Sensitivity to NNKOAc is associated with renal cancer risk

Risk of urinary tract cancers following arsenic exposure and tobacco smoking: a review

Bladder cancer, prostate cancer, and kidney cancer, due to their high morbidity and mortality rates, result in significant economic and health care costs. Arsenic exposure affects the drinking water of millions of people worldwide. Long-term exposure to arsenic, even in low concentrations, increases the risk of developing various cancers. Smoking is also one of the leading causes of bladder, prostate and kidney cancers. Accordingly, this research reviews the relationship between arsenic exposure and smoking with three kinds of urinary tract cancers (bladder cancer, prostate cancer, and kidney cancer) due to their widespread concern for their negative impact on public health globally. In this review, we have gathered the most current information from scientific databases [PubMed, Scopus, Google Scholar, ISI web of science] regarding the relationship between arsenic exposure and tobacco smoking with the risk of bladder, prostate, and kidney cancer. In several studies, a significant relationship was determined between the incidence and mortality rate of the above-mentioned cancers in humans with arsenic exposure and tobacco smoking. The decrease or cessation of smoking and consumption of arsenic-free water significantly declined the incidence of bladder, prostate, and kidney cancers.

Epidemiology of Renal Cell Carcinoma: 2022 Update

CONTEXT

International variations in the rates of kidney cancer (KC) are considerable. An understanding of the risk factors for KC development is necessary to generate opportunities to reduce its incidence through prevention and surveillance.

OBJECTIVE

To retrieve and summarize global incidence and mortality rates of KC and risk factors associated with its development, and to describe known familial syndromes and genetic alterations that represent biologic risk factors.

EVIDENCE ACQUISITION

A systematic review was conducted via Medline (PubMed) and Scopus to include meta-analyses, reviews, and original studies regarding renal cell carcinoma, epidemiology, and risk factors.

EVIDENCE SYNTHESIS

Our narrative review provides a detailed analysis of KC incidence and mortality, with significant variations across time, geography, and sex. In particular, while KC incidence has continued to increase, mortality models have leveled off. Among the many risk factors, hypertension, obesity, and smoking are the most well established. The emergence of new genetic data coupled with observational data allows for integrated management and surveillance strategies for KC care.

CONCLUSIONS

KC incidence and mortality rates vary significantly by geography, sex, and age. Associations of the development of KC with modifiable and fixed risk factors such as obesity, hypertension, smoking, and chronic kidney disease (CKD)/end-stage kidney disease (ESKD) are well described. Recent advances in the genetic characterization of these cancers have led to a better understanding of the germline and somatic mutations that predispose patients to KC development, with potential for identification of therapeutic targets that may improve outcomes for these at-risk patients.

PATIENT SUMMARY

We reviewed evidence on the occurrence of kidney cancer (KC) around the world. Currently, the main avoidable causes are smoking, obesity, and high blood pressure. Although other risk factors also contribute, prevention and treatment of these three factors provide the best opportunities to reduce the risk of developing KC at present.

Antidiabetic, Antiglycation, and Antioxidant Activities of Ethanolic Seed Extract of Passiflora edulis and Piceatannol In Vitro

