Review Article
A Contemporary Review of Risk Factors for Bladder Cancer
Lokeshwar SD1, Klaassen Z2 and Terris MK2*
1Miller School of Medicine, University of Miami, USA
2Department of Urology, Augusta University, USA
*Corresponding author: Martha K. Terris, Department of Urology, Medical College of Georgia– Augusta University, 1120 15th Street, Augusta, GA 30912, USA
Published: 19 Oct, 2016
Cite this article as: Lokeshwar SD, Klaassen Z, Terris MK.
A Contemporary Review of Risk Factors
for Bladder Cancer. Clin Oncol. 2016;
1: 1121.
Abstract
Increased risk of bladder cancer has historically been associated with smoking and environmental
exposure, however other factors have recently been investigated. The role of marijuana and bladder
cancer risk requires further validation, although there appears to be an inverse relationship perhaps
associated with decreased tobacco smoking. A correlation between obesity and increased risk
of bladder cancer has yet to be established, however the pro-inflammatory affect of obesity and
the operative challenges associated with obese patients suggest a potential relationship. African
Americans race is associated with a higher likelihood of mortality and recurrence after bladder
cancer diagnosis, likely secondary to poorer socioeconomic status and lack of access to healthcare.
Although men are more likely to present with bladder cancer, the mortality rates in women are
higher due to delayed diagnosis. Finally, radiation exposure from treatment of previous primary
malignancies increases bladder cancer risk, as does environmental contaminants such as arsenic.
Health care providers should ultimately seek to alleviate preventable disparities associated with
increased risk of bladder cancer, as well as be aware of less common, high-risk patient populations
when evaluating and educating patients and their families.
Keywords: Bladder cancer; Mortality; Lymphadenectomy
Introduction
In 2015, there were more than 76,000 new cases of bladder cancer and 16,300 bladder cancer
related deaths [1]. However, in the United States, bladder cancer incidence and mortality has
declined over the past decade [1]. This trend is likely secondary to reduced smoking rates among
the American population: from 20.9% of adults in 2004 to 16.8% in 2014 [2]. Tobacco smoking
is arguably the most established risk factor for bladder cancer [3], and recently the intensity of
smoking has been implicated in bladder cancer pathophysiology [4]. Heavy smokers are more likely
to present with high-grade muscle invasive disease compared to patients who were light smokers
or nonsmokers [4]. Furthermore, long-term heavy smokers also have worse prognosis after radical
cystectomy [5]. In addition to tobacco smoking, recent cohort and case-control studies have
suggested other important risk factors for developing bladder cancer. The purpose of this review is
to assess the literature and highlight these additional, contemporary risk factors.
Marijuana
With the recent advocating for legalization of marijuana in certain US states, side effects and
implications of cannabis use has garnered public interest, including a potential role in bladder cancer
risk. In 2006, prior to marijuana legalization, we suggested that marijuana smoking may increase
the risk of bladder cancer [6]. In this case-control study, 88.5% of patients with bladder cancer had
a history of habitual marijuana use compared to only 69.2% of age-matched controls. Subsequently,
a study of 84,000 Californian men aged 45-69 were followed for 11 years to determine their risk of
bladder cancer [7]. Cannabis consumption was associated with a 45% decrease in bladder cancer
incidence (HR, 0.55; 95% CI, 0.31-1.00) indicating cannabis use may be protective for risk of bladder
cancer. Research on this topic is limited and currently hypothesis generating. Perhaps marijuana
smoking is associated with decreased tobacco smoking, thus resulting in decreased risk for bladder
cancer. Further investigation is necessary to establish a possible causal relationship between cannabis
use and bladder cancer risk.
Obesity
Obesity and lack of physical activity among Western populations has recently emerged as a
potential risk factor for bladder cancer. A recent review article
analyzed 31 studies evaluating the relationship between obesity and
bladder cancer [8]. Among these studies, ten suggested a positive
association between obesity and increased bladder cancer risk, while
three found a negative association between physical activity and
bladder cancer risk [8]. A report from earlier this year assessed the
role of BMI on oncological outcomes in patients treated with radical
cystectomies for muscle invasive disease [9]. BMI 30 kg/m2 correlated
with both elevated risk of disease recurrence (HR 1.58; 95% CI 1.06-
2.34, p=0.02) and cancer-specific mortality (HR 1.58; 95% CI 1.01-
2.48; p=0.04). Although a causal association of obesity and increased
risk of bladder cancer has yet to be established, the pro-inflammatory
affect of obesity and the operative challenges associated with obese
patients suggest a potential relationship [9]. As the global obesity
pandemic continues to transpire, the role of obesity and sedentary
lifestyles on bladder cancer incidence and long-term outcomes will
be an important area of research.
