Bladder cancer is much more likely to be deadly for women and African-Americans, but the reasons long believed to explain the phenomenon account for only part of the differences for such patients compared to their white and male counterparts, according to results published in the Jan. 1 issue of the journal Cancer.
The results present a stark question for doctors and patients: If age, tumor type, and stage of the disease upon diagnosis don't account for all the increased lethality of the disease in women and African-Americans, then what does?
It's a gaping question facing researchers who have long confronted an irony of bladder cancer, the fifth-most-common type of cancer in America. The disease is more lethal in those patients who are less likely to get it.
Men are more than three times as likely as women to get the disease, and white people are nearly twice as likely to get the disease as African-Americans. Yet, once the disease is present, it's far deadlier in women and in African-Americans – anywhere from 73 percent to 114 percent more deadly in the first year after diagnosis, depending on the group.
In the Cancer paper, scientists and physicians at the University of Rochester Medical Center show for the first time that the factors traditionally thought to be responsible for the differing course are responsible for only about one-third of the difference between white men and women, and up to two-thirds of the difference between African-Americans and their white counterparts.
"We've known that the disease is likely to be more advanced in women and African-Americans by the time they're diagnosed," said corresponding author Edward Messing, M.D., a surgeon well known for his expertise in treating patients with bladder cancer. "Like many doctors, I long assumed that the delay in diagnosis was the reason why the disease is more deadly for these patients.
"I was surprised to find that recognized factors like a delay in diagnosis explain only part of the difference. There are clearly other important factors at work that make these patients more likely to die from the disease. There could be something different about the cancer itself, or there could be differences in the ways these groups are treated," said Messing, who is professor of Urology and Oncology as well as leader of the Prostate Cancer and Genitourinary Oncology team at the James P. Wilmot Cancer Center.
To do the study, scientists analyzed the records of more than 100,000 patients who were diagnosed with bladder cancer from 1990 to 2003. Their records are part of a national cancer registry known as SEER (Surveillance, Epidemiology, and End Results). The 101,249 patients came from 16 different regions: Atlanta, rural Georgia, Connecticut, Detroit, Seattle, Hawaii, Iowa, New Mexico, San Francisco, Los Angeles, San Jose, rural California, Kentucky, Louisiana, New Jersey, and Utah.
The statistical analysis was done by first author Emil Scosyrev, a graduate student in epidemiology; Katia Noyes, Ph.D., associate professor of Community and Preventive Medicine; and Changyong Feng, Ph.D., assistant professor of Computational Biology and Biostatistics. The work was funded by the Ashley Family Foundation.
The team found that in the first year after diagnosis, women were anywhere from about 80 percent to 114 percent more likely to die from the disease than their male counterparts. That increase was a bit lower in year two, when women were about 52 to 55 percent more likely to die.
When it came to race, the researchers found that African-Americans were about 73 percent to 103 percent more likely than their white counterparts to die from the disease within the first two years after diagnosis, and about 40 percent to 117 percent more likely to die three or four years after diagnosis.
Then the team sifted through the data to try to uncover the reasons behind these differences. The team found that the factors traditionally thought to be responsible for the differences – stage of the disease upon diagnosis, tumor type, and age – accounted for only about 30 percent of the difference between the genders among white people, and about 50 to 70 percent of the differences between the races and between the genders among African-Americans.