Risk of bladder cancer by geographic region in a U.S. cohort of male health professionals

Sulforaphane as a potential remedy against cancer: Comprehensive mechanistic review

Sulforaphane belongs to the active class of isothiocyanates capable of delivering various biological benefits for health promotion and disease prevention. This compound is considered vital to curtail numerous metabolic disorders. Various studies have proven its beneficial effects against cancer prevention and its possible utilization as a therapeutic agent in cancer treatment. Understanding the mechanistic pathways and possible interactions at cellular and subcellular levels is key to design and develop cancer therapeutics for humans. In this respect, a number of mechanisms such as modulation of carcinogen metabolism & phase II enzymatic activities, cell cycle arrest, activation of Nrf2, cytotoxic, proapoptotic and apoptotic pathways have been reported to be involved in cancer prevention. This article provides sufficient information by critical analysis to understand the mechanisms involved in cancer prevention attributed to sulforaphane. Furthermore, various clinical studies have also been included for design and development of novel therapies for cancer prevention and cure. PRACTICAL APPLICATIONS: Diet and dietary components are potential tools to address various lifestyle-related disorders. Due to plenty of environmental and cellular toxicants, the chances of cancer prevalence are quite large which are worsen by adopting unhealthy lifestyles. Cancer can be treated with various therapies but those are acquiring side effects causing the patients to suffer the treatment regime. Nutraceuticals and functional foods provide safer options to prevent or delay the onset of cancer. In this regard, sulforaphane is a pivotal compound to be targeted as a potential agent for cancer treatment both in preventive and therapeutic regimes. This article provides sufficient evidence via discussing the underlying mechanisms of positive effects of sulforaphane to further the research for developing anticancer drugs that will help assuage this lethal morbidity.

Cancer Biomarkers for Integrative Oncology

PURPOSE OF REVIEW

There has been an increasing interest in using complementary and alternative medicine (CAM) approaches to treat cancer. It is therefore relevant and timely to determine if CAM biomarkers can be identified and developed to guide cancer diagnosis and treatment. Herein, we review the status of cancer biomarkers in CAM research and treatment to stimulate further research in this area.

RECENT FINDINGS

Studies on promising anti-cancer natural products, such as PHY906, honokiol, bryostatin-1, and sulforaphane have demonstrated the existence of potential cancer biomarker(s). Additional studies are required to further develop and ultimately validate these biomarkers that can predict clinical activity of the anti-cancer natural products used alone or in combination with chemotherapeutic agents. A systematic approach is needed to identify and develop CAM treatment associated biomarkers and to define their role in facilitating clinical decision-making. The expectation is to use these biomarkers in determining potential options for CAM treatment, examining treatment effects and toxicity and/or clinical efficacy in patients with cancer.

Cruciferous Vegetables, Isothiocyanates, and Bladder Cancer Prevention

Bladder cancer is a significant health burden due to its high prevalence, risk of mortality, morbidity, and high cost of medical care. Epidemiologic evidence suggests that diets rich in cruciferous vegetables, particularly broccoli, are associated with lower bladder cancer risk. Phytochemicals in cruciferous vegetables, such as glucosinolates, which are enzymatically hydrolyzed to bioactive isothiocyanates, are possible mediators of an anticancer effect. In vitro studies have shown inhibition of bladder cancer cell lines, cell cycle arrest, and induction of apoptosis by these isothiocyanates, in particular sulforaphane and erucin. Although not yet completely understood, many mechanisms of anticancer activity at the steps of cancer initiation, promotion, and progression have been attributed to these isothiocyanates. They target multiple pathways including the adaptive stress response, phase I/II enzyme modulation, pro-growth, pro-survival, pro-inflammatory signaling, angiogenesis, and even epigenetic modulation. Multiple in vivo studies have shown the bioavailability of isothiocyanates and their antitumoral effects. Although human studies are limited, they support oral bioavailability with reasonable plasma and urine concentrations achieved. Overall, both cell and animal studies support a potential role for isothiocyanates in bladder cancer prevention and treatment. Future studies are necessary to examine clinically relevant outcomes and define guidelines on ameliorating the bladder cancer burden.

