International renal-cell cancer study. III. Role of weight, height, physical activity, and use of amphetamines

Lifetime Body Weight Trajectories and Risk of Renal Cell Cancer: A Large U.S. Prospective Cohort Study

BACKGROUND

Body mass index (BMI) is a known risk factor for renal cell cancer (RCC), but data are limited as to the effect of lifetime exposure to excess body weight.

METHODS

Using the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (N = 138,614, 527 incident RCCs), we identified several anthropometric measures to capture the lifetime BMI patterns: (i) BMI at specific ages; (ii) adulthood BMI trajectories; (iii) cumulative exposure to overweight/obesity denoted as weighted years of living overweight/obese (WYO); and (iv) weight change during each age span. We conducted multivariable Cox model to quantify the association between each anthropometric metric and incident RCC.

RESULTS

A higher BMI at ages 20 and 50 and at baseline was associated with a greater hazard of RCC. Compared with individuals who retained normal BMI throughout adulthood, we observed an increased hazard of RCC for BMI trajectory of progressing from normal BMI to overweight [HR, 1.49; 95% confidence interval (CI), 1.19-1.87], from normal BMI to obesity (HR, 2.22; 95% CI, 1.70-2.90), and from overweight to obesity (HR, 2.78; 95% CI, 1.81-4.27). Compared with individuals who were never overweight (WYO = 0), elevated HRs were observed among individuals who experienced low (HR, 1.31; 95% CI, 0.99-1.74), medium (HR, 1.57; 95% CI, 1.20-2.05), and high (HR, 2.10; 95% CI, 1.62-2.72) WYO tertile. Weight gain of ≥10 kg was associated with increased RCC incidence for each age span.

CONCLUSIONS

Across the lifespan, being overweight/obese, weight gain, and higher cumulative exposure to excess weight were all associated with increased RCC risk.

IMPACT

It is important to avoid weight gain and assess BMI from a life-course perspective to reduce RCC risk.

Effect of smoking, hypertension and lifestyle factors on kidney cancer - perspectives for prevention and screening programmes

Renal cell carcinoma (RCC) incidence has doubled over the past few decades. However, death rates have remained stable as the number of incidental renal mass diagnoses peaked. RCC has been recognized as a European health care issue, but to date, no screening programmes have been introduced. Well-known modifiable risk factors for RCC are smoking, obesity and hypertension. A direct association between cigarette consumption and increased RCC incidence and RCC-related death has been reported, but the underlying mechanistic pathways for this association are still unclear. Obesity is associated with an increased risk of RCC, but interestingly, improved survival outcomes have been reported in obese patients, a phenomenon known as the obesity paradox. Data on the association between other modifiable risk factors such as diet, dyslipidaemia and physical activity with RCC incidence are conflicting, and potential mechanisms underlying these associations remain to be elucidated.

Association between weight cycling and risk of kidney cancer: a prospective cohort study and meta-analysis of observational studies

PURPOSE

Weight cycling is common in populations. However, it is unclear whether frequency and magnitude of weight cycling is associated with kidney cancer risk, independent of body mass index (BMI).

METHODS

A prospective cohort study followed 85,562 participants from Health Professionals Follow-up Study and Nurses' Health Study (1992-2014). At baseline, participants reported frequency and magnitude of intentional weight loss in the past 4 years. Cox proportional hazard model was used to estimate hazard ratios (HR) and 95% confidence intervals (CI). We also conducted a meta-analysis of all available observational studies including our two cohorts.

RESULTS

During 22 years of follow-up, we identified 441 kidney cancer cases. Compared with non-weight cyclers (no attempt of intentional weight loss), severe cyclers (≥ 3 times of intentional weight loss of ≥ 4.5 kg) were at increased kidney cancer risk after adjusting for BMI before weight cycling (pooled multivariable-adjusted HR, 1.78; 95% CI, 1.19, 2.66). Additional adjustment for attained BMI after weight cycling had minimal influence. There was a positive trend between weight cycling by frequency and magnitude and kidney cancer risk (P-trend = 0.01). Moreover, the observed positive association did not differ by subtypes of cyclers (e.g., adiposity status, weight-loss methods). In the meta-analysis, we found a strong positive association between weight cycling and kidney cancer risk (summary relative risk for weight cyclers vs. non-cyclers, 1.51; 95% CI, 1.16, 1.96; I²: 52.2%; 6 studies).

CONCLUSION

Frequent substantial weight cycling was associated with increased risk of kidney cancer, independent of BMI. Our study suggests that weight cycling may be an important risk factor for kidney cancer.

Early life body size in relation to risk of renal cell carcinoma in adulthood: a Danish observational cohort study

Adult obesity increases risks of renal cell carcinoma (RCC). This study investigated if birth weight, child body mass index (BMI) and height are associated with adult RCC. The study included 301,418 children (152,569 boys) from the Copenhagen School Health Records Register born 1930-1985 with measured weights and heights at ages 7 to 13 years. Birth weight was obtained by parental report. BMI and height were transformed to z-scores, and BMI was categorized as normal BMI or overweight. RCC was identified by linkage to the Danish Cancer Registry. Hazard ratios (HR) and 95% confidence intervals (CI) were estimated by Cox proportional hazards regression. During follow-up, 1010 individuals (680 men) were diagnosed with RCC. BMI and height were positively associated with RCC with no significant sex-differences (age 13: HR = 1.14, 95% CI 1.06-1.23 per BMI z-score, HR = 1.12, 95% CI 1.05-1.20 per height z-score). Compared to children with normal BMI at ages 7 and 13 years, children with overweight only at age 13 had higher risks of RCC (HR = 1.67, 95% CI 1.24-2.26). Compared to children with average growth in height, persistently taller-than-average children (HR = 1.06, 95% CI 1.03-1.10) and children who changed from average to above-average height (HR = 1.08, 95% CI 1.01-1.15) had increased risks of RCC. Birth weight was positively associated with RCC (HR = 1.12, 95% CI 1.05-1.20 per 500 grams). Birth weight, childhood BMI and height were positively associated with RCC risk in men and women.

