Human renal cancer carcinogenesis: a review of recent advances

Risk of Malignant Neoplasms of Kidney and Bladder in a Cohort Study of the Diabetic Population in Taiwan With Age, Sex, and Geographic Area Stratifications

Diabetes has been reported to increase the risk of malignant neoplasms of kidney and bladder, but the studies' results are still inconclusive. Age, sex, and geographical area-specific incidence and relative risks of above neoplasms are also scarce in the literature. We prospectively investigated the age, sex, geographical area-specific incidence and relative risks of kidney and bladder neoplasms in diabetic population of Taiwan. Diabetic patients (n = 615,532) and age- and sex-matched controls (n = 614,871) were linked to inpatient claims (2000-2008) to identify the admissions for malignant neoplasm of kidney (International Classification of Diagnosis, 9th version, Clinical Modification: 189) and bladder (International Classification of Diagnosis, 9th version, Clinical Modification: 188). The person-year approach with Poisson assumption was used to evaluate the incidence density. We also estimated the age, sex, and geographical area-specific relative risks of above malignancy in relation to diabetes with Cox proportional hazard regression model. The overall incidence density of malignant neoplasm of kidney for diabetic men and women were 3.87 and 4.28 per 10,000 patient-years, respectively; the corresponding figures for malignant neoplasm of bladder were 5.73 and 3.25 per 10,000 patient-years. Compared with the controls, diabetic men were at significantly increased hazards of kidney (covariate adjusted hazard ratio [aHR]: 1.31, 95% confidence interval [CI] 1.18-1.46) and bladder aHR: 1.13, 95% CI 1.04-1.23). Diabetic women, on the contrary, only experienced significantly elevated hazard of kidney neoplasm (aHR: 1.14, 95% CI 1.04-1.26). Diabetic men aged >65 years showed the most significantly increased hazard of developing neoplasm of kidney (aHR: 1.40) and bladder (aHR: 1.13). The most significantly increased hazard of kidney neoplasm was noted for women diabetic patients aged >65 years. There was also a significant interactive effect of geographic area with diabetes on the incidence of kidney and bladder neoplasms in both sexes. Diabetic men >45 years and diabetic women >65 years were found to have significantly increased hazard of malignant neoplasm of kidney, but only diabetic men >65 years were at significantly increased hazard of bladder neoplasm. The significant geographic variations in incidence and relative hazard of kidney and bladder neoplasms warrant further investigations of the underlying reasons.

Type 2 diabetes and the risk of renal cell cancer in women

OBJECTIVE

Type 2 diabetes is associated with increased risks of several types of cancer; however, its relationship to renal cell cancer remains unclear.

RESEARCH DESIGN AND METHODS

A total of 118,177 women aged 30 to 55 years at baseline (1976) were followed up through 2008 in the Nurses' Health Study. Self-reports of physician-diagnosed diabetes were collected at baseline and updated biennially. Hazard ratios (HRs) were calculated using Cox proportional hazards models with adjustment for age, BMI, hypertension, smoking, and parity.

RESULTS

During 32 years of follow-up (3,531,170 person-years), 16,819 cases of type 2 diabetes and 330 cases of pathology-confirmed incident renal cell cancer were documented. After multivariate adjustment, type 2 diabetes was significantly associated with an increased risk of renal cell cancer (HR 1.60 [95% CI 1.19-2.17]). These associations were consistent across different strata of BMI, smoking, and hypertension (Pinteraction≥0.32). The risk of renal cell cancer increased with an increasing number of comorbidities, including obesity, hypertension, and type 2 diabetes (Ptrend<0.001). When compared with women without any comorbidity, women who had all three conditions had a HR of 4.13 (2.76-6.18) for renal cell cancer.

CONCLUSIONS

Type 2 diabetes is independently associated with an increased risk of renal cell cancer in women. In addition, comorbidity of obesity, hypertension, and type 2 diabetes substantially elevates the risk of renal cell cancer.

Obesity and renal cell carcinoma: epidemiology, underlying mechanisms and management considerations

The incidence of both renal cell carcinoma (RCC) and obesity are steadily rising in Western societies. Recent studies have established that obesity is a significant risk factor for the development of several malignancies, including RCC. However, the mechanisms underlying this relationship remain to be fully elucidated. We review herein the epidemiological links between obesity and RCC, the potential mechanisms by which obesity can influence RCC development and progression, and the special considerations related to the treatment of obese patients with RCC.

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.