Sulforaphane for the chemoprevention of bladder cancer: molecular mechanism targeted approach

The clinical course for both early and late stage Bladder Cancer (BC) continues to be characterized by significant patient burden due to numerous occurrences and recurrences requiring frequent surveillance strategies, intravesical drug therapies, and even more aggressive treatments in patients with locally advanced or metastatic disease. For these reasons, BC is also the most expensive cancer to treat. Fortunately, BC offers an excellent platform for chemoprevention interventions with potential to optimize the systemic and local exposure of promising agents to the bladder mucosa. However, other than smoking cessation, there is a paucity of research that systematically examines agents for chemoprevention of bladder cancers. Adopting a systematic, molecular-mechanism based approach, the goal of this review is to summarize epidemiological, in vitro, and preclinical studies, including data regarding the safety, bioavailability, and efficacy of agents evaluated for bladder cancer chemoprevention. Based on the available studies, phytochemicals, specifically isothiocyanates such as sulforaphane, present in Brassicaceae or “cruciferous” vegetables in the precursor form of glucoraphanin are: (a) available in standardized formulations; (b) bioavailable- both systemically and in the bladder; (c) observed to be potent inhibitors of BC carcinogenesis through multiple mechanisms; and (d) without toxicities at these doses. Based on available evidence from epidemiological, in vitro, preclinical, and early phase trials, phytochemicals, specifically isothiocyanates (ITCs) such as sulforaphane (SFN) represent a promising potential chemopreventitive agent in bladder cancer.

Seeding of a high-grade papillary urothelial carcinoma of the bladder along a nephroureterostomy tract

Percutaneous nephrostomy placement is a common treatment for obstructive uropathy of various causes. Although rare in the literature, tumor seeding along the nephrostomy tract is a potential risk of percutaneous nephrostomy in the treatment of obstructive symptoms secondary to urothelial carcinoma. In this case report, we present one such unusual outcome where urinary bladder urothelial cancer cells metastasized to the paravertebral soft tissues through apparent seeding along a nephroureterostomy tract.

Expression of FGFR3 Protein and Gene Amplification in Urinary Bladder Lesions in Relation to Schistosomiasis

BACKGROUND:

Bladder cancer represents the fifth most common malignancy worldwide and a major cause of cancer-related morbidity and death. Incidence and mortality rates have remained relatively constant over the past four decades. Urothelial bladder cancers have identified multiple risk factors.

AIM:

We aimed at evaluating the expression of the FGFR3 protein and gene amplification in the urothelial cells of neoplastic and non-neoplastic urothelial lesions of the urinary bladder, and correlation with tumour grade, stage and associated bilharziasis.

MATERIAL AND METHODS:

One hundred and five different urinary bladder lesions were studied, including 15 cystitis cases (9 bilharzial and 6 non-bilharzial cystitides), 75 urothelial carcinoma cases (18 bilharzial associated and 57 non-bilharzial associated) and 15 squamous cell carcinoma associated with bilharziasis, beside 5 control cases. Data concerning age, sex, tumour grade, stage, and associated bilharziasis were obtained. Each case was studied for FGFR3 expression, and FISH technique was applied on forty malignant cases that show high protein expression.

RESULTS:

The highest incidence of cystitis was in the fourth decade while of bladder cancer was in the seventh decade. Tumour grade was correlated significantly with tumour stage. FGFR3 correlates significantly with tumour grade, stage and with a bilharzial infestation. FGFR3 gene amplification was reported mainly in low grade and NNMBIC tumours.

CONCLUSIONS:

FGFR3 overexpression in malignant cases was significantly higher than in chronic cystitis. FGFR3 gene amplification was reported mainly in low grade and NNMBIC tumours. FGFR3 may be further studied as a subject for target therapy of bladder cancer.

