Are colon and rectal cancer considered different diseases?

From the Guidelines

Colon and rectal cancers are considered distinct diseases due to differences in their location, treatment approaches, and risk of local recurrence, as highlighted in the most recent guidelines 1. The distinction between colon and rectal cancer is crucial for proper treatment planning and management. Key differences include:

• Location: Colon cancer develops in the large intestine, while rectal cancer occurs in the last several inches of the colon (rectum) 1.
• Treatment approaches: Rectal cancers typically require radiation therapy before surgery, whereas colon cancers usually do not 1.
• Surgical techniques: Rectal cancer surgery is more complex due to the rectum's location in the confined space of the pelvis 1.
• Risk of local recurrence: Rectal cancers have a higher risk of local recurrence compared to colon cancers 1. Despite these differences, both cancers share similar risk factors, screening methods, and many treatment principles, and they have comparable cellular characteristics, as both typically begin as polyps that may become cancerous over time 1. Some of the key factors that influence the treatment of rectal cancer include:
• The intent of rectal cancer surgery (curative or palliative) 1
• The likely functional results of treatment, including the probability of maintaining or restoring normal bowel function/anal continence and preserving genitourinary functions 1
• The use of sequenced multimodality therapy, which combines chemoradiotherapy, chemotherapy, and operative treatment for most patients 1 Understanding these distinctions is essential for providing optimal care and improving patient outcomes, as emphasized in the latest guidelines 1.

From the Research

Overview of Colon and Rectal Cancer

• Colon and rectal cancer are often considered as a single entity, but they have distinct differences in terms of anatomy, staging, treatment, and biological characteristics 2, 3, 4.
• The anatomic continuity of the colon and rectum has led to the historical consideration of these cancers as equivalent, but recent studies suggest that they are highly related yet distinct diseases 4.

Differences in Anatomy and Treatment

• Rectal cancer requires different staging procedures, neo-adjuvant treatment, and surgical approaches compared to colon cancer, including the use of neoadjuvant radiotherapy or chemoradiotherapy 2, 3.
• The treatment of rectal cancer often involves a multidisciplinary approach, including the involvement of various medical specialists, and the goal is to optimize disease-free and overall survival while minimizing the risk of local recurrence and toxicity 3.

Biological and Clinical Characteristics

• Colon and rectal cancer differ in their embryological origin, metastatic patterns, and composition of drug targets, such as BRAF and EGFR 2.
• Proximal colon cancer, in particular, exhibits unique tumor biological characteristics and differs significantly from cancers of other anatomical subsites, including distal colon cancer and rectal cancer 5.
• The identification of these differences is crucial for the development of new therapeutic paradigms and for optimizing treatment approaches for patients with colon and rectal cancer 2, 4.

Implications for Treatment and Management

• The consideration of colon and rectal cancer as distinct diseases has implications for the development of new therapeutic paradigms and for the optimization of treatment approaches 4.
• A deeper understanding of the biological and clinical characteristics of colon and rectal cancer is necessary for accurate diagnosis and treatment, and for improving patient outcomes 2, 3, 5.