Lifetime exposure to ultraviolet radiation and the risk of multiple sclerosis in the US radiologic technologists cohort study.

BACKGROUND: Low exposure to ultraviolet radiation (UVR) from sunlight may be a risk factor for developing multiple sclerosis (MS). Possible pathways may be related to effects on immune system function or vitamin D insufficiency, as UVR plays a role in the production of the active form of vitamin D in the body. OBJECTIVE: This study examined whether lower levels of residential UVR exposure from sunlight were associated with increased MS risk in a cohort of radiologic technologists. METHODS: Participants in the third and fourth surveys of the US Radiologic Technologists (USRT) Cohort Study eligible (N = 39,801) for analysis provided complete residential histories and reported MS diagnoses. MS-specialized neurologists conducted medical record reviews and confirmed 148 cases. Residential locations throughout life were matched to satellite data from NASA's Total Ozone Mapping Spectrometer (TOMS) project to estimate UVR dose. RESULTS: Findings indicate that MS risk increased as average lifetime levels of UVR exposures in winter decreased. The effects were consistent across age groups <40 years. There was little indication that low exposures during summer or at older ages were related to MS risk. CONCLUSION: Our findings are consistent with the hypothesis that UVR exposure reduces MS risk and may ultimately suggest prevention strategies.

Lipid-lowering drugs, dyslipidemia, and breast cancer risk in a Medicare population.

PURPOSE: We sought to disentangle the effects of statins and other lipid-lowering drugs and the underlying dyslipidemia for which they are prescribed on breast cancer risk. METHODS: We conducted a case-control study within the linked Surveillance, Epidemiology, and End results (SEER)-Medicare data. Cases were women with invasive breast cancer aged 66 + years (N = 30,004) identified by SEER registries (years 2007-2011). Controls were women (N = 198,969) identified from a 5% random sample of Medicare recipients alive and breast cancer free in year of selection. Participants had a minimum of 13 months of Part A, Part B non-health maintenance organization Medicare and Part D Medicare coverage at least 13 months preceding cancer diagnosis/selection. Exposures were assessed until 12 months before diagnosis/control selection. Odds ratios (OR) and 99.9% confidence intervals (CI) were estimated using adjusted unconditional and multinomial logistic regression. RESULTS: ORs of invasive breast cancer associated with dyslipidemia, statins, and non-statin lipid-lowering drugs were 0.86 (99.9% CI 0.81-0.90), 1.07 (99.9% CI 1.03-1.13) and 1.03 (99.9% CI 0.95-1.11), respectively. Risk reductions with dyslipidemia were slightly greater when untreated than treated and did not vary much by time between dyslipidemia and breast cancer diagnosis. Whether treated or untreated, dyslipidemia was associated with greater reductions in risk for later stage than earlier stage breast cancer (p-heterogeneity < 0.0001). CONCLUSIONS: Lipid-lowering drugs did not account for the lower breast cancer risk associated with dyslipidemia. Our data do not support using statins or other lipid-lowering drugs to prevent breast cancer.

Relationship between ambient ultraviolet radiation and Hodgkin lymphoma subtypes in the United States.

BACKGROUND: There are few modifiable risk factors for Hodgkin lymphoma (HL), the most common cancer among young adults in Western populations. Some studies have found a reduced risk with exposure to ultraviolet radiation (UVR), but findings have been inconsistent and limited to HL as a group or the most common subtypes. METHODS: We evaluated UVR and incidence of HL subtypes using data from 15 population-based cancer registries in the United States from 2001 to 2010 (n=20 021). Ground-based ambient UVR estimates were linked to county of diagnosis. Incidence rate ratios (IRRs) and 95% confidence intervals (CIs) were calculated for UVR quintiles using Poisson regression models adjusted for age, sex, race/ethnicity, diagnosis year, and registry. RESULTS: Hodgkin lymphoma incidence was lower in the highest UVR quintile for nodular sclerosis (IRR=0.84, 95% CI=0.75-0.96, P-trend<0.01), mixed cellularity/lymphocyte-depleted (IRR=0.66, 95% CI=0.51-0.86, P-trend=0.11), lymphocyte-rich (IRR=0.71, 95% CI=0.57-0.88, P-trend<0.01), and nodular lymphocyte predominant HL (IRR=0.74, 95% CI=0.56-0.97, P-trend<0.01), but 'not otherwise specified' HL (IRR=1.19, 95% CI=0.96-1.47, P-trend=0.11). CONCLUSIONS: This is the largest study of UVR and HL subtypes covering a wide range of UVR levels; however, we lack information on personal UVR and other individual risk factors. These findings support an inverse association between UVR and HL.

