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Biomedical subjects

P Maingon

Publications and source records attributed to P Maingon.

At least 19 recordsLinked to original sources
PubMed2006

[Implementation of transabdominal ultrasound image guided conformal intensity modulated radiotherapy].

PURPOSE: Optically guided ultrasound imaging has been used in our department since 2003 in order to implement an on line correction scheme in intensity modulated radiation therapy of prostate carcinoma. PATIENTS AND METHODS: The corrections observed during the initial time period of the system (17 patients) are compared to those observed more recently (10 patients). Treatment margins are calculated. RESULTS: Overall systematic errors decreased between 2003 and 2006, and are presently statistically not different from zero. Random errors remain the same (max 4.3 mm). Proposed margins are 7 mm both in lateral and longitudinal direction and 8.4 mm in anteroposterior. CONCLUSION: Ultrasound can be used for on line correction of both positioning and internal organs motion errors and allows reduction of the margins between clinical and planning volume.

Abdomen↗
PubMed2006

[High precision radiotherapy with ultrasonic imaging guidance].

Conformal radiation therapy with or without intensity modulation is the standard treatment of localized prostate cancer and facilitates dose escalation. The implementation of three-dimensional conformal radiotherapy necessitates focusing on target volume delineation, dosimetry, reproducibility of treatment and quality control. Recently, ultrasound systems that allow direct daily visualization of the prostate have become available. This non-invasive technique can be used to correct both prostate organ motion and set-up error and leads to increase treatment accuracy.

Humans↗
PubMed2006

[What to do with a rising PSA after complete remission post-prostatectomy?].

Between twenty and to forty percent of patients will develop an isolated PSA failure after a radical prostatectomy. Pelvic irradiation is a therapeutic option with curative intention. It is the best therapeutic option for young people with good prognostic factors. Combined radiation with hormonal or chemotherapy should be evaluated in patients with poor prognostic factors. For patients with a short life expectancy, hormonotherapy or a watch and see policy are acceptable options.

Antineoplastic Agents, Hormonal↗
PubMed2005

[Radiotherapy for PSA failure after prostatectomy: which volumes?].

After prostatectomy, radiotherapy is a potential curable treatment. From the surgery series, it is possible to identify all the localization at risk in case of biochemical relapse after prostatectomy. The target volume of irradiation has to be defined according to the pathological findings. The CTV is limited to the pelvic fascia laterally, to the anterior wall of the rectum behind. The inferior limit includes the anastomosis, and the superior is easier to define with the length of the prostatic gland. The inclusion of area of seminal vesicles and pelvic node areas should be discussed. The use of surgical clips on the anastomosis and image fusionning techniques including the preoperative imaging would help physicians to define the CTV's limits.

Humans↗
PubMed2005

[Conformal radiation therapy with or without intensity modulation in the treatment of localized prostate cancer].

Conformal radiation therapy has now to be considered as a standard treatment of localized prostatic adenocarcinomas. Using conformational methods and intensity modulated radiation therapy requires a rigorous approach for their implementation in routine, focused on the reproducibility of the treatment, target volume definitions, dosimetry, quality control, setup positioning. In order to offer to the largest number of patients high-dose treatment, the clinicians must integrate as prognostic factors accurate definition of microscopic extension as well as the tolerance threshold of critical organs. High-dose delivery is expected to be most efficient in intermediary risks and locally advanced diseases. Intensity modulated radiation therapy is specifically dedicated to dose escalation. Perfect knowledge of classical constraints of conformal radiation therapy is required. Using such an approach in routine needs a learning curve including the physicists and a specific quality assurance program.

Adenocarcinoma↗
PubMed2005

[Nasopharyngeal carcinomas: from biology to clinic].

