My 75 Year Old, Future Mother-in-law Was Diagnosed 6 Months
Not a good prognosis.
Detailed Answer:
Hello dear, welcome to Ask a doctor service.
I read your query and here is my advice.
I am sorry of hearing this.
Encephalomalacia gets better with proper treatment ( surgical removal of the damage), but this procedure is difficult to be done to her because COPD and lung cancer history. Encephalomalacia can often lead to coma or death.
Also the small cell lung cancer is one of the most aggressive and invasive cancers.
I think she may get worse with time.
An exact life expectancy can't be said.
You can do your wedding earlier and your husband can be happy of having his mother in his wedding. Also thinking that she may get worse and may need more care latter, I suggest you to do weeding earlier.
Hope I have answered the question.
Let me know if I can assist you further.