When evaluating treatment response in non-nephrectomized patients with metastatic renal cell carcinoma (mRCC), the primary lesion does not have to be selected as the target lesion, researchers report.
Indeed, they found that selecting metastasis-only lesions as target lesions may be better for determining response to sunitinib and more representative of survival outcome.
"We confirmed that primary lesions do exhibit a response to sunitinib through size change and correlate with the size change of metastatic lesions," note Jae-Lyun Lee (University of Ulsan College of Medicine, Seoul, Korea) and colleagues.
"However, the degree of size change was generally smaller than the metastatic lesion and the response of the primary lesion in some patients moved in the opposite direction compared with the metastatic lesion."
The researchers used Response Evaluation Criteria in Solid Tumors to assess overall response changes in 41 patients, aged an average 59 years, with mRCC who were treated with sunitinib. All the patients had an intact primary tumor and at least one extrarenal measureable lesion. Lung was the most common site of metastasis (63%).
The average reduction in the sum of diameters as a result of treatment was smaller in the primary target lesion, at 6%, compared with 18% in the target metastatic lesion.
Over a median follow up of 29 months, 30 patients died. The median overall survival was 12.7 months and the time to progression was 6.8 months.
When patients were categorized into responders (complete or partial response) and nonresponders (stable or progressive disease) based on evaluation of primary and metastatic lesions, there was a nonsignificant difference in the time to progression (14.9 and 5.4 months, respectively) and overall survival (18.0 and 10.6 months, respectively).
When only metastatic target lesions were used, however, responders versus nonresponders had a significantly longer time to progression (14.9 vs 4.3 months) and lived longer (18.5 vs 9.6 months).
In the recent era of targeted molecular therapy, routine cytoreductive nephrectomy has declined and studies have suggested that it might not yield a survival benefit in poor-risk groups, the researchers note.
"Therefore, the response survival of mRCC patients without nephrectomy would be considered as a pressing problem to solve for better patient management," they say.
"We suggest that when treating nonnephrectomized mRCC patients, it would be better to evaluate the patient response using metastasis-only target lesions."
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