Tumor Enhancement on Dynamic CT: A Predictive Factor for Recurrence After Nephrectomy in Localized T1 Clear Cell Renal Cell Carcinoma

Aim: To investigate whether radiological parameters obtained on dynamic computed tomography (CT), especially those related to tumor enhancement, are predictive factors for recurrence after nephrectomy in localized stage T1 clear cell renal cell carcinoma (ccRCC). Materials and Methods: We retrospectively studied 88 patients with localized stage T1 ccRCC who underwent dynamic CT preoperatively. Seven patients had recurrent disease after surgery. Tumor attenuations were measured by placing a region of interest in the solid region. TA_pre and TA_neph were defined as the tumor attenuation values of the pre-contrast and nephrographic phase, respectively. The correlations between disease-free survival and clinicopathological factors, including the radiological parameter TA_neph – TA_pre (TA_neph), were analyzed by Cox proportional hazards model or Kaplan–Meier method with the log-rank test. Results: Only TA_neph was significantly and positively correlated with disease-free survival (p<0.05). Tumor size also tended to be negatively correlated with disease-free survival (p<0.1). The 5- and 10-year disease-free survival rates of the group with high TA_neph (≥86 HU) were 97.4% and 97.4%, while those of the group with low TA_neph (<86 HU) were 89.6% and 71.6%, respectively. Conclusion: Tumor enhancement in the nephrographic phase of CT was a predictive factor for recurrence after nephrectomy in patients with localized stage T1 ccRCC.

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