Bladder cancer (BC) is a significant health problem, and understanding the risk factors for this disease could improve prevention and early detection. To provide a systematic review and summary of novel developments in epidemiology and risk factors for BC. A systematic review of original articles was performed by two pairs of reviewers (M.G.C., I.J., F.E., and K.P.) using PubMed/Medline in December 2017, updated in April 2018. To address our primary objective of reporting contemporary studies, we restricted our search to include studies from the last 5yr. We subdivided our review according to specific risk factors (PICO [Population Intervention Comparator Outcome]). Our search found 2191 articles, of which 279 full-text manuscripts were included. We separated our manuscripts by the specific risk factor they addressed (PICO). According to GLOBOCAN estimates, there were 430000 new BC cases and 165000 deaths worldwide in 2012. Tobacco smoking and occupational exposure to carcinogens remain the factors with the highest attributable risk. The literature was limited by heterogeneity of data. Evidence is emerging regarding gene-environment interactions, particularly for tobacco and occupational exposures. In some populations, incidence rates are declining, which may reflect a decrease in smoking. Standardisation of reporting may help improve epidemiologic evaluation of risk. Bladder cancer is common worldwide, and the main risk factors are tobacco smoking and exposure to certain chemicals in the working and general environments. There is ongoing research to identify and reduce risk factors, as well as to understand the impact of genetics on bladder cancer risk.

Purpose: We hypothesized that bladder cancer patients with associated lymphovascular invasion (LVI) are at increased risk of occult metastases. Methods: A multi-institutional group (University of Texas Southwestern [Dallas, TX], Baylor College of Medicine [Houston, TX], Johns Hopkins University [Baltimore, MD]) carried out a retrospective study of 958 patients who underwent cystectomy for bladder cancer between 1984 and 2003. Of patients with transitional-cell carcinoma (n = 776), LVI status was available for 750. LVI was defined as the presence of tumor cells within an endothelium-lined space. Results: LVI was present in 36.4% (273 of 750) overall, involving 26% (151 of 581) and 72% (122 of 169) of node-negative and node-positive patients, respectively. Prevalence of LVI increased with higher pathologic stage (9.0%, 23%, 60%, and 78%, for T1, T2, T3, and T4, respectively; P < .001). Using multivariate Cox regression analyses including age, stage, grade, and number of pelvic lymph nodes removed, LVI was an independent predictor of local (HR = 2.03, P = .049), distant (HR = 2.60, P = .0011), and overall (HR = 2.02, P = .0003) recurrence in node-negative patients. LVI was an independent predictor of overall (HR = 1.84, P = .0002) and cause-specific (HR = 2.07, P = .0012) survival in node-negative patients. LVI maintained its independent predictor status in competing risks regression models (P = .013), where other-cause mortality was considered as a competing risk. LVI was not a predictor of recurrence or survival in node-positive patients. Conclusion: LVI is an independent predictor of recurrence and decreased cause-specific and overall survival in patients who undergo cystectomy for invasive bladder cancer and are node-negative. These patients represent a high risk group that may benefit from integrated therapy with cystectomy and perioperative systemic chemotherapy.