Early precursors of urogenital cancers in former college men

Cancer risk following surgical removal of tonsils and adenoids - a population-based, sibling-controlled cohort study in Sweden

BACKGROUND

Removal of tonsils and adenoids is among the most common surgical procedures worldwide. Evidence of increased risk of cancer following such surgery is, however, inconclusive.

METHODS

We conducted a population-based, sibling-controlled cohort study of 4,953,583 individuals in Sweden with a follow-up during 1980-2016. History of tonsillectomy, adenotonsillectomy, and adenoidectomy was identified from the Swedish Patient Register whereas incident cases of cancer during follow-up were identified from the Swedish Cancer Register. We used Cox models to calculate hazard ratios (HR) with 95% confidence intervals (CI) of cancer in both a population and a sibling comparison. The sibling comparison was used to assess the potential impact of familial confounding, due to shared genetic or non-genetic factors within a family.

RESULTS

We found a modestly increased risk for any cancer following tonsillectomy, adenoidectomy, or adenotonsillectomy in both the population (HR 1.10; 95%CI 1.07-1.12) and sibling (HR 1.15; 95%CI 1.10-1.20) comparisons. The association did not differ greatly by type of surgery, age at surgery, or potential indication for surgery, and persisted more than two decades after surgery. An excess risk was consistently observed for cancer of the breast, prostate, thyroid, and for lymphoma in both population and sibling comparisons. A positive association was observed for pancreatic cancer, kidney cancer, and leukemia in the population comparison whereas a positive association was observed for esophageal cancer in the sibling comparison.

CONCLUSIONS

Surgical removal of tonsils and adenoids is associated with a modestly increased risk of cancer during the decades following the surgery. The association is unlikely attributed to confounding due to shared genetic or non-genetic factors with a family.

Physical activity in relation to risk of prostate cancer: a systematic review and meta-analysis

Background

Prostate cancer (PCa) is one of the most common cancers among men, yet little is known about its modifiable risk and protective factors. This study aims to quantitatively summarize observational studies relating physical activity (PA) to PCa incidence and mortality.

Materials and methods

Published articles pertaining to PA and PCa incidence and mortality were retrieved in July 2017 using the Medline and EMBASE databases. The literature review yielded 48 cohort studies and 24 case-control studies with a total of 151 748 PCa cases. The mean age of the study participants at baseline was 61 years.

Results

In random-effects models, comparing the highest versus the lowest level of overall PA showed a summary relative risk (RR) estimate for total PCa incidence close to the null [RR = 0.99, 95% confidence interval (CI) = 0.94-1.04]. The corresponding RRs for advanced and non-advanced PCa were 0.92 (95% CI = 0.80-1.06) and 0.95 (95% CI = 0.85-1.07), respectively. We noted a statistically significant inverse association between long-term occupational activity and total PCa (RR = 0.83, 95% CI = 0.71-0.98, n studies = 13), although that finding became statistically non-significant when individual studies were removed from the analysis. When evaluated by cancer subtype, an inverse association with long-term occupational activity was noted for non-advanced/non-aggressive PCa (RR = 0.51, 95% CI = 0.37-0.71, n studies = 2) and regular recreational activity was inversely related to advanced/aggressive PCa (RR = 0.75, 95% CI = 0.60-0.95, n studies = 2), although these observations are based on a low number of studies. Moreover, PA after diagnosis was related to reduced risk of PCa mortality among survivors of PCa (summary RR based on four studies = 0.69, 95% CI = 0.55-0.85).

Conclusions

Whether PA protects against PCa remains elusive. Further investigation taking into account the complex clinical and pathologic nature of PCa is needed to clarify the PA and PCa incidence relation. Moreover, future studies are needed to confirm whether PA after diagnosis reduces risk of PCa mortality.