Relationship between plasma 25-hydroxyvitamin D and leucocyte telomere length by sex and race in a US study.

A few studies have examined the association between vitamin D and telomere length, and fewer still have examined the relationship in black or male populations. We investigated the cross-sectional association between the vitamin D metabolite 25-hydroxyvitamin D (25(OH)D) concentration in plasma and relative leucocyte telomere length (LTL) in 1154 US radiologic technologists who were 48-93 years old (373 white females, 278 white males, 338 black females, 165 black males). Plasma 25(OH)D concentration was measured by the chemiluminescence immunoassay, and relative LTL was measured by quantitative PCR. Logistic regression was used to obtain OR and 95 % CI for long v. short (based on median) LTL in relation to continuous 25(OH)D, quartiles of 25(OH)D and 25(OH)D deficiency. We found no significant association between continuous 25(OH)D and long LTL in all participants (P trend=0·440), nor in white females (P trend=0·845), white males (P trend=0·636), black females (P trend=0·967) or black males (P trend=0·484). Vitamin D deficiency (defined as 25(OH)D<30 nmol/l), however, was significantly associated with short LTL in whites (P=0·024), but not in other groups. In this population, we found little evidence to support associations between 25(OH)D and long LTL over the entire range of 25(OH)D in the overall study population or by sex and race.

Cancer Risks in U.S. Radiologic Technologists Working With Fluoroscopically Guided Interventional Procedures, 1994-2008.

OBJECTIVE: The purpose of this study was to examine risks of cancer incidence and mortality among U.S. radiation technologists performing or assisting with fluoroscopically guided interventional procedures. SUBJECTS AND METHODS: A nationwide prospective cohort of 90,957 radiologic technologists, who responded to a 1994-1998 survey that collected information on whether they had ever worked with fluoroscopically guided interventional procedures, was followed through completion of a subsequent cohort survey during 2003-2005 (for cancer incidence) or December 31, 2008 (for cancer mortality). Sex-adjusted hazard ratios (HRs) and 95% CIs were calculated by use of Cox proportional hazards models for incidence and mortality from all cancers other than nonmelanoma skin cancer and for specific cancer outcomes in participants who reported ever performing fluoroscopically guided interventional procedures compared with technologists who never performed these procedures. RESULTS: The analysis showed an approximately twofold increased risk of brain cancer mortality (HR, 2.55; 95% CI, 1.48-4.40) and modest elevations in incidence of melanoma (HR, 1.30; 95% CI, 1.05-1.61) and in breast cancer incidence (HR, 1.16; 95% CI, 1.02-1.32) but not mortality (HR, 1.07; 95% CI, 0.69-1.66) among technologists who performed fluoroscopically guided interventional procedures compared with those who never performed these procedures. Although there was a small suggestive increase in incidence of all cancers combined, excluding nonmelanoma skin cancers (HR, 1.08; 95% CI, 1.00-1.17), mortality from all cancers combined, excluding nonmelanoma skin cancers, was not elevated (HR, 1.00; 95% CI, 0.88-1.14). We similarly observed no elevated risk of cancers of the thyroid, skin other than melanoma, prostate, lung, or colon and rectum or of leukemia that was not chronic lymphocytic leukemia among workers who performed fluoroscopically guided interventional procedures. CONCLUSION: We observed elevated risks of brain cancer, breast cancer, and melanoma among technologists who performed fluoroscopically guided interventional procedures. Although exposure to low-dose radiation is one possible explanation for these increased risks, these results may also be due to chance or unmeasured confounding by nonradiation risk factors. Our results must be confirmed in other studies, preferably with individual radiation dose data.

