Suzushi Kusano

Visceral fat area and markers of insulin resistance in relation to colorectal neoplasia

OBJECTIVE Although abdominal obesity and related metabolic abnormalities are hypothesized to promote colorectal carcinogenesis, direct confirmation of this effect is required. Here, we examined the relation of early-stage colorectal neoplasia to visceral fat area and markers of insulin resistance. RESEARCH DESIGN AND METHODS Subjects were participants in a comprehensive health screening conducted at the Hitachi Health Care Center, Ibaraki, Japan. During a 3-year period (2004–2007), a total of 108 patients with early-stage colorectal neoplasia, including 22 with early cancer, were identified among individuals who received both colorectal cancer screening and abdominal computed tomography scanning. Three control subjects matched to each case subject were randomly selected from those whose screening results were negative. Conditional logistic regression analysis was used to examine the association of measures of obesity and markers of insulin resistance with colorectal neoplasia, with adjustment for smoking and alcohol drinking. RESULTS Visceral fat area, but not subcutaneous fat area, was significantly positively associated with colorectal cancer, with odds ratios (95% CI) for the lowest to highest tertile of visceral fat area of 1 (reference), 2.17 (0.45–10.46), and 5.92 (1.22–28.65), respectively (Ptrend = 0.02). Markers of insulin resistance, particularly fasting glucose, were also positively associated with colorectal cancer risk. In contrast, no associations were observed for colorectal adenomas. CONCLUSIONS These results suggest that visceral adipose tissue accumulation and insulin resistance may promote the development of early-stage cancer but not adenoma in the colorectum.

A decrease in lung cancer mortality following the introduction of low-dose chest CT screening in Hitachi, Japan

Recent US clinical trial demonstrated that CT screening prevents lung cancer death among high risk individuals. However, it remains unclear whether wide implementation of low-dose CT screening for lung cancer can decrease mortality in the community. Among residents in Hitachi City (Japan), where nearly 40% of inhabitants aged 50-69 years were estimated to have participated in the screening at least once from 1998 through 2009, the trend of lung cancer mortality was described in relation to the timing of implementation of the CT screening. Cancer mortality data were obtained from regional cancer registry and standardized mortality ratio (SMR) of lung cancer was calculated for each 5-year period during 1995-2009. In both men and women aged 60 years or older, age-specific lung cancer mortality rates were generally lower during 2005-2009 as compared with those during 1995-2004. For combined men and women aged 50-79 years, SMR was nearly unity prior to or during introductory phase of CT screening and during early period of implementation; however, it was significantly decreased during 2005-2009, well after the implementation of CT screening, with SMR (95% confidence interval) being 0.76 (0.67-0.86). Results suggest that wide implementation of low-dose chest CT screening may decrease lung cancer mortality in the community 4-8 years after introduction of the screening.

Long-term prognosis of patients with lung cancer detected on low-dose chest computed tomography screening

The effectiveness of lung cancer screening using low-dose chest computed tomography (CT) remains elusive. The present study examined the prognosis of patients with lung cancer detected on CT screening in Japanese men and women. Subjects were 210 patients with primary lung cancer identified on CT screening at two medical facilities in Hitachi, Japan, where a total of 61,914 CT screenings were performed among 25,385 screenees between 1998 and 2006. Prognostic status of these patients was sought by examining medical records at local hospitals, supplemented by vital status information from local government. The 5-year survival rate was estimated according to the characteristics of patients and lung nodule. A total of 203 (97%) patients underwent surgery. During a 5.7-year mean follow-up period, 19 patients died from lung cancer and 6 died from other causes. The estimated 5-year survival rate for all patients and for those on stage IA was 90% and 97%, respectively. Besides cancer stage, smoking and nodule appearance were independent predictors of a poor survival; multivariable-adjusted hazard ratio (95% confidence interval) was 4.7 (1.3, 16.5) for current and past smokers versus nonsmokers and 4.6 (1.6, 13.9) for solid nodule versus others. Even patients with solid shadow had a 5-year survival of 82% if the lesion was 20mm or less in size. Results suggest that lung cancers detected on CT screening are mostly curative. The impact of CT screening on mortality at community level needs to be clarified by monitoring lung cancer deaths.

Efficacy of computer-aided diagnosis in lung cancer screening with low-dose spiral computed tomography: receiver operating characteristic analysis of radiologists’ performance

PurposeThe aim of this study was to evaluate the efficacy of a computer-aided diagnosis (CAD) system we developed that can also respond to subsolid nodules, for lung cancer screening using low-dose spiral computed tomography (LDCT).Materials and methodsThe institutional review board approved this study. A total of 30 positive cases (including 15 lung cancer cases) that needed further examination and 30 negative cases were used for the observer performance study. Three thoracic radiologists, five general radiologists, and three residents participated in this study in which they first read the original CT image on its own and then reassessed the same image with the assistance of CAD. Radiologists’ performance was evaluated using receiver operating characteristic (ROC) analysis.ResultsThe Az values without and with CAD were 0.872 and 0.910 for the thoracic radiologists, 0.864 and 0.924 for general radiologists, and 0.875 and 0.837 for residents, respectively. The detection accuracy improved significantly for the thoracic and general radiologists with our CAD system; however, no statistically significant difference between without or with CAD was seen for residents.ConclusionThis CAD system is beneficial in the detection of pulmonary nodules on LDCT when used by experienced radiologists.