Nasopharyngeal carcinomas (NPC) are very different from other head and neck cancers because of their specific multifactorial etiology and their geographic distribution. Epstein-Barr Virus (EBV) is implicated in oncogenesis of NPC in association with genetic alterations such as inactivation of the p16/Ink4, p19/ARF, RASSF1 or Blu genes. Tumoral tissues include a very abundant characteristic lymphoid infiltrate. Inflammatory cytokines are produced by both malignant and infiltrating cells. There is no efficient immune response against the tumor. On the opposite, infiltrating lymphocytes might play a role in tumor development. Serological methods and detection of circulating viral DNA are expected to become useful for early detection of relapse and on a longer term for primary screening. NPC are often diagnosed at a late stage because patients may remain asymptomatic for a long time. Computed tomography (CT scan) and magnetic resonance imaging (MRI) are complementary for the initial evaluation. Positron emission tomography (PET) is efficient for the evaluation of treatment efficiency and detection of relapses. Treatment is based on radiotherapy and chemotherapy. Their optimal use needs to be evaluated by phase III trials but positive results have been obtained by concomitant association of radiotherapy and chemotherapy. Targeted therapies are being studied with strategies based on disruption of viral latency, use of replicative adenoviruses or anti-tumor vaccination.

Carcinoma↗
PubMed2005

Intensity modulated radiation therapy in head and neck squamous cell carcinoma: state of the art and future challenges.

Intensity-modulated radiation therapy (IMRT) for head and neck (HN) tumors refers to a new approach to the whole treatment procedure from patient immobilization to beam delivery. Implementation of IMRT thus requires knowledge of setup uncertainties, adequate selection and delineation of target volumes based on clinical examination and optimal imaging modalities, appropriate specification and dose prescription regarding dose-volume constraints, and ad hoc quality control of both the clinical and physical aspects of the whole procedure. A large number of issues still need to be resolved and/or further refined, such as the optimal selection and delineation of the target volume in particular, with the introduction of functional imaging, and a better integration of improved dose distribution into the fractionation strategy. IMRT is associated with a potentially increased incidence of carcinogenesis, although in the HN area this risk is relative to the intrinsic risk of co-morbidity and secondary cancer associated with the patient's lifestyle. Currently, the implementation of IMRT into routine clinical practice for HN cancers may not be a straightforward matter, and should probably be restricted to selected patients and selected institutions with adequate resources and experience. This review emphasizes the above aspects and provides some recommendations for the future use of IMRT in patients with HN tumors.

Carcinoma, Squamous Cell↗
PubMed2004

[To boost the tumor bed: the age of reason].

It is well known that the conservative reference treatment of infiltrative carcinoma of the breast, after en bloc complete excision, should be completed by irradiation of the whole breast delivering 50 Gy in 25 fractions. The discussion related to the validity and the procedures of delivery of the boost of the tumor bed has to be adjusted with our knowledge of specific prognostic factors of local recurrence. Through the two phase III randomized trials published in the literature, the young age of the patient, palpable tumor and negative receptor to progesterone may be recognized as statistically linked to a higher risk of local recurrence. Tumor size and palpable tumor remain unquestionable factors of bad prognosis. The true level of significativeness of age remains controversial as well as peri-tumoral characteristics such as ductal carcinoma in situ. Treatment technique should be rigorous either in terms of prescription of external radiation therapy or for the boost. They have a major impact on the cosmetic result and the fibrosis rate. Improvement of the results is expected through careful analysis of genic and molecularly prognostic factors of the tumor in order to select patients amenable to this type of technique.

Adult↗
PubMed2004

[Critical organs and external irradiation in gynaecological cancers: can water be used as contrast agent to make easier the delineation of the small intestine?].