Body fatness at a young age and risks of eight types of cancer: systematic review and meta-analysis of observational studies

The associations between body fatness at a young age (childhood, adolescence and young adulthood; age ≤ 30 years) and diffuse large B-cell lymphoma (DLBCL), oesophageal adenocarcinoma, gastric cardia cancer, hepatocellular carcinoma, multiple myeloma, pancreatic cancer, renal cell cancer and thyroid cancer remain inconclusive. We performed a comprehensive systematic literature review and meta-analysis of observational studies to clarify the associations between body fatness at a young age and the risks of these cancers. PubMed and Web of Science databases were searched for relevant observational studies. Fifty-six articles yielded data on 27,559 cancer cases, including 3,170 DLBCL, 1,491 oesophageal adenocarcinoma, 1,103 gastric cardia cancer, 1,067 hepatocellular carcinoma, 3,090 multiple myeloma, 7,220 pancreatic cancer, 6,212 renal cell cancer and 4,206 thyroid cancer cases. Each 5 kg m^-2 increase in body mass index at a young age was positively associated with DLBCL (relative risk [RR] 1.21, 95% confidence interval [CI] 1.09, 1.35), oesophageal adenocarcinoma (RR 1.88, 95% CI 1.37, 2.57), gastric cardia cancer (RR 1.59, 95% CI 1.15, 2.21), hepatocellular carcinoma (RR 1.31, 95% CI 1.13, 1.51), multiple myeloma (RR 1.23, 95% CI 1.15, 1.30), pancreatic cancer (RR 1.17, 95% CI 1.11, 1.24), renal cell cancer (RR 1.22, 95% CI 1.16, 1.28) and thyroid cancer (RR 1.12, 95% CI 1.07, 1.17). In summary, higher body fatness at a young age increases the risks of developing various types of cancer later in life. Prevention of overweight and obesity in children, adolescents and young adults should therefore be emphasized to reverse the obesity epidemic and thereby avoid further increases in the burden of cancer attributed to excess body fatness.

Weight Fluctuation and Cancer Risk in Postmenopausal Women: The Women's Health Initiative

Background: Weight cycling, defined by an intentional weight loss and subsequent regain, commonly occurs in overweight and obese women and is associated with some negative health outcomes. We examined the role of various weight-change patterns during early to mid-adulthood and associated risk of highly prevalent, obesity-related cancers (breast, endometrial, and colorectal) in postmenopausal women.Methods: A total of 80,943 postmenopausal women (age, 63.4 ± 7.4 years) in the Women's Health Initiative Observational Study were categorized by self-reported weight change (weight stable; weight gain; lost weight; weight cycled [1-3, 4-6, 7-10, >10 times]) during early to mid-adulthood (18-50 years). Three site-specific associations were investigated using Cox proportional hazard models [age, race/ethnicity, income, education, smoking, alcohol, physical activity, hormone therapy, diet, and body mass index (BMI)].Results: A total of 7,464 (breast = 5,564; endometrial = 788; and colorectal = 1,290) incident cancer cases were identified between September 1994 and August 2014. Compared with weight stability, weight gain was significantly associated with risk of breast cancer [hazard ratio (HR), 1.11; 1.03-1.20] after adjustment for BMI. Similarly, weight cycling was significantly associated with risk of endometrial cancer (HR = 1.23; 1.01-1.49). Weight cycling "4 to 6 times" was most consistently associated with cancer risk, showing a 38% increased risk for endometrial cancer [95% confidence interval (CI), 1.08-1.76] compared with weight stable women.Conclusions: Weight gain and weight cycling were positively associated with risk of breast and endometrial cancer, respectively.Impact: These data suggest weight cycling and weight gain increase risk of prevalent cancers in postmenopausal women. Adopting ideal body-weight maintenance practices before and after weight loss should be encouraged to reduce risk of incident breast and endometrial cancers. Cancer Epidemiol Biomarkers Prev; 26(5); 779-86. ©2017 AACR.

Reduced risk of incident kidney cancer from walking and running

PURPOSE

This study aimed to test whether incident kidney cancer risk is associated with exercise energy expenditure (i.e., metabolic equivalents, 1 MET) when calculated from distance walked or run.

METHODS

Hazard ratios (HR) and 95% confidence intervals (95% CI) from Cox proportional hazard analyses of self-reported physician-diagnosed incident kidney cancer versus MET-hours per week in 91,820 subjects recruited between 1991 and 1993 (7.7 yr follow-up of 42,833 subjects) and between 1998 and 1999 (6.4 yr follow-up of 33,053 subjects) as part of the National Runners' Health Study and between 1998 and 1999 as part of the National Walkers' Health Study (5.7 yr follow-up of 15,934 subjects).

RESULTS

Fifty-two incident cancers were reported. Age- and sex-adjusted risk declined 1.9% per MET-hour per week run or walked (HR = 0.981, 95% CI = 0.964-0.997, P = 0.02). Compared with walking or running below guidelines levels (<7.5 MET·h·wk(-1)), the risk for incident kidney cancer was 61% lower for meeting the guidelines (HR = 0.39, 95% CI = 0.11-1.08, P = 0.07 for 7.5-12.5 MET·h·wk(-1)), 67% lower for exercising one to two times the recommended level (HR = 0.33; 95% CI = 0.15-0.72, P = 0.005 for 12.6-25.1 MET·h·wk(-1)), and 76.3% lower for exercising two times or more the recommended level (HR = 0.24, 95% CI = 0.11-0.52, P = 0.0005 for ≥ 25.2 MET·h·wk(-1)). Incident kidney cancer risk also increased in association with baseline body mass index (P = 0.002), smoking (P = 0.02), and hypertensive (P = 0.007) and diabetes medication use (P = 0.01); however, exercise-associated reductions in kidney cancer risk persisted for 12.6-25.1 MET·h·wk(-1) (HR = 0.35, P = 0.01) and ≥ 25.2 MET·h·wk(-1) (HR = 0.29, P = 0.004) vis-à-vis <7.5 MET·h·wk(-1) when also adjusted for body mass index, hypertension, diabetes, and pack-years smoked.

CONCLUSION

Running and walking may reduce incident kidney cancer risk independent of its other known risk factors.

Epidemiology of Renal Cell Carcinoma

The increasing incidence of RCC in most populations may in part be due to increasing numbers of incidentally detected cancers with new imaging methods. Further, the increase is not only limited to small local tumours but also includes more advanced tumours, which may to some part explain the still high mortality rates. The variation in incidence between populations may have several other explanations. Traditionally the starting point has included thoughts of environmental exposures, which so far have only in part explained the causes of RCC, by means of cigarette smoking and obesity, which may account for approximately 40% of cases in high-risk countries (Table 2). Further, the genetic variations may be of importance as a cause of the difference between populations. Continued research in RCC is needed with the knowledge that nearly 50% of patients die within 5 years after diagnosis. The further search for environmental exposures should take in account the knowledge that RCC consists of different types with specific genetic molecular characteristics. These genetic alterations have in some cases been suggested to be associated with specific exposures. Furthermore, there might exist a modulating effect of genetic polymorphisms among metabolic activation and detoxification enzymes. Hence, a further understanding of the genetic and molecular processes involved in RCC will hopefully give us a better knowledge how to analyse and interpret exposure associations that have importance for both initiation and progression of RCC.

