Introduction:

Lung cancer screening trials have demonstrated that patients screened with chest computed tomography (CT) scans had more tumors identified and a reduced the risk of lung cancer death compared to patients screened with chest x-ray (CXR). Current AUA guidelines recommend surveillance CXR over chest CT for low and intermediate risk renal cell cancer (RCC) patients. The purpose in this study was to evaluate the diagnostic ability of CXR versus chest CT scans to detect RCC thoracic metastases among AUA risk groups following surgery.

Methods:

A prospectively maintained database of 1446 patients who underwent surgery for RCC from 2000 to 2021 was analyzed. Patients were classified from primary RCC lesion following surgery using AUA risk stratification. A fellowship-trained thoracic radiologist who was blinded to the outcomes independently reviewed imaging from 114 patients who had both CXR and chest CT at the time of diagnosis of metastatic RCC.

Results:

Of the 1446 patients, 240 (17%) developed thoracic metastases (Figure). Thoracic metastases were identified in 4% (33/810), 15% (22/145), 30% (96/323) and 53% (89/198) for low-, intermediate-, high- and very high-risk patients (p<0.001). Among low-risk patients, 0.6% (5/810) presented with thoracic metastases and 3.5% (28/810) developed thoracic metastases at a median of 41 months (IQR 19-83). Among intermediate-risk patients, 7.6% (11/145) presented with thoracic metastases and 7.6% (11/145) developed thoracic metastases at a median of 37 months (IQR 17-73).

114 patients (48%) with RCC thoracic metastases had both CXR and CT at the time of their metastatic diagnosis. After blinded independent review of CXR by a thoracic radiologist, known thoracic metastasis were not identified on CXR in 58/114 (51%) patients. No differences were noted in CXR vs CT diagnostic performance was between AUA risk groups, p=0.1 (Table).

Conclusion:

CXR fails to identify known RCC thoracic metastases in more than half of patients. With widespread availability of CT imaging and the risk for thoracic metastasis among all RCC risk groups, future guidelines should consider recommending CT instead of CXR to evaluate for thoracic metastasis.

Funding: N/A