PURPOSE: To validate the use of water as contrast agent for the delineation of the small intestine on the planning CT of external beam in patients treated with conformal radiotherapy for gynaecological tumours. PATIENTS AND METHODS: From March to September 2003, 20 patients received an external irradiation for a gynaecological carcinoma (13 with cervix carcinoma, seven with endometrial carcinoma) in the radiotherapy department of the Centre G.F. Leclerc of Dijon. The protocol of opacification of the small intestine consisted in administration of a "negative" contrast agent: water. The protocol commonly used for the bladder filling, i.e. absorption of 500 cm(3) of water from 60 to 30 min before the CT-scan, was applied for the evaluation of the visualisation of the small intestine in the 12 first patients (group I). For the last eight patients (group II), the absorption of the same amount of water was fractionated, every 10 min within half an hour before the start of the examination. RESULTS: The small bowel identification was possible in 100% of cases without any need of administration of a "positive" contrast agent. In overall, the identification of the small intestine was considered as easy in 14 patients (70%) and as difficult in two patients (10%). In group I, the delineation was considered as easy in 50% of cases, moderately easy in 33% of cases and none easy in 17% of cases. Conversely, no difficulty was encountered for the definition of the small bowel in all patients of group II. CONCLUSIONS: Water is an efficient "negative" contrast agent for the differentiation of the small bowel from the colon on the planning abdomino-pelvic CT. Nevertheless, the delineation was really made easier only when the fractionated protocol of water absorption within half an hour before CT was used.

Adult↗
PubMed2004

[Constraints to organs at risk for treatment of head and neck cancers by intensity modulated radiation therapy].

Constraint definitions in intensity modulated radiation therapy is a key point factor during the treatment planning process. In literature some data are available about dose constraints and volumes according to the tissue architectures. Following ICRU recommendations, organs at risk organized in a parallel structure could receive an acceptably small proportion of high dose component. Mean dose and dose volume histogram is a most convenient tool for incorporating such constraints. Organs described as a serial structure are supposed to receive less than the given maximum dose, directly linked to the occurrence of complications. Dmax is the best way to describe such events. These constraints are new tools in radiation therapy, available for optimizing the dose distribution in target volume, sparing the organs at risk to protect the organ function or at least decreasing the late functional damages like xerostomia. It is necessary to define with accuracy gross target volumes and clinical target volume with available radio-anatomical guidelines before introducing current constraints on each volume in the inverse dosimetry. The management of these constraints remains under the responsibility of the clinicians. A permanent compromise has to be chosen between homogeneity of the dose distribution in the target volume and the probability of preserving functions of organs at risk.

Brain Stem↗
PubMed2004

Conservative treatment of early glottic carcinomas with exclusive radiotherapy.

BACKGROUND: Early glottic carcinomas can be treated with radiotherapy or surgery with similar local control rates but with better functional results with radiotherapy. The aim of this study was to analyze the results of our experience of exclusive radiotherapy. PATIENTS AND METHODS: From 1975 to 2001, 155 patients with Tis, T1 and T2 glottic carcinomas were treated with exclusive radiotherapy. Prognostic factors of survival, local control and larynx-preservation rates were analyzed in uni and multivariate analyses. RESULTS: Median prescribed dose was 65 Gy in 44 days. Overall survival was 75% for the whole group, 75% for Tis, 85% for T1a, 72% for T1b, 59% for T2. Specific survival was 88% for the whole group, 75% for Tis, 94% for T1a, 90% for T1b, 69% for T2. Disease-free survival was 68% for the whole group, 75% for Tis, 77% for T1a, 51% for T1b, 58% for T2. Laryngeal preservation rate was 85% (133/155). Twenty-nine (29/155, 18%) patients developed a local relapse within 31 months. Out of the 10/86 (12%) T1a-Tis relapses, 7/10 patients underwent total laryngectomy and 79/86 larynx were preserved (92%). Out of the 8/22 (36%) T1b relapses, 4/8 patients underwent total laryngectomy. Out of the 11/47 (23%) T2 relapses, 8/11 patients underwent total laryngectomy. Increased overall treatment time, tumor stage, sub-glottis extension were associated with poorer local control. Second malignancies remain a major problem in the outcome of this population. CONCLUSION: Radiotherapy remains an efficient option in the treatment of early glottic carcinomas providing a high local control rate with excellent functional results in laryngectomy-free patients. This strategy should be discussed according to the tumor stage, feasibility of conservative surgery and patient's preferences.

Adult↗
PubMed2004

Preoperative chemoradiotherapy versus preoperative radiotherapy in rectal cancer patients: assessment of acute toxicity and treatment compliance. Report of the 22921 randomised trial conducted by the EORTC Radiotherapy Group.