Incidence and mortality risks for circulatory diseases in US radiologic technologists who worked with fluoroscopically guided interventional procedures, 1994-2008.

OBJECTIVES: Although fluoroscopically guided interventional procedures (FGIP) have provided major advances in the treatment of various common diseases, radiation exposures associated with these procedures may cause adverse health effects in workers. We assess risk of circulatory disease incidence and mortality in medical radiation workers performing FGIP. METHODS: A US nationwide prospective cohort study of 90,957 radiologic technologists who completed a cohort survey during 1994-1998 was followed until completion of a subsequent survey during 2003-2005 for circulatory disease incidence, or until 31 December 2008 for mortality. Incidence analyses were restricted to the 63,482 technologists who completed both the second survey (1994-1998) and the third survey (2003-2005). Cox proportional hazards models were used to assess adjusted HR and 95% CIs for mortality from all causes, all circulatory diseases, all heart diseases, ischaemic heart disease, stroke, acute myocardial infarction and hypertension in participants who reported ever performing FGIP compared to technologists who never performed FGIP procedures. Adjusted HRs were calculated for self-reported hypertension, stroke and myocardial infarction. RESULTS: We observed a 34% increase in stroke incidence (HR=1.34, 95% CI 1.10 to 1.64) in technologists who performed FGIP compared to those who never performed these procedures. Mortality from stroke was also modestly elevated, although not statistically significant (HR=1.22, 95% CI 0.85 to 1.73). We observed no statistically significant excess risks of incidence or mortality from any other outcome evaluated. CONCLUSIONS: Our finding of elevated risk of stroke in workers performing FGIP needs to be confirmed in studies with individual radiation dose data, but nonetheless underlines the need to keep radiation exposure as low as reasonably achievable without compromising key diagnostic information.

Prospective study of ultraviolet radiation exposure and risk of breast cancer in the United States.

Although there are few environmental risk factors for breast cancer, some epidemiologic studies found that exposure to solar UV radiation (UVR) may lower risk. Prior epidemiologic studies are limited by narrow ambient UVR ranges and lack lifetime exposure assessment. To address these issues, we studied a cohort with residences representing a wide range of ambient UVR. Using the nationwide U.S. Radiologic Technologists study (USRT), we examined the association between breast cancer risk and UVR based on ambient UVR, time outdoors, a combined variable of ambient UVR and time outdoors (combined UVR), and sun susceptibility factors. Participants reported location of residence and hours spent outdoors during five age periods. Ambient UVR was derived by linking satellite-based annual UVR estimates to self-reported residences. Lifetime values were calculated by averaging these measures accounting for years spent in that location. We examined the risk of breast cancer among 36,725 participants (n=716 cases) from baseline questionnaire completion (2003-2005) through 2012-2013 using Cox proportional hazards models. Breast cancer risk was unrelated to ambient UVR (HR for lifetime 5th vs 1st quintile=1.22, 95% CI: 0.95-1.56, p-trend=0.36), time outdoors (HR for lifetime 5th vs 1st quintile=0.87, 95% confidence interval (CI): 0.68-1.10, p-trend=0.46), or combined UVR (HR lifetime 5th vs 1st quintile =0.85, 95% CI: 0.67-1.08, p-trend=0.46). Breast cancer risk was not associated with skin complexion, eye or hair color, or sunburn history. This study does not support the hypothesis that UVR exposure lowers breast cancer risk.

Relationship between ambient ultraviolet radiation and non-Hodgkin lymphoma subtypes: a U.S. population-based study of racial and ethnic groups.

