A 62-year-old woman from Mumbai undergoes colonoscopy for iron-deficiency anaemia and is found to have a 4 cm mass in the caecum with biopsy-proven adenocarcinoma. Staging CT shows a single 2 cm lymph node in the hepatic hilum and no other metastases. The patient is fit for surgery. What is the most appropriate next step in management?

Explanation

## Clinical Scenario Analysis This patient has **colon cancer (caecal) with a single regional lymph node** in the hepatic hilum. The critical question is: **Is this a regional (N2) node or a distant metastasis (M1a)?** ## Lymph Node Classification in Colorectal Cancer **Key Point:** Lymph nodes are classified as **regional (N-stage)** if they are along the arterial blood supply of the primary tumour. For a caecal cancer, regional nodes include those along the ileocolic, right colic, and superior mesenteric vessels — **including hepatic hilum nodes** if they are along the hepatic artery branches. | Lymph Node Location | Caecal Cancer Classification | Significance | |---|---|---| | Ileocolic, right colic, SMA | Regional (N1/N2) | Part of D3 dissection | | Hepatic hilum (along hepatic artery) | Regional (N2) | Part of D3 dissection | | Coeliac, para-aortic | Distant (M1a) | Metastatic disease | | Liver parenchyma | Distant (M1a) | Metastatic disease | ## Management Algorithm ```mermaid flowchart TD A[Caecal cancer + hepatic hilum lymph node]:::outcome --> B{Node location along arterial supply?}:::decision B -->|Yes, regional N2| C[Right hemicolectomy with D3 dissection]:::action B -->|No, distant M1a| D[Palliative chemotherapy ± resection]:::action C --> E[Adjuvant chemotherapy if high-risk]:::action D --> F[Assess resectability of primary + mets]:::decision ``` **High-Yield:** A 2 cm lymph node in the hepatic hilum **adjacent to the hepatic artery** is considered **regional (N2) disease**, not distant metastasis. It should be included in the **D3 lymphadenectomy** (dissection of nodes along the arterial supply up to the origin of the feeding vessel). **Clinical Pearl:** The distinction between N2 and M1a is anatomical: if the node lies along the vascular pedicle of the primary tumour's blood supply, it is regional. This patient is **fit for surgery** and has no other metastases — **curative intent surgery is appropriate**. ## Why Right Hemicolectomy with D3 Dissection? 1. **Caecal location** requires right hemicolectomy (removal of caecum, ascending colon, and proximal transverse colon). 2. **D3 lymphadenectomy** means dissection of nodes along the ileocolic, right colic, and superior mesenteric vessels — **including hepatic hilum nodes** if they are along the hepatic artery. 3. This is **curative intent surgery** with potential for long-term survival, even in N2 disease. 4. **Adjuvant chemotherapy** (FOLFOX or capecitabine + oxaliplatin) will follow based on final pathology. **Mnemonic: D-STAGE LYMPH NODES — D3 = Dissection of nodes along the arterial supply** - D0 = no nodes examined - D1 = nodes within 5 cm of primary - D2 = nodes along feeding vessels - D3 = nodes up to origin of feeding vessel (includes hepatic hilum for right-sided cancers)