Renal cancer at unenhanced CT: imaging features, detection rates, and outcomes
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To describe and quantify the rate of detection of renal cancer on unenhanced CT.
This retrospective, HIPAA-compliant study was approved by the Institutional Review Board. Electronic health records for all patients who underwent unenhanced abdominal CT at our institution between 2000 and 2005 were reviewed to identify patients subsequently diagnosed with renal cancer during a follow-up period of up to 12 years. Images were reviewed to determine if the cancer was visible at index (first) unenhanced CT and their findings recorded. Original radiology reports were reviewed to determine whether the renal cancer was reported; Fisher’s Exact Test compared imaging features of detected and missed cancers. Clinical outcomes including time until diagnosis and stage at diagnosis were used to assess the potential impact of missed cancers.
Of 15,695 patients, 82 (0.52%) were diagnosed with renal cancer. Of these, 43/82 (52%) cancers were retrospectively detectable on index unenhanced CT. Among retrospectively detectable cancers, 63% (27/43) were originally detected and reported on index CT and 37% (16/43) were missed. Size was the only feature associated with detection; 83% (20/24) of cancers > 3.0 cm were detected versus 37% (7/19) of cancers ≤ 3.0 cm (p = 0.0036). Although none of the 16 missed renal cancers developed metastases between index CT and time of diagnosis (median 33.5 months), 4 (25%) progressed in stage.
Renal cancer was rare in patients undergoing unenhanced abdominal CT. Over one-third of potentially detectable cancers were missed prospectively. However, missed cancers did not metastasize and infrequently progressed in stage before being diagnosed.
KeywordsRenal mass Renal cell carcinoma Renal cancer Unenhanced CT CT
Compliance with ethical standards
Drs. Silverman and Khorasani have no Grants or other assistance to disclose; Dr. O’Connor received support from the Boston Area Research Training Program in Biomedical Informatics (National Library of Medicine Grant T15LM007092).
Conflict of interest
Dr. O’Connor declares that she has no conflict of interest. Dr. Silverman declares that he has no conflict of interest. Dr. Cochon declares that she has no conflict of interest. Dr. Khorasani declares that he has no conflict of interest.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
The requirement to obtain informed consent was waived by the study site’s Institutional Review Board.
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