My mother has bronchogenic carcinoma. what should i tell her?

Depends on stage: ...Among many other things. She should see doctors experienced in treating lung cancer. Teams of doctors from several specialties can be very helpful. She and you should discard any preconceived notions of what treatment is like. Past experiences of family/loved ones may have no resemblance to her treatment. Use the internet, but use it to get the questions to ask her doctors, not to answer them.

She has options: Discuss with her oncologist the extent of her lung cancer and the type and stage. The oncologist will tell you the options available to your mom for her condition and age. Depending on stage and what she is a candidate for, she will have options of surgery, radiation and chemotherapy available. Though sometimes the disease can be far advanced and cause symptoms, there are options.