The objective of this work was to investigate the antidiabetic, antiglycation, and antioxidant potentials of ethanolic extract of seeds of Brazilian Passiflora edulis fruits (PESE), a major by-product of the juice industry, and piceatannol (PIC), one of the main phytochemicals of PESE. PESE, PIC, and acarbose (ACB) exhibited IC₅₀ for alpha-amylase, 32.1 ± 2.7, 85.4 ± 0.7, and 0.4 ± 0.1 µg/mL, respectively, and IC₅₀ for alpha-glucosidase, 76.2 ± 1.9, 20.4 ± 7.6, and 252 ± 4.5 µg/mL, respectively. The IC₅₀ of PESE, PIC, and sitagliptin (STG) for dipeptidyl-peptidase-4 (DPP-4) was 71.1 ± 2.6, 1137 ± 120, and 0.005 ± 0.001 µg/mL, respectively. PESE and PIC inhibited the formation of advanced glycation end-products (AGE) with IC₅₀ of 366 ± 1.9 and 360 ± 9.1 µg/mL for the initial stage and 51.5 ± 1.4 and 67.4 ± 4.6 µg/mL for the intermediate stage of glycation, respectively. Additionally, PESE and PIC inhibited the formation of β-amyloid fibrils in vitro up to 100%. IC₅₀ values for 1,1-diphenyl-2-picrylhydrazyl radical (DPPH^•) scavenging activity of PESE and PIC were 20.4 ± 2.1, and 6.3 ± 1.3 µg/mL, respectively. IC₅₀ values for scavenging hypochlorous acid (HOCl) were similar in PESE, PIC, and quercetin (QCT) with values of 1.7 ± 0.3, 1.2 ± 0.5, and 1.9 ± 0.3 µg/mL, respectively. PESE had no cytotoxicity to the human normal bronchial epithelial (BEAS-2B), and alpha mouse liver (AML-12) cells up to 100 and 50 µg/mL, respectively. However, 10 µg/mL of the extract was cytotoxic to non-malignant breast epithelial cells (MCF-10A). PESE and PIC were found to be capable of protecting cultured human cells from the oxidative stress caused by the carcinogen NNKOAc at 100 µM. The in vitro evidence of the inhibition of alpha-amylase, alpha-glucosidase, and DPP-4 enzymes as well as antioxidant and antiglycation activities, warrants further investigation of the antidiabetic potential of P. edulis seeds and PIC.

Vitamin-Containing Antioxidant Formulation Reduces Carcinogen-Induced DNA Damage through ATR/Chk1 Signaling in Bronchial Epithelial Cells In Vitro

Lung cancer has the highest mortality rate worldwide and is often diagnosed at late stages, requiring genotoxic chemotherapy with significant side effects. Cancer prevention has become a major focus, including the use of dietary and supplemental antioxidants. Thus, we investigated the ability of an antioxidant formulation (AOX1) to reduce DNA damage in human bronchial epithelial cells (BEAS-2B) with and without the combination of apple peel flavonoid fraction (AF4), or its major constituent quercetin (Q), or Q-3-O-d-glucoside (Q3G) in vitro. To model smoke-related genotoxicity, we used cigarette-smoke hydrocarbon 4-[(acetoxymethyl)nitrosamino]-1-(3-pyridyl)-1-butanone (NNKOAc) as well as methotrexate (MTX) to induce DNA damage in BEAS-2B cells. DNA fragmentation, γ-H2AX immunofluorescence, and comet assays were used as indicators of DNA damage. Pre-exposure to AOX1 alone or in combination with AF4, Q, or Q3G before challenging with NNKOAc and MTX significantly reduced intracellular reactive oxygen species (ROS) levels and DNA damage in BEAS-2B cells. Although NNKOAc-induced DNA damage activated ATM-Rad3-related (ATR) and Chk1 kinase in BEAS-2B cells, pre-exposure of the cells with tested antioxidants prior to carcinogen challenge significantly reduced their activation and levels of γ-H2AX (p ≤ 0.05). Therefore, AOX1 alone or combined with flavonoids holds promise as a chemoprotectant by reducing ROS and DNA damage to attenuate activation of ATR kinase following carcinogen exposure.

Coffee intake and trace element blood concentrations in association with renal cell cancer among smokers

PURPOSE

To determine whether higher coffee intake may reduce the risk of renal cell cancer (RCC) associated with lead (Pb) and other heavy metals with known renal toxicity.

METHODS

We conducted a nested case-control study of male smokers (136 RCC cases and 304 controls) within the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study. Cases diagnosed with RCC at 5 or more years following cohort enrollment were matched to controls on age (± 7 years) and whole blood draw date (± 30 days). Conditional logistic regression (using two-sided tests) was used to test for main effects and additive models of effect modification.

