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Dive into the research topics where Mahmut Ozsahin is active.

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Featured researches published by Mahmut Ozsahin.


Cancer | 1994

Synchronous and metachronous head and neck carcinomas.

Laurent H. Schwartz; Mahmut Ozsahin; Ghua Ni Zhang; Emmanuel Touboul; Florent De Vataire; Pierre Andolenko; Jean Lacau-Saint-Guily; Alain Laugier; Michel Schlienger

Background. The incidence of head and neck cancer is increasing. To improve the survival of head and neck cancer patients, an effective program of screening and/or chemoprevention of second malignancies is essential. An analysis of the incidence, time to development, and risk factors of second malignant tumors in head and neck cancer patients can contribute to the design of effective screening and chemoprevention programs.


Journal of Clinical Oncology | 2004

Concomitant Cisplatin Significantly Improves Locoregional Control in Advanced Head and Neck Cancers Treated With Hyperfractionated Radiotherapy

Pia Huguenin; Karl T. Beer; Abdelkarim Said Allal; Kaspar Rufibach; Corinne Friedli; Jacques Bernard Davis; Bernhard C. Pestalozzi; Stephan Schmid; Armin Thöni; Mahmut Ozsahin; Jacques Bernier; Michael Töpfer; Roger Kann; Urs Richard Meier; Peter Thum; Sabine Bieri; Markus Notter; Norbert Lombriser; Christoph Glanzmann

PURPOSE To determine whether the application of two courses of cisplatin simultaneously with hyperfractionated radiotherapy improves the outcome in locally advanced and/or node-positive nonmetastatic carcinomas of the head and neck, compared with hyperfractionated radiotherapy alone. PATIENTS AND METHODS From July 1994 to July 2000, 224 patients with squamous cell carcinomas of the head and neck (excluding nasopharynx and paranasal sinus) were randomly assigned to hyperfractionated radiotherapy (median dose, 74.4 Gy; 1.2 Gy twice daily) or the same radiotherapy combined with two cycles of concomitant cisplatin (20 mg/m2 on 5 days of weeks 1 and 5). The primary end point was time to any treatment failure; secondary end points were locoregional failure, metastatic relapse, overall survival, and late toxicity. RESULTS There was no difference in radiotherapy between both treatment arms (74.4 Gy in 44 days). The full cisplatin dose was applied in 93% and 71% of patients during the first and second treatment cycles, respectively. Acute toxicity was similar in both arms. Median time to any treatment failure was not significantly different between treatment arms (19 months for combined treatment and 16 months for radiotherapy only, respectively) and the failure-free rate at 2.5 years was 45% and 33%, respectively. Locoregional control and distant disease-free survival were significantly improved with cisplatin (log-rank test, P = .039 and .011, respectively). The difference in overall survival did not reach significance (log-rank test, P = .147). Late toxicity was comparable in both treatment groups. CONCLUSION The therapeutic index of hyperfractionated radiotherapy is improved by concomitant cisplatin.


Clinical Cancer Research | 2005

CD4 and CD8 T-lymphocyte apoptosis can predict radiation-induced late toxicity: a prospective study in 399 patients.

Mahmut Ozsahin; Nigel E. A. Crompton; Sophie Gourgou; Andrew Kramar; Ling Li; Yu-Quan Shi; Wendy Jeanneret Sozzi; Abderrahim Zouhair; René O. Mirimanoff; D. Azria

Purpose: Predicting late effects in patients treated with radiation therapy by assessing in vitro radiation-induced CD4 and CD8 T-lymphocyte apoptosis can be useful in individualizing treatment. Experimental Design: In a prospective study, 399 curatively irradiated patients were tested using a rapid assay where fresh blood samples were in vitro irradiated with 8 Gy X-rays. Lymphocytes were collected and prepared for flow cytometric analysis. Apoptosis was assessed by associated condensation of DNA. The incidences of late toxicities were compared for CD4 and CD8 T-lymphocyte apoptoses using receiver-operating characteristic curves and cumulative incidence. Results: No association was found between early toxicity and T-lymphocyte apoptosis. Grade 2 and 3 late toxicities were observed in 31% and 7% of patients, respectively. More radiation-induced T-lymphocyte apoptosis was significantly associated with less grade 2 and 3 late toxicity (Grays test, P < 0.0001). CD8 (area under the curve = 0.83) was more sensitive and specific than CD4. No grade 3 late toxicity was observed for patients with CD4 and CD8 values greater than 15% and 24%, respectively. The 2-year cumulative incidence for grade 2 or 3 late toxicity was 70%, 32%, and 12% for patients with absolute change in CD8 T-lymphocyte apoptosis of ≤16, 16 to 24, and >24, respectively. Conclusions: Radiation-induced T-lymphocyte apoptosis can significantly predict differences in late toxicity between individuals. It could be used as a rapid screen for hypersensitive patients to radiotherapy. In future dose escalation studies, patients could be selected using the apoptosis assay.


