Objective: To evaluate the percentage of negative chest radiograph in patients with symptomatic lung cancer.

Materials and Methods: The authors retrospectively reviewed the chest radiographs of 263 patients with symptomatic lung cancer. The findings were divided into two categories and three subgroups, negative findings as normal, no abnormality detected or abnormal, or no cancer suspected, and positive findings as abnormal or cancer suspected. The recorded data included the tumor size, location, features of all lesions, the duration of symptom, and time intervals between the first chest radiograph until diagnosis. Computed tomography (CT) scan of the negative finding chest radiographs were reviewed to verify whether the causes of unsuspected malignancy were on a radiograph.

Results: Negative chest radiographs in the present study were 12.9%. Three patients (1.1%) were classified as entirely normal. Most findings in the abnormal, no cancer suspected group were patchy infiltration (8.4%), interstitial infiltration (1.9%), and thin wall lung cavity (1.1%). The major causes of negative findings were tumor location, size, conspicuity, obscured primary tumor, pulmonary tuberculosis mimicking lung cancer, and characteristic of lung cavity on the radiograph.

Conclusion: Negative chest radiographs can be found even in patients with symptomatic lung cancer, resulting in delayed diagnosis and treatment. Using chest radiograph as a first-line imaging investigation, especially in high-risk lung cancer patients, should be cognizant of false negatives.

Keywords: Lung cancer; Chest radiograph

DOI: 10.35755/jmedassocthai.2022.12.13716

Received 8 August 2022 | Revised 12 October 2022 | Accepted 28 October 2022