Postnatal risk factors for testicular cancer: The EPSAM case-control study

Testicular cancer is considered to originate from an impaired differentiation of fetal germ cells, but puberty could represent another time window of susceptibility. Our study aimed at investigating the association between environmental exposures acting during puberty/adolescence (13-19 years of age) and the risk of testicular cancer. We used data of the EPSAM study, a case-control study on germ-cell testicular cancer conducted in the province of Turin, Italy, involving cases diagnosed between 1997 and 2008. Histologically confirmed cases (n = 255) and controls (n = 459) completed a postal questionnaire focusing in particular on the pubertal period (namely age 13 years) with questions on physical activity (competitive sports, gardening), lifestyle (alcohol consumption, smoking), occupational history and medical conditions. All analyses were adjusted for the matching variables, cryptorchidism and educational level. Having done at least one competitive sport during puberty (odds ratio [OR]: 0.72, 95% confidence interval: 0.52-1.00), gardening activities during puberty (OR: 0.62, 0.42-0.94) and having a lower weight than peers during puberty (OR: 0.64, 0.42-0.97) were all inversely associated with the risk of testicular cancer. No evidence of association between smoking or alcohol consumption during puberty and the risk of testicular cancer was observed. Regarding agriculture-related occupations, we found an association with the risk of testicular cancer both for occasional jobs during puberty (OR: 2.40, 95% CI: 1.08-5.29) and ever employment in adolescence (OR: 2.59, 95% CI: 0.83-8.10). Our results suggest that postnatal exposures could play a role in testicular cancer aetiology, at least when acting in puberty or adolescence.

A systematic review and meta-analysis of tobacco use and prostate cancer mortality and incidence in prospective cohort studies

CONTEXT

An association between tobacco smoking and prostate cancer (PCa) incidence and mortality was suggested in an earlier meta-analysis of 24 prospective studies in which dose-response associations and risks per unit of tobacco use were not examined.

OBJECTIVE

We investigated the association between several measures of tobacco use and PCa mortality (primary outcome) and incidence (secondary outcome) including dose-response association.

EVIDENCE ACQUISITION

Relevant articles from prospective studies were identified by searching the PubMed and Web of Science databases (through January 21, 2014) and reference lists of relevant articles. Combined relative risks (RRs) and 95% confidence intervals (CIs) were calculated using random effects methods. We also calculated population attributable risk (PAR) for smoking and PCa mortality.

EVIDENCE SYNTHESIS

We included 51 articles in this meta-analysis (11823 PCa deaths, 50349 incident cases, and 4,082,606 cohort participants). Current cigarette smoking was associated with an increased risk of PCa death (RR: 1.24; 95% CI, 1.18-1.31), with little evidence for heterogeneity and publication bias. The number of cigarettes smoked per day had a dose-response association with PCa mortality (p=0.02; RR for 20 cigarettes per day: 1.20). The PAR for cigarette smoking and PCa deaths in the United States and Europe were 6.7% and 9.5%, respectively, corresponding to >10000 deaths/year in these two regions. Current cigarette smoking was inversely associated with incident PCa (RR: 0.90; 95% CI, 0.85-0.96), with high heterogeneity in the results. However, in studies completed in 1995 or earlier (considered as completed before the prostate-specific antigen screening era), ever smoking showed a positive association with incident PCa (RR: 1.06; 95% CI, 1.00-1.12) with little heterogeneity.

CONCLUSIONS

Combined evidence from observational studies shows a modest but statistically significant association between cigarette smoking and fatal PCa. Smoking appears to be a modifiable risk factor for PCa death.

PATIENT SUMMARY

Smoking increases the chance of prostate cancer death. Not smoking prevents this harm and many other tobacco-related diseases.

Prostate cancer: is it time to expand the research focus to early-life exposures?

Although the contribution of lifestyle and environment (non-genetic factors) to prostate carcinogenesis is indicated by international variation in prostate cancer occurrence and migration studies, no conclusive modifiable risk factors have yet been identified. One possible reason for this may be the dearth of epidemiological research on exposures experienced early in life, when the immature prostate may be more susceptible to carcinogenic exposures. In this Opinion article, we summarize the rationale for studying early-life exposures, describe the small body of early-life research and its associated challenges, and point to solutions for future research.

Association of body mass index in early adulthood and middle age with future site-specific cancer mortality: the Harvard Alumni Health Study

BACKGROUND

The association between adiposity in early adulthood and subsequent development of specific malignancies is unclear. Further, the potential for mediation by adiposity in middle age has not been well examined. In a rare study, we investigated the association of body mass index (BMI) in early adulthood with mortality from several site-specific cancers.

DESIGN

In the Harvard Alumni Health Study cohort, 19 593 males had a physical examination at the university between 1914 and 1952 (mean age: 18.4 years) and returned a questionnaire in 1962 or 1966 (mean age = 45.1 years). BMI was computed using weight (kg)/height(2) (m(2)) at both time points. Vital status follow up continued for a maximum of 82 years.