Associations between ultraviolet radiation (UVR) exposure and non-Hodgkin lymphoma (NHL) have been inconsistent, but few studies have examined these associations for specific subtypes or across race/ethnicities. We evaluated the relationship between ambient UVR exposure and subtype-specific NHL incidence for whites, Hispanics and blacks in the United States for years 2001-2010 (n = 187,778 cases). Incidence rate ratios (IRRs) and 95% confidence intervals (CIs) were calculated for UVR quintiles using Poisson regression. Incidence was lower for the highest UVR quintile for chronic/small lymphocytic/leukemia (CLL/SLL) (IRR = 0.87, 95% CI: 0.77-0.97), mantle cell (IRR = 0.82, 95% CI: 0.69-0.97), lymphoplasmacytic (IRR = 0.58, 95% CI: 0.42-0.80), mucosa-associated lymphoid tissue (MZLMALT) (IRR = 0.74, 95% CI: 0.60-0.90), follicular (FL) (IRR = 0.76, 95% CI: 0.68-0.86), diffuse large B-cell (IRR = 0.84, 95% CI: 0.76-0.94;), peripheral T-cell other (PTCL) (IRR = 0.76, 95% CI: 0.61-0.95) and PTCL not otherwise specified (PNOS) (IRR = 0.77, 95% CI: 0.61-0.98). Trends were significant for MZLMALT, FL, DLBCL, BNOS and PTCL, with FL and DLBCL still significant after Bonferroni correction. We found interaction by race/ethnicity for CLL/SLL, FL, Burkitt, PNOS and MF/SS, with CLL/SLL and FL still significant after Bonferroni correction. Some B-cell lymphomas (CLL/SLL, FL and Burkitt) suggested significant inverse relationships in whites and Hispanics, but not in blacks. Some T-cell lymphomas suggested the most reduced risk for the highest quintile of UVR among blacks (PNOS and MF/SS), though trends were not significant. These findings strengthen the case for an inverse association of UVR exposure, support modest heterogeneity between NHL subtypes and suggest some differences by race/ethnicity.

Shedding light on UVR and Hodgkin lymphoma.

In this issue of Blood, Monnereau and colleagues pool 4 retrospective (case-control), observational epidemiologic studies to demonstrate an inverse association between UV radiation (UVR) exposure and risk of developing Hodgkin lymphoma (HL).

Cancer and circulatory disease risks in US radiologic technologists associated with performing procedures involving radionuclides.

OBJECTIVES: The number of nuclear medicine procedures has increased substantially over the past several decades, with uncertain health risks to the medical workers who perform them. We estimated risks of incidence and mortality from cancer and circulatory disease associated with performing procedures involving the use of radionuclides. METHODS: From a nationwide cohort of 90,955 US radiologic technologists who completed a mailed questionnaire during 1994-1998, 22,039 reported ever performing diagnostic radionuclide procedures, brachytherapy, radioactive iodine therapy, or other radionuclide therapy. We calculated multivariable-adjusted HRs and 95% CIs for incidence (through 2003-2005) and mortality (through 2008) associated with performing these procedures. RESULTS: Ever (versus never) performing radionuclide procedures was not associated with risks for most end points examined. However, we observed increased risks for squamous cell carcinoma of the skin (HR=1.29, 95% CI 1.01 to 1.66) with ever performing diagnostic radionuclide procedures, for myocardial infarction incidence (HR=1.37, 95% CI 1.10 to 1.70), all-cause mortality (HR=1.10, 95% CI 1.00 to 1.20) and all-cancer mortality (HR=1.20, 95% CI 1.01 to 1.43) with ever performing brachytherapy, and for mortality from all causes (HR=1.14, 95% CI 1.01 to 1.30), breast cancer (HR=2.68, 95% CI 1.10 to 6.51), and myocardial infarction (HR=1.76, 95% CI 1.02 to 3.04) with ever performing other radionuclide therapy procedures (excluding brachytherapy and radioactive iodine); increasing risks were also observed with greater frequency of performing these procedures, particularly before 1980. CONCLUSIONS: The modest health risks among radiologic technologists performing procedures using radionuclides require further examination in studies with individual dose estimates, more detailed information regarding types of procedures performed and radionuclides used, and longer follow-up.

Occupational ionising radiation and risk of basal cell carcinoma in US radiologic technologists (1983-2005).

