How do you measure if tarceva (erlotinib) is working on the lung cancer? how do you measure the efficacy?

Repeat CT scanning: Repeat ct scaning after 2-3 months of tarceva (erlotinib) use is done to measure the size of lung cancer lesions and to see if they are shrinking. Patients who get a severe skin rash with tarceva (erlotinib) are often likely to benefit more from tarceva (erlotinib) therapy.

How to measure: At least two ways- - clinically- there is a correlation between the presence of acneiform rash -usually on the head/face-after you take tarceva (erlotinib)- with the efficacy of tarceva (erlotinib). The rash will start to appear within the first 2-3 weeks after you start tarceva (erlotinib). ~ imaging finding. Ct scan or pet/ct after a few months on tarceva (erlotinib)- will tell you whether the cancer responds to tarceva (erlotinib).