By Kerry Grens
NEW YORK (Reuters Health) - White patients with the most common form of kidney cancer, called renal cell carcinoma, are slightly more likely to survive the disease than black patients, according to a large new study.
The researchers looked at nearly 40,000 cases and found that black patients tend to start out with more favorable types of renal carcinomas, but "despite that, we still see poorer survival among African Americans," said Wong-Ho Chow, the lead author of the study and a professor at the University of Texas MD Anderson Cancer Center.
It's been known that blacks have higher rates of renal cancer than whites, and smaller studies have also pointed to racial disparities in how patients make out after their diagnosis. But experts have disagreed on the reasons.
About 64,000 people will be diagnosed with some type of kidney cancer this year in the U.S., according to the National Cancer Institute, making the disease the number 12 cause of cancer deaths for Americans.
Chow and her colleagues looked to a large national database to confirm whether African Americans fare worse with renal cell carcinoma and to look for any clues to why that might be the case.
The researchers collected information on 39,350 patients - 4,359 of whom were black and 34,991 white - diagnosed with renal cell carcinoma from 1992 to 2007.
They found that 72.6 percent of white patients survived at least five years out from their diagnosis, while 68 percent of blacks lived for at least five years.
Chow's group reports in the medical journal Cancer that 66.7 percent of black patients and 61.9 percent of whites were diagnosed with tumors that had not yet spread.
"It wasn't related to cancers being diagnosed at a later stage," said Dr. Charles Modlin, the director of the Minority Men's Health Center at the Cleveland Clinic's Glickman Urological Institute, who was not involved in the study. "African Americans were more likely to be diagnosed when tumors were smaller, more localized."
In addition, a greater proportion of black patients had a less dangerous type of renal cell carcinoma than white patients, "and still they didn't do as well," Modlin pointed out.
"I'm thinking maybe it has something to do with the type or quality of care that they receive," he told Reuters Health.
Survival rates were much lower, and equally so, among both black and white patients who did not have surgery to remove their tumors. But whereas 10.5 percent of white patients got no surgery, 14.5 percent of black patients did not have surgery, the study found.
It's also possible there could be underlying health conditions more common among blacks that predispose them to a worse outcome, researchers said.
"We know African Americans are more prone to hypertension, which, by the way, is a risk factor for renal cell cancer," said Chow.
But, she added, information on how many people had hypertension was not in this dataset.
"At this point we don't have the data to explain (the study findings) yet," Chow said.
Another unknown that could have influenced the outcomes, Chow told Reuters Health, is whether some patients might have made lifestyle changes, such as losing weight or quitting smoking, after their diagnosis, but she wasn't able to get that information either.
She added that until doctors have a better understanding of what's driving this disparity, there's not much advice to offer with regard to treating patients.
Modlin said it's important to at least be aware of these disparities.
"Because one thing we see is that healthcare providers are not really aware or don't take into consideration that these health care disparities are real and (are) significant problems," he said.
SOURCE: http://bit.ly/ZCl7Y4 Cancer, online November 12, 2012.