What is the Difference Between Synchronous and Metachronous

The key difference between synchronous and metachronous depends on the time of the onset of the second primary cancer. Synchronous cancers develop within 6 months of the diagnosis of first primary cancer, while metachronous cancers develop after 6 months from the diagnosis of first primary cancer.

Cancer is a condition characterized by uncontrolled cell division. The developmental stages of cancer vary depending on the type of cancer. Cancerous tumors spread into or invade nearby tissues and can travel to distant places in the body to form new tumors in a process called metastasis. Synchronous and metachronous cancers are two types of second primary cancers developed after the diagnosis of primary cancer.

CONTENTS

1. Overview and Key Difference
2. What is Synchronous 
3. What is Metachronous
4. Similarities – Synchronous and Metachronous
5.  Synchronous vs Metachronous in Tabular Form
6. Summary – Synchronous vs Metachronous

What is Synchronous?

Synchronous cancer is the state of cancer where a second primary cancer is developed within 6 months of the first primary cancer. Synchronous cancer can be explained in relation to colorectal carcinoma, where it refers to the occurrence of more than one primary colorectal carcinoma within a period of 6 months. The most common sites of synchronous colorectal cancer are the regions of the colon and the rectum. However, in certain cases, many colorectal synchronous carcinomas were found distributed in the large intestine and close proximity areas. Therefore, further adenomas could arise as a result of synchronous development.

Genetics plays an important role in the onset of a synchronous carcinoma. Mutations and microsatellite instability are two key things that promote synchronous carcinoma in individuals. Epigenetic mechanisms also play an important role via methylation to promote the onset of synchronous cancers.

What is Metachronous?

Metachronous cancer is a state of cancer in which the second primary cancer develops after 6 months of the onset of the first primary cancer. Colorectal carcinoma also shows a metachronous development trend. In this regard, the diagnosis of a metachronous carcinoma should take place after 6 months of the detection of cancer. The synchronous nature of carcinoma can be eliminated. However, repeated monitoring is required at time intervals within 1 year, 3 years, 10 years, and so on. This will allow the accurate monitoring of any metastases resulting from the onset of the second primary cancer.

The main identification of the metachronous nature of carcinoma in colorectal cancer is the identification of metachronous lesions in the large intestine, the rectum, and the colon. The probability of synchronous cancer developing into a metachronous cancer is very high in colorectal cancer. However, the phenomenon of metachronous nature is more common in colorectal cancers rather than synchronous cancers.

What are the Similarities Between Synchronous and Metachronous?

• Both are related to the onset of the second primary cancer following the first cancer.
• They are genetically determined.
• Both lead to metastases of cancer.
• They can be diagnosed by biopsies or scopy tests.
• Both are more prevalent in colorectal cancers.

What is the Difference Between Synchronous and Metachronous?

The key difference between synchronous and metachronous is based on the onset of the second primary cancer. Synchronous carcinoma develops within 6 months of the onset of the first primary cancer. Metachronous carcinoma develops after 6 months of the onset of the first primary cancer.

The following table summarizes the difference between synchronous and metachronous.

Summary – Synchronous vs Metachronous

Synchronous and metachronous carcinomas lead to the metastasis of cancer. Synchronous carcinoma develops within 6 months of the onset of the first primary cancer while metachronous carcinoma develops after 6 months from the onset of the second primary cancer. Genetics plays an important role in synchronous and metachronous carcinoma. The diagnosis of synchronous and metachronous carcinoma takes place via biopsies and scopy tests. So, this summarizes the difference between synchronous and metachronous.

Reference:

1. J. Lindberg, S. Ladelund. “Risk of Synchronous and Metachronous Colorectal Cancer: Population-Based Estimates in Denmark with Focus on Non-Hereditary Cases Diagnosed after Age 50.” SAGE Journals.
2. Lam, Alfred King-Yin, et al. “Synchronous Colorectal Cancer: Clinical, Pathological and Molecular Implications.” World Journal of Gastroenterology, Baishideng Publishing Group Inc, 14 June 2014.

Image Courtesy:

1. “Blausen 0246 ColorectalCancer” By Blausen Medical Communications, Inc. – see ticket for details (CC BY 3.0) via Commons Wikimedia