Obesity and Kidney Cancer

Renal cell cancer (RCC) is the major type of kidney cancer with increasing incidence. Obesity is one of the well-established risk factors for RCC. Meta-analyses including multiple cohort and case-control studies have found a consistent positive association between obesity and RCC. The association appeared to be independent of other RCC risk factors including hypertension and has been often stronger in women, although a positive association has also been observed in men. Obesity has been largely measured as body mass index (BMI). Studies which evaluated other measures of obesity including waist circumference (WC), waist-to-hip ratio (WHR) as well as increase in weight have reported similar positive associations with RCC. Although the mechanisms by which obesity influences renal carcinogenesis have been under-explored, insulin resistance and certain growth factors including insulin-like growth factor (IGF-1), sex steroid hormones, and biochemical markers such as adiponectin may be involved. The positive association with obesity has been observed with the clear cell type of RCC, which is the major histological subtype. On the other hand, the association between obesity and RCC survival appears to be much more complex. An apparent inverse association between obesity at time of diagnosis and RCC survival has been observed in some studies' generating speculation of an "obesity paradox" hypothesis. However, this "paradox" may be due to reverse causation, selection bias, or other forms of bias rather than a true biological association.

Physical activity and renal cell carcinoma among black and white Americans: a case-control study

Background

Renal cell carcinoma (RCC) has a higher incidence in blacks than in whites. Physical activity may influence the risk of renal cell cancer, but the evidence is inconsistent. No previous study has investigated this relationship in the black population.

Methods

We examined the association between self-reported physical activity at different ages and risk of RCC in a population based case-control study of 1217 cases (361 black, 856 white) and 1235 controls (523 black, 712 white) frequency-matched on age, race, and gender. Multivariate-adjusted odds ratios (OR) and 95% confidence intervals (CI) were estimated using unconditional logistic regression.

Results

Among whites, increased risks of RCC were observed among participants reporting low levels of transportation-related activity in their 20’s (OR _{<1 hr/wk vs >7 hr/wk} (95% CI): 1.42 (1.10, 1.83)) and leisure time activity in their 50’s (OR _{<1 hr/wk vs >7 hr/wk} (95% CI): 1.49 (1.00, 2.20)). We found no association between physical activity and RCC risk among blacks.

Conclusion

Our results suggest that physical activity may be inversely associated with RCC risk in whites, but there was no evidence of such an association in blacks. As this is the first study evaluating the effect of physical activity on RCC risk among blacks, further investigations are needed to clarify the relationship in this population.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2407-14-707) contains supplementary material, which is available to authorized users.

Urological complications of illicit drug use

Illicit drug use is prevalent worldwide; over 24 million people are estimated to have used recreational drugs during the past month in the UK and USA alone. Illicit drug use can result in a wide spectrum of potential medical complications that include many urological manifestations. To ensure optimal care and treatment, urologists need to be cognizant of these complications in their patients, particularly among youths. Ketamine uropathy is thought to affect over one-quarter of ketamine users and can lead to severe lower urinary tract symptoms, as well as upper tract obstruction. Cannabis use has been associated with an increased risk of bladder cancer, prostate cancer and nonseminomatous germ cell tumours in case-control studies. Fournier's gangrene has been reported following injection of heroin and cocaine into the penis. Excessive use of cough medicines can lead to the development of radiolucent stones composed of ephedrine, pseudoephedrine and guaifenesin. As the current evidence is mostly limited to case reports and case series, future epidemiological studies are needed to fully address this issue.

The association between physical activity and renal cancer: systematic review and meta-analysis

Background:

Physical activity may decrease renal cancer risk by reducing obesity, blood pressure, insulin resistance, and lipid peroxidation. Despite plausible biologic mechanisms linking increased physical activity to decreased risk for renal cancer, few epidemiologic studies have been able to report a clear inverse association between physical activity and renal cancer, and no meta-analysis is available on the topic.

Methods:

We searched the literature using PubMed and Web of Knowledge to identify published non-ecologic epidemiologic studies quantifying the relationship between physical activity and renal cancer risk in individuals without a cancer history. Following the PRISMA guidelines, we conducted a systematic review and meta-analysis, including information from 19 studies based on a total of 2 327 322 subjects and 10 756 cases. The methodologic quality of the studies was examined using a comprehensive scoring system.

Results:

Comparing high vs low levels of physical activity, we observed an inverse association between physical activity and renal cancer risk (summary relative risk (RR) from random-effects meta-analysis=0.88; 95% confidence interval (CI)=0.79–0.97). Summarising risk estimates from high-quality studies strengthened the inverse association between physical activity and renal cancer risk (RR=0.78; 95% CI=0.66–0.92). Effect modification by adiposity, hypertension, type 2 diabetes, smoking, gender, or geographic region was not observed.

Conclusion:

Our comprehensive meta-analysis provides strong support for an inverse relation of physical activity to renal cancer risk. Future high-quality studies are required to discern which specific types, intensities, frequencies, and durations of physical activity are needed for renal cancer risk reduction.

Body mass index and renal cell cancer: the influence of race and sex

BACKGROUND

Obesity is a risk factor for renal cell (or renal) cancer. The increasing prevalence of obesity may be contributing to the rising incidence of this cancer over the past several decades. The effects of early-age obesity and change in body mass index (BMI) on renal cancer have been studied less thoroughly, and the influence of race has never been formally investigated.

METHODS

Using data gathered as part of a large case-control study of renal cancer (1214 cases and 1234 controls), we investigated associations with BMI at several time points, as well as with height. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were computed using logistic regression modeling. Race- and sex-stratified analyses were conducted to evaluate subgroup differences.

RESULTS

Obesity (BMI ≥ 30 kg/m) early in adulthood (OR = 1.6 [95% CI = 1.1 to 2.4]) and 5 years before diagnosis (1.6 [1.1 to 2.2]) was associated with renal cancer. The association with early-adult obesity was stronger among whites than blacks (test for interaction, P = 0.006), whereas the association with obesity near diagnosis was marginally stronger in women than men (test for interaction, P = 0.08). The strongest association with renal cancer was observed for obese whites both in early adulthood and before interview (2.6 [1.5 to 4.4]); this association was not present among blacks. Estimates of the annual excess rate of renal cancer (per 100,000 persons) attributed to both overweight and obesity (BMI > 25 kg/m) ranged from 9.9 among black men to 5.6 among white women.

CONCLUSION

Obesity, both early and later in life, is associated with an increased risk of renal cancer. The association with early obesity seems to be stronger among whites than blacks.

Epidemiology of renal cell cancer

Renal cell cancer (RCC) is increasingly diagnosed at an early stage in many countries, which likely contributes to the recent leveling of RCC mortality in the United States and many European countries. However, over all stages nearly 50% of the patients die within 5 years after diagnosis. Smoking and obesity may account for approximately 40% of all incidental cases in high-risk countries. Besides obesity, rising prevalence of hypertension may play a growing role. Several other occupational and lifestyle factors may also affect the risk of RCC. Genetic variations may be an important factor in the differing incidence among populations.

Prospective evaluation of analgesic use and risk of renal cell cancer

BACKGROUND

Epidemiologic data suggest that analgesic use increases the risk of renal cell cancer (RCC), but few prospective studies have been published. We investigated the association between analgesic use and RCC in 2 large prospective studies.

