Diagnostic Yield and False-Referral Rate of Staging Chest CT in Patients with Colon Cancer

Abstract

Purpose To measure the diagnostic yield and false-referral rate (FRR) of staging contrast material-enhanced chest CT based on the clinical stage from contrast-enhanced abdominal CT in patients with colon cancer. Materials and Methods This retrospective study included 1743 patients (mean age, 63.4 years; range, 18-96 years) with a diagnosis of colon cancer. The primary outcomes were diagnostic yield and FRR of contrast-enhanced chest CT in the detection of thoracic metastasis. The proportions of patients with occult thoracic metastasis and those undergoing pulmonary metastasectomy for true-positive metastases were key secondary outcomes. The outcomes were stratified according to clinical stage at contrast-enhanced abdominal CT. Results The diagnostic yields in clinical stage 0/I, cII, cIII, and cIV were 0% (95% confidence interval [CI]: 0%, 0.8%), 1.3% (95% CI: 0.4%, 3.3%), 4.4% (95% CI: 3.0%, 6.1%), and 43.3% (95% CI: 36.8%, 49.9%), respectively. The corresponding FRRs were 5.7% (95% CI: 3.8%, 8.2%), 2.9% (95% CI: 1.3%, 5.5%), 6.7% (95% CI: 5.0%, 8.8%), and 6.1% (95% CI: 3.4%, 10.0%), respectively. The proportions of patients with occult metastasis were 0% (95% CI: 0%, 0.8%), 3.3% (95% CI: 1.6%, 5.9%), 1.5% (95% CI: 0.8%, 2.7%), and 6.1% (95% CI: 3.4%, 10.0%), respectively. The proportion of patients who underwent pulmonary metastasectomy was 0% (none of 474; 95% CI: 0%, 0.8%) for clinical stage 0/I tumors. Conclusion In clinical stages 0 and I, the diagnostic yield of staging contrast-enhanced chest CT in detecting thoracic metastasis was zero. For clinical stages II, III, and IV, contrast-enhanced chest CT as a baseline examination was helpful for the detection of thoracic metastasis and allowed for the possibility of a curative metastasectomy. There was no significant association between clinical stage and false-referral rate. © RSNA, 2018 Online supplemental material is available for this article.

Usefulness of staging chest-CT in patients with operable breast cancer

“…To determine the usefulness of staging chest-CT, diagnostic yield and false-referral rates were evaluated, which indicated true positive or false positive results. Diagnostic yield was calculated as the number of patients with true positive results for lung metastasis divided by the number of eligible patients who underwent staging chest-CT. False-referral rate was calculated as the number of patients with false positive results for lung metastasis divided by the number of eligible patients who underwent staging chest-CT [21,23]. Incidentally detected primary lung cancer was considered as an important ancillary finding and the data were recorded separately from lung metastasis.…”

“…Additionally, as we assessed important ancillary findings other than metastasis, we could estimate the diagnostic accuracy of clinically meaningful CT findings, in addition to pulmonary metastasis. Finally, we defined the reference standard based on the pre-existing criteria, which were carefully determined by a multidisciplinary team discussion from a previous study [21].…”

“…Sub-solid nodules rarely represent pulmonary metastasis; therefore, only solid nodules were assigned a score of 3 or 4 [19,20]. We considered the two lower scores (score 1 and 2) as a negative result and the two higher scores (score 3 and 4) as a positive result [21].…”

“…Pulmonary nodules were classified as true metastasis if the nodules were: 1) pathologically confirmed as metastasis, 2) increased in size on follow-up CT scan, 3) decreased in size after chemotherapy in accordance with primary tumor or metastatic lesions, and 4) showed hypermetabolism (the maximum standardized uptake value more than 2.5) on 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT with suspected of metastasis by nuclear medicine doctor, and were clinically considered metastasis [21]. Pulmonary lesions were classified as true negative for lung metastasis if the following criteria were satisfied: 1) nodules were pathologically confirmed as negative for metastasis, 2) nodules decreased in size without treatment, and 3) nodules remained stable for �12 months as determined by follow-up CT [21]. Patients who failed to meet any of the above criteria were considered indeterminate and excluded (n = 776).…”

Lung Nodules in Melanoma Patients: Morphologic Criteria to Differentiate Non-Metastatic and Metastatic Lesions

“…According to the methodology used by Lee et al [ 16 ], patients were considered as having pulmonary metastases if any baseline nodules were either pathologically confirmed as metastases, had increased in size at subsequent follow-up CT or had decreased after chemotherapy in accordance with RECIST evaluation. If nodules decreased in size while the RECIST classification of this patient was stable or progressive disease, nodules were categorized as benign nodules.…”