Race
Bladder cancer has traditionally been associated with Caucasian
patients, however recent data has emerged suggesting increased trends
in African Americans and Hispanic populations [10]. Although the
raw number of new bladder cancer cases is still highest in Caucasians,
mortality rates for bladder cancer are higher among non-white
patients [10]. Many reports have hypothesized possible explanations
for these racial discrepancies. Utilizing state inpatient databases
for New York, Florida and Maryland, Barocas et al. [11] found
that African Americans were more often treated by lower volume
surgeons and hospitals, had lower receipt of pelvic lymphadenectomy
and continent diversion, and had higher rates of complications
compared to Caucasian patients. A SEER-Medicare study of 74,000
bladder cancer patients, found that African American race imparted
a greater risk of disease progression and mortality [12]. To assess for
race specific outcomes, the University of Alabama followed patients
from 2001-2012 that underwent radical cystectomy and reported that
race was independently associated with tumor recurrence (HR, 3.1;
95% CI, 1.2-7.4) [13]. Additionally, in a recent SEER study performed
by our group, patients with metastatic disease at diagnosis were more
commonly female, African American, and unmarried compared to
patients with non-metastatic disease at diagnosis [14]. The importance
of equal access care for improving outcomes in African American
patients has also been evaluated by the Department of Defense, where
universal healthcare is provided irrespective of racial background. In
this setting, there was comparable overall survival between Caucasian
and African American bladder cancer patients (HR: 0.96, 95% CI:
0.76-1.22) [15], suggesting that access to care may be more important
than disease biology. These findings highlight the importance of
healthcare access (specifically hospitals and providers equipped for
evaluating and treating bladder cancer patients), patient education
and administrative support for patients of lower socioeconomic
status.
Gender
Although men have a higher incidence of bladder cancer (3:1),
women have a higher mortality rate relative to disease incidence [1].
Rather than a more aggressive disease entity, research has suggested
that these discrepancies may be secondary to delayed diagnosis.
Among patients presenting with hematuria, the time from the
hematuria evaluation to bladder cancer diagnosis was 85.4 days in
women, compared to 73.6 days in men (p <0.001) [16]. Exceptionally
long delays in diagnosis (>6 months) were also higher in women
compared to men. Furthermore, a study published this year found
that women are less likely to be treated with systemic chemotherapy
for advanced bladder cancer than men (45% vs. 52%; adjusted
relative risk 0.91, 95% CI 0.88-0.94) [17]. Additionally, women also
experienced delays in systemic chemotherapy administration (9.8
months vs. men 8.0 months; p <0.001) [17]. Similar to US data [14],
an Austrian Cancer Registry study evaluating 27,773 patients found
that women more frequently have advanced stage disease at diagnosis
[18]. In a study evaluating 27,912 patients in Europe and North
America, survival rates after radical cystectomy were lower in women
compared to men (pooled HR 1.20, 95%CI 1.09-1.32) [19].
Whether females have more aggressive disease or primarily suffer
from delayed diagnosis and more advanced presentation remains to
be fully elucidated. However, when presenting with irritative voiding
symptoms with bladder cancer risk factors, women are generally
treated for voiding complaints and alleged UTIs (i.e. antibiotics)
without more in depth investigation [17]. Educating primary health
care providers to the significance of these presenting symptoms,
specifically in women with long-term tobacco smoking and/or
environmental risk factors, will lead to early diagnosis/appropriate
urologic referral and may alleviate these seemingly correctable gender
disparities.
Radiation exposure
The most common radiation exposure leading to increased risk of
bladder cancer is pelvic radiotherapy for a prior malignancy, including
prostate, uterine, cervical and rectal cancer. In a retrospective
cohort study of 56,681 patients with primary uterine cancer, the
prevalence of subsequent bladder cancer for patients treated with
radiation therapy was 0.93% versus 0.48% in those who did not
receive radiation therapy [20]. Furthermore, the prevalence of fatal
bladder cancer in the radiation therapy cohort was 0.25% compared
to 0.09% in patients without radiation therapy [20]. Patients with
localized prostate cancer treated with adjuvant radiation therapy after
radical prostatectomy are 1.7 times more likely to develop bladder
cancer compared to those undergoing radical prostatectomy [21].
