Hello, My Wife Was Diagnosed With Non-small Cell Lung Cancer

Hello,

My wife was diagnosed with non-small cell lung cancer and 2 weeks ago had 5 days of radiation treatments. She is 73 years old and has had two artificial heart valves for 25 years. Since the treatments she has experienced a lot of muscle weakness and has difficulty standing up from a sitting position even with help. She is on multiple medications including atenolol, ramipril, warfarin, digoxin, decadron, and glyburide. What may be causing the weakness?