Tarceva general info when best used before chemo or after or before raidotheraphy or after both?

Erlotinib ( er-LOE-tye-nib) belongs to the group of medicines called antineoplastics. It is used to treat non-small cell lung cancer after the failure of other chemotherapy treatment. It is also used together with another medicine called gemcitabine (e.g., Gemzar) to treat cancer of the pancreas.
Please see the web pages for more details on Erlotinib (generic name) Tarceva (brand name).