OBJECTIVE: To determine risk for incident basal cell carcinoma from cumulative low-dose ionising radiation in the US radiologic technologist cohort. METHODS: We analysed 65,719 Caucasian technologists who were cancer-free at baseline (1983-1989 or 1994-1998) and answered a follow-up questionnaire (2003-2005). Absorbed radiation dose to the skin in mGy for estimated cumulative occupational radiation exposure was reconstructed for each technologist based on badge dose measurements, questionnaire-derived work history and protection practices, and literature information. Radiation-associated risk was assessed using Poisson regression and included adjustment for several demographic, lifestyle, host and sun exposure factors. RESULTS: Cumulative mean absorbed skin dose (to head/neck/arms) was 55.8 mGy (range 0-1735 mGy). For lifetime cumulative dose, we did not observe an excess radiation-related risk (excess relative risk/Gy=-0.01 (95% CI -0.43 to 0.52). However, we observed that basal cell carcinoma risk was increased for radiation dose received before age 30 (excess relative risk/Gy=0.59, 95% CI -0.11 to 1.42) and before 1960 (excess relative risk/Gy=2.92, 95% CI 1.39 to 4.45). CONCLUSIONS: Basal cell carcinoma risk was unrelated to low-dose radiation exposure among radiologic technologists. Because of uncertainties in dosimetry and sensitivity to model specifications, both our null results and our findings of excess risk for dose received before age 30 and exposure before 1960 should be interpreted with caution.

The risk of amyotrophic lateral sclerosis after cancer in U.S. elderly adults: a population-based prospective study.

Although epidemiologic studies have examined the risk of amyotrophic lateral sclerosis (ALS) in relation to cancer, none have been large population-based studies using incident ALS and adjusting for medical surveillance. Addressing those limitations, all first primary cancer cases from the Surveillance, Epidemiology and End Results (SEER) Program (1992-2005), linked to Medicare claims data were used. Cases were followed from cancer diagnosis until the earliest date of ALS diagnosis, a break in Medicare claims data, death, age 85 or December 31, 2005. A comparison group from a 5% random Medicare sample in the SEER areas who were cancer-free and censored as above, or until a cancer diagnosis were selected. ALS outcomes were derived from medical claims. The proportional hazards models to estimate ALS hazard ratios (HRs), using age as the time scale, adjusting for sex, race and physician visits, and stratifying the baseline hazard on birth year and SEER registry were used. A total of 303 ALS cases were ascertained in cancer patients (2,154,062 person-years) compared with 246 ALS cases (2,467,634 person-years) in the reference population. There was no overall relationship between cancer and ALS (HR = 0.99; 95% CI = 0.81-1.22), nor by gender or race. Except for an elevated ALS risk in the first year after a leukemia diagnosis, the relationship between site-specific cancers and ALS was null after correcting for multiple comparisons. Having a cancer diagnosis was not associated with an overall risk of incident ALS. The short-term ALS risk after leukemia may reflect screening or reporting errors.

Association between class III obesity (BMI of 40-59 kg/m2) and mortality: a pooled analysis of 20 prospective studies.