METHODS

We examined the relationship between analgesic use and RCC risk in the Nurses' Health Study and the Health Professionals Follow-up Study. Use of aspirin, other nonsteroidal anti-inflammatory drugs (NSAIDs), and acetaminophen was ascertained in 1990 in the Nurses' Health Study and in 1986 in the Health Professionals Follow-up Study, and every 2 years thereafter. We evaluated baseline and duration of use of analgesics.

RESULTS

During follow-up of 16 years among 77,525 women and 20 years among 49,403 men, we documented 333 RCC cases. Aspirin and acetaminophen use were not associated with RCC risk. However, regular use of nonaspirin NSAIDs was associated with an increased RCC risk; the pooled multivariate relative risk was 1.51 (95% confidence interval, 1.12-2.04) at baseline. The absolute risk differences for users vs nonusers of nonaspirin NSAIDs were 9.15 per 100 000 person-years in women and 10.92 per 100,000 person-years in men. There was a dose-response relationship between duration of nonaspirin NSAID use and RCC risk; compared with nonregular use, the pooled multivariate relative risks were 0.81 (95% confidence interval, 0.59-1.11) for use less than 4 years, 1.36 (0.98-1.89) for 4 to less than 10 years, and 2.92 (1.71-5.01) for use for 10 or more years (P < .001 for trend).

CONCLUSION

Our prospective data suggest that longer duration of use of nonaspirin NSAIDs may increase the risk of RCC.

Epidemiologic characteristics and risk factors for renal cell cancer

Incidence rates of renal cell cancer, which accounts for 85% of kidney cancers, have been rising in the United States and in most European countries for several decades. Family history is associated with a two- to four-fold increase in risk, but the major forms of inherited predisposition together account for less than 4% of renal cell cancers. Cigarette smoking, obesity, and hypertension are the most consistently established risk factors. Analgesics have not been convincingly linked with renal cell cancer risk. A reduced risk of renal cell cancer among statin users has been hypothesized but has not been adequately studied. A possible protective effect of fruit and vegetable consumption is the only moderately consistently reported dietary finding, and, with the exception of a positive association with parity, evidence for a role of hormonal or reproductive factors in the etiology of renal cell cancer in humans is limited. A recent hypothesis that moderate levels of alcohol consumption may be protective for renal cell cancer is not strongly supported by epidemiologic results, which are inconsistent with respect to the categories of alcohol consumption and the amount of alcohol intake reportedly associated with decreased risk. For occupational factors, the weight of the evidence does not provide consistent support for the hypotheses that renal cell cancer may be caused by asbestos, gasoline, or trichloroethylene exposure. The established determinants of renal cell cancer, cigarette smoking, obesity, and hypertension, account for less than half of these cancers. Novel epidemiologic approaches, including evaluation of gene–environment interactions and epigenetic mechanisms of inherited and acquired increased risk, are needed to explain the increasing incidence of renal cell cancer.

Serum insulin-like growth factor-1 is an independent predictor of prognosis in patients with renal cell carcinoma

Obesity is associated with an increased risk of certain cancers, including renal cell carcinoma. A possible mediator of this risk is insulin-like growth factor-1 (IGF-1). The authors evaluated the prognostic information of IGF-1, IGFBP-3, leptin, and prealbumin in sera sampled at diagnosis from 256 consecutive patients with renal cell carcinoma. Insulin-like growth factor-1 and leptin were positively correlated to body mass index (BMI). Insulin-like growth factor-1 and IGFBP-3 did not correlate to tumour stage or grade. Leptin and prealbumin were both inversely related to tumour stage and grade. When survival was analysed in patients with levels above a median of IGF-1, leptin, and prealbumin, prognosis was more favourable, compared with those with lower levels (p=0.017; p=0.024, and p<0.0001, respectively). In a multivariate analysis, tumour stage and serum IGF-1 levels were independent prognostic factors. The results indicate that serum IGF-1 at diagnosis is related to prognosis in renal cell carcinoma.

Lifestyle Factors, Exposures, Genetic Susceptibility, and Renal Cell Cancer Risk: A Review

Malignant kidney tumors account for approximately 2% of all new primary cancer cases diagnosed in the United States, with an estimated 30,000 cases occurring annually. Although a variety of agents, chemical and biological, have been implicated as causal agents in the development of renal cell carcinoma (RCC), the etiology remains enigmatic. The strongest association has been developed between cigarette smoking and renal cancer however consistent, positive associations between RCC and obesity, diabetes, and hypertension have also been reported. In addition, more recent investigations of familial kidney cancer syndromes indicate that a strong genetic component contributes to RCC development. Several genes have been identified through investigation of familial kidney cancer syndromes. This review article describes recent trends in RCC incidence and the currently identifiable etiological causes that account for approximately half of the RCC cases diagnoses. The remainder of this review then focuses on additional risk factors that have thus far not been well examined but may be helpful in explaining the increasing incidence trends and the geographic or racial variation observed nationally and worldwide.

Energy balance, physical activity, and cancer risk

This chapter posits that cancer is a complex and multifactorial process as demonstrated by the expression and production of key endocrine and steroid hormones that intermesh with lifestyle factors (physical activity, body size, and diet) in combination to heighten cancer risk. Excess weight has been associated with increased mortality from all cancers combined and for cancers of several specific sites. The prevalence of obesity has reached epidemic levels in many parts of the world; more than 1 billion adults are overweight with a body mass index (BMI) exceeding 25. Overweight and obesity are clinically defined indicators of a disease process characterized by the accumulation of body fat due to an excess of energy intake (nutritional intake) relative to energy expenditure (physical activity). When energy intake exceeds energy expenditure over a prolonged period of time, the result is a positive energy balance (PEB), which leads to the development of obesity. This physical state is ideal for intervention and can be modulated by changes in energy intake, expenditure, or both. Nutritional intake is a modifiable factor in the energy balance-cancer linkage primarily tested by caloric restriction studies in animals and the effect of energy availability. Restriction of calories by 10 to 40% has been shown to decrease cell proliferation, increasing apoptosis through anti-angiogenic processes. The potent anticancer effect of caloric restriction is clear, but caloric restriction alone is not generally considered to be a feasible strategy for cancer prevention in humans. Identification and development of preventive strategies that "mimic" the anticancer effects of low energy intake are desirable. The independent effect of energy intake on cancer risk has been difficult to estimate because body size and physical activity are strong determinants of total energy expenditure. The mechanisms that account for the inhibitory effects of physical activity on the carcinogenic process are reduction in fat stores, activity related changes in sex-hormone levels, altered immune function, effects in insulin and insulin-like growth factors, reduced free radical generation, and direct effect on the tumor. Epidemiologic evidence posits that the cascade of actions linking overweight and obesity to carcinogenesis are triggered by the endocrine and metabolic system. Perturbations to these systems result in the alterations in the levels of bioavailable growth factors, steroid hormones, and inflammatory markers. Elevated serum concentrations of insulin lead to a state of hyperinsulinemia. This physiological state causes a reduction in insulin-like growth factor-binding proteins and promotes the synthesis and biological activity of insulin-like growth factor (IGF)-I, which regulates cellular growth in response to available energy and nutrients from diet and body reserves. In vitro studies have clearly established that both insulin and IGF-I act as growth factors that promote cell proliferation and inhibit apoptosis. Insulin also affects on the synthesis and biological availability of the male and female sex steroids, including androgens, progesterone, and estrogens. Experimental and clinical evidence also indicates a central role of estrogens and progesterone in regulating cellular differentiation, proliferation, and apoptosis induction. Hyperinsulinemia is also associated with alterations in molecular systems such as endogenous hormones and adipokines that regulate inflammatory responses. Obesity-related dysregulation of adipokines has the ability to contribute to tumorigenesis and tumor invasion via metastatic potential. Given the substantial level of weight gain in industrialized countries in the last two decades, there is great interest in understanding all of the mechanisms by which obesity contributes to the carcinogenic process. Continued focus must be directed to understanding the various relationships between specific nutrients and dietary components and cancer cause and prevention. A reductionist approach is not sufficient for the basic biological mechanisms underlying the effect of diet and physical activity on cancer. The joint association between energy balance and cancer risk are hypothesized to share the same underlying mechanisms, the amplification of chemical mediators that modulate cancer risk depending on the responsiveness to those hormones to the target tissue of interest. Disentangling the connection between obesity, the insulin-IGF axis, endogenous hormones, inflammatory markers, and their molecular interaction is vital.

