the resistance.

CONCLUSION

After external irradiation, the thickness parameter of the intima decreased significantly in comparison with the control group with similar resistance. Media fibrosis and necrosis need to be confirmed by further investigation.

[Respiration-gated radiotherapy: current techniques and potential benefits]

Respiration-gated radiotherapy offers a significant potential for improvement in the irradiation of tumor sites affected by respiratory motion such as lung, breast and liver tumors. An increased conformality of irradiation fields leading to decreased complications rates of organs at risk (lung, heart...) is expected. Respiratory gating is in line with the need for improved precision required by radiotherapy techniques such as 3D conformal radiotherapy or intensity modulated radiotherapy. Reduction of respiratory motion can be achieved by using either breath hold techniques or respiration synchronized gating techniques. Breathhold techniques can be achieved with active, in which airflow of the patient is temporarily blocked by a valve, or passive techniques, in which the patient voluntarily breath-hold. Synchronized gating techniques use external devices to predict the phase of the respiration cycle while the patient breaths freely. These techniques presently investigated in several medical centers worldwide. Although promising, the first results obtained in lung and liver cancer patients require confirmation. Physical, technical and physiological questions still remain to be answered. This paper describes the most frequently used gated techniques and the main published clinical reports on the use of respiration-gated radiotherapy in order to evaluate the impact of these techniques.

[Hyperplasia of the arterial intima due to smooth muscle cell proliferation. Current data, experimental treatments and perspectives]

Restenosis after vascular surgery using bypasses or endovascular techniques for dilatation or recanalisation remains the major Achilles' heel for these techniques. The progressive decrease of vessel lumen in an anastomose leading to graft failure or after arterial transluminal angioplasty is due to a complex process: intimal hyperplasia. This process can be compared to an hypertrophic healing into the intimal layer, reducing the lumen of the vessel. This process appears shortly after surgery or dilatation, between the 3rd and the 18th month. Mechanisms leading to this process are particularly complex, involving several cells and many regulatory processes still unclear. Smooth muscle cells are the main actor by their ability to proliferate and to secrete matrix into the media layer but stimulation and control of this process appear nevertheless complicated. The present review focuses on the pathophysiology of intimal hyperplasia, on different cells acting and on their regulation. Also, we reviewed the experimental and clinical trials evaluating approaches to the prevention of intimal hyperplasia in arteries.

[High-dose external ionizing radiation prevents intimal hyperplasia and limits secretion of growth factors PDGFbb, bFGF, and TGFb1. Experiments and results]

PURPOSE

To evaluate the ionizing radiation for intimal hyperplasia prevention and to assess the production of growth factors.

METHODS

An oversized injury using an embolectomy catheter was performed on a rabbit distal aorta (N=23), associated (test group; N=12) or not (control group; N=11) with a post-operative external radiation (25 Gy). At t=45 days, histological studies and morphometric studies were performed on the aorta. Smooth muscular cells and endothelial cells were stained using immuno-histologic revelation. Immuno-histological analysis was performed on arteries for growth factors PDGFbb, bFGF and TGFb1.

RESULTS

Twenty-one animals survived the procedure, 11 were in the test group and 10 in the control group. Intimal thickness and ratio intima/media were significantly lower after radiation (respectively p=0.008, p=0.008). There was no difference for the medial thickness (p=0.155). Immuno-histochemical positive staining for PDGF and TGFb1 was lower after radiation (respectively 18.44 +/- 2.963% versus 47.64 +/- 6.86%, p<0.001 and 10.11 +/- 3.18% versus 29.45 +/- 4.156%, p<0.001). There was no difference for the expression of bFGF growth factor. After radiation, the media was found to be reduced and replaced by interstitial fibrosis.

CONCLUSION

After external radiation the thickness parameter of the intima and the ratio intima/media decreased significantly in comparison with the control group. PDGF and TGFb1 were also less expressed in the artery irradiated. Fibrosis recasting needs to be confirmed by further investigation.