RESULTS

Positive early adulthood cancer mortality gradients by BMI were found for all malignancies combined (adjusted hazard ratio [HR] = 1.11; 95% confidence interval [CI]: 1.05-1.17 for a one standard deviation increase in early adulthood BMI), and for lung (HR = 1.24; 95% CI = 1.10-1.40) and skin (HR = 1.29; 95% CI = 0.96-1.75) cancers. There were also apparent associations for cancers of the oesophagus and urogenital sites. Mediation by BMI in middle age was found to be minimal.

CONCLUSION

Higher BMI in early adulthood appears to be a direct risk factor for selected malignancies several decades later.

A systematic review and meta-analysis of the relationship between body size and testicular cancer

Background:

Studies assessing the relationships of anthropometry and testicular germ-cell tumour (TGCT) have reported heterogeneous findings.

Methods:

We undertook a systematic review and meta-analysis of the associations between adult height, weight, body mass index (BMI), and testicular cancer. Search strategies were conducted in PubMed, EMBASE, Scopus, and Web of Science on 26 May 2009. Studies that met our inclusion criteria were included in meta-analytic models using STATA 11.

Results:

A total of 3255 references were retrieved, of which 14 met the inclusion criteria. Random effects meta-analysis found adult height (odds ratio (OR) per 5-cm increase 1.13, 95% confidence interval (CI) 1.07–1.19, P<0.001) and weight (OR overweight vs normal 0.92, 95% CI 0.86–0.98, P=0.011) to be associated with TGCT. The meta-analysis of weight and TGCT produced a summary estimate, which indicated no association, although an analysis restricted studies to North American was suggestive of association (OR per 1-kg increase 1.01, 95% CI 1.00–1.01, P<0.001).

Conclusions:

This systematic review and meta-analysis has found evidence for a positive association of adult height and TGCT, and tentative evidence for an inverse association of BMI and TGCT.

Energy balance, the PI3K-AKT-mTOR pathway genes, and the risk of bladder cancer

We evaluated the association between energy balance and risk of bladder cancer and assessed the joint effects of genetic variants in the mammalian target of rapamycin (mTOR) pathway genes with energy balance. The study included 803 Caucasian bladder cancer patients and 803 healthy Caucasian controls matched to cases by age (+/-5 years) and gender. High energy intake [odds ratio, 1.60; 95% confidence interval (95% CI), 1.23-2.09] and low physical activity (odds ratio, 2.82; 95% CI, 2.10-3.79) were each associated with significantly increased risk of bladder cancer with dose-response pattern (P(trend) < 0.001). However, obesity (body mass index, > or =30) was not associated with the risk. Among 222 single nucleotide polymorphisms, 28 single nucleotide polymorphisms located in six genes of mTOR pathway were significantly associated with the risk. Further, the risk associated with high energy intake and low physical activity was only observed among subjects carrying a high number of unfavorable genotypes in the pathway. Moreover, when physical activity, energy intake, and genetic variants were analyzed jointly, the study population was clearly stratified into a range of low- to high-risk subgroups as defined energy balance status. Compared with subjects within the most favorable energy balance category (low energy intake, intensive physical activity, low number of unfavorable genotypes), subjects in the worst energy balance category (high energy intake, low physical activity, and carrying > or =7 unfavorable genotypes) had 21.93-fold increased risk (95% CI, 6.7-71.77). Our results provide the first strong evidence that physical activity, energy intake, and genetic variants in the mTOR pathway jointly influence bladder cancer susceptibility and that these results have implications for bladder cancer prevention.

Etiologic factors in testicular germ-cell tumors

Globally, testicular cancer incidence is highest among men of northern European ancestry and lowest among men of Asian and African descent. Incidence rates have been increasing around the world for at least 50 years, but mortality rates, at least in developed countries, have been declining. While reasons for the decreases in mortality are related to improvements in therapeutic regimens introduced in the late 1970s, reasons for the increase in incidence are less well understood. However, an accumulating body of evidence suggests that testicular cancer arises in fetal life. Perinatal factors, including exposure to endocrine-disrupting chemicals, have been suggested to be related to risk.