Energy intake, physical activity, energy balance, and cancer: epidemiologic evidence

Energy intake, physical activity, and obesity are modifiable lifestyle factors. This chapter reviews and summarizes the epidemiologic evidence on the relation of energy intake, physical activity, and obesity to cancer. High energy intake may increase the risk of cancers of colon-rectum, prostate (especially advanced prostate cancer), and breast. However, because physical activity, body size, and metabolic efficiency are highly related to total energy intake and expenditure, it is difficult to assess the independent effect of energy intake on cancer risk. There are sufficient evidences to support a role of physical activity in preventing cancers of the colon and breast, whereas the association is stronger in men than in women for colon cancer and in postmenopausal than in premenopausal women for breast cancer. The evidence also suggests that physical activity likely reduces the risk of cancers of endometrium, lung, and prostate (to a lesser extent). On the other hand, there is little or no evidence that the risk of rectal cancer is related to physical activity, whereas the results have been inconsistent regarding the association between physical activity and the risks of cancers of pancreas, ovary and kidney. Epidemiologic studies provide sufficient evidence that obesity is a risk factor for both cancer incidence and mortality. The evidence supports strong links of obesity with the risk of cancers of the colon, rectum, breast (in postmenopausal women), endometrium, kidney (renal cell), and adenocarcinoma of the esophagus. Epidemiologic evidence also indicates that obesity is probably related to cancers of the pancreas, liver, and gallbladder, and aggressive prostate cancer, while it seems that obesity is not associated with lung cancer. The role of obesity in other cancer risks is unclear.

[Gender-specific characteristics and survival of renal cell carcinoma]

BACKGROUND

Renal cell carcinoma (RCC) occurs twice as often in men as in women; however, the influence of gender on stage, grade, subtype and prognosis has not been studied in detail.

METHODS

This study included 780 patients treated by (partial) nephrectomy at our institution in Marburg between 1990 and 2005. The mean follow-up was 5.44 years.

RESULTS

Of the 780 patients, 486 (62%) were men and 294 (38%) were women. Women were significantly older (mean, 65.3 vs. 62.2 years; p<0.001, t-test), presented at lower T stages (p=0.046, chi(2)) and suffered metastasis less frequently at diagnosis (p=0.026, chi(2)). In addition, women more frequently had clear cell tumours (85.2% vs. 78.3%) and less frequently papillary tumours (11.0% vs. 18.8%) than men (p=0.026, chi(2)). In contrast, men had an increased risk of death from RCC (HR 1.23, CI 0.92-1.63); Kaplan-Meier curves revealed a significant difference in tumour-specific survival between men and women (p=0.033, log rank; 5-year survival 74% vs. 83%). However, unlike tumour stage and tumour grade, gender could not be retained as a significant independent prognostic marker in multivariate analysis.

CONCLUSION

In general, RCC in men is characterized by higher tumour stages and more frequent metastasis at diagnosis along with inferior tumour-specific survival. However, as gender failed to qualify as an independent prognostic marker for tumour-specific survival, delayed diagnosis due to insufficient routine medical check-up and/or a more aggressive tumour biology might be be a concurrent cause. Thorough regular medical check-ups for men, also with regard to RCC, are thus mandatory.

Obesity and cancer

The prevalence of obesity, defined as a BMI of > or =30.0 kg/m2, has increased substantially over previous decades to about 20% in industrialized countries, and a further increase is expected in the future. Epidemiological studies have shown that obesity is a risk factor for: post-menopausal breast cancer; cancers of the endometrium, colon and kidney; malignant adenomas of the oesophagus. Obese subjects have an approximately 1.5-3.5-fold increased risk of developing these cancers compared with normal-weight subjects, and it has been estimated that between 15 and 45% of these cancers can be attributed to overweight (BMI 25.0-29.9 kg/m2) and obesity in Europe. More recent studies suggest that obesity may also increase the risk of other types of cancer, including pancreatic, hepatic and gallbladder cancer. The underlying mechanisms for the increased cancer risk as a result of obesity are unclear and may vary by cancer site and also depend on the distribution of body fat. Thus, abdominal obesity as defined by waist circumference or waist:hip ratio has been shown to be more strongly related to certain cancer types than obesity as defined by BMI. Possible mechanisms that relate obesity to cancer risk include insulin resistance and resultant chronic hyperinsulinaemia, increased production of insulin-like growth factors or increased bioavailability of steroid hormones. Recent research also suggests that adipose tissue-derived hormones and cytokines (adipokines), such as leptin, adiponectin and inflammatory markers, may reflect mechanisms linked to tumourigenesis.

Body size and renal cell cancer incidence in a large US cohort study

Renal cell cancer (RCC) incidence has increased in the United States over the past three decades. The authors analyzed the association between body mass index (BMI) and invasive RCC in the National Institutes of Health (NIH)-AARP Diet and Health Study, a large, prospective cohort aged 50-71 years at baseline initiated in 1995-1996, with follow-up through December 2003. Detailed analyses were conducted in a subcohort responding to a second questionnaire, including BMI at younger ages (18, 35, and 50 years); weight change across three consecutive age intervals; waist, hip, and waist-to-hip ratio; and height at age 18 years. Incident RCC was diagnosed in 1,022 men and 344 women. RCC was positively and strongly related to BMI at study baseline. Among subjects analyzed in the subcohort, RCC associations were strongest for baseline BMI and BMI recalled at age 50 years and were successively attenuated for BMI recalled at ages 35 and 18 years. Weight gain in early (18-35 years of age) and mid- (35-50 years of age) adulthood was strongly associated with RCC, whereas weight gain after midlife (age 50 years to baseline) was unrelated. Waist-to hip ratio was positively associated with RCC in women and with height at age 18 years in both men and women.