Adjuvant radiation therapy also increases bladder cancer mortality
(HR=1.28 P=0.05) [21], perhaps secondary to these patients more
commonly presenting with locally advanced tumors [22]. Finally,
a study from Taiwan highlighted the increased risk of secondary
bladder cancer diagnosis after cervical cancer radiation, reporting a
standardized incidence ratio of 2.26 [23]. While primary or adjuvant
radiation therapy may be clinically indicated for patients with pelvic
malignancies, health care providers should be aware of the increased
risk of bladder cancer in this patient population.
Industrial & environmental exposure
The long-term carcinogenic effects of industrial and environmental
exposure are currently being elucidated. A French cohort of 2,897
uranium processing workers with at least 6 months of chemical
exposure was studied for bladder cancer incidence [24]. Interestingly,
exposure to aromatic solvents was associated with developing bladder
cancer after adjusting for other chemical exposure (HR 6.53, 95%
CI 1.14-37.41). Tetrachloroethylene exposure (used during drycleaning)
has a relative risk of 1.50 for bladder cancer when adjusted
for smoking [25]. In study of New York state rubber manufacturing
workers, o-toluidine exposure was associated with a relative risk of
6.13 for bladder cancer compared to the general population [26].
Recent studies have highlighted environmental bladder cancer risk
factors, particularly in water and food supplies. A hospital-based case
control study from Spain reported that drinking water with nitrates
for >20 years at high nitrate levels (>9.5 mg/L) was associated with a
1.4x increased risk for bladder cancer [27]. Results from World Health
Organization (WHO) food consumption data have also implicated
arsenic as a risk factor for bladder cancer, suggesting that inorganic
arsenic in food may account for 9,129 to 119,176 additional cases of
bladder cancer each year [28]. Occupational risk factors may account
for ~10% of bladder cancer risk factors [29], highlighting the need
for clinicians to be aware of these unique at-risk patient populations.
Conclusion
Tobacco smoking is the most well-known and publicized risk factor for bladder cancer, however a number of other important risk factors exist. In addition to prior radiation, industrial and environmental risk factors, certain gender and racial disparities in diagnosis and treatment are prevalent. Health care providers should seek to alleviate preventable disparities, as well as be aware of less common, high-risk patient populations when evaluating and educating patients and their families.
References
- Siegel RL, Miller KD, Jemal A. Cancer statistics, 2016. CA: A Cancer Journal for Clinicians. 2016; 66: 7–30.
- Centers for Disease Control and Prevention - Trends in Current Cigarette Smoking - Smoking & Tobacco Use.
- Wynder EL, Onderdonk J, Mantel N. An epidemiological investigation of cancer of the bladder. Cancer. 1963; 16: 1388–1407.
- Pietzak EJ, Mucksavage P, Guzzo TJ, Malkowicz SB. Heavy Cigarette Smoking and Aggressive Bladder Cancer at Initial Presentation. Urology. 2015; 86: 968-973.
- Rink M, Zabor EC, Furberg H, Xylinas E, Ehdaie B, Novara G, et al. Impact of smoking and smoking cessation on outcomes in bladder cancer patients treated with radical cystectomy. Eur Urol. 2013; 64: 456-464.
- Chacko JA, Heiner JG, Siu W, Macy M, Terris MK. Association between marijuana use and transitional cell carcinoma. Urology. 2006; 67: 100-104.
- Thomas AA, Wallner LP, Quinn VP, Slezak J, Van Den Eeden SK, Chien GW, et al. Association between cannabis use and the risk of bladder cancer: results from the California Men's Health Study. Urology. 2015; 85: 388-392.
- Noguchi JL, Liss MA, Parsons JK. Obesity, Physical Activity and Bladder Cancer. Curr Urol Rep. 2015; 16: 74.
- Dabi Y, Rouscoff Y, Anract J, Delongchamps NB, Sibony M, Saighi D, et al. Impact of body mass index on the oncological outcomes of patients treated with radical cystectomy for muscle-invasive bladder cancer. World J Urol. 2016.
- Cancer of the Urinary Bladder - SEER Stat Fact Sheets. 2016.
- Barocas DA, Alvarez J, Koyama T, Anderson CB, Gray DT, Fowke JH, et al. Racial variation in the quality of surgical care for bladder cancer. Cancer. 2014; 120: 1018-1025.
