Lung cancer risk following detection of pulmonary scarring by chest radiography

Pulmonary scars as a result of pulmonary fibrosis are frequently found near to the lung cancer at the time of diagnosis. However, the nature of the relationship between pulmonary scarring and lung cancer remains uncertain.

Researchers at the National Cancer Institute, National Institute of Health, Rockville, Maryland, USA, lead by Dr Ying-Ying Yu, aimed to test whether localised pulmonary scarring was associated with increased lung cancer risk.

Analysis of data from the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial included 66,863 cancer-free trial participants aged 55 to 74 years, who received a baseline chest radiographic examination and were followed up subsequently for up to 12 years.

Proportional hazard models were used to estimate likelihood of lung cancer associated with scarring, adjusting for age, sex, race, and cigarette smoking, and in relation to laterality of scarring. The main outcome measure was incident of lung cancer.Scarring was present on the baseline chest radiograph for 5041 subjects (7.5%). Scarring was associated with elevated lung cancer risk (809 lung cancer cases).  This association was specific for cancer in the lung on the same side as the scar and absent for cancer in the opposite lung.

The relationship between pulmonary scarring and lung cancer was specific to the same lung and extended over time. The findings are consistent with the idea that localised inflammatory processes associated with scarring promote the subsequent development of lung cancer.

The researchers commented: “Our findings provide support for a model whereby pulmonary scarring and localised inflammation promote subsequent development of lung cancer. Lung scarring can result from a variety of infections, environmental exposures, and pulmonary diseases. Further research is needed to elucidate the biological mechanisms underlying the associations between pulmonary scarring, inflammation, and lung cancer. Additional research is also necessary to determine whether persons with pulmonary scarring would benefit from clinical monitoring for the development of lung cancer.”

Article: "Lung Cancer Risk Following Detection of Pulmonary Scarring by Chest  Radiography in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial"
Arch Intern Med. 2008;168(21):2326-2332