Physical activity during adulthood and adolescence in relation to renal cell cancer

Evidence for a relation between physical activity and renal cell cancer has been inconsistent. The authors examined physical activity in relation to renal cell cancer in a large, prospective US cohort study of 482,386 participants (289,503 men and 192,883 women) aged 50-71 years at baseline (1995-1996). At baseline, participants reported their frequency of exercise of at least 20 minutes' duration, intensity of daily routine activity, and frequency of physical activity during adolescence. During 8.2 years of follow-up (through December 2003), 1,238 cases of renal cell cancer were ascertained. In multivariate Cox regression models adjusted for renal cell cancer risk factors, the authors observed that current exercise, routine physical activity, and activity during adolescence were associated with a reduced risk of renal cell cancer. The multivariate relative risks for the highest activity level as compared with the lowest were 0.77 (95% confidence interval (CI): 0.64, 0.92; p(trend) = 0.10) for current exercise, 0.84 (95% CI: 0.57, 1.22; p(trend) = 0.03) for routine physical activity, and 0.82 (95% CI: 0.68, 1.00; p(trend) = 0.05) for activity during adolescence. The authors conclude that increased physical activity, including activity during adolescence, is associated with reduced risk of renal cell cancer.

State ranks of incident cancer burden due to overweight and obesity in the United States, 2003

OBJECTIVE

Given links between obesity and cancer, we estimated incident cancer burden due to overweight and obesity at the state level in the United States.

METHODS AND PROCEDURES

Using state rankings by per capita burden of incident cancer cases diagnosed in 2003 that were related to overweight and obesity, we examined the frequency with which states ranked in the highest and lowest quintiles of weight-related burden for cancers of the postmenopausal breast, endometrium, kidney, colon, and prostate. In this study, data from the Behavioral Risk Factor Surveillance System (BRFSS), US Census, US Mortality Public Use Data Tapes, and National Cancer Institute Surveillance, Epidemiology, and End Results (SEER) Program were used.

RESULTS

Western states had the lowest weight-related cancer burden for both sexes. Iowa, South Dakota, and West Virginia had the highest burden for all three types of male cancers. West Virginia is the only state that ranked in the quintile of highest weight-related burden for all four cancers considered in women.

DISCUSSION

For certain cancers, including endometrial, postmenopausal breast, and colon cancers, states with high burdens clustered in geographic regions, warranting further inquiry. Although state ranks for the total cancer burden and the prevalence of overweight and obesity correlated with state ranks for weight-related incident cancer burden, they often served poorly as its proxy. Such a finding cautions against simply targeting states with high overweight and obesity or high total burdens of cancers for which overweight and obesity are risk factors, as this approach may not reach areas of unrecognized burden.

Shared occupational risks for transitional cell cancer of the bladder and renal pelvis among men and women in Sweden

BACKGROUND

Unlike cancer of the bladder, cancer of the renal pelvis is not considered an occupational cancer and little is known about risks among women.

METHODS

Using the Swedish national census and cancer registry-linked data (1971-1989), we identified transitional cell cancers of the renal pelvis (N = 1,374) and bladder (N = 21,591). Correlation between cancer sites for the standardized incidence ratios (SIR) were determined using Pearson's coefficient of the log SIR. Relative risks of job exposure matrix variables were calculated using Poisson regression.

RESULTS

Both cancer sites were significantly elevated among women and men employed in the machine/electronics industry, sedentary work, and indoor work, and men in the metal industry. The highest proportion of the bladder (12%) and renal pelvis (14%) cancers occurred among men employed in shop and construction metal work. Risks by industry were more correlated among women (r = 0.49, P = 0.002) than men (r = 0.24, P = 0.04). Cancers of the renal pelvis were elevated in several occupational and industry groups for which there was no elevated bladder cancer risk.

CONCLUSION

Cancers of the renal pelvis and bladder share common occupational risk factors that may be more frequent among women. In addition, there may be some jobs that pose an increased risk specifically for cancer of the renal pelvis but not bladder.

Association between obesity and kidney disease: a systematic review and meta-analysis

This study aimed to comprehensively assess epidemiologic evidence on the relation between obesity and kidney disease (KD). From 247 retrieved articles via PubMed (1980-2006), 25 cohorts, 3 cross-sectional, and 19 case-control studies met inclusion criteria. Related data were extracted using a standardized protocol. We estimated the pooled relative risk (RR) and 95% confidence interval (95% CI) of KD for each body mass index (BMI) category compared with normal weight using meta-analysis models. Population attributable risk was also calculated. Compared with normal-weight individuals (18.5<BMI<25), overweight individuals (25< or =BMI<30) had elevated risk for KD (RR=1.40; 95% CI 1.30-1.50); obese individuals were at much higher risk (RR=1.83 (1.57-2.13)). Obesity in women was associated with a higher risk than in men (RR=1.92 (1.78-2.07) vs 1.49 (1.36-1.63); P<0.001). Results from cohort studies in patient populations and cross-sectional and case-control studies all indicated a positive association between BMI and risks for KD outcomes. We estimated that 24.2% and 33.9% of KD cases among US men and women, respectively, and in industrialized countries, 13.8% in men and 24.9% in women, could be related to overweight and obesity. Obesity increases the risk for KD in the general population, and the association appears to be stronger in women than in men. Obesity adversely affects the progress of KD among patients with kidney-related diseases.

Renal cell cancer and body size at different ages: an Italian multicenter case-control study

An increased risk of renal cell cancer (RCC) has been reported in overweight persons. The authors aimed to clarify which anthropometric measures are associated with risk of RCC and whether risk may vary according to selected variables. Between 1992 and 2004, they carried out an Italian multicenter case-control study including 767 (494 men, 273 women) incident cases of RCC and 1,534 hospital controls, frequency-matched to cases. To estimate odds ratios and 95% confidence intervals, they used conditional logistic regression matched on study center, sex, and age and adjusted for period of interview, years of education, smoking habits, and family history of kidney cancer. Using body-size measurements taken 1 year prior to diagnosis/interview, the authors found an odds ratio of 1.3 (95% confidence interval (CI): 1.0, 1.7) among obese persons (body mass index (BMI; weight (kg)/height (m)(2)) > or =30) versus normal-weight persons (BMI <25) and an odds ratio of 1.5 (95% CI: 1.1, 2.0) among persons in the highest tertile of waist-to-hip ratio. Direct associations emerged for BMI > or =30 (vs. <25) at ages 30 years (odds ratio = 1.5, 95% CI: 1.0, 2.3) and 50 years (odds ratio = 1.5, 95% CI: 1.1, 2.0). The direct association with waist-to-hip ratio was stronger among women than among men. RCC risks among overweight and obese persons were apparently higher in never smokers, persons with the clear-cell histologic type, and persons with a Fuhrman nuclear grade of G3-G4.