The European Organisation for Research and Treatment of Cancer (EORTC) 22921 four-arm randomised trial questioned the value of preoperative chemoradiation (XRT-CT) versus preoperative radiation (XRT) and the value of additional postoperative chemotherapy (CT) versus none in T3-T4 M0 resectable rectal cancer patients. We report on the preoperative toxicity, treatment compliance and early deaths (all deaths up to 30 days after surgery) of the two treatment modalities in patients who were entered into trial before January 2001. In the XRT Group (group A), patients received 45 Gy, 25 fractions over 5 weeks. In the XRT-CT Group (group B), two 5-day courses of CT were added to the first and fifth weeks of XRT. For each CT course: 5-fluorouracil (5-FU) 350 mg/m2/day and Leucovorin (LV) 20 mg/m2/day were given. 398 and 400 patients started treatment in groups A and B, respectively. Grade 2+acute diarrhoea occurred in 17.3 and 34.3% of patients in groups A and B, respectively (P<0.005). The other side-effects remained unchanged or were only marginally increased. The compliance with RT was 98.5 and 95.5% in groups A and B, respectively. In group B, 78.7 and 71.1% of the patients received 95-105% of the planned CT doses at the first and second courses, respectively. 6 patients died preoperatively, 2 from toxicity in group B. 8 patients (1%) died within the 30 days after surgery in both groups. At the doses recommended in the protocol, the addition of 5-FU-LV to preoperative XRT slightly increased the amount of acute toxicity. However, the compliance with the radiation protocol or the feasibility of surgery did not decrease.

Adult↗
PubMed2004

[Recommendations for the definition of target volumes on computerized dosimetry in oropharyngeal cancers].

The oropharynx includes the base of tongue, tonsil pillars, soft palate, lateral and posterior wall of the hypopharynx. Tumors involving each part of these areas are often treated by external beam radiation therapy. The development of conformal approaches and the implementation of intensity modulated radiation therapy, combined with accurate definition of target volumes, endorsed by the international community, allows to propose guidelines for definition of target volumes. First of all imaging acquisition for dosimetry is reminded. For tumors involving the base of tongue and vallecula, early superficial tumors should be distinguished from tumors involving the muscles, indicating an increased margin defining the clinical target volume around the tumor to 1.5 cm. Tumors developed in the posterior wall of the hypopharynx should include constrictor muscles of the pharynx inside of the CTV. Tonsil carcinomas should be treated with a 1.5 cm margin around the tumor in the three dimensions. In spite of modern imaging, external beam treatment of tumors developed in the soft palate and in palatine arch remains difficult. The high rate of nodal involvement of these tumors and significant rates of bilateral extension have to be taken into consideration. Accurate criteria have been available to integrate a probability of bilateral extension in oropharyngeal tumors. It should be analyzed according to the size of the tumor and the rate of extension in the base of the tongue and in the palatine arch.

Brachytherapy↗
PubMed2004

[Preliminary results of the assessment of intensity modulated radiotherapy (IMRT) for prostatic and head and neck tumors (STIC 2001)].

INTRODUCTION: Between May 2002 and May 2004, eight French comprehensive cancer centres did a prospective nonrandomized study including 200 patients, 100 with cancer of the prostate and 100 with head and neck cancers. Half of each patient group was treated by IMRT and the others by RTC 3D. This clinical study was associated with an economic study and a physics study. We report here the first results. PATIENTS AND METHODS: For the clinical study, the analysis of the data of the first 88 patients irradiated for a prostatic cancer shows that 39 received RTC and 49 IMRT with a mean dose of 78 Gy at the ICRU point at 2 Gy per fraction. For H&N tumours, the preliminary analysis was done on the 87 first patients with a mean follow-up of 11.5 months (2 to 25 months) and a median of 8.4 months for the IMRT groups and 13.2 months for the RTC group. The economic study was done on the first 157 patients included during the first 18 months: 71 treated by RTC (35 for H&N and 36 for prostate) and 86 treated by IMRT (38 for H&N and 48 for prostate). The assessment of the direct costs was realized by a micro-costing technique. The physical study compared dose distributions for both techniques and has created quality control recommendations. RESULTS: Clinical studies of the acute reactions do not show any difference between groups, but we want to point out the short follow-up and the relatively high dose delivered to cancers of the prostate. The physics study demonstrates that IMRT is technically feasible in good clinical conditions with high quality assurance, a good reproducibility and precision. Dosimetric data show that IMRT could certainly spare organs at risk more than RTC for H&N tumours. The direct costs of "routine" treatments for H&N tumours were 4922 euros for IMRT versus 1899 euros for RTC and for the prostatic cancers 4911 euros for IMRT versus 2357 for RTC.

