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Nasopharyngeal Tumors (nasopharyngeal + tumor)

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Medical Sciences	100%

Selected Abstracts

Comparison of intensity modulated radiation therapy (IMRT) treatment techniques for nasopharyngeal carcinoma

INTERNATIONAL JOURNAL OF CANCER, Issue 2 2001
Jason Chia-Hsien Cheng M.D.
Abstract We studied target volume coverage and normal tissue sparing of serial tomotherapy intensity modulated radiation therapy (IMRT) and fixed-field IMRT for nasopharyngeal carcinoma (NPC), as compared with those of conventional beam arrangements. Twelve patients with NPC (T2-4N1-3M0) at Mallinckrodt Institute of Radiology underwent computed tomography simulation. Images were then transferred to a virtual simulation workstation computer for target contouring. Target gross tumor volumes (GTV) were primary nasopharyngeal tumor (GTVNP) with a prescription of 70 Gy, grossly enlarged cervical nodes (GTVLN) with a prescription of 70 Gy, and the uninvolved cervical lymphatics [designated as the clinical tumor volume (CTV)] with a prescription of 60 Gy. Critical organs, including the parotid gland, spinal cord, brain stem, mandible, and pituitary gland, were also delineated. Conventional beam arrangements were designed following the guidelines of Intergroup (SWOG, RTOG, ECOG) NPC Study 0099 in which the dose was prescribed to the central axis and the target volumes were aimed to receive the prescribed dose ± 10%. Similar dosimetric criteria were used to assess the target volume coverage capability of IMRT. Serial tomotherapy IMRT was planned using a 0.86-cm wide multivane collimator, while a dynamic multileaf collimator system with five equally spaced fixed gantry angles was designated for fixed-beam IMRT. The fractional volume of each critical organ that received a certain predefined threshold dose was obtained from dose-volume histograms of each organ in either the three-dimensional or IMRT treatment planning computer systems. Statistical analysis (paired t -test) was used to examine statistical significance. We found that serial tomotherapy achieved similar target volume coverage as conventional techniques (97.8 ± 2.3% vs. 98.9 ± 1.3%). The static-field IMRT technique (five equally spaced fields) was inferior, with 92.1 ± 8.6% fractional GTVNP receiving 70 Gy ± 10% dose (P < 0.05). However, GTVLN coverage of 70 Gy was significantly better with both IMRT techniques (96.1 ± 3.2%, 87.7 ± 10.6%, and 42.2 ± 21% for tomotherapy, fixed-field IMRT, and conventional therapy, respectively). CTV coverage of 60 Gy was also significantly better with the IMRT techniques. Parotid gland sparing was quantified by evaluating the fractional volume of parotid gland receiving more than 30 Gy; 66.6 ± 15%, 48.3 ± 4%, and 93 ± 10% of the parotid volume received more than 30 Gy using tomotherapy, fixed-field IMRT, and conventional therapy, respectively (P < 0.05). Fixed-field IMRT technique had the best parotid-sparing effect despite less desirable target coverage. The pituitary gland, mandible, spinal cord, and brain stem were also better spared by both IMRT techniques. These encouraging dosimetric results substantiate the theoretical advantage of inverse-planning IMRT in the management of NPC. We showed that target coverage of the primary tumor was maintained and nodal coverage was improved, as compared with conventional beam arrangements. The ability of IMRT to spare the parotid glands is exciting, and a prospective clinical study is currently underway at our institution to address the optimal parotid dose-volume needs to be spared to prevent xerostomia and to improve the quality of life in patients with NPC. © 2001 Wiley-Liss, Inc. [source]

Particle beam radiotherapy for head and neck tumors: Radiobiological basis and clinical experience

HEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 8 2006
Barbara Alicja Jereczek-Fossa MD
Abstract Background. Head and neck tumors are often located near critical organs, making it impossible to deliver a dose of conventional radiotherapy high enough to eradicate the disease. Our aim was to review the potential benefits and available clinical experience of particle beam therapy (hadrontherapy) in the treatment of these tumors. Methods. A review of the literature was carried out through a MEDLINE search (publications between 1980 and 2005). Results. A review of the available clinical data shows that particle beam therapy can offer several radiobiological and physical advantages over conventional photon radiotherapy: improved dose distribution permits dose escalation within the target and optimal sparing of normal tissue. Preclinical and clinical studies suggest that there may be benefits to using hadrontherapy for tumors characterized by poor radiosensitivity and critical location. At present, the most used hadrons are protons and, as yet on an experimental basis, carbon ions. It is now well accepted that there are certain indications for using proton therapy for skull base tumors (chordoma and chondrosarcoma), paranasal sinus carcinomas, selected nasopharyngeal tumors, and neutron/ion therapy for salivary gland carcinomas (in particular, adenoid cystic tumors). Its viability in other cases, such as locally advanced squamous cell carcinoma, melanoma, soft tissue sarcoma, and bone sarcoma, is still under investigation. Conclusions. Hadrontherapy can be beneficial in the treatment of tumors characterized by poor radiosensitivity and critical location. Further clinical and radiobiological studies are warranted for improved selection of patient population. © 2006 Wiley Periodicals, Inc. Head Neck, 2006 [source]

Occupational risk in health care and research,

AMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 4 2003
Daniela Vecchio MS
Abstract Background Working in the health care and research sectors has been linked to various hazards. Methods Studies published in the peer-reviewed literature that are pertinent to the exposures or diseases relevant to these fields were reviewed. Results The most important exposures include infectious agents, formaldehyde, anesthetic agents, antineoplastic drugs, and ethylene oxide. The best-documented evidence is that of infectious risk primarily among clinical personnel. Monitoring studies of persons occupationally exposed to anesthetics clearly demonstrate behavioral effects, possible risk of reproductive problems, as well as cytogenetic effects of unknown significance. The latter two impairments are also observed among those exposed to antineoplastic drugs and ethylene oxide. Exposure to formaldehyde appears to be associated with nasopharyngeal tumors. Whereas increased risk of cancer of certain sites, particularly the brain and lymphohematopoietic system, is found among research and health care personnel, no specific exposure has been linked to these neoplasms. Conclusions Although some results are inconsistent, continued environmental and biological monitoring will allow better assessment of exposures and of implemented protection measures. Am. J. Ind. Med. 43:369,397, 2003. © 2003 Wiley-Liss, Inc. [source]

In Vivo Diagnosis of Nasopharyngeal Carcinoma Using Contact Rhinoscopy

THE LARYNGOSCOPE, Issue 8 2001
Martin Wai Pak FRCSEd(ORL)
Abstract Objectives To evaluate the potential use of contact endoscopy for the diagnosis of nasopharyngeal carcinoma (NPC). Study Design Prospective study to examine the nasopharynx of 30 patients with nasopharyngeal carcinoma and 18 subjects with normal nasopharynx in a clinic setting using contact rhinoscopes (Karl Storz, Tuttlingen, Germany, 7215 AA, 00 and 7215 BA, 300; 23 cm long; 4 mm in diameter). Methods The superficial cells of the normal nasopharynx and the nasopharyngeal tumors were stained with 1% methylene blue and examined with contact rhinoscopes at high magnifications (×60 and ×150). The areas under examination were then biopsied. The contact endoscopic images were compared with the corresponding hematoxylin and eosin-stained histologic sections of the biopsied tissues. Results Sixty-six procedures were performed in 48 patients. The images of normal pseudostratified ciliated epithelium and squamous epithelium were readily recognized by contact endoscopy in all subjects with normal nasopharynx (10 men and 8 women; mean age, 51.9 y). Twenty-six of 30 patients with NPC (86.6%; 18 men and 8 women; mean age, 50.6 y) were successfully examined by contact endoscopy under local anesthesia. In these 26 patients, two patterns of malignant cells were identified with contact endoscopy. The patterns of contact endoscopic images corresponded well with the histologic findings. Conclusion Contact endoscopy is an accurate and reliable office-based procedure, which allows for in-vivo diagnosis of nasopharyngeal carcinoma. [source]