Body mass index, physical activity, and bladder cancer in a large prospective study

Increased body size and lack of physical activity are associated with increased risk of several cancers, but the relations of body mass index (BMI) and physical activity to bladder cancer are poorly understood. We investigated the associations between BMI, physical activity, and bladder cancer in the NIH-AARP Diet and Health Study, a prospective cohort of 471,760 U.S. men and women, followed from 1995 to 2003. During 3,404,642 person-years of follow-up, we documented 1,719 incident cases of bladder cancer. Compared with normal weight, obesity was associated with an up to 28% increased risk for bladder cancer. The multivariate relative risks of bladder cancer for BMI values of 18.5 to 24.9 (reference), 25.0 to 29.9, 30.0 to 34.9, and >or=35 kg/m2 were 1.0, 1.15, 1.22, and 1.28 (95% confidence interval, 1.02-1.61; P trend = 0.028). The association between BMI and bladder cancer was consistent among subgroups defined by gender, education, smoking status, and other potential effect modifiers. In contrast, physical activity showed no statistically significant relation with bladder cancer. After multivariate adjustment, including BMI, the relative risks of bladder cancer for increasing frequency of physical activity [0 (reference), <1, 1-2, 3-4, and >or=5 times a week] were 1.0, 0.85, 0.89, 0.91, and 0.87 (95% confidence interval, 0.74-1.02; P trend = 0.358), respectively. In conclusion, these findings provide support for a modest adverse effect of adiposity on risk for bladder cancer. In contrast, our results do not suggest a relation between physical activity and bladder cancer.

Tallness is associated with risk of testicular cancer: evidence for the nutrition hypothesis

The pathogenesis of testicular germ cell tumours (GCTs) is potentially influenced by high-energy nutrition during infancy. As adult height is a proxy for childhood nutrition, we investigated the role of nutrition in GCT pathogenesis by comparing stature of patients with healthy men. In a matched case–control study, 6415 patients with GCT were compared with healthy army conscripts (1:6 matching modus) with regard to height (cm) and body mass index (BMI; kg/m²). Statistical analysis involved tabulation of descriptive height measures and BMI. Conditional logistic regression models were used to quantify the association of GCT with height, with odds ratios (OR) adjusted for BMI. The literature was searched for studies on stature in GCT patients. Body size is significantly associated with risk of GCT, very tall men (>195 cm) having a GCT risk of OR=3.35 (95% confidence intervals (CI): 2.88–3.90; adjusted). Short stature is protective (OR=0.798; 95% CI: 0.68–0.93). Both histologic subgroups are associated with tallness. Of 16 previous reports, 7 were confirmative, 5 had null and 4 equivocal results. The association of stature with GCT risk accords with the nutrition hypothesis of GCT. This study expands the current view of GCT tumorigenesis by suggesting that high-calorie intake in childhood promotes GCT precursors originating in utero.

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.

Diabetes mellitus, body size and bladder cancer risk in a prospective study of Swedish men

Epidemiologic studies on diabetes and body size in relation to risk of bladder cancer have yielded inconsistent results. We examined prospectively the associations between a history of diabetes, height, weight, body mass index and waist circumference, and the incidence of bladder cancer in the Cohort of Swedish Men, a prospective study of 45,906 men aged 45-79 years at baseline. During follow-up from 1998 through December 2007, 414 incident cases of bladder cancer were ascertained. A history of diabetes was not associated with risk of bladder cancer (multivariate rate ratio=1.16; 95% confidence interval=0.81-1.64). Similarly, no associations were observed for height, weight, body mass index or waist circumference. These findings in men do not support a role for diabetes, height or excess body mass in the aetiology of bladder cancer.

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.

Prospective study of body mass index, height, physical activity and incidence of bladder cancer in US men and women