Lifetime physical activity and the risk of renal cell cancer

The relation between lifelong physical activity at work and during leisure-time and the risk of renal cell cancer (RCC) was analyzed in a case-control study conducted in Italy between 1992 and 2004. Cases were 767 subjects with incident, histologically confirmed RCC, and controls were 1,534 patients hospitalized for acute nonneoplastic conditions. Odds ratios (OR) and 95% confidence intervals (CI) for RCC were computed by multiple logistic regression models, conditioned on study center, sex and age, and adjusted for main covariates. Compared to the lowest level of occupational physical activity, the multivariate OR of RCC for the highest level were 0.65 (95% CI 0.49-0.87) at age 12 years, 0.67 (95% CI 0.53-0.84) at age 15-19, 0.74 (95% CI 0.59-0.93) at age 30-39 and 0.71 (95% CI 0.55-0.92) at age 50-59 years, with significant inverse trends in risk. The inverse association was consistent in strata of sex, age at diagnosis, body mass index, smoking habit and alcohol drinking. No significant association was found for leisure-time physical activity. The inverse association between occupational physical activity and RCC risk, if real, may be related to the effects of insulin-like growth factors, or lipid peroxidation and about 9% of cases of RCC in Italy could be avoided by increasing physical activity. However the inverse association might involve confounding by indirect mechanisms, such as body composition or other social class correlates.

Low adiponectin levels are associated with renal cell carcinoma: a case-control study

Adiponectin is a novel endogenous insulin sensitizer, secreted by mature adipocytes. Circulating levels of adiponectin are inversely associated with obesity and insulin resistance. Because obesity is a risk factor for renal cell carcinoma (RCC), we hypothesized that low adiponectin levels are associated with RCC. To evaluate this hypothesis, we conducted a case- control study of 70 patients with histologically confirmed RCC and 280 healthy controls matched by gender, age and county of residence. Study subjects were interviewed and blood samples were collected during a 32-month period in Athens, Greece. Serum adiponectin levels were statistically, significantly and inversely associated with RCC when compared with controls (OR=0.76, p=0.05) and this association remained practically unchanged after controlling for BMI; the introduction of waist to hip ratio along with adiponectin in the multiple logistic regression analysis model rendered the association between adiponectin and RCC risk insignificant, indicating that altered levels of adiponectin may mediate the effect of central or intra-abdominal obesity on RCC. Prospective studies as well as studies exploring underlying mechanisms are needed to fully explore the role of adiponectin in predicting future risk of RCC in humans.

Imaging of kidney cancer

Advances in molecular genetics have expanded the understanding of renal cell tumors. Now it is understood that renal cortical tumors are a family of neoplasms with distinct cytogenetics and molecular defects, unique histopathologic features, and different malignant potentials. Imaging contributes to clinical management of patients with renal tumors in providing diagnostic information for tumor detection, characterization, staging, treatment planning, and follow-up.

The epidemiology of renal cell carcinoma

PURPOSE

We identified and examined risk factors for renal cell cancer, some of which may explain in part the trends of steadily increasing incidence rates, particularly in black Americans.

MATERIALS AND METHODS

Epidemiological studies were identified through a MEDLINE(R) search of the literature through February 2006. A qualitative summary of the results of individual studies is presented.

RESULTS

Cigarette smoking and obesity are the most consistently established causal risk factors, accounting for about 20% and 30% of renal cell cancers, respectively. Hypertension appears to independently influence renal cell cancer risk. Neither acetaminophen nor other analgesics have been convincingly linked with renal cell cancer. With respect to diet a general protective effect of fruit and vegetable consumption is the only consistently reported finding. For occupational factors the weight of the evidence provides no consistent support for the hypotheses that renal cell cancer may be caused by asbestos, gasoline or trichloroethylene exposure. Self-reported family history is associated with 2 to 3-fold increases in risk and the major inherited forms of renal cell cancer together account for about 2% of this malignancy.

CONCLUSIONS

A further reduction in cigarette smoking, and a decrease in the rates of obesity and hypertension would likely moderate the increasing incidence of renal cell cancer. Epidemiological studies, including evaluation of gene-environment interactions, are needed to specifically identify reasons for the increasing incidence, particularly for assessing the roles of obesity and hypertension. Special attention should be focused on black Americans since their incidence rate recently increased to significantly surpass that in white Americans.

Obesity, High Energy Intake, Lack of Physical Activity, and the Risk of Kidney Cancer

The authors conducted a population-based case-control study of 810 cases with histologically confirmed incident kidney cancer and 3,106 controls to assess the effect of obesity, energy intake, and recreational physical activity on renal cell and non-renal cell cancer risk in Canada from 1994 to 1997. Compared with normal body mass index (BMI; 18.5 to <25.0 kg/m2), obesity (BMI, >or=30.0 kg/m2) was associated with multivariable-adjusted odds ratios (OR) and 95% confidence intervals (95% CI) of 2.57 (2.02-3.28) for renal cell cancer and 2.79 (1.70-4.60) for non-renal cell cancer. The OR (95% CI) associated with the highest quartiles of calorie intake was 1.30 (1.02-1.66) for renal cell cancer and 1.53 (0.92-2.53) for non-renal cell cancer. Compared with the lowest quartile of total recreational physical activity, the highest quartile of total activity was associated with an OR (95% CI) of 1.00 (0.78-1.28) and 0.79 (0.46-1.36) for the two subtypes. There were no apparent differences between men and women about these associations. The influence of obesity and physical activity on the risk of renal cell and non-renal cell cancer did not change by age, whereas the effect of excess energy intake was stronger among older people. No significant effect modifications of physical activity on BMI among both genders and of energy intake on BMI among men were observed, with a synergic effect of obesity and high energy intake on renal cell cancer risk found among women. This study suggests that obesity and excess energy intake are important etiologic risk factors for renal cell and non-renal cell cancer. The role of physical activity needs further investigation.

Body mass index, physical activity, and risk of renal cell carcinoma

OBJECTIVE

To investigate the association between obesity and risk of renal cell carcinoma and to examine whether the association is modified by physical activity.

SUBJECTS

A population-based case-control study of 406 patients with renal cell carcinoma and 2434 controls conducted in Iowa.

METHODS

Information was collected on weight at the ages 20-29, 40-49, and 60-69 years, height, nonoccupational physical activity, diet, and other lifestyle factors. Renal cell carcinoma risk was estimated by odds ratios (ORs) and 95% confidence intervals (CIs), adjusting for age, total energy intake, and other confounding factors.

RESULTS

Height and total energy intake were not associated with risk in either sex. In men, neither physical activity nor level of obesity in any period of life was significantly associated with risk. In women, lower physical activity was associated with higher risk (OR=2.5; 95% CI=1.2-5.2 comparing exercise <1 time/month to >1 time/day). Compared with women in the lowest quartile for BMI, the risks of renal cell carcinoma for women in the highest 10% of BMI in their 20s, 40s, and 60s were 1.4 (CI=0.6-3.1), 1.9 (CI=0.9-4.2), and 2.3 (CI=0.9-6.0), respectively. When analyses were limited to self-respondent data, the corresponding ORs were 2.9 (CI=1.2-7.4), 3.2 (CI=1.3-7.5), and 2.1 (CI=0.7-6.4), respectively. There was little evidence that physical activity modifies the association of BMI with renal cell carcinoma.