Expression of tumor suppressive microRNA-34a is associated with a reduced risk of bladder cancer recurrence

Bladder cancer is the fourth most common cancer among men in the United States and more than half of patients experience recurrences within 5 years after initial diagnosis. Additional clinically informative and actionable biomarkers of the recurrent bladder cancer phenotypes are needed to improve screening and molecular therapeutic approaches for recurrence prevention. MicroRNA-34a (miR-34a) is a short noncoding regulatory RNA with tumor suppressive attributes. We leveraged our unique, large, population-based prognostic study of bladder cancer in New Hampshire, United States to evaluate miR-34a expression levels in individual tumor cells to assess prognostic value. We collected detailed exposure and medical history data, as well as tumor tissue specimens from bladder patients and followed them long-term for recurrence, progression and survival. Fluorescence-based in situ hybridization assays were performed on urothelial carcinoma tissue specimens (n = 229). A larger proportion of the nonmuscle invasive tumors had high levels of miR-34a within the carcinoma cells compared to those tumors that were muscle invasive. Patients with high miR-34a levels in their baseline nonmuscle invasive tumors experienced lower risks of recurrence (adjusted hazard ratio 0.57, 95% confidence interval 0.34-0.93). Consistent with these observations, we demonstrated a functional tumor suppressive role for miR-34a in cultured urothelial cells, including reduced matrigel invasion and growth in soft agar. Our results highlight the need for further clinical studies of miR-34a as a guide for recurrence screening and as a possible candidate therapeutic target in the bladder.

Bladder Cancer Mortality in the United States: A Geographic and Temporal Analysis of Socioeconomic and Environmental Factors

PURPOSE

We assessed the association of temporal, socioeconomic and environmental factors with bladder cancer mortality in the United States. Our hypothesis was that bladder cancer mortality is associated with distinct environmental and socioeconomic factors with effects varying by region, race and gender.

MATERIALS AND METHODS

NCI (National Cancer Institute) age adjusted, county level bladder cancer mortality data from 1950 to 2007 were analyzed to identify clusters of increased bladder cancer death using the Getis-Ord Gi* statistic. Socioeconomic, clinical and environmental data were assessed using geographically weighted spatial regression analysis adjusting for spatial autocorrelation. County level socioeconomic, clinical and environmental data were obtained from national databases, including the United States Census, CDC (Centers for Disease Control and Prevention), NCHS (National Center for Health Statistics) and County Health Rankings.

RESULTS

Bladder cancer mortality hot spots and risk factors for bladder cancer death differed significantly by gender, race and geographic region. From 1996 to 2007 smoking, unemployment, physically unhealthy days, air pollution ozone days, percent of houses with well water, employment in the mining industry and urban residences were associated with increased rates of bladder cancer mortality (p <0.05). Model fit was significantly improved in hot spots compared to all American counties (R(2) = 0.20 vs 0.05).

CONCLUSIONS

Environmental and socioeconomic factors affect bladder cancer mortality and effects appear to vary by gender and race. Additionally there were temporal trends of bladder cancer hot spots which, when persistent, should be the focus of individual level studies of occupational and environmental factors.

Inhibition of bladder cancer by broccoli isothiocyanates sulforaphane and erucin: characterization, metabolism, and interconversion

SCOPE

Epidemiologic evidence suggests diets rich in cruciferous vegetables, particularly broccoli, are associated with lower bladder cancer risk. Our objectives are to investigate these observations and determine the role of isothiocyanates in primary or secondary bladder cancer prevention.

METHODS AND RESULTS

We initially investigate the mechanisms whereby broccoli and broccoli sprout extracts and pure isothiocyanates inhibit normal, noninvasive (RT4), and invasive (J82, UMUC3) human urothelial cell viability. Sulforaphane (IC(50) = 5.66 ± 1.2 μM) and erucin (IC(50) = 8.79 ± 1.3 μM) are found to be the most potent inhibitors and normal cells are least sensitive. This observation is associated with downregulation of survivin, epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 2 (HER2/neu), G(2) /M cell cycle accumulation, and apoptosis. In a murine UMUC3 xenograft model, we fed semipurified diets containing 4% broccoli sprouts, or 2% broccoli sprout isothiocyanate extract; or gavaged pure sulforaphane or erucin (each at 295 μmol/kg, similar to dietary exposure); and report tumor weight reduction of 42% (p = 0.02), 42% (p = 0.04), 33% (p = 0.04), and 58% (p < 0.0001), respectively. Sulforaphane and erucin metabolites are present in mouse plasma (micromolar range) and tumor tissue, with N-acetylcysteine conjugates as the most abundant. Interconversion of sulforaphane and erucin metabolites was observed.

