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The introduction of antiangiogenic agents is likely one key factor that led to the mortality decrease, said authors of the analysis of Surveillance, Epidemiology, and End Results data from 1992 to 2015.
Incidence trends are likely more complex and may reflect the interplay between increased detection, on one hand, and decreases in modifiable risk factors such as smoking on the other, the authors reported in Clinical Genitourinary Cancer.
The analysis, conducted by Anas M. Saad, a final-year medical student at Ain Shams University, Cairo; Thai H. Ho, MD, PhD, of Mayo Clinic Cancer Center, Phoenix; and coinvestigators, included a total of 104,584 patients with an RCC diagnosis, of whom nearly 64% were male and 80% were white. The majority of tumors were small and localized at diagnosis, and clear cell was the histologic subtype in 44%, according to the report.
Overall incidence of RCC was 11.3 per 100,000 person-years over the 1992-2015 study period, Dr. Saad and coauthors said in their report.
The incidence rate increased by about 2.4% per year, averaged over the course of the entire study period, though the plateau in rates began around 2008, according to the investigators. A figure in their report shows that the age-adjusted rate was just over 8 per 100,000 person-years in 1992; it climbed steadily until 2008, at which point it remained in the range of about 12-14 per 100,000 person-years for the next 7 years.
The uptick in incidence from 1992 to 2008 was concentrated mostly in localized and regional RCC, rather than distant disease, according to Dr. Saad and colleagues.
The overall incidence-based mortality rate for RCC was 5.3 per 100,000 person-years from 1992 to 2015, Dr. Saad and coauthors said.
Mortality rates increased from 1992 and peaked in 2001, at which point they started to drop at an ever accelerating pace. The annual percent decrease in that mortality rate was 1.5% between 2001 and 2008, 9.3% between 2008 and 2013, and 32.2% from 2013 to 2015, according to the report.
Incidence rate trends are probably affected by increases in incidental diagnoses and changes in RCC risk factor prevalence, investigators noted. For example, there has been a significant increase in use of advanced abdominal imaging, which has improved sensitivity in picking up renal masses, but cannot reliably distinguish between benign and malignant features, they said. On the other hand, smoking, which increases risk of RCC, has been trending downward for decades, which they said correlated with RCC trends.
Authors said RCC survival has been improved by antiangiogenic agents known as vascular endothelial growth factor inhibitors, and more recently immune checkpoint therapies, as clinical trials have shown.
“The decreasing mortality trend starting in 2007 and continuing until 2015 is associated with the introduction of such therapies for RCC treatment,” Dr. Saad and coauthors said in their report.
Support for the study came from the National Cancer Institute and the Department of Defense. Dr. Saad and coauthors declared that they had no conflicts of interest.
SOURCE: Saad AM et al. Clin Genitourin Cancer. 2018. doi: 10.1016/j.clgc.2018.10.002.