Adolescent↗
PubMed2003

Intramural neovascularization and haemorrhages are major long-term effects of intravascular gamma-radiation after stenting.

Structural changes that might influence the structural integrity of the vessel in response to intravascular brachytherapy (IVB) and stenting were examined, focus being on the importance of neovascularization in rabbit stented arteries. Stents were implanted in the infrarenal aortas of rabbits, immediately followed by gamma IVB or a sham radiation procedure, and the arteries harvested at 6 months. Labelling for von Willebrand factor showed an increase in adventitial and medial neovascularization in irradiated versus control arteries group (5.04+/-0.89 versus 1.51+/-0.23 mm(-2), respectively; p=0.004). Moreover, intramedial haemorrhages (free hemosiderin deposition) and inflammation (macrophages) were only observed in irradiated arteries. No significant change in expression of matrix metalloproteinase 1, 2 or 3 was observed between the irradiated and control group while collagen content decreased in the irradiated versus the control group (10.05%+/-1.48% versus 31.92%+/-3.12%, respectively; p<0.001). The study supports the hypothesis that IVB associated with stenting induces late deleterious effects on the medial layer, characterized by formation of intramural neovessels, haemorrhages and a decrease in collagen content.

Animals↗
PubMed2003

Effect of in vivo heart irradiation on coronary reactivity in the rat.

The frequent exposure of the heart to radiation during thoracic tumor radiotherapy often results in chronic impairment of myocardial function. The aim of the present investigation was to evaluate the effect of irradiation on coronary vascular tone in rat hearts exposed in vivo to a single dose of 20 Gy gamma rays. The ability of rat hearts to respond to changes in coronary reactivity was analyzed 1, 15, 30 and 60 days following cardiac irradiation, using the Langendorff model, after perfusion of either L-nitro-arginine (LNA), an inhibitor of nitric oxide synthetase or SIN 1, a nitric oxide donor drug. LNA-induced vasoconstriction and SIN 1-induced vasodilation were lost respectively 15 days and 30 days after irradiation, and associated with smooth muscle cell alterations observed in microscopy, but without any changes in myocardial MDA levels. Thus, our results suggest that 1) endothelium may represent an early and specific radiation target, characterized by radiation-induced vascular tone dysfunctions, with no detectable microscopical changes; 2) alterations are progressive, resulting first from endothelial damage, followed by smooth muscle cell injuries. In conclusion, a local cardiac irradiation induced cellular dysfunction, characterized by a loss of coronary reactivity without changes of the lipid peroxidation index in the hearts.

Animals↗
PubMed2003

[Endometrial carcinoma: which radiotherapy for which patient?].

The endometrial carcinoma is the third most common cancer in women. The endometrioid adenocarcinomas represent 75% to 80% of the pathologic sub-types, and 90% of the lesions are stages I or II at diagnosis. The treatment strategies are based upon surgery and radiotherapy, but the respective place of external irradiation and vaginal cuff brachytherapy is not strictly established. The role of the pelvic lymphadenectomy and the role of chemotherapy for aggressive histologies or locally advanced diseases remain also controversial issues. The question "which radiotherapy for which patient?" is still a current question, however, the answers we will bring do not permit yet to remove all uncertainties.

Age Factors↗