BACKGROUND: The prevalence of class III obesity (body mass index [BMI]≥40 kg/m2) has increased dramatically in several countries and currently affects 6% of adults in the US, with uncertain impact on the risks of illness and death. Using data from a large pooled study, we evaluated the risk of death, overall and due to a wide range of causes, and years of life expectancy lost associated with class III obesity. METHODS AND FINDINGS: In a pooled analysis of 20 prospective studies from the United States, Sweden, and Australia, we estimated sex- and age-adjusted total and cause-specific mortality rates (deaths per 100,000 persons per year) and multivariable-adjusted hazard ratios for adults, aged 19-83 y at baseline, classified as obese class III (BMI 40.0-59.9 kg/m2) compared with those classified as normal weight (BMI 18.5-24.9 kg/m2). Participants reporting ever smoking cigarettes or a history of chronic disease (heart disease, cancer, stroke, or emphysema) on baseline questionnaires were excluded. Among 9,564 class III obesity participants, mortality rates were 856.0 in men and 663.0 in women during the study period (1976-2009). Among 304,011 normal-weight participants, rates were 346.7 and 280.5 in men and women, respectively. Deaths from heart disease contributed largely to the excess rates in the class III obesity group (rate differences = 238.9 and 132.8 in men and women, respectively), followed by deaths from cancer (rate differences = 36.7 and 62.3 in men and women, respectively) and diabetes (rate differences = 51.2 and 29.2 in men and women, respectively). Within the class III obesity range, multivariable-adjusted hazard ratios for total deaths and deaths due to heart disease, cancer, diabetes, nephritis/nephrotic syndrome/nephrosis, chronic lower respiratory disease, and influenza/pneumonia increased with increasing BMI. Compared with normal-weight BMI, a BMI of 40-44.9, 45-49.9, 50-54.9, and 55-59.9 kg/m2 was associated with an estimated 6.5 (95% CI: 5.7-7.3), 8.9 (95% CI: 7.4-10.4), 9.8 (95% CI: 7.4-12.2), and 13.7 (95% CI: 10.5-16.9) y of life lost. A limitation was that BMI was mainly ascertained by self-report. CONCLUSIONS: Class III obesity is associated with substantially elevated rates of total mortality, with most of the excess deaths due to heart disease, cancer, and diabetes, and major reductions in life expectancy compared with normal weight. Please see later in the article for the Editors' Summary.

Body mass index and risk of death in Asian Americans.

OBJECTIVES: We investigated the association between body mass index (BMI) and mortality among Asian Americans. METHODS: We pooled data from prospective cohort studies with 20 672 Asian American adults with no baseline cancer or heart disease history. We estimated hazard ratios and 95% confidence intervals (CIs) with Cox proportional hazards models. RESULTS: A high, but not low, BMI was associated with increased risk of total mortality among individuals aged 35 to 69 years. The BMI was not related to total mortality among individuals aged 70 years and older. With a BMI 22.5 to < 25 as the reference category among never-smokers aged 35 to 69 years, the hazard ratios for total mortality were 0.83 (95% CI = 0.47, 1.47) for BMI 15 to < 18.5; 0.91 (95% CI = 0.62, 1.32) for BMI 18.5 to < 20; 1.08 (95% CI = 0.86, 1.36) for BMI 20 to < 22.5; 1.14 (95% CI = 0.90, 1.44) for BMI 25 to < 27.5; 1.13 (95% CI = 0.79, 1.62) for BMI 27.5 to < 30; 1.82 (95% CI = 1.25, 2.64) for BMI 30 to < 35; and 2.09 (95% CI = 1.06, 4.11) for BMI 35 to 50. Higher BMI was also related to increased cardiovascular disease and cancer mortality. CONCLUSIONS: High BMI is associated with increased mortality risk among Asian Americans.

Work history and mortality risks in 90,268 US radiological technologists.

OBJECTIVES: There have been few studies of work history and mortality risks in medical radiation workers. We expanded by 11 years and more outcomes our previous study of mortality risks and work history, a proxy for radiation exposure. METHODS: Using Cox proportional hazards models, we estimated mortality risks according to questionnaire work history responses from 1983 to 1989 through 2008 by 90,268 US radiological technologists. We controlled for potential confounding by age, birth year, smoking history, body mass index, race and gender. RESULTS: There were 9566 deaths (3329 cancer and 3020 circulatory system diseases). Mortality risks increased significantly with earlier year began working for female breast (p trend=0.01) and stomach cancers (p trend=0.01), ischaemic heart (p trend=0.03) and cerebrovascular diseases (p trend=0.02). The significant trend with earlier year first worked was strongly apparent for breast cancer during baseline through 1997, but not 1998-2008. Risks were similar in the two periods for circulatory diseases. Radiological technologists working ≥5 years before 1950 had elevated mortality from breast cancer (HR=2.05, 95% CI 1.27 to 3.32), leukaemia (HR=2.57, 95% CI 0.96 to 6.68), ischaemic heart disease (HR=1.13, 95% CI 0.96 to 1.33) and cerebrovascular disease (HR=1.28, 95% CI 0.97 to 1.69). No other work history factors were consistently associated with mortality risks from specific cancers or circulatory diseases, or other conditions. CONCLUSIONS: Radiological technologists who began working in early periods and for more years before 1950 had increased mortality from a few cancers and some circulatory system diseases, likely reflecting higher occupational radiation exposures in the earlier years.

