ASCO GU 2018: Incidence and mortality of Renal Cell Carcinoma in the U.S.: A SEER-based Study Investigating Trends Over the Last Four Decades

San Francisco, CA ( Renal cell carcinoma (RCC) is the third most common urologic malignancy worldwide – due to increasing cross-sectional imaging, there have been prior studies demonstrating increasing incidence of RCC, particularly localized RCC. While there are many histologic subtypes, the majority of RCC’s present with clear cell subtype.

While there have been numerous studies assessing the epidemiology of the RCC, the authors again use the SEER database examine RCC incidence and mortality trends by demographic and tumor characteristics. This is not novel, but perhaps provides an update on the status of RCC in the United States.

They queried the SEER database for RCC cases between 1973 and 2014. Incidence and mortality rates were calculated by sex, age, race, state, stage, size, and histological subtype of RCC. They then calculated annual percent change (APC) to provide information regarding the changing incidence.

As can be expected, over this 40 year experience, they identified a large number of patients - 96,058 RCC cases associated with 54,000 RCC deaths. The overall incidence was 9.712 per 100,000 persons-years, with the highest incidence being males (13.698), blacks (11.886), and people older than 65 years (38.693). Incidence rates of localized cases (5.845) and tumors smaller than 7 cm (6.550) were higher than other tumor subgroups; distant disease incidence was very uncommon, representing 1.773 per 100,000 persons-years. Note these are all at the time of diagnosis.

In terms of trends, overall incidence rates increased by 2.709% (95% CI, 2.544-2.875, p < .001) per year over the study period, but rates stabilized from 2007 onward. After 2007, there was only an increase in the incidence of clear-cell subtype (2.538%; 95% CI, 1.300-3.791, p < .001).

Overall RCC mortality rates have been declining since 2000; while this may be attributable to increasing diagnosis of small renal masses and localized disease, they also noted that mortality in patients diagnosed with distant disease has been decreasing since 2008, with the most profound decline in the period between 2012 and 2014 with APC of -22.635% (-37.419- -4.359, P = .019). This may correspond to the introduction of targeted therapy in 2006.

Again, this abstract does not provide any original data, but its always interesting to assess how the disease space is changing. Not much has changed in RCC management since the introduction of targeted therapy. However, perhaps novel therapies in the pipeline can make another dent in the mortality of this disease.

Limitations / Discussion Points:
1. No temporal follow-up – all staging was the time of diagnoses.
2. No information regarding treatment options and treatment changes
3. Uncertain if they accounted for the increasing number of registries added to SEER at multiple timepoints between 1973-2014 – may affect the at-risk population in earlier eras, thereby artificially decreasing the incidence in earlier eras if unaccounted for.

Speaker: Mohamed Gad

Co-Authors: Anas M Saad, Muneer J Al-Huseini, Inas A. Ruhban, Mohamad B. Sonbol

Institution(s): Ain Shams University, Cairo, Egypt; Damascus University, Damascus, Syrian Arab Republic; Mayo Clinic, Phoenix, AZ

Written by: Thenappan Chandrasekar, MD, Clinical Fellow, University of Toronto, Twitter: @tchandra_uromd at the 2018 American Society of Clinical Oncology Genitourinary (ASCO GU) Cancers Symposium, February 8-10, 2018 - San Francisco, CA

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