CONCLUSION

This work supports development of fully characterized, novel food products containing broccoli components for phase I/II human studies targeting bladder cancer prevention.

Association between smoking and risk of bladder cancer among men and women

CONTEXT

Previous studies indicate that the population attributable risk (PAR) of bladder cancer for tobacco smoking is 50% to 65% in men and 20% to 30% in women and that current cigarette smoking triples bladder cancer risk relative to never smoking. During the last 30 years, incidence rates have remained stable in the United States in men (123.8 per 100,000 person-years to 142.2 per 100,000 person-years) and women (32.5 per 100,000 person-years to 33.2 per 100,000 person-years); however, changing smoking prevalence and cigarette composition warrant revisiting risk estimates for smoking and bladder cancer.

OBJECTIVE

To evaluate the association between tobacco smoking and bladder cancer.

DESIGN, SETTING, AND PARTICIPANTS

Men (n = 281,394) and women (n = 186,134) of the National Institutes of Health-AARP (NIH-AARP) Diet and Health Study cohort completed a lifestyle questionnaire and were followed up between October 25, 1995, and December 31, 2006. Previous prospective cohort studies of smoking and incident bladder cancer were identified by systematic review and relative risks were estimated from fixed-effects models with heterogeneity assessed by the I(2) statistic.

MAIN OUTCOME MEASURES

Hazard ratios (HRs), PARs, and number needed to harm (NNH).

RESULTS

During 4,518,941 person-years of follow-up, incident bladder cancer occurred in 3896 men (144.0 per 100,000 person-years) and 627 women (34.5 per 100,000 person-years). Former smokers (119.8 per 100,000 person-years; HR, 2.22; 95% confidence interval [CI], 2.03-2.44; NNH, 1250) and current smokers (177.3 per 100,000 person-years; HR, 4.06; 95% CI, 3.66-4.50; NNH, 727) had higher risks of bladder cancer than never smokers (39.8 per 100,000 person-years). In contrast, the summary risk estimate for current smoking in 7 previous studies (initiated between 1963 and 1987) was 2.94 (95% CI, 2.45-3.54; I(2) = 0.0%). The PAR for ever smoking in our study was 0.50 (95% CI, 0.45-0.54) in men and 0.52 (95% CI, 0.45-0.59) in women.

CONCLUSION

Compared with a pooled estimate of US data from cohorts initiated between 1963 and 1987, relative risks for smoking in the more recent NIH-AARP Diet and Health Study cohort were higher, with PARs for women comparable with those for men.

Minerals and vitamins and the risk of bladder cancer: results from the New Hampshire Study

Objective

Although the effect of fruit and vegetables on the risk of bladder cancer has been widely studied, little is known about their micronutrient components. Our aim was to investigate associations between minerals and vitamins and bladder cancer.

Methods

A case–control study was conducted in New Hampshire, USA. Dietary data were collected from 322 cases and 239 controls using a 121-item food frequency questionnaire. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using logistic regression adjusting for sex, age, smoking characteristics, and energy intake.

Results

The ORs (95% CI) for highest quartile versus lowest quartile for total intake of vitamin E was 0.66 (0.36–1.20; p trend = 0.09) and 0.49 (0.21–1.17; p trend = 0.13) for dietary phosphorus. The odds of bladder cancer for heavy smokers with the highest total intake of vitamin E, carotenoids, and niacin were 0.58 (0.34–0.99), 0.62 (0.36–1.09), and 0.66 (0.39–1.14), respectively. Higher total intakes of carotenoids, vitamin D, thiamin, niacin, and vitamin E were inversely related to bladder cancer risk among older individuals.

Conclusion

Our findings suggest further investigation of the effect of vitamin E, carotenoids, vitamin D, thiamin, and niacin on bladder cancer risk may be warranted. Future studies should focus on high risk groups such as heavy smokers and older individuals.