RESULTS

After a mean follow-up of 16.3 years, coffee consumption was not significantly associated with renal cell cancer risk, when adjusting for blood concentrations of Cd, Hg, and Pb and RCC risk factors (age, smoking, BMI, and systolic blood pressure) (p-trend, 0.134). The association with above median blood Pb and RCC (HR = 1.69, 95% CI 1.06, 2.85) appeared to be modified by coffee consumption, such that RCC risk among individuals with both increased coffee intake and higher blood lead concentration were more than threefold higher RCC risk (HR = 3.40, 95% CI 1.62, 7.13; p-trend, 0.003).

CONCLUSION

Contrary to our initial hypothesis, this study suggests that heavy coffee consumption may increase the previously identified association between higher circulating lead (Pb) concentrations and increased RCC risk. Improved assessment of exposure, including potential trace element contaminants in coffee, is needed.

Association between ACYP2 polymorphisms and the risk of renal cell cancer

BACKGROUND

Kidney cancer is the predominant form of malignancy of the kidney and accounts for approximately 3%-4% of all cancers. Renal cell cancer (RCC) represents more than 85% of kidney cancer. It has been reported that genetic factors may predispose individuals to RCC. This study evaluated the association between Acylphosphatase 2 (ACYP2) gene polymorphisms and RCC risk in the Han Chinese population.

METHODS

Twelve single-nucleotide polymorphisms (SNPs) in ACYP2 were genotyped using the Agena MassARRAY platform from 293 RCC patients and 495 controls. The Chi-squared test, genetic models, haplotype, and stratification analyses were used to evaluate the association between SNPs and the risk of RCC. The relative risk was estimated using the odds ratio (OR) and 95% confidence interval (CI).

RESULTS

We observed that the rs6713088 allele G (OR = 1.26, 95% CI: 1.03-1.53, p = .023) and rs843711 allele T (OR = 1.29, 95% CI: 1.06-1.57, p = .010) were associated with increased RCC risk. Genetic model analyses found that rs843711 was significantly associated with an increased RCC risk under the recessive model and log-additive model after adjusting for age and gender. Haplotype analysis showed that the haplotype "TTCTCGCC" (OR = 0.67, 95% CI: 0.48-0.94, p = .021) was associated with a decreased risk of RCC in the Han Chinese population. Stratification analysis also found that rs6713088 and rs843711 were significantly associated with increased RCC risk.

CONCLUSION

In summary, the results suggested that ACYP2 polymorphisms could be used as a genetic marker for RCC. Additional functional and association studies are required to validate our results.

Prognostic biomarkers in renal cell carcinoma: is there a relationship with obesity?

Obesity is a recognized risk factor for renal cell carcinoma (RCC) the commonest form of kidney cancer. Both obesity and RCC are serious diseases with increasing incidence yearly. This review examined certain obesity associated measurements and adipokines as detection/prognostic indicators for RCC. The obesity related measurements such as body mass index (BMI), waist circumstance (WC), waist-hip ratio (WHR) in predicting RCC are valid when used in conjunction with other risk factors such as age and sex or with histological findings. The adipokine adiponectin holds promising outcomes as a predictive marker in assessing the risk of developing RCC. In addition, tissue leptin/leptin receptor may be a distinguishing marker for RCC subtypes. However, circulating leptin may not be a suitable detection or prognostic biomarker for RCC. The other less investigated adipokines; omentin, visfatin, apelin and resistin are also expressed in RCC but their prognostic capabilities are still inconclusive. BMI, WC and adipokines may be useful additions in a nomogram which includes TNM staging and pathological grading system to detect, confirm and follow-up RCC cases.

