USC (US) — Smoking causes bladder cancer, and people who smoke heavily have greater odds of developing more aggressive and deadly versions of the disease.
The study, published in Cancer, also shows that testing for certain bladder cancer markers can predict which cases have the highest risk of being deadly.
Researchers have known that smoking is one of the most common causes of bladder cancer, but they’ve wondered whether it also affects how the disease progresses. To investigate, the researchers analyzed bladder tumors and smoking history in 212 multi-ethnic patients recruited through the Los Angeles County Cancer Surveillance Program between 1987 and 1996.
The researchers found that the bladder cancers that developed in individuals who smoked intensely were more likely to be deadly than bladder cancers that developed in those who never smoked, or who smoked less. The study also revealed that changes in particular proteins are often present in bladder cancers that have become deadly.
“We have identified a panel of nine molecular markers that can robustly and reproducibly predict bladder cancer prognosis independent of standard clinical criteria and smoking history,” says study leader Anirband P. Mitra of the Keck School of Medicine at the University of Southern California (USC).
Patients with alterations in six to nine markers had a very poor outcome, raising the hypothesis that these individuals could have benefited from more aggressive treatments.
Because the number of changes in these proteins was directly proportional to patients’ health outcomes in a progressive fashion, the findings confirm the theory that an accumulation of changes is more important than individual changes in determining the characteristics of a given cancer. The link between smoking intensity and prognosis found in this study points to the incrementally harmful effects of smoking.
“The study’s findings are extremely clinically relevant as bladder cancer is one of the most expensive malignancies to treat,” says the study’s co-leader Richard J. Cote, formerly of USC and now with the University of Miami Miller School of Medicine. “Personalized patient management is urgently needed for this disease as current clinical stratification cannot predict outcomes of individual patients.”