Part of the Series: From dietary antioxidants to regulators in cellular signaling and gene regulation

The association of decreased cancer risk with intake of cruciferous vegetables and selenium is stronger than that reported for fruits and vegetables in general. An active constituent in cruciferae is sulforaphane. Chemopreventive effects of both, sulforaphane and selenium have been attributed to an antioxidant action which certainly is too simplicistic. Sulforaphane induces via activation of the Nrf2/Keap1 system phase 2 enzymes that protect against carcinogens and oxidants. Induced enzymes comprise the selenoproteins thioredoxin reductase-1 (TrxR1) and gastrointestinal glutathione peroxidase (GI-GPx, GPx2), which contain antioxidant response elements (ARE) in their promoter regions. Translational realisation of the enhanced transcripts depends on adequate selenium supply, which explains the synergism of Nrf2 activators and selenium. Regarding tumorigenesis the role of TrxR1 is ambiguous: it is essential for fast tumor cell growth but also diminishes vascularisation of tumors. The anticarcinogenic role of GI-GPx is evident from enhanced gastrointestinal tumor formation in gpx2/gpx1 double KO mice.

The effect of smoking on the male excess of bladder cancer: a meta-analysis and geographical analyses

Smoking is considered the primary risk factor for bladder cancer. Although smoking prevalence and bladder cancer incidence vary around the world, bladder cancer is on average 4 times more common in males than in females. This article describes the observed male-female incidence ratio of bladder cancer for 21 world regions in 2002 and 11 geographical areas during the time period 1970-1997. A meta-analysis, including 34 studies, was performed to ascertain the increased risk for bladder cancer in males and females when smoking. The summary odds ratios (SORs) calculated in the meta-analysis were used to estimate the male-female incidence ratio of bladder cancer that would be expected for hypothetical smoking prevalence scenarios. These expected male-female incidence ratios were compared with the observed ratios to evaluate the role of smoking on the male excess of bladder cancer. The male-female incidence ratio of bladder cancer was higher than expected worldwide and over time, based on a smoking prevalence of 75% in males, 10% in females and an increased risk (SOR) of bladder cancer associated with smoking of 4.23 for males and 1.35 for females, respectively. This implied that, at least in the Western world, smoking can only partially explain the difference in bladder cancer incidence. Consequently, other factors are responsible for the difference in bladder cancer incidence.

Nonsteroidal antiinflammatory drug use and risk of bladder cancer in the health professionals follow-up study

Nonsteroidal antiinflammatory drugs (NSAIDs) use, particularly aspirin, may lower the risk of several cancers, including bladder. NSAIDs may reduce development of bladder tumors by decreasing inflammation, inhibiting cycloxygenase-2, inhibiting proliferation and inducing apoptosis of cancer cells. However, acetaminophen, a major metabolite of phenacetin, may be positively associated with bladder cancer risk. Results from case-control studies on NSAIDs and acetaminophen use and bladder cancer risk are inconsistent. We investigated the association between NSAID and acetaminophen use and bladder cancer risk in a large cohort of US males. Among 49,448 men in the Health Professionals Follow-Up Study, 607 bladder cancer cases were confirmed during 18 years of follow-up. Relative risks (RR) and 95% confidence intervals (CI) were calculated by Cox proportional hazards models. Multivariate RR were adjusted for age, current smoking status, pack years, geographic region and fluid intake. No significant associations were observed for regular aspirin (> or =2 tablets per week), (RR = 0.99, 95% CI 0.83-1.18), ibuprofen (RR = 1.11, 95% CI 0.81-1.54), acetaminophen (RR = 0.96, 95% CI 0.67-1.39) or total NSAID use (not including acetaminophen; RR = 1.01, 95% CI 0.85-1.20) and bladder cancer risk compared with nonuse. Consistent use (over 6 years) of aspirin, ibuprofen, acetaminophen and total NSAIDs, compared to nonuse, was not associated with bladder cancer risk. No association was observed between aspirin frequency and dose and bladder cancer risk. We observed no effect-modification by smoking, age or fluid intake. Our results suggest that regular NSAID or acetaminophen use has no substantial impact on bladder cancer risk among men.