Clinical Cancer Research | 2008

Single nucleotide polymorphisms, apoptosis, and the development of severe late adverse effects after radiotherapy.

David Azria; Mahmut Ozsahin; Andrew Kramar; Sheila Peters; David P. Atencio; Nigel E. A. Crompton; F. Mornex; André Pèlegrin; Jean-Bernard Dubois; René O. Mirimanoff; Barry S. Rosenstein

Purpose: Evidence has accumulated in recent years suggestive of a genetic basis for a susceptibility to the development of radiation injury after cancer radiotherapy. The purpose of this study was to assess whether patients with severe radiation-induced sequelae (RIS; i.e., National Cancer Institute/CTCv3.0 grade, ≥3) display both a low capacity of radiation-induced CD8 lymphocyte apoptosis (RILA) in vitro and possess certain single nucleotide polymorphisms (SNP) located in candidate genes associated with the response of cells to radiation. Experimental Design: DNA was isolated from blood samples obtained from patients (n = 399) included in the Swiss prospective study evaluating the predictive effect of in vitro RILA and RIS. SNPs in the ATM, SOD2, XRCC1, XRCC3, TGFB1, and RAD21 genes were screened in patients who experienced severe RIS (group A, n = 16) and control subjects who did not manifest any evidence of RIS (group B, n = 18). Results: Overall, 13 and 21 patients were found to possess a total of <4 and ≥4 SNPs in the candidate genes. The median (range) RILA in group A was 9.4% (5.3-16.5) and 94% (95% confidence interval, 70-100) of the patients (15 of 16) had ≥4 SNPs. In group B, median (range) RILA was 25.7% (20.2-43.2) and 33% (95% confidence interval, 13-59) of patients (6 of 18) had ≥4 SNPs (P < 0.001). Conclusions: The results of this study suggest that patients with severe RIS possess 4 or more SNPs in candidate genes and low radiation-induced CD8 lymphocyte apoptosis in vitro.


Radiotherapy and Oncology | 2009

High rate of severe radiation dermatitis during radiation therapy with concurrent cetuximab in head and neck cancer: Results of a survey in EORTC institutes

Christian Giro; Bernhard Berger; Edwin Bölke; I. Frank Ciernik; Fréderic Duprez; Laura Locati; Sophie Maillard; Mahmut Ozsahin; Raphael Pfeffer; A. Gerry Robertson; Johannes A. Langendijk; Wilfried Budach

OBJECTIVE Examination of the rate of grade III or grade IV radiation dermatitis during treatment of head and neck cancer (HNC) with radiotherapy (RT) and concurrent cetuximab in EORTC centres. MATERIALS AND METHOD A questionnaire was sent to all members of the EORTC Radiation Oncology Group and Head and Neck Group (111 institutions) to evaluate the widespread use of cetuximab and radiotherapy in HNC and to estimate the frequency of grades III and IV skin reactions in the radiation portals associated with this protocol. Co-morbidities, RT schedules and co-medications were also recorded. RESULTS We received responses from 28 institutions in 11 countries. A total of 125 HNC patients from 15 institutions were treated with cetuximab and concurrent RT. Information about the skin reactions was available from 71 patients. Of these 36 had no grade III/IV adverse effects in the RT field, 15 had a grade III and 20 had grade IV radiation dermatitis. No detectable relation of grades III and IV radiation dermatitis with co-morbidities such as liver insufficiency or renal dysfunction was found. CONCLUSION According to the results of the questionnaire, grade III/IV radiation dermatitis is observed in 49% of HNC patients treated with cetuximab and concurrent RT. A systematic clinical monitoring of cutaneous side effects during RT plus cetuximab is advised to ensure the safety of this protocol.


