Tarceva for someone over 90 years old

My Dad was just diagnosed today with advanced lung cancer. I am his primary caretaker. He doesn't fully understand so it's difficult for me to speak with him about his options. One of his doctors said they could do a biopsy and then he could take Tarceva. Another doctor advised us against that because of his weakened state. He can take care of his basic needs but he needs me here to cook and make sure he's taking his medications. Lately it's been hard for him to get out of bed. I don't know what to do about the Tarceva. The doctor who suggested it said there are no side effects. After reading about it, that's not true. I'm afraid if I start him on the pills they will take him out of the little comfort zone he's in right now. He is 93 years old. Can I have your opinions? I'm basically all alone so I have to decide everything by myself so your thoughts are appreciated.Also, would they prescribe Tarceva without a biopsy? My Dad got a PET scan which showed advanced cancer. One tumor is over 9cm and it's spread to lymphs. The doctor who doesn't think he should take treatment also doesn't think he should do the biopsy.