J.C is an 82-year-old white man who was evaluated by GI specialist due to abdominal discomfort, loss of appetite, weight lost, weakness and occasional nausea.
Past Medical History (PMH):
Patient is Diabetic, controlled with Metformin 500 mg by mouth twice a day, Lantus 15 units SC bedtime. Hypertensive, controlled with Olmesartan 20 mg by mouth once a day. Atrial Fibrillation, controlled with Rivaroxaban 15 mg by mouth once a day and bisoprolol 10 mg by mouth once a day.
Labs:
Hb 12.7 g/dl; Hct 38.8% WBC 8.2; Glycemia 74mg/dl; Creatinine 0.8 mg/dl; BUN 9.8 mg/dl; AST 21 U/L ALT 17 U/L; Bil T 1.90 mg/dl; Ind 0.69 mg/dl; Dir 1.21 mg/dl.

Diagnostic test:
Endoscopic Ultrasound of the Pancreas. Solid mass in the head of pancreas 4 cms, infiltrating Wirsung duct. The solid mass impress to infiltrate the superior mesenteric vein. Perilesional node is detected, 1.5 cms, metastatic aspect. Fine needle aspiration (FNA) biopsy: Ductal adenocarcinoma.
Case study questions:

Please name the potential most common sites for metastasis on J.C and why?
What are tumor cell markers and why tumor cell markers are ordered for a patient with pancreatic cancer?
Based on the case study described, proceed to classify the tumor based on the TNM Stage classification. Why this classification important?
Discussed characteristic of malignant tumors regarding it cells, growth and ability to spread.
Describe the carcinogenesis phase when a tumor metastasizes.
Choose the tissue level that is affected on the patient discussed above: Epithelial, Connective, Muscle or Neural. Support your answer.