A critical review of the chest CT scans performed to detect asymptomatic synchronous metastasis in new and recurrent breast cancers

Abstract

Background: Chest computed tomography (CTC) has now replaced chest X-ray (CXR) as the first choice of investigation to stage breast cancers in most centers in Australia. Routine staging is not recommended in early breast cancers (EBCs). This recommendation is based largely on the use of conventional tests like CXR as staging investigations (SIs). We looked at our experience with CTC in detecting asymptomatic synchronous distant metastasis (ASM) in new and recurrent breast cancers (RBCs).

Materials and methods: Breast cancer patients from Eastern Health Breast Unit during the period from January 2012 to March 2016 were included in the study. Cases were grouped into early, advanced, and recurrent breast cancers, and outcome of CTC was assessed in each group. Relative risk of potential risk factors (tumor size, axillary nodal status, presence of lymphovascular invasion and estrogen, and HER2 receptor status) with a positive result in CTC was determined.

Results: Fourteen ASMs were detected from 335 CTCs giving an overall yield of 4% (95% CI 1.89-6.47). The overall false-positive rate was 10% due to 35 indeterminate findings that were found not to be metastases after further tests or observation. Even with selective use, CTCs have a low yield of 2% (95% CI - 0.19-4.19) in EBCs. Advanced breast cancers have a 9% incidence of ASMs. None of the clinically isolated locoregionally recurrent diseases were associated with detectable distant metastasis in CTC. The most common cause of indeterminate findings was small pulmonary nodules.

Conclusion: Even with selective use, CTC has a very low yield in EBCs. Advanced breast cancers can benefit from CTC in their initial evaluation due to the higher yield. Locoregional RBCs were not usually associated with detectable metastasis on CTC. The usefulness of CTC in all stages of breast cancer is further reduced by its high rate of false-positive results.

Fig. 1

Flowchart of the study population. From 726 breast cancer cases treated during the study period, 335 had available staging CTC data. Fourteen (4%) new metastases and one incidental lung cancer were identified through these scans. Eighty-five percent of all scans only showed benign or normal findings, while 10% had indeterminate findings that were identified as false positive after further tests or observation

Fig. 2

Typical indeterminate pulmonary lesion. The high sensitivity of CTC leads to the identification of very small lesions that would not be obvious on normal chest X-ray. These indeterminate results require further tests or observation to characterize the true nature of these lesions. This results in a high false-positive rate for staging CTC (10%)

Fig. 3

Incidentally found duplication cyst of the esophagus. Incidental lesions can be a cause of false-positive results as in this case. This posterior mediastinal lesion needed required positron emission tomography to characterize its true nature. These types of findings on staging CTC lead to further expensive tests and can be a cause of significant anxiety for patients