AJR May 2016
An interview with lead author Andreas Hötker, Department of
Diagnostic and Interventional Radiology, University Medical Center of
the Johannes Gutenberg University, Mainz, Germany. The study discussed
below was performed at Memorial Sloan Kettering Cancer Center, New York,
during Hötker's clinical research fellowship.
Clear Cell Renal Cell Carcinoma: Associations Between CT Features and Patient Survival
An interview with lead author Andreas Hötker, Department of Diagnostic and Interventional Radiology, University Medical Center of the Johannes Gutenberg University, Mainz, Germany. The study discussed below was performed at Memorial Sloan Kettering Cancer Center, New York, during Hötker's clinical research fellowship.
Your research article states that the incidental detection of renal cortical tumors has increased in recent years. Why is this?
Indeed, kidney cancer incidence rates have been rising in the United States for the past few decades and are now stabilizing at a high level. The rise in incidence is partly attributed to the increased use of abdominal imaging in patients who seek care for conditions unrelated to a kidney tumor (e.g., chronic back pain or abdominal pain) and the incidental discovery of small renal tumors on these patients’ images. In addition, several – unfortunately still very common – risk factors for the development of kidney cancer have been identified, including smoking, obesity, and hypertension, which have contributed to the increase in renal cancers.
The increasing discovery of small renal tumors has posed new medical challenges, particularly in frail and elderly patients. As of today, surgical resection remains the standard of care in all patients with newly discovered renal cortical tumors; however, avoidance of surgery would be particularly desirable in subgroups of patients with existing medical co-morbidities (e.g., chronic renal failure). The identification of imaging features that could help distinguish between more and less aggressive renal tumors would be of value for patient counseling and treatment planning in these subgroups.
Did the study result in identifying features that directly affect the prognosis of a patient and that might aid in risk assessment for the individual patient?
In the study, renal vein invasion and extensive tumor necrosis on CT imaging were associated with poorer survival. These associations remained statistically significant even after controlling for pathological tumor stage, which suggests it may be possible to further refine the pathological staging system by using pre-therapeutic imaging.
The differences in survival observed among patients with the same tumor subtype (clear cell renal cell carcinoma [RCC]) and comparable tumor stage indicate the presence of differences that are not yet appreciated in a routine workup, but may be based on genomic mutations. As some genetic mutations (e.g., KDM5C and BAP1) are already known to be associated with a higher rate of renal vein invasion on CT imaging, further investigations are needed to understand the implications of imaging findings for designing appropriate personalized treatments.
Did the study result in any unexpected information?
The authors were surprised to see that none of the purely cystic clear cell RCC in the study showed any sign of disease progression or caused a disease-specific death. This is probably because these tumors represented multilocular cystic RCC, a rare histopathological subtype that was defined by the World Health Organization in 2004 and seems to have an excellent prognosis and a distinct genomic makeup. While this finding could be of particular help in counseling frail and elderly patients who might not benefit from surgical resection of such tumors, it also provides incentive for more targeted radiological research in this area.