Evaluating the lung area that is normal, or healthy, can help predict the survival of patients with combined pulmonary fibrosis and emphysema (CPFE) at the time of lung cancer diagnosis, according to a new study.
The research, “Reduced area of the normal lung on high-resolution computed tomography predicts poor survival in patients with lung cancer and combined pulmonary fibrosis and emphysema,” was published in the journal Respiratory Investigation.
CPFE is a clinical syndrome characterized by emphysema and pulmonary fibrosis. People with CPFE typically have impaired diffusing capacity of the lung for carbon monoxide (%DLCO) — a test of the lungs’ capacity to transfer oxygen from the air sacs into the blood — but preserved forced expiratory volume in the first second (FEV1) and forced vital capacity (FVC), two measures of lung function.
The modified gender, age, and physiology (mGAP) score is an index of severity in patients with lung cancer and interstitial pneumonia. However, whether this score is useful in cases of CPFE and lung cancer remains unknown.
A normal lung score (the proportion of normal/healthy lung in the whole lung) as assessed with high-resolution computed tomography (HRCT) has been reported to have predictive value in patients with pulmonary hypertension and idiopathic interstitial pneumonia, as well as in those with advanced non-small cell lung cancer and interstitial lung disease.
As such, rather than the extent of emphysema or fibrosis alone, the extent of the normal lung area may mirror CPFE prognosis, researchers in Japan hypothesized.
To test the hypothesis, the team investigated predictors of poor survival through HRCT, and tried to characterize the clinical features in patients with CPFE and lung cancer. CPFE was defined as chronic interstitial pneumonia with an emphysematous change of at least 10% on HRCT.
Researchers reviewed medical charts and HRCT data of 81 patients with CPFE and 92 patients with primary lung cancers (mean age 70.9 years). The medical data included performance status, pulmonary function testing, clinical and radiological diagnoses of interstitial pneumonia, treatment information, outcome, and lung cancer type.
Eight HRCT images were selected per patient to analyze tumor location, association with fibrosis (or scarring), and/or emphysema, and interstitial pneumonia pattern. The team also determined the normal lung, modified Goddard (for emphysema) and fibrosis scores of each patient.
The analyses revealed that the patients were heavy smokers, and that the most common diagnosis of PF was IPF (44 patients). Forty patients had squamous cell carcinoma, while 31 had adenocarcinoma, and most tumors developed in the lungs’ peripheral areas.
As expected, pulmonary function was preserved, but %DLCO was moderately impaired.
The primary cause of death was lung cancer, and the median survival time in the whole set of patients was 17.7 months.
Researchers found correlations between normal lung score and the modified Goddard score for emphysema; performance status and malignant tumor stage; and %FVC and both %FEV1 and %DLCO.
Importantly, a higher normal lung score — meaning greater reduction in normal lung area — on HRCT was found to be a significant predictor for poor survival at lung cancer diagnosis. Advanced malignant tumor stage was also a significant predictor of poor survival in CPFE patients and in those with normal lungs.
Overall, the team concluded that “the normal lung score is a helpful, independent radiologic predictor of poor survival in CPFE and lung cancer” patients.
In addition, the malignant tumor stage system “functioned as a predictor of poor survival of patients with CPFE, as well in patients with lung cancer as with normal lungs,” they stated.