High expression of F2RL3 correlates with aggressive features and poor survival in clear cell renal cell carcinoma

Background: Specific lifestyle factors including tobacco-exposure are vital etiologic factors for renal cell carcinoma (RCC), F2R Like Thrombin/Trypsin Receptor 3 (F2RL3) is associated with smoking but it is unknown whether its expression translate into poor survival of clear cell RCC (ccRCC). In the current study, the expression profiling and prognostic value of F2RL3 in Chinese patients with ccRCC were investigated. Methods: Using Quantitative PCR analysis and immunohistochemistry, the relative expression levels of F2RL3 in 367 paired ccRCC and adjacent normal tissues were calculated. Cox regression analysis was used to identify independent prognostic factors and Kaplan-Meier analysis and a log-rank test were employed to evaluate the prognostic value of F2RL3. Results: We observed that high expression of F2RL3 mRNA and protein were strongly correlated with shorten progression-free survival (PFS) of ccRCC with hazard ratios (HR; 95% confidence interval (CI)) of 2.060 (1.410-3.009) and 1.657 (1.193-2.300), respectively, as well as with poor overall survival (OS) with HRs (95%CI) of 2.826 (1.713-4.662) and 1.712 (1.140-2.569), respectively. After adjustment for confounding factors including smoking status, elevated HRs (95%CI) of 2.113 (1.445-3.089) and 1.692 (1.218-2.352) were presented for PFS, respectively, and 2.936 (1.777-4.851) and 1.811 (1.203-2.725) were present for OS, respectively. Meanwhile, increased F2RL3 mRNA and protein level were reported to significantly associate with smoking-exposure and well-known prognostic factors (higher TNM stage and ISUP grade). Conclusion: These findings suggested that F2RL3 mRNA and protein level in ccRCC is a robust predictor of poorly prognostic phenotype. Exploring the causal relevance of F2RL3 in ccRCC development further warrants in the future study.

Racial Disparities and Preventive Measures to Renal Cell Carcinoma

Kidney cancer ranks among the top 10 cancers in the United States. Although it affects both male and female populations, it is more common in males. The prevalence rate of renal cell carcinoma (RCC), which represents about 85% of kidney cancers, has been increasing gradually in many developed countries. Family history has been considered as one of the most relevant risk factors for kidney cancer, although most forms of an inherited predisposition for RCC only account for less than four percent. Lifestyle and other factors such as occupational exposure, high blood pressure, poor diet, and heavy cigarette smoking are highly associated with its incidence and mortality rates. In the United States, White populations have the lowest prevalence of RCC compared to other ethnic groups, while Black Americans suffer disproportionally from the adverse effects of RCC. Hence, this review article aims at identifying the major risk factors associated with RCC and highlighting the new therapeutic approaches for its control/prevention. To achieve this specific aim, articles in peer-reviewed journals with a primary focus on risk factors related to kidney cancer and on strategies to reduce RCC were identified. The review was systematically conducted by searching the databases of MEDLINE, PUBMED Central, and Google Scholar libraries for original articles. From the search, we found that the incidence and mortality rates of RCC are strongly associated with four main risk factors, including family history (genetics), lifestyle (poor diet, cigarette smoking, excess alcohol drinking), environment (community where people live), and occupation (place where people work). In addition, unequal access to improvement in RCC cancer treatment, limited access to screening and diagnosis, and limited access to kidney transplant significantly contribute to the difference observed in survival rate between African Americans and Caucasians. There is also scientific evidence suggesting that some physicians contribute to racial disparities when performing kidney transplant among minority populations. New therapeutic measures should be taken to prevent or reduce RCC, especially among African Americans, the most vulnerable population group.

Duration-dependent effects of nicotine exposure on growth and AKT activation in human kidney epithelial cells

