Kidney cancer rates appear to be declining

New data published in Kidney Cancer by the University of California, Davis Institute for Population Health Improvement (IPHI) shows the trend of increased incidence of small kidney tumors, renal cell carcinoma (RCC), and early-stage disease in California may be coming to an end. The increase in incidence observed in that state from 1988 through 2009 has declined and/or stabilized in recent years.

This is the first report to demonstrate that the rising rate of kidney cancer in the US during the past 20 years may be coming to a close. The study also updates kidney cancer incidence and mortality trends, and documents the significant increase in partial nephrectomy in early-stage disease to preserve long-term kidney function.  

"The increased incidence of small, localized tumors without a corresponding increase in kidney cancer deaths suggests that the incidence trends, until around 2009, were mostly driven by incidental findings associated with the increased use in advanced diagnostic imaging," said Cyllene Morris, DVM, PhD, lead author of the study and Chief Epidemiologist in IPHI's California Cancer Reporting and Epidemiologic Surveillance (CalCARES) Program.

The authors reported that the use of ultrasound doubled, CT scans tripled, MRIs quadrupled, and PET scans increased tenfold after 2004. The use of CT scans grew at an annual rate of 14.3% from 2000 through 2005, followed by an annual increase of 7.1% in 2006 and 1.4% in 2009.

"The greatest challenge in managing patients with small kidney tumors is distinguishing between aggressive tumors which require surgical treatment and less aggressive tumors that may be appropriately managed with active surveillance," said Kenneth W. Kizer, MD, MPH, Distinguished Professor of Emergency Medicine and IPHI's Director. "It's an important distinction because not all small renal tumors are indolent, and metastatic disease can be present at the time of diagnosis."

Using the California Cancer Registry, researchers evaluated the records of more than 77,000 confirmed cases of kidney cancer in California from 1988 through 2013. The registry is a population-based cancer surveillance system that has collected data on tumor characteristics, diagnosis, treatment, follow-up, and demographic information since 1988. The data were collected through a network of regional registries that are also affiliated with the National Cancer Institute’s SEER program.

Results showed incidence of RCC increased by about 1.5% annually from 1988 through 2000, and then rose by about 4.8% annually until 2008. After that, rates stabilized.

During the study period, 91% of patients with localized RCC had surgery. The proportion of patients undergoing partial nephrectomy increased from 6.3% in 1988 to 56% in 2013. When tumors larger than 4 cm were excluded, partial nephrectomies increased from 13.8% in 1988 to 74.6% in 2013.

Kidney cancer is the eighth most commonly diagnosed cancer in California. In 2013, there were more than 5,600 new cases diagnosed, and 1,350 deaths. The majority of these cancers are RCCs, which are twice as likely to be diagnosed among males.

To read more about the study, click here.