Esophageal cancer begins in the long, hollow tube that carries food from the throat to the stomach.

• Types: Squamous cell carcinoma and adenocarcinoma
• Symptoms: Difficulty swallowing (dysphagia), chest discomfort, persistent acidity, weight loss, and vomiting
• Risk factors: Smoking, alcohol consumption, chronic acid reflux, and Barrett's esophagus
• Diagnosis: Endoscopy and biopsy
• Treatment: Surgery, chemotherapy, radiation therapy, or a combination depending on the stage

Stomach cancer develops from the inner lining of the stomach, most commonly as adenocarcinoma.

• Progression: Often begins slowly, progressing from early precancerous changes to more advanced disease
• Early symptoms: Indigestion, bloating, mild pain
• Advanced symptoms: Vomiting, weight loss, and difficulty eating
• Risk factors: Helicobacter pylori infection, smoking, high-salt diets, and family history
• Treatment: Gastrectomy (partial or total removal of stomach), chemotherapy, targeted therapy, and radiation

Duodenal cancer arises in the first part of the small intestine, just after the stomach.

• Characteristics: A rare but serious cancer
• Symptoms: Abdominal pain, vomiting, anemia, or unexplained weight loss
• Complications: Blockage in the duodenum can cause persistent vomiting after meals
• Most common type: Adenocarcinoma
• Diagnosis: Endoscopy, imaging, and biopsy
• Treatment: Surgery (such as Whipple procedure in some cases), along with chemotherapy when needed

Small intestine cancers (excluding the duodenum) develop in the jejunum or ileum.

• Prevalence: Rare compared to stomach or colon cancer
• Types: Adenocarcinoma, lymphoma, sarcoma, and neuroendocrine tumors
• Symptoms: Abdominal cramps, gastrointestinal bleeding, persistent anemia, or bowel obstruction
• Diagnosis: CT scan, capsule endoscopy, or enteroscopy
• Treatment: Varies based on type, but may include surgery, chemotherapy, immunotherapy, or targeted therapy

Colorectal cancer affects the colon and rectum, which are responsible for absorbing water and storing waste before elimination.

• Development: Usually starts as small polyps that grow slowly and may become cancerous over time
• Symptoms: Changes in bowel habits, blood in stool, abdominal discomfort, fatigue, and unexplained weight loss
• Risk factors: Age, low-fiber diet, obesity, smoking, inflammatory bowel disease, and genetic syndromes
• Early detection: Colonoscopy greatly improves outcomes
• Treatment: Surgery, chemotherapy, radiation (especially for rectal cancer), and advanced targeted therapies

Retroperitoneal cancers form in the deep space behind the abdominal organs.

• Common types: Most are retroperitoneal sarcomas, including liposarcoma and leiomyosarcoma
• Detection challenge: Because this space can expand silently, tumors often grow large before causing symptoms
• Symptoms: Abdominal fullness, back pain, early satiety, leg swelling, or urinary issues
• Diagnosis: Typically involves CT/MRI scans and biopsy
• Treatment: Complex and often requires specialized surgical expertise, sometimes combined with radiation or chemotherapy depending on the tumor type