We evaluated prospectively the association between body mass index (BMI), height, recreational physical activity and the risk of bladder cancer among US adults. Data were used from 2 ongoing cohorts, the Health Professionals Follow-up Study and the Nurses' Health Study, with 3,542,012 years of follow-up and 866 incident bladder cancer cases (men = 507; women = 359) for the anthropometric analysis and 1,890,476 years of follow-up and 706 incident bladder cancer cases (men = 502; women = 204) for the physical activity analysis. Cox proportional hazard models were used to estimate incidence rate ratios (RR) and 95% confidence intervals (CI) between BMI, height, physical activity and bladder cancer risk adjusting for age, pack-years of cigarette smoking and current smoking. Estimates from each cohort were pooled using a random-effects model. We observed no association between baseline BMI and bladder cancer risk, even when we compared a BMI of > or =30 kg/m(2) to a BMI of 18-22.9 kg/m(2) [pooled multivariate (MV) RR, 1.16; 95% CI: 0.89-1.52]. A weak, but statistically significant, association was observed for the same comparison after excluding bladder cancer cases diagnosed within the first 4 years of follow-up (pooled MV RR, 1.33; 95% CI: 1.01-1.76). Height was not related to bladder cancer risk (pooled MV RR, 0.82; 95% CI: 0.65-1.03, top vs. bottom quintile). Total recreational physical activity also was not associated with the risk of bladder cancer (pooled MV RR, 0.97; 95% CI: 0.77-1.24, top vs. bottom quintile). Our findings do not support a role for BMI, height or physical activity in bladder carcinogenesis.

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.

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.

Clinical epidemiology of testicular germ cell tumors

Clinical epidemiology is sometimes called the basic science of clinical medicine. In terms of the pathogenesis of testicular germ cell tumors (GCTs), clinical epidemiology analyzes suspected risk factors. The present review highlights the risk factors established so far and briefly summarizes those factors currently under investigation. In analogy to the methods of evidence based medicine, this review attributes levels of evidence to each of the putative risk factors. Level I represents highest quality of evidence while level V denotes the lowest level. So far, undescended testis (UDT), contralateral testicular GCT and familial testis cancer are established risk factors attaining high levels of evidence (levels I-III a). In a meta-analysis of 21 studies exploring the association of UDT with GCT risk, an over-all relative risk (RR) of 4.8 (95% confidence interval 4.0-5.7) was found. Contralateral testicular GCT involves a roughly 25-fold increased RR of GCT, while familial testis cancer constitutes a RR of 3-10. Infertility, testicular atrophy, and twin-ship represent risk factors with lesser levels of evidence (level III a). There is also some evidence for HIV infection being a predisposing factor for GCT (level IV a). Scrotal trauma is probably not associated with GCT risk. The estrogen excess theory implies high estrogen levels during the first trimester of pregnancy. As a consequence, primordial germ cells lose track of the normal developmental line and transform into premalignant cells that later become testicular intraepithelial neoplasia (TIN), the precursor of full-blown testicular GCT. Surrogate parameters for high gestational estrogen levels are investigated in case control studies. Such factors are maternal age >30 years, first-born, low birth weight, maternal breast cancer, high sex-ratio of siblings. So far, the sum of evidence is promising but still conflicting (especially for level III b). Another novel theory is the childhood nutrition hypothesis. This concept postulates a modulating or "catalyzing" effect by high dietary intake during childhood on the pathogenesis of testicular GCT. A surrogate parameter of early childhood nutrition is adult height. So far, 12 controlled studies have looked to the possible association of attained height and GCT risk of which six demonstrated a significant association. Thus, the sum of evidence corresponds to level III b. This concept is appealing because it would explain several hitherto unexplained epidemiological features of GCT.

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.

Are coffee and tea consumption associated with urinary tract cancer risk? A systematic review and meta-analysis

BACKGROUND

Narrative reviews have concluded that there is a small association between coffee consumption and an increased risk of urinary tract cancer, possibly due to confounding by smoking. No association for tea consumption has been indicated. This systematic review attempts to summarize and quantify these associations both unadjusted and adjusted for age, smoking and sex.

METHOD

Thirty-four case-control and three follow-up studies were included in this systematic review. Summary odds ratios (OR) were calculated by meta-regression analyses.

RESULTS

The unadjusted summary OR indicated a small increased risk of urinary tract cancer for current coffee consumers versus non-drinkers. The adjusted summary OR were: 1.26 (95% CI : 1.09-1.46) for studies with only men, 1.08 (95% CI : 0.79-1.46) for studies with only women and 1.18 (95% CI : 1.01-1.38) for studies with men and women combined. Neither unadjusted nor adjusted summary OR provided evidence for a positive association between tea consumption and urinary tract cancer. Even though studies differed in methodology, the results were rather consistent. We did not perform dose-response analyses for coffee and tea consumption due to sparse data.

