Indeterminate pulmonary nodules among patients with new diagnosis of colorectal cancer: Prevalence and significance assessment

Background: In Saudi Arabia, colorectal cancer (CRC) accounts for 11.5% of cancer incidence, where nearly one-third is metastatic. Global guidelines recommend accurate pretreatment staging to determine resectability and stage-directed treatment. Computed tomography (CT) scan is among the widely used imaging for staging. However, at times, the characterization of abnormalities detected by CT scan is perplexing. Indeterminate pulmonary nodules (IPNs) are nodules that are neither benign nor malignant, which are incidentally detected on baseline staging chest CT. We aimed to estimate the prevalence of IPN that were identified among CRC patients. Materials and Methods: We conducted a retrospective record review of all newly diagnosed CRC patients between June 2013 and June 2018 from an academic hospital in Jeddah, Kingdom of Saudi Arabia (KSA). Demographics and certain prespecified variables were collected. The presence of IPN on staging chest CT as per consultant radiologist report was documented, and the ability of other modalities to identify the nature of IPN was compared. Data were analyzed using SPSS and a P value < 0.05 was considered significant. Results: Of 283 CRC patients, 208 (73.5%) underwent chest CT, and the mean age was 57.4 years (±SD 13.1). The prevalence of IPN among CRC patients is 17.7%. Thirty IPN patients had a follow-up chest CT for IPN, which identified IPN nature in 18(60%) of them. The likelihood of IPN to be CRC-related metastasis was significantly associated with the presence of synchronous liver metastasis (P = 0.0005), younger age (P = 0.022), and colon cancer (P = 0.011). Conclusion: The prevalence of IPN was 17.7%, which is different in comparison to other studies from different countries. There is a vital need for unified guidelines describing IPN to accurately stage CRC patients, decrease unnecessary follow-ups, and acquire the exact prevalence of IPN.