Hi, Thanks for writing in. Sorry to hear the progress of disease in your father. In my experience with patients of lung cancer stage 4 have a survival of 2 years might be expected. Cancer is a difficult condition to treat and every tumor behaves in a different way. However we must fight cancer till the end. As it is stage 4 therefore surgery is not a treatment. Chemotherapy and radiation can be given to control the disease and prevent it from spreading in to new areas. This treatment can add few months to a year and that is significant. Parallel treatment with siddha medicines can be given as long they do not interfere with chemotherapy or cause any side effects which will slow his recovery. Most siddha medications are made from herbal sources. Research has shown that aswagandha has potential against cancer-related fatigue, in addition to improving the quality of life. Praying for a quick recovery for your husband.