CONCLUSIONS

In accordance with earlier reviews, we found that coffee consumption increases the risk of urinary tract cancer by approximately 20%. The consumption of tea seems not to be related to an increased risk of urinary tract cancer.

Obesity, hypertension, and the risk of kidney cancer in men

BACKGROUND

Obesity and hypertension have been implicated as risk factors for the development of renal-cell cancer.

METHODS

We examined the health records of 363,992 Swedish men who underwent at least one physical examination from 1971 to 1992 and were followed until death or the end of 1995. Men with cancer (renal-cell cancer in 759 and renal-pelvis cancer in 136) were identified by cross-linkage of data with the nationwide Swedish Cancer Registry. Poisson regression analysis was used to estimate relative risks, with adjustments for age, smoking status, body-mass index, and diastolic blood pressure.

RESULTS

As compared with men in the lowest three eighths of the cohort for body-mass index, men in the middle three eighths had a 30 to 60 percent greater risk of renal-cell cancer, and men in the highest two eighths had nearly double the risk (P for trend, <0.001). There was also a direct association between higher blood pressures and a higher risk of renal-cell cancer (P for trend, <0.001 for diastolic pressure; P for trend, 0.007 for systolic pressure). After the first five years of follow-up had been excluded to reduce possible effects of preclinical disease, the risk of renal-cell cancer was still consistently higher in men with a higher body-mass index or higher blood pressure. At the sixth-year follow-up, the risk rose further with increasing blood pressures and decreased with decreasing blood pressures, after adjustment for base-line measurements. Men who were current or former smokers had a greater risk of both renal-cell cancer and renal-pelvis cancer than men who were not smokers. There was no relation between body-mass index or blood pressure and the risk of renal-pelvis cancer.

CONCLUSIONS

Higher body-mass index and elevated blood pressure independently increase the long-term risk of renal-cell cancer in men. A reduction in blood pressure lowers the risk.

Risk factors for testicular cancer: a case-control study in twins

Early life and anthropometric risk factors for testicular cancer were examined in a case-control study in England and Wales in which affected male twins were compared with their unaffected male co-twins. Questionnaire data was obtained for 60 twin pairs. Significantly raised risk of testicular cancer occurred in twins who had longer arms and legs than their co-twin. There was a significant excess of testicular cancer reported in non-twin brothers, as well as in twin brothers, of cases. Risk was also significantly raised in relation to cryptorchidism. The results on limb length suggest that factors, perhaps nutritional, affecting growth before puberty, may be causes of testicular cancer. The results on risk in brothers add to evidence of a large genetic component in aetiology of the tumour. The risk associated with cryptorchidism in the twins accords with the hypothesis that cryptorchidism is causally associated with testicular cancer because it is a cause of the malignancy, rather than because the same maternal factors experienced in utero cause both conditions.

Prostate cancer and smoking: a review of case-control and cohort studies

BACKGROUND

The purpose of this study was to undertake a systematic analysis of the relation between smoking and prostate cancer.

METHODS

All published case-control and cohort studies including relevant data on this topic were collected. The magnitude of potential sources of divergent results among case-control studies was estimated comparing current, former, and ever to never smokers, stratified by type of controls (hospital vs. population) and by race. Cohort studies were discussed individually.

RESULTS

Neither a clinically nor a statistically significant association between smoking and prostate cancer seems likely, but it cannot be ruled out entirely. The association between other purported risk factors and prostate cancer is not likely to be confounded by the incomplete measurement and control for smoking habits because smoking and prostate cancer are not related.

CONCLUSIONS

For a valid assessment of other risk factors in prostate cancer patients the collection of complete smoking information is therefore less critical than in patients with other diseases. For a definitive assessment of the effect of smoking on prostate cancer incidence and mortality however, future studies need to focus on the collection of information on lifetime smoking habits, including tar exposure.

