Researchers from Plymouth University in the UK have discovered a trigger that spurs bladder cancer to become invasive and spread to other parts of the body. Invasive bladder cancer is much more difficult to treat, and the discovery raises hope of new treatments that target this trigger.
A scientific paper on the findings has just been published in American Journal of Physiology - Renal Physiology.
National Cancer Institute statistics on estimated new cases and deaths from bladder cancer predict that over 70,000 people in the US will receive a diagnosis this year. Over 15,000 deaths are also likely in 2013.
The disease affects men more than women. The best-established risk factor for bladder cancer in both men and women is tobacco smoking.
A study published in The Journal of the American Medical Association in 2011 suggests the risk of bladder cancer due to smoking is higher than previously thought, and estimates that a current smoker has four times the risk of developing the cancer versus a non-smoker.
In invasive bladder cancer, the tumor grows into the deeper muscle walls of the bladder. Once this happens, there is a high chance the cancer will travel to other parts of the body. By this stage, survival rates decline rapidly, with only a quarter of patients likely to survive three years after diagnosis and treatment.
One of the study leaders, Professor Raymond Playford, told the press:
"Although bladder cancer can be readily treated if caught early enough, once it starts to invade into deeper tissues and spread to distant sites, it is a much more difficult, painful and life-affecting cancer to live with."
Until this study, the molecular mechanism that triggers an otherwise benign polyp to become the starting point for an invasive tumor was largely unknown.
The molecule at the center of the investigation is a protein called pancreatic secretory trypsin inhibitor (PSTI), which is found in most bladder cancers. Prof. Playford and colleagues found that PSTI plays an important role in the signaling process that allows the cancer to spread.
They ran a number of tests that showed PSTI appears to encourage cell migration and tissue invasion, but does not appear to help cell proliferation.
The discovery suggests that targeting this process could lead to new treatments.
Prof. Raymond Playford says:
"By identifying the mechanism by which bladder cancer develops and spreads, we hope that in time therapies that manipulate this mechanism may be developed to improve the quality of life and survival rates of those with invasive bladder cancer."
The discovery follows a study by another group of UK researchers who made a urine tester that "sniffs" out the early stages of bladder cancer.
Bladder cancer is thought to be the most expensive cancer to treat. One reason is the repeated use of scopes to monitor the development of the cancer cells in the bladder. The "urine sniffer" promises to dramatically cut these costs by reducing scope use.