Pulmonary scar carcinoma in South Africa.

Background: The association between lung scarring and the subsequent development of cancer remains controversial. South Africa has one of the highest incidences of tuberculosis in the world, and resultant scarring may predispose to malignancy. The country also carries a very high burden of smoking and smoking-related diseases that may be synergistic in malignant transformation.

Objective: To assess the frequency of pulmonary scarring in patients with lung cancer.

Methods: All patients with confirmed lung cancer and a staging computed tomography (CT) scan of the chest were included in this 2-year retrospective study. Pulmonary scarring was categorised according to location as present in: (i) the same lobe as the primary tumour, (ii) a different lobe of the same lung, or (iii) the contralateral lung; or (iv) as diffuse. Post-obstructive bronchiectasis and other changes secondary to cancer were considered not to represent scarring.

Results: We identified 435 cases of primary lung cancer. In total, 95 patients (21.8%) had CT evidence of pulmonary scarring. Eighty-three of 85 patients (97.6%) had focal scarring in the same lobe as the primary tumour. Of these, 37 (43.5%) also had scarring involving a different lobe of the same lung, whereas only one (1.2%; p<0.001) had scarring isolated to a different lobe of the same lung. Moreover, 21 patients (24.7%) also had scarring of the opposite lung, but only one patient (1.2%; p<0.001) had scarring isolated to the contralateral lung. Ten patients had diffuse scarring, caused by bronchiectasis (n=5), idiopathic pulmonary fibrosis (n=4) and silicosis (n=1).

Conclusion: At least one in five patients with lung cancer had scarring, which was significantly more likely to be present in the same lobe as the tumour, suggesting a predisposition to malignancy.