Lancet Oncology | 2006

Boost radiotherapy in young women with ductal carcinoma in situ: a multicentre, retrospective study of the Rare Cancer Network

Aurelius Omlin; Maurizio Amichetti; D. Azria; Bernard F. Cole; Philippe Fourneret; Philip Poortmans; Diana Naehrig; Robert C. Miller; Marco Krengli; Cristina Gutierrez Miguelez; D.A.L. Morgan; Hadassah Goldberg; Luciano Scandolaro; Pauline Gastelblum; Mahmut Ozsahin; Dagmar Dohr; David Christie; Ulrich Oppitz; Ufuk Abacioglu; Guenther Gruber

BACKGROUND Outcome data in young women with ductal carcinoma in situ (DCIS) are rare. The benefits of boost radiotherapy in this group are also unknown. We aimed to assess the effect of boost radiotherapy in young patients with DCIS. METHODS We included 373 women from 18 institutions who met the following inclusion criteria: having tumour status Tis and nodal status (N)0, age 45 years or younger at diagnosis, and having had breast-conserving surgery. 57 (15%) patients had no radiotherapy after surgery, 166 (45%) had radiotherapy without boost (median dose 50 Gy [range 40-60]), and 150 (40%) had radiotherapy with boost (60 Gy [53-76]). The primary outcome was local relapse-free survival. FINDINGS Median follow-up was 72 months (range 1-281). 55 (15%) patients had local relapse. Local relapse-free survival at 10 years was 46% (95% CI 24-67) for patients given no radiotherapy, 72% (61-83) for those given radiotherapy without boost, and 86% (78-93) for those given radiotherapy and boost (difference between all three groups, p<0.0001). Age, margin status, and radiotherapy dose were significant predictors of local relapse-free survival. Compared with patients who had no radiotherapy, those who had radiotherapy had a decreased risk of local relapse (without boost, hazard ratio 0.33 [95% CI 0.16-0.71], p=0.004; with boost, 0.15 [0.06-0.36], p<0.0001). INTERPRETATION In the absence of randomised trials, boost radiotherapy should be considered in addition to surgery for breast-conserving treatment for DCIS.


International Journal of Radiation Oncology Biology Physics | 2003

Outcome and prognostic factors in orbital lymphoma: a Rare Cancer Network study on 90 consecutive patients treated with radiotherapy.

Sylvie Martinet; Mahmut Ozsahin; Yazid Belkacemi; Christine Landmann; Philip Poortmans; Christoph Oehlere; Luciano Scandolaro; Marco Krengli; Philippe Maingon; Raymond Miralbell; Gabriela Studer; B. Chauvet; Simone Marnitz; Abderrahim Zouhair; René-Olivier Mirimanoff

PURPOSE To assess the outcome and prognostic factors in patients with orbital lymphoma treated by radiotherapy (RT). METHODS AND MATERIALS Between 1980 and 1999, 90 consecutive patients with primary orbital lymphoma were treated in 13 member institutions of the Rare Cancer Network. A full staging workup was completed in 56 patients. Seventy-eight patients had low-, 6 intermediate-, and 6 high-grade lymphoma, and 75 had a single orbital localization. All patients underwent RT with a median dose of 34.2 Gy (range 4.0-50.4). Eleven patients received chemotherapy in addition to RT. RESULTS After RT, local control was achieved in 97% of the patients. Local progression occurred in 2% and local relapse 1%. The rate of systemic relapse was 20%, and 9% of the patients developed metachronous contralateral eye involvement. The 5-year disease-free survival, overall survival, and cause-specific survival rate was 65%, 78%, and 87%, respectively. In univariate analyses, the statistically significant favorable prognostic factors were younger age, low grade, normal erythrocyte sedimentation rate, absence of muscular infiltration, complete response to treatment, conjunctival localization, and normal lactate dehydrogenase value for overall survival, disease-free survival, and freedom from treatment failure. In multivariate analysis, the favorable factors were younger age and low grade for overall and disease-free survival; a favorable response, conjunctival localization, and complete staging were highly significant for disease-free survival and freedom from treatment failure. Neither the RT technique nor the total dose influenced the outcome. Cataract and xerophthalmia were the most prominent late toxicities. CONCLUSION Moderate- to low-dose RT alone is able to control primary orbital lymphoma with low morbidity. A full staging workup is warranted in these patients. Prognostic factors were identified that could be useful in the overall management of this uncommon site of primary lymphoma.


