Comparison of repositioning accuracy of two commercially available immobilization systems for treatment of head-and-neck tumors using simulation computed tomography imaging.

PURPOSE: To compare the setup accuracy, comfort level, and setup time of two immobilization systems used in head-and-neck radiotherapy. METHODS AND MATERIALS: Between February 2004 and January 2005, 21 patients undergoing radiotherapy for head-and-neck tumors were assigned to one of two immobilization devices: a standard thermoplastic head-and-shoulder mask fixed to a carbon fiber base (Type S) or a thermoplastic head mask fixed to the Accufix cantilever board equipped with the shoulder depression system. All patients underwent planning computed tomography (CT) followed by repeated control CT under simulation conditions during the course of therapy. The CT images were subsequently co-registered and setup accuracy was examined by recording displacement in the three cartesian planes at six anatomic landmarks and calculating the three-dimensional vector errors. In addition, the setup time and comfort of the two systems were compared. RESULTS: A total of 64 CT data sets were analyzed. No difference was found in the cartesian total displacement errors or total vector displacement errors between the two populations at any landmark considered. A trend was noted toward a smaller mean systemic error for the upper landmarks favoring the Accufix system. No difference was noted in the setup time or comfort level between the two systems. CONCLUSION: No significant difference in the three-dimensional setup accuracy was identified between the two immobilization systems compared. The data from this study reassure us that our technique provides accurate patient immobilization, allowing us to limit our planning target volume to <4 mm when treating head-and-neck tumors.

Occupation and larynx and hypopharynx cancer: an international case-control study in France, Italy, Spain, and Switzerland.

OBJECTIVE: To estimate risks for laryngeal/hypopharyngeal cancer associated with occupational titles and industrial activities. METHODS: A multicentre population-based case-control study was conducted in the early 1980s in six southern European areas. Analyses included 1010 male cases and 2176 controls. Odds ratios (ORs) (adjusted for age, study area, tobacco consumption, and alcohol consumption) were estimated for 156 occupations and 70 industrial activities. RESULTS: An excess risk has been confirmed for categories of construction workers, potters (OR: 5.91, 95% confidence intervals 1.46-24.0), butchers (2.53, 1.22-5.22), barbers (2.33, 1.00-5.40), laborers not otherwise specified (1.52, 1.12-2.06), as well as for men who had been employed in railway transport (1.52, 0.97-2.39), shipbuilding (2.05, 0.89-4.94), and hotels (2.06, 0.89-4.75). An association was also found for shoe finishers (3.23, 0.75-13.9), loggers (2.07, 0.87-4.90), and some groups of metal workers. ORs for loggers, butchers, railway transport workers, laborers, and reinforced concreters increased with duration of employment. The suggestion of a risk for machine operators among woodworkers (3.10, 0.92-10.5) conflicts with previous findings. No significant excess of risk was found for categories previously reported to be associated with laryngeal and hypopharyngeal cancer, such as drivers, mechanics, welders, machinists, and painters. CONCLUSIONS: The present study provides additional evidence to the hypothesis of a risk of cancer of the larynx/ hypopharynx for workers engaged in jobs in the construction, metal, textile, ceramic, and food industries and in railway transport. Loggers were also found at risk; a previously unreported finding.

Occupation and larynx and hypopharynx cancer: a job-exposure matrix approach in an international case-control study in France, Italy, Spain and Switzerland.

OBJECTIVE: To investigate the effect of exposure to occupational agents on the risk of hypopharyngeal/laryngeal cancer. METHODS: Case-control study conducted during 1979-1982 in six centres in South Europe. An occupational history and information on exposure to non-occupational factors were collected for 1010 male cases of hypopharyngeal/ laryngeal cancer as well as for 2176 population controls. The exposure to 10 occupational agents was assessed through a job-exposure matrix. As occupational histories had been collected since 1945 major analyses were restricted to subjects aged less than 55 years (315 cases and 819 controls). RESULTS: Significant elevated risks adjusted for non-occupational variables (smoking, alcohol consumption and diet) and other occupational exposures were consistently found for organic solvents (odds ratio (OR) for ever-exposure: 1.7, 95% confidence interval: 1.1-2.5) and asbestos (OR: 1.6, 1.0-2.5). A significant positive trend for both probability of exposure and duration was found for exposure to solvents. A positive association between exposure to formaldehyde and laryngeal cancer was also suggested. No association was found for exposure to arsenic and compounds, chromium and compounds, and polycyclic aromatic hydrocarbons. Analyses restricted to subjects aged 55 or more did not show elevated risks, with the exception of wood dust (OR: 1.8, 1.3-2.7). CONCLUSIONS: In our study occupational exposure to solvents was associated with an increased risk of hypopharyngeal/laryngeal cancer. Results also provide additional evidence of an excess of risk for exposure to asbestos.

Diagnostic changes as a reason for the increase in papillary thyroid cancer incidence in Geneva, Switzerland.

OBJECTIVE: Several studies have reported upward incidence trends of papillary thyroid cancer. It is unclear whether these trends reflect a real risk increase, by some attributed to iodine supplementation, or an artificial one, due to increased diagnostic activity or changed histological criteria. This study examines if these artificial factors explain the increased papillary thyroid cancer incidence in the Swiss canton of Geneva. METHODS: All thyroid carcinomas (n = 436) recorded between 1970 and 1998 at the Geneva Cancer Registry were considered. European age-adjusted incidence trends were estimated using linear regression analysis. For papillary cancers we evaluated diagnostic modalities and way of presentation (in particular microcarcinoma < 1 cm or silent carcinoma). In addition, we reviewed the histological slides of follicular carcinomas. RESULTS: Papillary thyroid cancer incidence increased significantly from 0.7 to 1.8/100,000 for men and from 3.1 to 4.3/100,000 for women between 1970-74 and 1995-98. The proportion of microcarcinomas and silent carcinomas increased from 17% to 24% between 1970-79 and 1990-98. At histological review, follicular cancers were more often reclassified as papillary cancer for cases diagnosed between 1970 and 1979 than for cases diagnosed between 1990 and 1998 (45% vs 25%, p = n.s.). CONCLUSIONS: The increasing papillary thyroid cancer incidence seems mainly due to changes in histological diagnostic criteria and, to a lesser extent, to increased diagnostic activity. If confirmed, the results of this study indicate that fears of increasing incidence rates of papillary thyroid cancer should not prevent implementation of adequate programs of iodine supplementation in the many areas where iodine deficiency still prevails.