Study: Imaging is helping identify kidney cancer, even small tumors, earlier
More cancers detected due to widespread medical imaging. Source:  
Smaller tumors in U.S. patients are now much more likely to be diagnosed in the earliest, most treatable stage of kidney cancer compared to a decade ago, leading to a slightly higher survival rate, according to the results of a national study published online for the May 2008 edition of Cancer.

Christopher J. Kane, MD, chief of urology at University of California San Diego (UCSD) Medical Center and the Moores UCSD Cancer Center, and colleagues analyzed the records of more than 200,000 kidney cancer patients from the National Cancer Database to look investigate how kidney cancer presentation has changed over a 12-year period.

The American College of Surgeons and the Joint Commission on Cancer sponsors the National Cancer Database, which includes information from hospital tumor registries in the United States.

“The changes in kidney cancer presentation are visible nationally and quite dramatic. If you are diagnosed with kidney cancer today, it is more likely to be at the earliest ‘stage I’ level as opposed to more advanced ‘stage II, III or IV’ just a decade ago,” said Kane, who specializes in treating kidney and prostate cancers. “The study also reveals a small but significantly higher survival rate for recently diagnosed kidney cancers. This is good news for the more than 50,000 kidney cancer patients who will be identified this year.”

The researchers examined kidney cancer data from 1993 through 2004. The findings reveal that stage I kidney cancers increased from approximately 43 percent in 1993 to 57 percent in 2004, but decreased in stages II-IV of the disease, the authors wrote.

The researchers reported that the average size of the stage I tumors decreased from 4.1 cm in 1993 to 3.6 cm in 2003. Overall, survival for all patients with kidney cancer increased 3.3 percent between 1993 and 2003, according to Kane and colleagues.

They reported that the five-year survival rate for people with stage I kidney cancer is now 88 percent or better.

While the reason for the downward trend is not known with certainty, the low stage presentation of tumors appears to be due to the more widespread use of medical imaging such as ultrasound, CT scans and MRIs to evaluate other medical conditions, according to the researchers.

The authors wrote that cancerous growths, which often have not yet caused symptoms, are found unexpectedly as a result of the imaging tests. The “incidentally detected” masses are more likely to be benign, smaller, and, when confirmed to be kidney cancer, to have better rates of survival, according to investigators.

“What we are seeing is that gynecologic or abdominal imaging to evaluate pain or other complaints is picking up other forms of disease such as kidney cancer,” said Kane. “The increased and widespread use of medical imaging in the United States is helping to diagnose cancer in its non-symptomatic stages when it is easier to treat successfully.”

“The message to patients is not to go out and request an ultrasound or CT scan,” said Kane. “Keep in mind that this is a rare form of cancer. However, if abdominal imaging is done and a mass or masses in the kidney are recognized, evaluation by an urologist is recommended.”

Deaths due to kidney cancer account for about 3 percent of all cancer deaths in the United States with approximately 12,890 deaths in 2007.