Pulmonary staging in colorectal cancer: a review

Aim Assessment of the chest in colorectal cancer (CRC) staging is variable. The aim of this review was to look at different chest staging strategies and determine which has the greatest efficacy. Method A review of studies assessing chest staging modalities for patients with CRC was performed. Modalities included chest X-ray (CXR), CT and positron emission tomography (PET). Results The majority of data consisted of case series. Two studies identified a low pick-up rate for CXR as a staging tool. Five studies showed increased detection rates of pulmonary metastases for chest CT vs CXR and abdominal CT. The clinical benefit of the increased detection rates was not clear. The incidence of indeterminate lung lesions (ILL) on staging chest CT varied from 4 to 42%. The majority (= 70%) of ILLs did not have any clinical significance. On CT scans, the incidence of pulmonary metastases in patients with rectal cancer ranged from 10 to 18% and in patients with colon cancer the incidence of pulmonary metastases ranged from 56%. The incidence of synchronous liver and pulmonary metastases compared with the overall incidence of pulmonary metastases ranged from 45 to 70%. There was no evidence reporting the superiority of PET/CT vs CT for the detection of pulmonary metastases or characterization of ILL. Conclusion Studies show that chest CT scanning increases the detection rates for ILL and pulmonary metastases. The clinical benefit of the increased detection rates is not clear. There is a paucity of data assessing the optimal chest staging strategy for patients presenting with CRC.