The condition and the treatments
Lung cancer is grouped into 2 main types depending on how it looks under the microscope: small‑cell lung cancer and non‑small‑cell-lung cancer. There are 3 main types of non‑small‑cell lung cancer: squamous cell carcinoma, adenocarcinoma and large‑cell carcinoma.
Locally advanced or metastatic cancer means that it has spread to surrounding tissues or to other parts of the body.
Cancer tissue can be tested to check whether the cells have epidermal growth factor receptor tyrosine kinase (EGFR‑TK) mutations (changes). If they do, the cancer is 'EGFR‑TK mutation-positive'. The EGFR‑TK mutations make the cancer more likely to respond to drugs that block the EGFR (called EGFR‑TK inhibitors).
Erlotinib (Tarceva) and gefitinib (Iressa) are EGFR‑TK inhibitors.
NHS Choices may be a good place to find out more.