Exposure to nicotine is known to cause adverse effects in many target organs including kidney. Epidemiological studies suggest that nicotine-induced kidney diseases are prevalent worldwide. However, the impact of duration of exposure on the nicotine-induced adverse effects in normal kidney cells and the underlying molecular mechanism is still unclear. Hence, the objective of this study was to evaluate both acute and long-term effects of nicotine in normal human kidney epithelial cells (HK-2). Cells were treated with 1 and 10 µM nicotine for acute and long-term duration. The result of cell viability showed that the acute exposure to 1 µM nicotine has no significant effect on growth. However, the 10 µM nicotine caused significant decrease in the growth of HK-2 cells. The long-term exposure resulted in significantly increased cell growth in both 1 and 10 µM nicotine-treated groups. Analysis of cell cycle and expression of marker genes related to proliferation and apoptosis further confirmed the effects of nicotine. Additionally, the analysis of growth signaling pathway revealed the decreased level of pAKT in cells with acute exposure whereas the increased level of pAKT in long-term nicotine-exposed cells. This suggests that nicotine, through modulating the AKT pathway, controls the duration-dependent effects on the growth of HK-2 cells. In summary, this is the first report showing long-duration exposure to nicotine causes increased proliferation of human kidney epithelial cells through activation of AKT pathway.

Renal cell carcinoma: links and risks

This review provides an overview of the incidence of renal cell carcinoma (RCC) and a summary of the most commonly associated risk factors. A literature review was performed with a focus on recent studies with a high level of evidence (large prospective cohort studies and meta-analyses). The incidence rate of RCC varies globally, with the rate rising rapidly in more developed regions, demonstrating the effects of increased use of diagnostic imaging and prevalence of modifiable risk factors. Based on the current evidence, cigarette smoking, obesity, and hypertension are the most well-established risk factors for sporadic RCC worldwide. Acquired cystic kidney disease is also a significant risk factor, specifically in dialysis patients. There is increasing evidence for an inverse association between RCC risk and moderate alcohol consumption. Certain analgesics and occupational exposure have been linked to an increased risk of RCC, although data are limited. Diets rich in fruits and vegetables may provide a protective effect.

Effects of cigarette smoking and nicotine metabolite ratio on leukocyte telomere length

Studies of the effects of smoking on leukocyte telomere length (LTL) using cigarettes smoked per day or pack years smoked (PYS) present limitations. Reported high levels of smoking may not increase toxin exposure levels proportionally. Nicotine metabolism ratio (NMR) predicts total cigarette puff volume and overall exposure based on total N-nitrosamines, is highly reproducible and independent of time since the last cigarette. We hypothesized that smokers with higher NMRs will exhibit increased total puff volume, reflecting efforts to extract more nicotine from their cigarettes and increasing toxin exposure. In addition, higher levels of smoking could cause a gross damage in LTL. The urinary cotinine, 3-OH cotinine and nicotine levels of 147 smokers were analyzed using a LC/MS system Triple-Q6410. LTL and CYP2A6 genotype was determined by PCR in blood samples. We found a significant association between NMR and CYP2A6 genotype. Reduction in LTL was seen in relation to accumulated tobacco consumption and years smoking when we adjusted for age and gender. However, there were no significant differences between NMR values and LTL. In our study the higher exposure was associated with lower number of PYS. Smokers with reduced cigarette consumption may exhibit compensatory smoking behavior that results in no reduced tobacco toxin exposure. Our results suggest that lifetime accumulated smoking exposure could cause a gross damage in LTL rather than NMR or PYS. Nevertheless, a combination of smoking topography (NMR) and consumption (PYS) measures may provide useful information about smoking effects on health outcomes.

Epidemiology and staging of renal cell carcinoma

Incidence and mortality trends attributed to kidney cancer exhibit marked regional variability, likely related to demographic, environmental, and genetic factors. Efforts to identify reversible factors, which lead to the development of renal cell carcinoma (RCC), have led not only to a greater understanding of the etiology of RCC but also the genetic and histologic characteristics of renal tumors. This article describes this evolution by discussing contemporary RCC incidence and mortality data, the risk factors for development of RCC, the histologic features, and anatomic and integrated staging systems that guide treatment.