Nutrition and renal cell cancer

Epidemiologic evidence on the relation between nutrition and renal cell cancer is reviewed. Kidney cancer, comprising 1.7 percent of all malignant diseases diagnosed worldwide, shows about a 20-fold international variation in the incidence in men and 10-fold in women. This substantial variation indicates an important causal role of environmental factors. Renal cell (parenchymal) cancer (RCC) accounts for about 80 percent of all kidney cancers. While the etiology of RCC is incompletely understood, analytic epidemiologic studies provide consistent support for a positive association of obesity with risk of RCC; the dose-response observed supports a causal relationship. Only a few prospective studies, all of them limited in size, have been published, while ecologic and case-control studies suggest that diet may be important in the etiology of RCC. However, contradictory results and methodologic limitations in some case-control studies prevent definite conclusions concerning diet and RCC. A positive association of protein and fat intake, as well as their main food sources (meat, milk, fats), with risk of RCC-as suggested by ecologic studies-has no clear support in analytic epidemiologic studies. A protective effect of vegetables and fruits has been observed in most case-control studies, while the majority do not show an association between alcohol, coffee, and risk of RCC. Recent reports indicated an increased risk of RCC associated with consumption of fried/sautéed meat and low intakes of magnesium or vitamin E. An apparent positive association with total energy intake, perhaps due to bias, needs further investigation.

Smoking and drinking habits in relation to prostate cancer

OBJECTIVE

To evaluate the role of tobacco and alcohol consumption in the aetiology of prostate cancer.

PATIENTS AND METHODS

In a case-control study conducted in the Netherlands, information on smoking and drinking habits was obtained from questionnaires completed by 345 patients exhibiting primary prostate cancer and by 1346 controls with benign prostate hyperplasia. The response rate was 79%.

RESULTS

No association was observed between drinking habits and the risk of prostate cancer (324 cases versus 1237 controls; odds ratio 1.36; 95%CI 0.84-2.22). A significantly elevated odds ratio was found for individuals who had smoked at any time during their lives (329 cases versus 1212 controls; odds ratio 2.12; 95%CI 1.24-3.62). However, no relationship was observed between the number of cigarettes smoked, the duration of smoking, the age at which the subjects started smoking or with the calendar period in which they were born. Odds ratios calculated for individuals who smoked in consecutive 5-year periods between 1940 and 1989 did not show any trend. Furthermore, the risk of prostate cancer among ex-smokers did not differ significantly from the risk among current smokers, even when smoking was stopped more than 25 years previously.

CONCLUSION

From these findings, which do not point to the causative agent, it would appear that neither smoking nor alcohol consumption seriously increases the risk of prostate cancer.

Bladder cancer and coffee drinking: a summary of case-control research

An association between coffee drinking and cancer of the lower urinary tract (LUT) was first suggested 20 years ago and has been the subject of many epidemiological studies. We have undertaken a critical review and statistical summary of 35 case-control studies of this association published between 1971 and 1992. Predefined methodological criteria were applied to the available reports. Studies were classified as either meeting the criteria (core studies) or failing to satisfy at least one of the requirements for design or analysis (non-core studies). The summarised data from the 8 core studies showed no evidence of an increase in risk of LUT cancer with coffee drinking in men or women after adjustment for the effects of cigarette smoking (odds ratio 1.07 [95% CI 1.00-1.14] for men, 0.91 [0.81-1.03] for women). The measures of association from the non-core studies were higher on average than those from the core studies, although the inclusion of these data in an overall summarised estimate did not substantially change the findings from the core analysis. We conclude that the best available data do not suggest a clinically important association between the regular use of coffee and development of cancer of the LUT in men or women.

Birth order and risk of testicular cancer

To explore the etiology of testicular cancer, cases of testicular cancer were identified among members of a cohort of Danish boys born between 1941 and 1957 (inclusive), who had attended schools in Copenhagen and Gentofte and whose school health records were contained in an archive under the supervision of the Danish Cancer Registry. One hundred and eighty-three cases of testicular cancer diagnosed before 31 December 1984 were identified; 366 controls, matched to cases by sex and age, were selected from the same cohort. Information on potential risk factors and confounders was obtained from two sources: school health records and midwife protocols, both of which were recorded prior to the diagnosis of testicular cancer in cases. Relative risks (RR) approximated by the odds ratios were calculated and, in logistic regression analyses, adjustments were done for known or suspected confounders. A decreasing risk of testicular cancer with increasing birth order was observed (P = 0.020). Compared with being firstborn, being number four or more in birth order was associated with a significantly decreased RR for all testicular cancers (RR = 0.3, 95 percent confidence interval [CI] = 0.3-0.8) and testicular seminoma (RR = 0.1, CI = 0.02-0.9). No association was observed between high social class and the risk of testicular cancer (RR = 1.4, CI = 0.8-2.3); neither was age at which the study subjects had mumps or measles related to risk of testicular cancer. No cases of mumps orchitis were observed before or during school years. A slightly increased RR for testicular cancer among boys from small families could be explained by the association between family size and birth order.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult dietary intake and prostate cancer risk in Utah: a case-control study with special emphasis on aggressive tumors

