I am really sorry to hear about your mother-in law. My mother was diagnosed with extensive (stage IV) small cell lung cancer last Dec. 29, 06. She was also give 1 to 3 months at diagnosis if she did NOT have chemo. With chemo, they were giving her till the end of this year. My Mom is still with us today. Everyone is different and treatments affect everyone differently. She only had 3 rounds of chemo (didn't make the last round because she was so weak and frail she fell and broke two pelvic bones; she is also an amputee ...right leg above knee) and it is a battle each and every day of her life. She is aware that she is terminal .....as the doctors told her at the time of diagnosis...but she chose to get the chemo because she had "unfinished business" here on earth and she needed time to straighten things out. She has accomplished this and has been preparing herself for eternal life with GOD. She is now so much at PEACE with EVERYTHING now. I left the decision of chemo vs. no chemo up to my mom as she is the only one who could really make that decsion for herself. There was no question in her mind that she was going to get chemo. (I personally did not see the point as to lengthen the time period of suffering and dying from this awful disease, but as I mentioned before, she NEEDED that time to finsh her work here on earth).
I am so grateful now that I let her make her own decision and gave her 100% of my support. It's been a very long, hard road this past year. But it has also been a blessing as our relationship was able to become much better now.
I've been taking care of my mom for the past 10 years (the last five of which she has been living with me and my family). If there are any specific questions you might have, I would be more than happy to try and help answer them for you as we have been through a real lot already.
Take care and my prayers are with you.