Hormonal and reproductive factors and the risk of bladder cancer in women

Gender and cigarette smoking are among the most consistent predictors of bladder cancer risk. After adjustment for known risk factors, an excess risk remains for males, suggesting that other factors may be responsible for the gender differences. Given limited data on hormonal or reproductive factors and bladder cancer risk, the authors examined these factors among women in the US Nurses' Health Study cohort. During 26 years of follow-up (1976-2002), 336 incident cases of bladder cancer were diagnosed. Cox proportional hazards models were used to estimate incidence rate ratios and 95% confidence intervals between hormonal and reproductive factors and bladder cancer risk. Postmenopausal women, compared with premenopausal women, were at increased risk (incidence rate ratio = 1.93, 95% confidence interval: 0.99, 3.78). For postmenopausal women, early age at menopause (</=45 years) compared with late age at menopause (>/=50 years) was associated with a statistically significant increased risk of bladder cancer (incidence rate ratio = 1.63, 95% confidence interval: 1.20, 2.23). The association between age at menopause and bladder cancer risk was modified by cigarette smoking status (p for interaction = 0.01). The authors observed no significant associations of age at menarche, parity, age at first birth, and exogenous hormone use with bladder cancer risk. Findings suggest that menopausal status and age at menopause may play a role in modifying bladder cancer risk among women.

Gender and geographic influence on the racial disparity in bladder cancer mortality in the US

BACKGROUND

In 2005, there were an estimated 63,210 new cases of bladder cancer and 13,180 related deaths in the US. African Americans reportedly have a lower incidence of bladder cancer, but a higher mortality. The objective of this study was to evaluate the gender and geographic differences in bladder cancer survival between Caucasians and African Americans to better understand the racial disparity in bladder cancer survival.

STUDY DESIGN

Surveillance Epidemiology and End Results Program (SEER) data were used to evaluate racial differences in bladder cancer survival from 1973 to 1999. Bivariate and multivariate Cox proportional hazard models were performed to determine the relationship between race and survival, adjusting for cancer stage and grade, marital status, region of country, treatment received, and the interaction between race and region.

RESULTS

African Americans were diagnosed with higher grade (p < 0.001) and higher stage (p < 0.001) tumors, compared with Caucasians. In the multivariable model, African-American race was an independent predictor of poor survival, adjusting for age, marital status, region of the country, stage, grade, treatment received, and interaction between race and region. Surprisingly, African Americans diagnosed in the Atlanta metropolitan area had a substantially worse survival.

CONCLUSIONS

African Americans were diagnosed with more aggressive and more advanced tumors. Adjusted multivariable models demonstrated a survival advantage for Caucasians, with African-American race being an independent predictor of poor survival, especially when diagnosed in the Atlanta metropolitan area. Racial disparity continues to exist in bladder cancer presentation and survival in the US.

Peptic ulcer disease and the risk of bladder cancer in a prospective study of male health professionals

Helicobacter pylori is a risk factor for gastric and duodenal ulcers, but gastric ulcers generally occur in individuals who have low acid production and diffuse gastritis, whereas duodenal ulcers are more likely to occur with high acid output and antrum-predominant gastritis. Low acid production, gastritis, and ulcer healing each contribute to poor antioxidant absorption, oxidative stress, and elevated nitrite levels in the stomach. N-Nitrosamines are known carcinogens, and nitrate ingestion has been related to bladder cancer risk. Consequently, we hypothesized that the gastric conditions associated with gastric ulcers may contribute to elevated bladder cancer risk. We thus examined the association between self-reported history of peptic ulcer disease and the risk of bladder cancer (414 cases) over 14 years of follow-up in the Health Professional Follow-Up Study. Cox proportional hazards models were performed to adjust for known risk factors of bladder cancer. Men who reported a gastric ulcer before 1986 had a significantly higher risk of bladder cancer compared with those with no history of gastric ulcer (relative risk = 1.55, 95% confidence interval = 1.03-2.33, controlling for smoking and other potential confounders). No association was observed for duodenal ulcers (multivariate relative risk = 0.97, 95% confidence interval = 0.68-1.38). The ulcers in this study were based solely on self-report and not medical records; consequently, misclassification of ulcers may have occurred. Although intriguing, these findings need to be replicated.