CONCLUSION

Nonoccupational physical activity was inversely associated and obesity was positively associated with risk of renal cell carcinoma among women. The risk appeared to be greater for women in the highest 10% of BMI in their 40s. Our finding of little evidence of an interaction between physical activity and BMI requires confirmation.

Health ramifications of the obesity epidemic

For the first time in human history, the numbers of overweight and underweight individuals are about the same, at 2.1 billion each. Along with the current worldwide obesity epidemic is the explosion of obesity- and overweight-related health problems, including diabetes and the metabolic syndrome, musculoskeletal disorders,cardiovascular disease, pulmonary disorders, and certain forms of cancer. Obesity and overweight account for a significant percentage of overall health care costs and contribute significantly to morbidity and mortality in the United States and around the world.

Body size and risk of renal cell carcinoma in the European Prospective Investigation into Cancer and Nutrition (EPIC)

Previous studies suggest that obesity is related to increased risk of renal cell carcinoma (RCC); however, only a few studies report on measures of central vs. peripheral adiposity. We examined the association between anthropometric measures, including waist and hip circumference and RCC risk among 348,550 men and women free of cancer at baseline from 8 countries of the European Prospective Investigation into Cancer and Nutrition (EPIC). During 6.0 years of follow-up we identified 287 incident cases of RCC. Relative risks were calculated using Cox regression, stratified by age and study center and adjusted for smoking status, education, alcohol consumption, physical activity, menopausal status, and hormone replacement therapy use. Among women, an increased risk of RCC was conferred by body weight (relative risk [RR] in highest vs. lowest quintile = 2.13; 95% confidence interval [CI] = 1.16-3.90; p-trend = 0.003), body mass index (BMI) (RR = 2.25; 95% CI = 1.14-4.44; p-trend = 0.009), and waist (RR = 1.67; 95% CI = 0.94-2.98; p-trend = 0.003) and hip circumference (RR = 2.30; 95% CI = 1.22-4.34; p-trend = 0.01); however, waist and hip circumference were no longer significant after controlling for body weight. Among men, hip circumference (RR = 0.44; 95% CI = 0.20-0.98; p-trend = 0.03) was related significantly to decreased RCC risk only after accounting for body weight. Height was not related significantly to RCC risk. Our findings suggest that obesity is related to increased risk of RCC irrespective of fat distribution among women, whereas low hip circumference is related to increased RCC risk among men. Our data give further credence to public health efforts aiming to reduce the prevalence of obesity to prevent RCC, in addition to other chronic diseases.

Relation of height, body mass, energy intake, and physical activity to risk of renal cell carcinoma: results from the Netherlands Cohort Study

Data from the Netherlands Cohort Study on Diet and Cancer were used to investigate the association between anthropometry, energy intake, and physical activity and risk of renal cell carcinoma (RCC). The Netherlands Cohort Study on Diet and Cancer consists of 120,852 men and women aged 55-69 years who completed a self-administered questionnaire at baseline (1986). A case-cohort approach was used. After 9.3 years of follow-up, 275 microscopically confirmed incident cases were available for analysis. Incidence rate ratios for RCC were estimated using Cox proportional hazards models. Height was associated with RCC risk only in women (per 5-cm increment, rate ratio (RR) = 1.23, 95% confidence interval (CI): 1.03, 1.46). Body mass index (weight (kg)/height (m)(2)) was associated with increased risk of RCC (per 1-kg/m(2 )increment, RR = 1.07, 95% CI: 1.02, 1.12) for men and women, as was gain in body mass index from age 20 years to baseline (per 1-kg/m(2 )increment, RR = 1.06, 95% CI: 1.01, 1.10). Energy intake was not related to RCC risk, while a possible protective effect was observed for physical activity in men. These results suggest that body mass index and gain in body mass index since age 20 are associated with increased risk of RCC.

The association between obesity and the progression of prostate and renal cell carcinoma

Obesity has been linked to the incidence and mortality of several malignancies, including prostate and renal cancer. Increased body mass appears to have a more consistent association with prostate cancer mortality than incidence and recent studies suggest that it may be related to higher recurrence rates after radical prostatectomy. Obesity has an even stronger association with the development and progression of renal cancer, particularly in women. Since obesity is one of few modifiable risk factors that may impact the clinical course of these cancers, lifestyle and dietary changes to limit obesity should be recommended.

The expression of insulin-like growth factor-I receptor correlates with Fuhrman grading of renal cell carcinomas

Recent reports have shown significant correlation between Fuhrman nuclear grade of renal cell carcinoma (RCC) and patient survival. However, no one specific gene alteration has yet been described to account for this correlation. This study investigated the expression of the insulin-like growth factor-I receptor (IGF-IR) in RCC and correlated the results to the tumor Fuhrman nuclear grade. Formalin-fixed, paraffin-embedded sections from 68 cases of RCC were stained using the immunohistochemical avidin-biotin-peroxidase method. An anti-human IGF-IR rabbit polyclonal antibody was used. The stains were semiquantitatively evaluated using the Allred score system, assessing intensity of stain and percentage of positive tumor cells. Statistical analysis was performed using the Kruskal-Wallis test. Strong and diffuse cytoplasmic IGF-IR stain (Allred score 7 to 8) was identified in 25 of 25 (100%) of grade 3 and 4 RCCs. Grade 2 RCCs had a median IGF-IR Allred score of 4. Ten of 10 (100%) grade 1 RCCs were negative. Even in the positive high-nuclear-grade tumors, areas of low nuclear grade, when present, were IGF-IR negative. Statistical analysis using the Kruskal-Wallis test demonstrated significant correlation between increasing Fuhrman nuclear grade and increasing IGF-IR Allred score (P <0.0001). Thus we report the novel finding of significant statistical correlation between IGF-IR protein expression and Fuhrman nuclear grade of RCC, and consequentially with patient survival.

Risk factors for adult renal cell carcinoma

This study confirmed several independent risk and protective factors for RCC identified in the authors' previous study. Protective factors such as oral contraceptive use and moderate alcohol consumption were identified only in women. Tobacco consumption and severe obesity were the main independent risk factors. There were other modifiable risk markers, however, such as occupational exposure, thiazidic drug intake, and urinary tract infections. The associations between risk factors and RCC were weak, even for tobacco, for which the association was weaker than that for lung cancer. The identified risks involve a large proportion of the population, however, and the risk attributable to these types of exposure is high. The authors' recommendations for the prevention of RCC are therefore similar to those for the prevention of cardiovascular disease and cancer, and should be disseminated to the general population. The high-risk groups identified are too large for a specific early-screening program for RCC, but such screening might be appropriate if restricted to selected age groups.