Single CT Appointment for Double Lung and Colorectal Cancer Screening: Is the Time Ripe?

Abstract

Annual screening of lung cancer (LC) with chest low-dose computed tomography (CT) and screening of colorectal cancer (CRC) with CT colonography every 5 years are recommended by the United States Prevention Service Task Force. We review epidemiological and pathological data on LC and CRC, and the features of screening chest low-dose CT and CT colonography comprising execution, reading, radiation exposure and harm, and the cost effectiveness of the two CT screening interventions. The possibility of combining chest low-dose CT and CT colonography examinations for double LC and CRC screening in a single CT appointment is then addressed. We demonstrate how this approach appears feasible and is already reasonable as an opportunistic screening intervention in 50-75-year-old subjects with smoking history and average CRC risk. In addition to the crucial role Computer Assisted Diagnosis systems play in decreasing the test reading times and the need to educate radiologists in screening chest LDCT and CT colonography, in view of a single CT appointment for double screening, the following uncertainties need to be solved: (1) the schedule of the screening CT; (2) the effectiveness of iterative reconstruction and deep learning algorithms affording an ultra-low-dose CT acquisition technique and (3) management of incidental findings. Resolving these issues will imply new cost-effectiveness analyses for LC screening with chest low dose CT and for CRC screening with CT colonography and, especially, for the double LC and CRC screening with a single-appointment CT.

Keywords: CT colonography; chest CT; colorectal cancer; computed tomography; lung cancer; screening.

Figure 1

(A–D) Nodular presentations of early stage lung cancer and precancerous lesions in baseline chest low-dose CT screening in four subjects. Lung cancers (arrows) appearing as solid [(A) stage I adenocarcinoma; (B) stage I squamous cell carcinoma] or part-solid (C) stage I adenocarcinoma) nodules. Atypical adenomatous hyperplasia (arrow) appearing as a pure ground glass nodular opacity (D).

Figure 2

(A–F) Non-nodular presentations of lung cancer and precancerous lesions in chest low-dose CT screening in three subjects. Lung cancer associated with cystic airspace (arrow) at baseline LDCT (A) and two years later (B); lung cancer presenting as perifissural abnormality (arrow) at baseline LDCT (C) and appearing as solid nodule 2 years later (D); lung cancer presenting as scar-like abnormality (arrow) at baseline LDCT (E) and appearing as a solid nodule 1 year later (F). All images reproduced modified from Mascalchi et al. [74].

Figure 3

(A–G) Colon cancer and polyp presentation in CT colonography in three subjects. Stenosing colon cancer in 2D (A) and 3D (virtual endoscopy) (B) images in subject 1. Vegetating colon cancer (arrow) in 2D (C) and 3D (virtual endoscopy) (D) images in subject 2. Colon polyp (arrow) in source 2D images obtained in supine (E) and prone (F) position and in a 3D (virtual endoscopy) (G) image in subject 3.