Cancer incidence in the US radiologic technologists health study, 1983-1998

BACKGROUND

Workers exposed to low doses of radiation can provide information regarding cancer risks that are of public concern. However, characterizing risk at low doses requires large populations and ideally should include a large proportion of women, both of which rarely are available.

METHODS

Among 90305 radiologic technologists in the U.S. (77% women) who were followed during 1983-1998, data concerning incident cancer occurrence was obtained from mailed questionnaires and from death records. Standardized incidence ratios (SIRs) were computed using age-specific, gender-specific, race-specific, and calendar year-specific cancer rates from the Surveillance, Epidemiology, and End Results Program.

RESULTS

The SIR for all cancers in both genders combined was 1.04 (95% confidence interval [95% CI], 1.00-1.07; n = 3292 technologists). Female technologists had an elevated risk for all solid tumors combined (SIR = 1.06; 95% CI, 1.02-1.10; n = 2168 women) and for breast cancers (SIR = 1.16; 95% CI, 1.09-1.23; n = 970 women), melanoma (SIR = 1.66; 95% CI, 1.43-1.89; n = 181 women), and thyroid cancers (SIR = 1.54; 95% CI, 1.24-1.83; n = 107 women). Male technologists experienced a decreased risk for solid tumors (SIR = 0.92; 95% CI, 0.85-0.98; n = 755 men); however, melanoma (SIR = 1.39; 95% CI, 1.00-1.79; n = 56 men) and thyroid cancers (SIR = 2.23; 95% CI, 1.29-3.59; n = 17 men) were increased. Among both genders, the risks were decreased for buccal cavity/pharyngeal cancers (SIR = 0.73; 95% CI, 0.55-0.90; n = 54 technologists), rectal cancers (SIR = 0.62; 95% CI 0.48-0.76; n = 53 technologists), and lung cancers (SIR = 0.77, 95% CI, 0.70-0.85; n = 307 technologists).

CONCLUSIONS

The elevated risk for breast cancer may have been related to occupational radiation exposure. The observed excesses of melanoma and thyroid cancers may reflect, at least in part, earlier detection among medical workers with easy access to health care.

An estimate of premature cancer mortality in the U.S. due to inadequate doses of solar ultraviolet-B radiation

BACKGROUND

There are large geographic gradients in mortality rates for a number of cancers in the U.S. (e.g., rates are approximately twice as high in the northeast compared with the southwest). Risk factors such as diet fail to explain this variation. Previous studies have demonstrated that the geographic distributions for five types of cancer are related inversely to solar radiation. The purpose of the current study was to determine how many types of cancer are affected by solar radiation and how many premature deaths from cancer occur due to insufficient ultraviolet (UV)-B radiation.

METHODS

UV-B data for July 1992 and cancer mortality rates in the U.S. for between 1970-1994 were analyzed in an ecologic study.

RESULTS

The findings of the current study confirm previous results that solar UV-B radiation is associated with reduced risk of cancer of the breast, colon, ovary, and prostate as well as non-Hodgkin lymphoma. Eight additional malignancies were found to exhibit an inverse correlation between mortality rates and UV-B radiation: bladder, esophageal, kidney, lung, pancreatic, rectal, stomach, and corpus uteri. The annual number of premature deaths from cancer due to lower UV-B exposures was 21,700 (95% confidence interval [95% CI], 20,400-23,400) for white Americans, 1400 (95% CI, 1100-1600) for black Americans, and 500 (95% CI, 400-600) for Asian Americans and other minorities.

CONCLUSIONS

The results of the current study demonstrate that much of the geographic variation in cancer mortality rates in the U.S. can be attributed to variations in solar UV-B radiation exposure. Thus, many lives could be extended through increased careful exposure to solar UV-B radiation and more safely, vitamin D3 supplementation, especially in nonsummer months.