A 51-year-old male patient came for a routine physical check-up. he has a history of diabetes and hypertension (has also suffered from angina 3 years ago)  and has a 20-pack-year history of cigarette smoking.

Laboratory studies show: Sodium 136mEq/L Potassium 4.5 mEq/L Chloride lOBmEq/L BUN 24mgldL Creatinine 0.9 mgldL Calcium 11.5 mgldL Albumin 3.4 gldL What is the most likely diagnosis?