The urinary bladder is a membranous sac that functions as a receptacle to store urine excreted by the kidneys before it is discharged through the urethra. The bladder is lined with transitional epithelial cells, known as urothelial tissue.
Incidence and survival rates
Around 430,000 new cases of bladder cancer were recorded globally in 2012, accounting for 3 per cent of all new cases of cancer. This makes bladder cancer the ninth most common cancer worldwide.
Men are over four times more likely than women to develop bladder cancer, and it is more common in older adults. For example, the average age at diagnosis in the US is 73 years.
Sixty per cent of cases of bladder cancer occur in higher-income countries, with the highest incidence rates seen in North America and Europe, and the lowest in Asia, Latin America and the Caribbean.
Although bladder cancer is the 13th most common cause of death from cancer, survival rates vary across the world. The five-year survival rate is 76 per cent in the US, and 68 per cent in Europe, but survival tends to be better in higher-income than lower-income countries.
Lifestyle factors and bladder cancer risk
In this report from our Continuous Update Project (CUP) – the world’s largest source of scientific research on cancer prevention and survivorship through diet, nutrition and physical activity – we analyse global research on how certain lifestyle factors affect the risk of developing bladder cancer. This webpage forms part of the World Cancer Research Fund/American Institute for Cancer Research Third Expert Report Diet, Nutrition, Physical Activity and Cancer: a Global Perspective.
Findings on bladder cancer
There is strong evidence that:
- drinking water containing arsenic INCREASES the risk of bladder cancer
There is some evidence that:
- greater consumption of vegetables and fruit might decrease the risk of bladder cancer
- greater consumption of tea might decrease the risk of bladder cancer
Other causes of bladder cancer
In addition to the findings on diet, nutrition and physical activity outlined above, other established causes of bladder cancer include:
The risk of developing bladder cancer is between two and six times higher in smokers compared with non-smokers.
- infection and infestation
Infection from the parasitic worm schistosoma haematobium, causing schistosomiasis, is a major risk factor, especially for squamous cell carcinomas. This is a less common type of bladder cancer that occurs more frequently in countries with high parasitic infection rates (notably Africa and the Middle East).
- occupational exposure
People who work with metalworking fluids – such as sheet metalworkers and machine operators – have a significantly higher risk of bladder cancer, which increases with duration of employment. Exposure to aromatic amines and polyaromatic hydrocarbons (chemicals used in the plastic and chemical industries) has also been strongly associated with an elevated risk for this cancer.
Dietary carcinogens, as well as those from tobacco smoke or other environmental sources, are often excreted in the urine, where the lining of the bladder is exposed to these agents.
Urothelial cell carcinomas start as superficial bladder carcinomas. The majority have low rates of progression, although they can occur at multiple sites. Low-risk lesions may never progress, but if they become invasive the prognosis can be poor.
The superficial lesion that carries the highest risk is carcinoma in situ, which progresses to invasive cancer in more than 50 per cent of cases if it is not treated. These high-risk lesions are often found with multiple papillary tumours, but because they may involve different molecular changes, they are likely to have different pathways of development to low-risk lesions.
Squamous cell carcinoma may be caused by chronic inflammation, for instance from latent schistosomiasis, chronic infections or long-term catheter use.
Mutations in the p53 tumour suppressor gene, as well as abnormalities in chromosome 9, are common in invasive bladder cancer. Inherited mutations of two other genes, glutathione S-transferase (GSTM1) and NAT2 (n-acetyltransferase), also increase risk for bladder cancer. NAT2 is involved in detoxifying aromatic amines present in cigarette smoke, and a slow acetylation phenotype in both genes is estimated to be responsible for 20–46 per cent of bladder cancers.
Full references and a summary of the mechanisms underpinning all the findings can be found in the bladder cancer report.
How the research was conducted
The global scientific research on diet, nutrition, physical activity and the risk of bladder cancer was systematically gathered and analysed, and then independently assessed by a panel of leading international scientists in order to draw conclusions about which of these factors increase or decrease the risk of developing bladder cancer.
Published findings in peer-reviewed journals
Selected findings from this report have been published in peer-reviewed journals. Details of the papers and links to the abstract in PubMed are below:
Fruits, vegetables, and bladder cancer risk: a systematic review and meta-analysis. Vieira AR, Vingeliene S, Chan DS, Aune D, Abar L, Navarro Rosenblatt D, Greenwood DC, Norat T. Cancer Med. 2015; 4(1): 136-46. Abstract
This webpage is a summary.
For much more, download the full chapter.