Physical activity and risk of renal cell carcinoma

The role of physical activity in the development of renal cell carcinoma was examined using a population-based case-control study conducted in the province of Ontario. Physical activity was examined in several ways, including by intensity and during various life periods. Frequency-matching by 5-year age groups and sex produced sets of 486 females (133 cases and 353 controls) and 447 males (172 cases, 275 controls). Unconditional logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI). After adjusting for age, body mass index and smoking, women who performed relatively high amounts of recent recreational activity (OR = 0.41, 95% CI 0.21-0.82 for the highest vs. lowest quartile of activity, 2 years ago), as well as strenuous recreational activity (OR = 0.40, 95% CI 0.22-0.75), had a reduced risk of developing the disease. In general, moderate recreational activity did not appear to be associated with risk in females. In males, a relatively high frequency of total and moderate recreational activity was associated with reduced risk (total, OR = 0.49, 95% CI 0.27-0.87; moderate, OR = 0.49, 95% CI 0.27-0.89), especially during the teen years. Recreational activity during one's 30s was not associated with cancer risk. There was also no association between occupational activity and cancer risk in females or males. The results of our study, in general, suggest that physical activity may be associated with a decreased risk of developing renal cell carcinoma.

Physical activity and renal cell cancer risk in a cohort of male smokers

Few studies have examined exercise in relation to risk of renal cell cancer. We examined the association between leisure-time and occupational physical activity and renal cell cancer in a cohort of 29,133 male smokers 50-69 years of age in the Alpha-Tocopherol, Beta-Carotene (ATBC) Cancer Prevention Study. Physical activity was assessed at baseline using a self-administered questionnaire that inquired about usual level of physical activity during leisure-time and at work during the past year. Cox proportional hazards modeling was used to adjust simultaneously for known or suspected risk factors for renal cell cancer. During 12 years (354,407 person-years) of follow-up, 210 incident cases of renal cell cancer were identified. In age-adjusted analysis, the RRs of renal cell cancer in increasing categories of leisure-time physical activity (light, moderate and heavy) were 1.0, 0.89 (95% CI = 0.67-1.17) and 0.38 (95% CI = 0.15-0.94), respectively (p-value for trend = 0.06). After adjustment for body mass index, energy intake, smoking, hypertension, education and fruit and vegetable intake, the multivariate RRs of renal cell cancer in increasing categories of leisure-time physical activity (light, moderate and heavy), were 1.0, 0.89 (95% CI = 0.66-1.19), and 0.46 (95% CI = 0.18-1.13) (p-value for trend = 0.12). Occupational physical activity was unrelated to renal cell cancer risk. These data suggest that recreational physical activity may play a role in the prevention of renal cell cancer in men.

Pregnancy and risk of renal cell cancer: a population-based study in Sweden

Epidemiological findings indicate that hormonal influences may play a role in the etiology of renal cell cancer (RCC). The possible effect of childbearing remains enigmatic; while some investigators have reported a positive association between number of births and renal cell cancer risk, others have not. A case-control study, nested within a nation-wide Fertility Register covering Swedish women born 1925 and later, was undertaken to explore possible associations between parity and age at first birth and the risk of renal cell cancer. Among these women a total of 1465 cases of RCC were identified in the Swedish Cancer Register between 1958 and 1992 and information on the number of live childbirths and age at each birth was obtained by linkage to the Fertility Database. For each case, five age-matched controls were randomly selected from the same register. Compared to nulliparous women, ever-parous women were at a 40% increased risk of RCC (Odds Ratio [OR]=1.42; 95% CI 1.19-1.69). The corresponding OR for women of high parity (five or more live births) was 1.91 (95% CI 1.40-2.62). After controlling for age at first birth among parous women, each additional birth was associated with a 15% increase in risk (OR=1.15; 95% CI 1.08-1.22). The observed positive association between parity and renal cell cancer risk is unlikely to be fully explained by uncontrolled confounding, but warrants further evaluation in large studies, with allowance for body mass index.

Obesity and renal cell cancer--a quantitative review

Obesity has been associated with an increased risk of renal cell cancer among women, while the evidence for men is considered weaker. We conducted a quantitative summary analysis to evaluate the existing evidence that obesity increases the risk of renal cell cancer both among men and women. We identified all studies examining body weight in relation to kidney cancer, available in MEDLINE from 1966 to 1998. The quantitative summary analysis was limited to studies assessing obesity as body mass index (BMI, kg m(-2)), or equivalent. The risk estimates and the confidence intervals were extracted from the individual studies, and a mixed effect weighted regression model was used. We identified 22 unique studies on each sex, and the quantitative analysis included 14 studies on men and women, respectively. The summary relative risk estimate was 1.07 (95% CI 1.05-1.09) per unit of increase in BMI (corresponding to 3 kg body weight increase for a subject of average height). We found no evidence of effect modification by sex. Our quantitative summary shows that increased BMI is equally strongly associated with an increased risk of renal cell cancer among men and women.