Prospective study of ultraviolet radiation exposure and mortality risk in the United States.

Geographic variations in mortality rate in the United States could be due to several hypothesized factors, one of which is exposure to solar ultraviolet radiation (UVR). Limited evidence from previous prospective studies has been inconclusive. The association between ambient residential UVR exposure and total and cause-specific mortality risks in a regionally diverse cohort (346,615 white, non-Hispanic subjects, 50-71 years of age, in the National Institutes of Health (NIH)-AARP Diet and Health Study) was assessed, with accounting for individual-level confounders. UVR exposure (averaged for 1978-1993 and 1996-2005) from NASA's Total Ozone Mapping Spectrometer was linked to the US Census Bureau 2000 census tract of participants' baseline residence. Multivariate-adjusted Cox proportional-hazards models were used to estimate hazard ratios and 95% confidence intervals. Over 12 years, UVR exposure was associated with total deaths (n = 41,425; hazard ratio for highest vs. lowest quartiles (HRQ4 vs. Q1) = 1.06, 95% confidence interval (CI): 1.03, 1.09; Ptrend < 0.001) and with deaths (all Ptrend < 0.05) due to cancer (HRQ4 vs. Q1 = 1.06, 95% CI: 1.02, 1.11), cardiovascular disease (HRQ4 vs. Q1 = 1.06, 95% CI: 1.00, 1.12), respiratory disease (HRQ4 vs. Q1 = 1.37, 95% CI: 1.21, 1.55), and stroke (HRQ4 vs. Q1 = 1.16, 95% CI: 1.01, 1.33) but not with deaths due to injury, diabetes, or infectious disease. These results suggest that UVR exposure might not be beneficial for longevity.

A prospective study of medical diagnostic radiography and risk of thyroid cancer.

Although diagnostic x-ray procedures provide important medical benefits, cancer risks associated with their exposure are also possible, but not well characterized. The US Radiologic Technologists Study (1983-2006) is a nationwide, prospective cohort study with extensive questionnaire data on history of personal diagnostic imaging procedures collected prior to cancer diagnosis. We used Cox proportional hazard regressions to estimate thyroid cancer risks related to the number and type of selected procedures. We assessed potential modifying effects of age and calendar year of the first x-ray procedure in each category of procedures. Incident thyroid cancers (n = 251) were diagnosed among 75,494 technologists (1.3 million person-years; mean follow-up = 17 years). Overall, there was no clear evidence of thyroid cancer risk associated with diagnostic x-rays except for dental x-rays. We observed a 13% increase in thyroid cancer risk for every 10 reported dental radiographs (hazard ratio = 1.13, 95% confidence interval: 1.01, 1.26), which was driven by dental x-rays first received before 1970, but we found no evidence that the relationship between dental x-rays and thyroid cancer was associated with childhood or adolescent exposures as would have been anticipated. The lack of association of thyroid cancer with x-ray procedures that expose the thyroid to higher radiation doses than do dental x-rays underscores the need to conduct a detailed radiation exposure assessment to enable quantitative evaluation of risk.

Sunlight and other determinants of circulating 25-hydroxyvitamin D levels in black and white participants in a nationwide U.S. study.

Circulating 25-hydroxyvitamin D (25(OH)D), a marker for vitamin D status, is associated with bone health and possibly cancers and other diseases; yet, the determinants of 25(OH)D status, particularly ultraviolet radiation (UVR) exposure, are poorly understood. Determinants of 25(OH)D were analyzed in a subcohort of 1,500 participants of the US Radiologic Technologists (USRT) Study that included whites (n = 842), blacks (n = 646), and people of other races/ethnicities (n = 12). Participants were recruited monthly (2008-2009) across age, sex, race, and ambient UVR level groups. Questionnaires addressing UVR and other exposures were generally completed within 9 days of blood collection. The relation between potential determinants and 25(OH)D levels was examined through regression analysis in a random two-thirds sample and validated in the remaining one third. In the regression model for the full study population, age, race, body mass index, some seasons, hours outdoors being physically active, and vitamin D supplement use were associated with 25(OH)D levels. In whites, generally, the same factors were explanatory. In blacks, only age and vitamin D supplement use predicted 25(OH)D concentrations. In the full population, determinants accounted for 25% of circulating 25(OH)D variability, with similar correlations for subgroups. Despite detailed data on UVR and other factors near the time of blood collection, the ability to explain 25(OH)D was modest.

