Field cancerization

Concept in oncology describing the presence of pre-cancerous changes in a tissue area

Field cancerization is a concept in oncology that describes the presence of pre-cancerous changes in a large area of tissue, which may lead to the development of multiple primary tumors. This phenomenon is particularly relevant in tissues that are exposed to carcinogens, such as the oral cavity, esophagus, lung, skin, and colon.

History

The term "field cancerization" was first introduced by Slaughter et al. in 1953, who observed that patients with oral squamous cell carcinoma often had multiple independent tumors in the oral cavity. This led to the hypothesis that a "field" of tissue had undergone pre-cancerous changes, making it susceptible to developing multiple tumors.

Pathophysiology

Field cancerization involves the presence of genetically altered cells in a large area of tissue. These cells may have mutations in key oncogenes or tumor suppressor genes, leading to a predisposition to cancer development. The process is thought to occur in several stages:

1. Initiation: Exposure to carcinogens causes genetic mutations in a group of cells.
2. Promotion: These mutated cells proliferate, creating a field of pre-cancerous cells.
3. Progression: Additional mutations occur, leading to the development of one or more tumors within the field.

Image of resected colon segment with cancer and nearby polyps

Clinical Implications

Field cancerization has significant implications for cancer diagnosis and treatment. It suggests that even after the removal of a primary tumor, the surrounding tissue may still harbor pre-cancerous changes, leading to a high risk of recurrence or the development of new primary tumors. This is particularly important in cancers of the head and neck, lung, and colon.

Diagnosis

The diagnosis of field cancerization is challenging, as it involves detecting subtle genetic changes in tissue that appears normal under a microscope. Techniques such as molecular profiling, genomic sequencing, and the analysis of biomarkers are used to identify fields of pre-cancerous cells.

Prevention and Management

Preventive strategies for field cancerization focus on reducing exposure to known carcinogens, such as tobacco and alcohol, and monitoring high-risk patients closely. Management may involve more extensive surgical resection to remove the entire field of altered tissue, as well as adjuvant therapies to target residual pre-cancerous cells.

Expression of DNA repair proteins in field defect

Research Directions

Ongoing research is focused on understanding the molecular mechanisms underlying field cancerization and developing targeted therapies to prevent the progression of pre-cancerous fields to invasive cancer. Studies are also exploring the role of epigenetic changes and the tumor microenvironment in field cancerization.

Related pages

• Carcinogenesis
• Tumor suppressor gene
• Oncogene
• Squamous cell carcinoma