The rate of lung cancer identified on follow-up chest CT recommended for incidental pulmonary findings on neck CT is low, according to a study published December 10 in the Journal of the American College of Radiology.
The results could indicate that follow-up chest CT may not be necessary in this situation -- although further research is warranted, wrote a team led by Masoud Hassanzadeh, DDS, of Brigham and Women's Hospital and Harvard Medical School in Boston, MA.
"[Our] results suggest that the frequency of recommendations for chest CT should likely be substantially decreased, but analysis of larger data sets is needed to inform best practices," the group noted.
While prior research has assessed the prevalence of incidental pulmonary findings on neck imaging examinations, none have evaluated lung cancer detection rates for these findings on neck CT or MRI exams, according to the team. To this end, the group investigated the two-year incidence rate of lung cancer diagnoses made as the result of radiologist recommendations for additional thoracic imaging to further characterize incidental lung abnormalities identified on neck CT and MR imaging. It also assessed the rate of fulfillment of the report recommendation for further imaging, with special focus on whether this fulfillment varied between lung nodules and other lung abnormalities.
The study included data from 273 patients without a prior history of lung cancer who received recommendations in neck, brachial plexus, and parathyroid CT and MRI reports for follow-up chest CT between June 2021 and May 2022. Median follow-up time was 34 months, and the chest CT exam recommended in the neck imaging reports was accomplished in 62.6% of patients. The follow-up scans were less likely to be performed for pulmonary nodules than for other pulmonary abnormalities, with an odds ratio of 0.46.
Although six out of the 273 patients were initially identified as having a primary lung cancer -- and all underwent chest CT -- only one of these cases was actually cancer, an indolent adenocarcinoma. This result translated to a two-year incidence rate of 0.4%, Hassanzadeh and colleagues wrote.
The incidental lung cancer rate in the study is lower than other studies of incidental pulmonary nodules detected at chest CT, which range between 4% and 5%, the group noted. But "nodule malignancy risk is highly dependent upon nodule size and density and the substantially lower malignancy rate in this study may be partly due to inclusion of other pulmonary abnormalities that are unlikely to be malignant (e.g., airspace disease)," the team explained.
In any case, the research findings should prompt discussion about appropriate imaging, according to the authors.
"Ensuring radiologist recommendations for additional imaging are evidence-based, judicious, and performed, remain critical factors in ensuring appropriate follow-up and early detection of lung cancer," they wrote. "These factors likely will require local implementations of tracking systems, enhanced communication methods, artificial intelligence-based tools, and broad public health strategies."
Access the full study here.