[Upper aerodigestive tract cancers: clinical benefits of conformal radiotherapy and intensity modulation]

The conformal radiotherapy approach, three-dimensional conformal radiotherapy (3DCRT) or intensity-modulated radiotherapy (IMRT), is based on modern imaging modalities, efficient 3D treatment planning systems, sophisticated immobilization systems and rigorous quality assurance and treatment verification. The central objective of conformal radiotherapy is to ensure a high dose distribution tailored to the limits of the target volume while reducing exposure of normal tissues. These techniques would then allow further tumor dose escalation. Head-and-neck tumors are some of the most attractive localizations to test conformal radiotherapy. They combine ballistic difficulties due to particularly complex shapes (nasopharynx, ethmoid) and problems due to the number and low tolerance of neighbouring organs like parotids, eyes, brainstem and spinal cord. The therapeutic irradiation of head-and-neck tumors thus remains a challenge for the radiation oncologist. Conformal radiotherapy does have a significant potential for improving local control and reducing toxicity when compared to standard radiotherapy. However, in the absence of prospective randomized trials, it is somewhat difficult at present to evaluate the real benefits drawn from 3DCRT and IMRT. The published clinical reports on the use of conformal radiotherapy are essentially dealing with dosimetric comparisons on relatively small numbers of patients. Recently, a few publications have emphasized the clinical experience of several precursor teams with a suitable follow-up. This paper describes the current state-of-the-art of 3DCRT and IMRT in order to evaluate the impact of these techniques on head-and-neck cancers irradiation.

[Non-small-cell bronchial cancers: improvement of survival probability by conformal radiotherapy]

The conformal radiotherapy approach, three-dimensional conformal radiotherapy (3DCRT) and intensity-modulated radiotherapy (IMRT), is based on modern imaging modalities, efficient 3D treatment planning systems, sophisticated immobilization devices and demanding quality assurance and treatment verification. The main goal of conformal radiotherapy is to ensure a high dose distribution tailored to the limits of the target volume while reducing exposure of healthy tissues. These techniques would then allow a further dose escalation increasing local control and survival. Non-small cell lung cancer (NSCLC) is one of the most difficult malignant tumors to be treated. It combines geometrical difficulties due to respiratory motion, and number of low tolerance neighboring organs, and dosimetric difficulties because of the presence of huge inhomogeneities. This localization is an attractive and ambitious example for the evaluation of new techniques. However, the published clinical reports in the last years described very heterogeneous techniques and, in the absence of prospective randomized trials, it is somewhat difficult at present to evaluate the real benefits drawn from those conformal radiotherapy techniques. After reviewing the rationale for 3DCRT for NSCLC, this paper will describe the main studies of 3DCRT, in order to evaluate its impact on lung cancer treatment. Then, the current state-of-the-art of IMRT and the last technical and therapeutic innovations in NSCLC will be discussed.

[Accidents in radiotherapy: historical account]

Radiotherapy accidents are exceedingly rare. However, they may have major negative consequences: for health (and sometimes life) of victims as well as for the trust that patients put in radiotherapy and radiation oncologists. Each accident must be pointed out, analysed and reported, in order to allow preventive actions, avoiding repetitive accidents. Through examples of majors accidents occurred all over the world in the last decades, affecting professionals, public or patients themselves, the necessity of transparency is demonstrated. The International Commission of Radiobiological Protection has drawn positive lessons from such accidents and insists on following recommendations: necessity of sufficient number and competent professionals, importance of continuous and initial education, information of professionals and, in general, a strict Quality Assurance program. It is clear that each radiotherapy center remains at risk for errors. It is essential to develop preventive procedures to avoid transformation of errors into accidents. In that context, complete and detailed description and reports of each anomaly or incident must be encouraged as it is done for sectors of aviation or nuclear industry. Radiation oncology must develop such a culture of transparency and of systematic report of all incidents.