Radiation Oncology | 2006

The epidermal growth factor receptor (EGFR) in head and neck cancer: its role and treatment implications

Michel Zimmermann; Abderrahim Zouhair; D. Azria; Mahmut Ozsahin

Epidermal growth factor receptor (EGFR) is a member of the ErbB family of receptors. Its stimulation by endogenous ligands, EGF or transforming growth factor-alpha (TGF-α) results in activation of intracellular tyrosine kinase, therefore, cell cycle progression. High levels of EGFR expression are correlated with poor prognosis and resistance to radiation therapy in a variety of cancers, mostly in squamous-cell carcinoma of the head and neck (SCCHN). Blocking the EGFR by a monoclonal antibody results in inhibition of the stimulation of the receptor, therefore, in inhibition of cell proliferation, enhanced apoptosis, and reduced angiogenesis, invasiveness and metastases. The EGFR is a prime target for new anticancer therapy in SCCHN, and other agents in development include small molecular tyrosine kinase inhibitors and antisense therapies.


Radiotherapy and Oncology | 2009

EGFr inhibitor toxicityHigh rate of severe radiation dermatitis during radiation therapy with concurrent cetuximab in head and neck cancer: Results of a survey in EORTC institutes

Christian Giro; Bernhard Berger; Edwin Bölke; I. Frank Ciernik; Fréderic Duprez; Laura Locati; Sophie Maillard; Mahmut Ozsahin; Raphael Pfeffer; A. Gerry Robertson; Johannes A. Langendijk; Wilfried Budach

OBJECTIVE Examination of the rate of grade III or grade IV radiation dermatitis during treatment of head and neck cancer (HNC) with radiotherapy (RT) and concurrent cetuximab in EORTC centres. MATERIALS AND METHOD A questionnaire was sent to all members of the EORTC Radiation Oncology Group and Head and Neck Group (111 institutions) to evaluate the widespread use of cetuximab and radiotherapy in HNC and to estimate the frequency of grades III and IV skin reactions in the radiation portals associated with this protocol. Co-morbidities, RT schedules and co-medications were also recorded. RESULTS We received responses from 28 institutions in 11 countries. A total of 125 HNC patients from 15 institutions were treated with cetuximab and concurrent RT. Information about the skin reactions was available from 71 patients. Of these 36 had no grade III/IV adverse effects in the RT field, 15 had a grade III and 20 had grade IV radiation dermatitis. No detectable relation of grades III and IV radiation dermatitis with co-morbidities such as liver insufficiency or renal dysfunction was found. CONCLUSION According to the results of the questionnaire, grade III/IV radiation dermatitis is observed in 49% of HNC patients treated with cetuximab and concurrent RT. A systematic clinical monitoring of cutaneous side effects during RT plus cetuximab is advised to ensure the safety of this protocol.


BMC Cancer | 2006

Prognostic factors in solitary plasmacytoma of the bone: a multicenter Rare Cancer Network study

David Knobel; Abderrahim Zouhair; Richard Tsang; Philip Poortmans; Yazid Belkacemi; Michel Bolla; Fazilet Dinçbas Oner; Christine Landmann; Bernard Castelain; Mahmut Ozsahin

BackgroundSolitary plasmacytoma (SP) of the bone is a rare plasma-cell neoplasm. There are no conclusive data in the literature on the optimal radiation therapy (RT) dose in SP. Therefore, in this large retrospective study, we wanted to assess the outcome, prognostic factors, and the optimal RT dose in patients with SP.MethodsData from 206 patients with bone SP without evidence of multiple myeloma (MM) were collected. Histopathological diagnosis was obtained for all patients. The majority (n = 169) of the patients received RT alone; 32 chemotherapy and RT, and 5 surgery. Median follow-up was 54 months (7–245).ResultsFive-year overall survival, disease-free survival (DFS), and local control was 70%, 46%, and 88%; respectively. Median time to MM development was 21 months (2–135) with a 5-year probability of 51%. In multivariate analyses, favorable factors were younger age and tumor size < 5 cm for survival; younger age for DFS; anatomic localization (vertebra vs. other) for local control. Older age was the only predictor for MM. There was no dose-response relationship for doses 30 Gy or higher, even for larger tumors.ConclusionYounger patients, especially those with vertebral localization have the best outcome when treated with moderate-dose RT. Progression to MM remains the main problem. Further investigation should focus on adjuvant chemotherapy and/or novel therapeutic agents.

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Philip Poortmans

Radboud University Nijmegen

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