Gabriel Chodick

Risk of cataract after exposure to low doses of ionizing radiation: a 20-year prospective cohort study among US radiologic technologists.

The study aim was to determine the risk of cataract among radiologic technologists with respect to occupational and nonoccupational exposures to ionizing radiation and to personal characteristics. A prospective cohort of 35,705 cataract-free US radiologic technologists aged 24-44 years was followed for nearly 20 years (1983-2004) by using two follow-up questionnaires. During the study period, 2,382 cataracts and 647 cataract extractions were reported. Cigarette smoking for >or=5 pack-years; body mass index of >or=25 kg/m(2); and history of diabetes, hypertension, hypercholesterolemia, or arthritis at baseline were significantly (p <or= 0.05) associated with increased risk of cataract. In multivariate models, self-report of >or=3 x-rays to the face/neck was associated with a hazard ratio of cataract of 1.25 (95% confidence interval: 1.06, 1.47). For workers in the highest category (mean, 60 mGy) versus lowest category (mean, 5 mGy) of occupational dose to the lens of the eye, the adjusted hazard ratio of cataract was 1.18 (95% confidence interval: 0.99, 1.40). Findings challenge the National Council on Radiation Protection and International Commission on Radiological Protection assumptions that the lowest cumulative ionizing radiation dose to the lens of the eye that can produce a progressive cataract is approximately 2 Gy, and they support the hypothesis that the lowest cataractogenic dose in humans is substantially less than previously thought.

Assessment of ecological regression in the study of colon, breast, ovary, non-Hodgkin's lymphoma, or prostate cancer and residential UV.

Recent ecological studies have suggested a possible association between exposure to ultraviolet-B (UVB) radiation and reduction in the risk of various cancers; however, ecological studies are known to be subject to bias. The objective of this study was to demonstrate difficulties with the ecological approach. We conducted a multicountry ecological study using cancer incidence rates, residential UV levels, dietary intake, and different sociodemographic variables for 38 locations spanning 33 countries worldwide. The effect of residential UV exposure on cancer incidence was assessed using multiple linear regression models. The results of our multivariate analyses show no indication of an inverse association between residential UV levels and the risk of colon, non-Hodgkins lymphoma (NHL), ovarian, prostate, or breast cancer in women. For colon cancer and NHL, a significant positive association was calculated. The rates of melanoma, which were used to examine the methods of this study, showed a strong and significant (P<0.01) association with solar radiation. Our results provide no evidence to support previous ecological results that UV exposure may reduce the risk of NHL, colon, breast, ovary, or prostate cancer. The study demonstrates the high sensitivity of ecological studies to adjustments for various confounders, and casts doubts on results of ecological analyses in this field.

Risk of cataract extraction among adult retinoblastoma survivors

OBJECTIVE To investigate the risk of cataract extraction among adult retinoblastoma survivors. DESIGN A retrospective cohort study was performed on retinoblastoma survivors who received the diagnosis from 1914 to 1984 and were interviewed in 2000. Lens doses were estimated from radiotherapy records. The cumulative time interval to cataract extraction between dose groups was compared using the log-rank test and Cox regression. RESULTS Seven hundred fifty-three subjects (828 eyes) were available for analysis for an average of 32 years of follow-up. During this period, 51 cataract extractions were reported. One extraction was reported in an eye with no radiotherapy compared with 36 extractions in 306 eyes with 1 course of radiotherapy and 14 among 38 eyes with 2 or 3 treatments. The average time interval to cataract extraction in irradiated eyes was 51 years (95% confidence interval [CI], 48-54) following 1 treatment and 32 years (95% CI, 27-37) after 2 or 3 treatments. Eyes exposed to a therapeutic radiation dose of 5 Gy or more had a 6-fold increased risk (95% CI, 1.3-27.2) of cataract extraction compared with eyes exposed to 2.5 Gy or less. CONCLUSIONS The results emphasize the importance of ophthalmologic examination of retinoblastoma survivors who have undergone radiotherapy. The risk of cataract extraction in untreated eyes with retinoblastoma is comparable with the risk of the general population.

Computer-Assisted Flagging of Individuals at High Risk of Colorectal Cancer in a Large Health Maintenance Organization Using the ColonFlag Test

PURPOSE To evaluate in a sample of adults who had been noncompliant with colorectal cancer (CRC) screening whether screening could be enhanced by an automated patient recall system based on identifying high-risk individuals using the ColonFlag test and an electronic medical record database. METHODS A total of 79,671 individuals who were determined to be noncompliant with current screening recommendations were identified in the Maccabi Health Services program in Israel. Their cancer risk was determined by ColonFlag using information on age, sex, and CBC results. Doctors of individuals who were flagged as high risk were notified and asked to follow up with their patients. RESULTS The ColonFlag identified 688 men and women who scored in the highest 0.87 percentile. Of these individuals, 254 had colonoscopies performed by Maccabi physicians, and 19 CRCs (7.5%) were found. An additional 15 cancers primarily identified outside of Maccabi were found through code matching. CONCLUSION The ColonFlag test is a rapid, efficient, and inexpensive test that can be applied to scan electronic medical records to identify individuals at high risk of CRC who would otherwise avoid screening.