In vitro and in vivo models of colorectal cancer: antigenotoxic activity of berries

The etiology of colorectal cancer (CRC), a common cause of cancer-related mortality globally, has strong associations with diet. There is considerable epidemiological evidence that fruits and vegetables are associated with reduced risk of CRC. This paper reviews the extensive evidence, both from in vitro studies and animal models, that components of berry fruits can modulate biomarkers of DNA damage and that these effects may be potentially chemoprotective, given the likely role that oxidative damage plays in mutation rate and cancer risk. Human intervention trials with berries are generally consistent in indicating a capacity to significantly decrease oxidative damage to DNA, but represent limited evidence for anticarcinogenicity, relying as they do on surrogate risk markers. To understand the effects of berry consumption on colorectal cancer risk, future studies will need to be well controlled, with defined berry extracts, using suitable and clinically relevant end points and considering the importance of the gut microbiota.

Comprehensive assessment of the impact of cigarette smoking on survival of clear cell kidney cancer

PURPOSE

The impact of modifiable environmental factors on kidney cancer specific outcomes is under studied. We evaluated the impact of smoking exposure on cancer specific survival in patients with clear cell renal cell carcinoma treated with surgery.

MATERIALS AND METHODS

From a prospectively maintained database at a single center we collected the characteristics of 1,625 patients with clear cell renal cell carcinoma treated with surgery between 1995 through 2012. We determined the associations of smoking status with advanced disease, defined as AJCC (American Joint Committee on Cancer) stage greater than 2, and with cancer specific survival.

RESULTS

The prevalence rate of current, former and never smoking at diagnosis was 16%, 30% and 54%, respectively. Of the patients 62% reported a smoking history of 20 pack-years or greater. Median followup in survivors was 4.5 years (IQR 2.2-7.9). On univariable analysis a smoking history of 20 pack-years or greater was associated with a significantly increased risk of advanced disease (OR 1.43, 95% CI 1.02-2.00). However, it did not achieve an independent association after adjusting for age and gender. Pathological stage and Fuhrman grade adversely affected cancer specific survival on multivariable competing risks analysis. Although the association between smoking and cancer specific survival did not achieve statistical significance on multivariable analysis, the direction of the central estimate (HR 1.5, 95% CI 0.89-2.52) suggested that smoking adversely impacts cancer specific survival. Current smokers faced a higher risk of death from another cause than never smokers (HR 1.93, 95% CI 1.29-2.88).

CONCLUSIONS

Smoking exposure substantially increases the risk of death from another cause and adversely impacts cancer specific survival in patients with clear cell renal cell carcinoma. Treatment plans to promote smoking cessation are recommended for these patients.

The epidemiology and risk factors for renal cancer

BACKGROUND

Renal cancer is a frequently occurring malignancy with over 270,000 new cases diagnosed and it being responsible for 110,000 deaths annually on a global basis. Incidence rates have gradually increased whilst mortality rates are starting to plateau.

OBJECTIVE

To review epidemiology and risk factors for renal cancer.

METHODS

The current data is based on a thorough review of available original and review articles on epidemiology and risk factors for renal cancer with a systemic literature search utilising Medline.

RESULTS

The prevalence of associated risk factors such as genetic susceptibility, smoking, hypertension and obesity are changing and could account for the changes in incidence whilst the role of diet and occupational exposure to carcinogens requires further investigation.

CONCLUSION

Despite the evidence of various associated risk factors, further work is required from well designed studies to gain a greater understanding of the etiology of renal cancer.

4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) metabolism-related enzymes gene polymorphisms, NNK metabolites levels and urothelial carcinoma

