Basic facts and ICD classification

Lung cancer is the uncontrolled growth of abnormal cells in one or both of the lungs, causing lump (tumour) growth and disrupting the normal functioning of the organ.

The ICD-10 classifies these cancers under rubric C34 as malignant neoplasms of the bronchus and lung. For the purpose of reporting, routine statistics for the lung and bronchus are often pooled with those of the trachea (C33).

This EUphact only covers tumours that originate in the lung. Malignant neoplasms that affect the lungs, but do not originate in the cells of the bronchus or lung are not covered within the scope of this EUphact.

Microscopic subtypes and smoking habits

Cancers that originate from lung cells can be divided into two groups, small cell lung cancers (SCLC) and non-small cell lung cancers (NSCLC), according to their microscopic characteristics. NSCLC's include squamous cell carcinoma (SQC), large-cell carcinoma (LCC) and adenocarcinoma (AD). Tobacco smoking causes all types of lung cancer, but predominantly increases the incidence of SQC. The incidence of this subtype is therefore more sensitive to the history of smoking in any given population.

The AD subtype dominates among non-smokers. It therefore appears to be more common among European women who took up the smoking habit considerably later than men.

The relative frequency of the different subtypes is therefore strongly influenced by the prevalence, duration and intensity of tobacco smoking in the population. For men, the typical distribution by subtype is 15% SCLC, 23% AD and 41% SQC. For women, it is 13% SCLC, 40 % AD and 23 SQC.