A population-based case-control study in Utah of 358 cases diagnosed with prostate cancer between 1984 and 1985, and 679 controls categorically matched by age and county of residence, were interviewed to investigate the association between dietary intake of energy (kcal), fat, protein, vitamin A, beta-carotene, vitamin C, zinc, cadmium, selenium, and prostate cancer. Dietary data were ascertained using a quantitative food-frequency questionnaire. Data were analyzed separately by age (45-67, 68-74) and by tumor aggressiveness. The most significant associations were seen for older males and aggressive tumors. Dietary fat was the strongest risk factor for these males, with an odds ratio (OR) of 2.9 (95 percent confidence interval [CI] 1.0-8.4) for total fat; OR = 2.2 (CI = 0.7-6.6) for saturated fat; OR = 3.6 (CI = 1.3-9.7) for monounsaturated fat; and OR = 2.7 (CI = 1.1-6.8) for polyunsaturated fat. Protein and carbohydrates had positive but nonsignificant associations. Energy intake had an OR of 2.5 (CI = 1.0-6.5). In these older men, no effects were seen for dietary cholesterol, body mass, or physical activity. There was little association between prostate cancer and dietary intake of zinc, cadmium, selenium, vitamin C, and beta-carotene. Total vitamin A had a slight positive association with all prostate cancer (OR = 1.6, CI = 0.9-2.4), but not with aggressive tumors. No associations were found in younger males, with the exception of physical activity which showed active males to be at an increased but nonsignificant risk for aggressive tumors (OR = 2.0, CI = 0.8-5.2) and beta-carotene which showed a nonsignificant protective effect (OR = 0.6, CI = 0.3-1.6). The findings suggest that dietary intake, especially fats, may increase risk of aggressive prostate tumors in older males.

Testis cancer: post-natal hormonal factors, sexual behaviour and fertility

The relationship of risk of testis cancer, and subdivisions of the tumour by histology, to variables which may be related to hormonal status, sexual behaviour and fertility was investigated in data from a case-control study with 259 cases and 2 sets of controls. No consistent association was found between testis cancer risk and age at puberty, need to shave, obesity, alcohol intake, animal fat intake, and sexual behaviour. There was a significant excess of seminomas in very tall men. Testis cancer cases showed lower fertility than controls according to various measures, but this reflected the greater frequency of cryptorchidism among cases compared to controls. Among non-cryptorchid subjects there was no clear evidence that infertility was associated with risk of testis cancer.

The role of staging in urologic cancer. Physical assessment and risk factors

Patients with urologic cancer may have improved survival if their diagnosis is made early. This task begins in the primary care physician's office through patient education on prevention and early detection procedures. A thorough history which provides for risk factor evaluation including life-style and environmental factors, a careful family history, past personal history, and finally, symptoms of current and past illness is the keystone of prevention and early diagnosis. The general physical examination as well as a specific examination of the scrotum and its contents, the penis, the prostate, and the kidney carefully done by an experienced examiner may improve chances for survival. The office urinalysis which should be available in every primary care physician's office is evaluated for its usefulness in early diagnosis. This report relates urologic cancer and its precursors to the history and physical examination with the urinalysis which in turn may be associated with morbidity and mortality.

Prenatal and familial associations of testicular cancer

In a case-control study of testis cancer 259 cases with testicular cancer, 238 controls treated at radiotherapy centres and 251 non-radiotherapy hospital in-patient controls were interviewed about some possible prenatal and familial risk factors for the tumour. For firstborn men, the risk of testis cancer increased significantly according to maternal age at the subject's birth, and this effect was most marked for seminoma. The association with maternal age was not apparent for cases other than firstborn. The risk of testis cancer was also significantly raised for men from small sibships and of early birth order. These results accord with the theory that raised maternal levels of available oestrogen during the early part of pregnancy are aetiological for testicular cancer in the son, although other explanations are possible; there is evidence that seminoma risk may particularly be affected.