Laparoscopic nephrectomy for renal cell carcinoma

Since the first reported case of laparoscopic nephrectomy by Clayman et al. in 1991, laparoscopy is gaining acceptance as a viable alternative to open surgery for renal cell carcinoma. The benefits of laparoscopy include improved quality of life and lower incidence of perioperative morbidity. The perceived risks of laparoscopic nephrectomy for renal cell carcinoma include port-site metastasis, increased operative time, and the concern for inadequate surgical resection. The preliminary data concerning laparoscopy in renal cell carcinoma, however, indicate that rates of tumor recurrence are equivalent to open surgery while resulting in better cosmesis, decreased level of perioperative analgesic use, and decreased length of time to full convalescence.

Occupational physical activity and renal cell cancer: a nationwide cohort study in Sweden

The causes of renal cell cancer remain incompletely understood. In one previous retrospective case-control study, high occupational physical activity has been associated with a decreased risk among men, but not among women. Our aim was to investigate the association between occupational physical activity and renal cell cancer in a large cohort in Sweden. A cohort of Swedish men and women was identified in the nationwide censuses in 1960 and 1970, and the reported occupations were classified into 4 levels of physical demands. Follow-up from 1971 through 1989 was accomplished through record linkages to the Swedish Cancer Registry. Multivariate Poisson regression models were used to estimate relative risk (RR) and 95% confidence intervals (CI). We found a monotonic increase in risk of renal cell cancer with decreasing level of occupational physical activity among men (p for trend <0.001). After adjustment for socio-economic status, place of residence, and calendar year of follow-up, men with long-term sedentary jobs had a 25% (RR = 1.25, 95% CI 1.02-1.53) increased risk compared to men with physically demanding occupations. Among women there was no association, the dose-risk trend was not significant (p for trend >0.50). Occupational physical activity was inversely associated with renal cell cancer among men. The absence of association among women might be due to smaller range of exposure, confounding by household work or reproductive factors, or to a difference in biological response to physical activity in men and women.

Cytochrome P450 CYP3A in human renal cell cancer

Renal cell cancer is the main malignant tumour of the kidney and has an increasing incidence. This type of tumour has a poor prognosis and shows intrinsic resistance to several anti-cancer drugs. The CYP3A P450 family, which consists of three closely related forms, is involved in the oxidative activation and deactivation of a variety of carcinogens and several anti-cancer drugs. In this study the presence and cellular localization of CYP3A has been investigated using a combination of immunohistochemistry, immunoblotting and reverse transcriptase polymerase chain reaction (RT-PCR) in renal cell cancer and corresponding normal kidney. CYP3A was consistently expressed in both renal call cancer and in normal kidney. In renal cell cancer, CYP3A was localized to tumour cells and in normal kidney the predominant cellular localization of CYP3A was to proximal tubular epithelial cells. RT-PCR showed that both CYP3A5 mRNA and CYP3A7 mRNA were consistently present in both tumour and normal samples, while CYP3A4 mRNA was present in 65% of tumours and 90% of normal samples. This study indicates that individual members of the CYP3A family are expressed in renal cell cancer. The presence of CYP3A in renal cell cancer might be important in the metabolic potentiation as well as the detoxification of chemotherapeutic agents used to renal cancer.

Somatic mutations of von Hippel-Lindau (VHL) tumor-suppressor gene in European kidney cancers

Somatic mutations of von Hippel Lindau (VHL) tumor-suppressor gene have been identified in kidney cancers from North America and Japan. We studied VHL gene mutation in 31 kidney tumors from France. Of these tumors, 45% (14/31) displayed mutations, 60% of which occurred at A:T base pairs. The frequency and the spectrum of mutations identified in kidney tumors from Europe were similar to those reported for tumors from other geographical locations.

Growth factors and renal cancer: characterization and therapeutic implications

The heterogeneiety renal-cell carcinoma can lead to unpredictable behavior: the ability to achieve a large volume yet not metastasize, the ability to demonstrate late recurrence or spontaneous regression, or the capability to metastasize at a relatively small volume. One-third of all patients who undergo radical nephrectomy for presumed localized disease will eventually have metastasis. Since renal-cell carcinoma is not significantly radio- or chemosensitive, it is important to investigate new avenues for treatment of this tumor once it has spread, specifically at the molecular level. This review discusses the most recent work on growth factors and renal cancer and proposes possible modalities for treatment.