- Chamie K, Litwin MS, Bassett JC, Daskivich TJ, Lai J, Hanley JM, et al. Recurrence of high-risk bladder cancer: a population-based analysis. Cancer. 2013; 119: 3219-3227.
- Paluri RK, Morgan CJ, Mooney DJ, Mgbemena O, Yang ES, Wei S, et al. Effect of African-American Race on Tumor Recurrence After Radical Cystectomy for Urothelial Carcinoma of the Bladder. Clin Genitourin Cancer. 2015; 13: 469-475.
- Klaassen Z, Dibianco JM, Jen RP, Evans AJ, Reinstatler L, Terris MK, et al. Female, Black, and Unmarried Patients Are More Likely to Present With Metastatic Bladder Urothelial Carcinoma. Clin Genitourin Cancer. 2016; 14: e489-e492.
- Schinkel JK, Shao S, Zahm SH, Mcglynn KA, Shriver CD, Zhu K. Overall and recurrence-free survival among black and white bladder cancer patients in an equal-access health system. Cancer Epidemiol. 2016; 42: 154-158.
- Cohn JA, Vekhter B, Lyttle C, Steinberg GD, Large MC. Sex disparities in diagnosis of bladder cancer after initial presentation with hematuria: a nationwide claims-based investigation. Cancer. 2014; 120: 555-561.
- Rose TL, Deal AM, Nielsen ME, Smith AB, Milowsky MI. Sex disparities in use of chemotherapy and survival in patients with advanced bladder cancer. Cancer. 2016; 122: 2012-2020.
- Waldhoer T, Berger I, Haidinger G, Zielonke N, Madersbacher S. Sex Differences of ≥pT1 Bladder Cancer Survival in Austria: A Descriptive, Long-Term, Nation-Wide Analysis Based on 27,773 Patients. Urol Int. 2015; 94: 383-389.
- Liu S, Yang T, Na R, Hu M, Zhang L, Fu Y, et al. The impact of female gender on bladder cancer-specific death risk after radical cystectomy: a meta-analysis of 27,912 patients. Int Urol Nephrol. 2015; 47: 951-958.
- Baack kukreja JE, Scosyrev E, Brasacchio RA, Toy EP, Messing EM, Wu G. Bladder cancer incidence and mortality in patients treated with radiation for uterine cancer. BJU Int. 2014; 114: 844-851.
- Abern MR, Dude AM, Tsivian M, Coogan CL. The characteristics of bladder cancer after radiotherapy for prostate cancer. Urol Oncol. 2013; 31: 1628-1634.
- Bostrom PJ, Soloway MS, Manoharan M, Ayyathurai R, Samavedi S. Bladder cancer after radiotherapy for prostate cancer: detailed analysis of pathological features and outcome after radical cystectomy. J Urol. 2008; 179: 91-95.
- Teng CJ, Huon LK, Hu YW, Yeh CM, Chao Y, Yang MH, et al. Secondary Primary Malignancy Risk in Patients With Cervical Cancer in Taiwan: A Nationwide Population-Based Study. Medicine (Baltimore). 2015; 94: e1803.
- Zhivin S, Laurier D, Caër-lorho S, Acker A, Guseva canu I. Impact of chemical exposure on cancer mortality in a French cohort of uranium processing workers. Am J Ind Med. 2013; 56: 1262-1271.
- Vlaanderen J, Straif K, Ruder A, Blair A, Hansen J, Lynge E, et al. Tetrachloroethylene exposure and bladder cancer risk: a meta-analysis of dry-cleaning-worker studies. Environ Health Perspect. 2014; 122: 661-666.
- Carreón T, Hein MJ, Hanley KW, Viet SM, Ruder AM. Bladder cancer incidence among workers exposed to o-toluidine, aniline and nitrobenzene at a rubber chemical manufacturing plant. Occup Environ Med. 2014; 71: 175-182.
- Espejo-herrera N, Cantor KP, Malats N, Silverman DT, Tardon A, Garcia-Closas R, et al. Nitrate in drinking water and bladder cancer risk in Spain. Environ Res. 2015; 137: 299-307.
- Oberoi S, Barchowsky A, Wu F. The global burden of disease for skin, lung, and bladder cancer caused by arsenic in food. Cancer Epidemiol Biomarkers Prev. 2014; 23: 1187-1194.
- Ferrís J, Garcia J, Berbel O, Ortega JA. Constitutional and occupational risk factors associated with bladder cancer. Actas Urol Esp. 2013; 37: 513-522.