I am very sorry, but Metastatic poorly differentiated non-small cell carcinoma has a very poor prognosis , especially for a person who is 73 year old .Surgery is almost never an option considering the age and also the fact that it is a metastatic small cell carcinoma.
The only options available are chemotherapy and stereotactic radiotherapy with adjuvant pain management.
Here are the treatment options available-
1) If the patient does not have concomitant renal or cardiac problem chemotherapy can be started. Usually for younger individuals 2 drug regimen is used but in an older individual a single "Targeted therapy" is done to reduce the symptoms as well as prolong the survival. But chemotherapy needs intensive observation, especially for a 70 yr. old because of its side effects.
2) Full body Stereotactic radiotherapy is the main form of management of this patient and leads to considerable decrease in pain and improvement of symptoms. It has to be done in multiple sittings and does not have as many side effects as chemotherapy.
3) Aggressive pain management forms an important form of management and can be in the form of self-regulated epidural morphine.
Hope I have been of help.