Optimizing the size variation threshold for the CT evaluation of response in metastatic renal cell carcinoma treated with sunitinib.
BACKGROUND
In metastatic renal cell carcinoma (mRCC), antiangiogenic treatments rarely achieve a reduction of -30% in the sum of longest diameters (SLD) of target lesions required by RECIST for an 'objective response', although they objectively improve progression-free survival (PFS). We sought to determine a threshold for the computed tomography evaluation of these patients' best reflecting patient outcome.


METHODS
In 334 mRCC patients treated with sunitinib, we tested thresholds from -45% to +10%. We classified patients as 'responders' when the best relative variation of the sum of longest diameters (DeltaSLD) reached the tested threshold and as 'nonresponders' otherwise. For each tested threshold, the median PFS of the two groups were compared. Receiver operating characteristic (ROC) analysis was also carried out among the 103 patients that progressed during follow-up. Finally, the 'optimal' threshold was retested on an independent cohort of 39 patients.


RESULTS
The DeltaSLD threshold of -10% gave the most significant difference. It divided patients into 256 responders and 78 nonresponders (median PFS 11.1 and 5.6 months). The same -10% threshold was found using the ROC analysis. Results were confirmed on the external validation cohort.


CONCLUSIONS
A variation of -10% in the SLD accurately and rapidly identifies mRCC patients benefiting from sunitinib.
Thiam
R
R
Department of Radiology, Georges Pompidou European Hospital, Assistance Publique Hôpitaux de Paris, Paris Descartes University, Paris, France.
Fournier
L S
LS
Trinquart
L
L
Medioni
J
J
Chatellier
G
G
Balvay
D
D
Escudier
B
B
Dromain
C
C
Cuenod
C A
CA
Oudard
S
S
D020533:Angiogenesis Inhibitors / Q000627:therapeutic use*; D002292:Carcinoma, Renal Cell / Q000000981:diagnostic imaging* / Q000188:drug therapy*; D017322:Clinical Trials, Phase II as Topic; D017326:Clinical Trials, Phase III as Topic; D015331:Cohort Studies; D005500:Follow-Up Studies; D006801:Humans; D007211:Indoles / Q000627:therapeutic use*; D007680:Kidney Neoplasms / Q000000981:diagnostic imaging* / Q000188:drug therapy*; D008875:Middle Aged; D015337:Multicenter Studies as Topic; D009362:Neoplasm Metastasis; D011758:Pyrroles / Q000627:therapeutic use*; D012372:ROC Curve; D016032:Randomized Controlled Trials as Topic; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D000077210:Sunitinib; D015996:Survival Rate; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
D020533:Angiogenesis Inhibitors; D007211:Indoles; D011758:Pyrroles; D000077210:Sunitinib