An aggregated analysis of hormonal factors and endometrial cancer risk by parity.

BACKGROUND: Nulliparity is associated with an increased risk of endometrial cancer. It is less clear whether nulliparity modifies the association between other established hormone-related risk factors. The proportion of nulliparous women has increased since the mid-1970s, but most individual studies to date have been too small to test the hypothesis that endometrial cancer risk factors may be associated more strongly with risk among nulliparous women compared with parous women. METHODS: Data were aggregated on 26,936 postmenopausal, Caucasian, nulliparous women (360 endometrial cancers) and 146,583 postmenopausal, Caucasian, parous women (1378 endometrial cancers) from 4 US prospective studies (1979-2006). Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated in stratified analyses. RESULTS: The risk of endometrial cancer was higher among nulliparous women than among parous women, as expected (nulliparous vs parous: HR, 1.42; 95% CI, 1.26-1.60). Stratified associations between endometrial cancer and hormone-related risk factors did not differ between nulliparous versus parous women: For both groups, oral contraceptives and earlier menopause were associated with reduced risk. The highest HRs were for obesity: A body mass index ≥30 kg/m(2) (vs <25 kg/m(2) ) increased the risk of endometrial cancer 3-fold among nulliparous women (HR, 3.04; 95% CI, 2.34-3.94) and parous women (HR, 2.88; 95% CI, 2.52-3.29). CONCLUSIONS: The results from this large, pooled analysis of data from 4 large prospective studies suggested that nulliparity does not modify the risks of endometrial cancer associated with established hormone-related risk factors.

Body-mass index and mortality among 1.46 million white adults.

BACKGROUND: A high body-mass index (BMI, the weight in kilograms divided by the square of the height in meters) is associated with increased mortality from cardiovascular disease and certain cancers, but the precise relationship between BMI and all-cause mortality remains uncertain. METHODS: We used Cox regression to estimate hazard ratios and 95% confidence intervals for an association between BMI and all-cause mortality, adjusting for age, study, physical activity, alcohol consumption, education, and marital status in pooled data from 19 prospective studies encompassing 1.46 million white adults, 19 to 84 years of age (median, 58). RESULTS: The median baseline BMI was 26.2. During a median follow-up period of 10 years (range, 5 to 28), 160,087 deaths were identified. Among healthy participants who never smoked, there was a J-shaped relationship between BMI and all-cause mortality. With a BMI of 22.5 to 24.9 as the reference category, hazard ratios among women were 1.47 (95 percent confidence interval [CI], 1.33 to 1.62) for a BMI of 15.0 to 18.4; 1.14 (95% CI, 1.07 to 1.22) for a BMI of 18.5 to 19.9; 1.00 (95% CI, 0.96 to 1.04) for a BMI of 20.0 to 22.4; 1.13 (95% CI, 1.09 to 1.17) for a BMI of 25.0 to 29.9; 1.44 (95% CI, 1.38 to 1.50) for a BMI of 30.0 to 34.9; 1.88 (95% CI, 1.77 to 2.00) for a BMI of 35.0 to 39.9; and 2.51 (95% CI, 2.30 to 2.73) for a BMI of 40.0 to 49.9. In general, the hazard ratios for the men were similar. Hazard ratios for a BMI below 20.0 were attenuated with longer-term follow-up. CONCLUSIONS: In white adults, overweight and obesity (and possibly underweight) are associated with increased all-cause mortality. All-cause mortality is generally lowest with a BMI of 20.0 to 24.9.