Gene polymorphisms of the 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) metabolism-related enzymes-cytochrome P450 (CYP) monooxygenase 2A13 (CYP2A13) and UDP-glucuronosyltransferases (UGT)-2B7 could contribute to the levels of NNK-related metabolites in urine, thereby increasing the susceptibility to urothelial carcinoma (UC). Therefore, our study aimed to evaluate the roles of two gene polymorphisms (CYP2A13 and UGT2B7) of NNK metabolism-related enzymes in the carcinogenesis of UC in Taiwan. A hospital-based pilot case-control study was conducted. There were 121 UC cases and 121 age- and sex-matched healthy participants recruited from March 2007 to April 2009. Urine samples were analyzed for NNK-related metabolites using the liquid chromatography-tandem mass spectrometry method. Genotyping was conducted using a polymerase chain reaction-restriction fragment length polymorphism technique. ANCOVA and multivariate logistic regression were applied for data analyses. In healthy controls, former smokers had significantly higher total NNAL and higher NNAL-Gluc than never smokers or current smokers. Subjects carrying the UGT2B7 268 His/Tyr or Tyr/Tyr genotype had significantly lower total NNAL than those carrying His/His genotype. However, no association was seen between gene polymorphisms of CYP2A13 and UGT2B7 and UC risk after adjustment for age and sex. Significant dose -response associations between total NNAL, free NNAL, the ratios of free NNAL/total NNAL and NNAL-Gluc/total NNAL and UC risk were observed. In the future, large-scale studies will be required to verify the association between the single nucleotide polymorphisms of NNK metabolism-related enzymes and UC risk.

Nasopharyngeal carcinoma risk by histologic type in central China: impact of smoking, alcohol and family history

The role of cigarette smoking, alcohol use, family history of cancer and the interaction of cigarettes and family history in the etiology of Nasopharyngeal carcinoma (NPC) in general and within each histologic type are unclear. We conducted a case-control study among 1,044 Han Chinese patients with NPC and 1,095 Han Chinese cancer-free control subjects. Logistic regression was used to analyze the association between histologic type of NPC and cigarette smoking, alcohol drinking and family history. The results indicated that NPC was significantly associated with cigarette smoking [adjusted odds ratio (OR) = 2.97, 95% confidence interval (CI), 2.38-3.70], and the association exhibited a dose-response relationship for intensity, duration, and cumulative consumption of cigarettes (p(trend) < 0.0001 for intensity, duration and cumulative consumption of cigarettes). Positive family history of cancer led to a significant 12-fold elevated risk of NPC (adjusted OR = 12.95, 95% CI, 7.12-23.54) and acted jointly with cigarettes in contributing to NPC risk (adjusted OR = 56.68, 95% CI, 17.25-186.19). The association of NPC risk with cigarettes was stronger for nonkeratinizing carcinoma than for keratinizing squamous cell carcinoma (KSCC), whereas family history was more closely associated with KSCC. NPC risk was not associated with alcohol consumption. Our study demonstrated that cigarette smoking and family history of cancer could serve independently and jointly as risk factors for etiology of NPC and might affect the risk of histology-specific NPC differently. This knowledge may help facilitate comprehension of NPC etiology in general as well as within each histologic type, and thereby improve prevention efforts.

Epidemiology and risk factors for kidney cancer

After more than two decades of rising rates, in recent years the total kidney cancer incidence worldwide has shown signs of stabilizing, or even decreasing. In adults, kidney cancer consists of renal cell carcinoma (RCC), the predominant form, and renal transitional cell carcinoma (RTCC); these types primarily arise in the renal parenchyma and renal pelvis, respectively. Although temporal trends by kidney cancer type are not well established worldwide, incidence of RCC in the US has continued to rise, mainly for early-stage tumors, while that of RTCC has declined, and total kidney cancer mortality rates have leveled. Stabilization of kidney cancer mortality rates has also been reported in Europe. These trends are consistent with reports of increasing incidental diagnoses and a downward shift in tumor stage and size in clinical series. The changing prevalence of known risk factors for RCC, including cigarette smoking, obesity, and hypertension, is also likely to affect incidence trends, although their relative impact may differ between populations. Accumulating evidence suggests an etiologic role in RCC for physical activity, alcohol consumption, occupational exposure to trichloroethylene, and high parity among women, but further research is needed into the potential causal effects of these factors. Genetic factors and their interaction with environmental exposures are believed to influence risk of developing RCC, but a limited number of studies using candidate-gene approaches have not produced conclusive results. Large consortium efforts employing genome-wide scanning technology are underway, which hold promise for novel discoveries in renal carcinogenesis.