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. 2013 Apr;22(4):521-7.
doi: 10.1158/1055-9965.EPI-13-0084.

Precursors in cancer epidemiology: aligning definition and function

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Free PMC article

Precursors in cancer epidemiology: aligning definition and function

Sholom Wacholder. Cancer Epidemiol Biomarkers Prev. 2013 Apr.
Free PMC article

Abstract

A precursor of a disease is a definable pathologic state that progresses directly to disease without a known intermediate step and whose presence substantially increases the likelihood of disease. Precancers, or precursors of cancer, can help provide detail about the dynamic pathogenesis process before clinical disease. Thereby, ascertainment of properly defined precancers can increase precision of estimates and power in epidemiologic and clinical studies. Besides providing targets for direct treatment and improving tools for risk assessment in screening programs, precancers can help establish temporal ordering of cause and effect; can identify relatively homogeneous subsets of cancer that have passed through a given precancer state; and provide a basis for choosing high-risk individuals for detailed longitudinal study. Although the most appropriate definition of the precancer will vary with its function in particular research or clinical applications, the proportion of cancers that progress from the precancer and risk of cancer progressing from the precancer can be important measures of the value of a precancer in translational efforts.

Conflict of interest statement

The author has no conflicts of interest to report.

Figures

Figure 1
Figure 1. Depictions of simple causal pathways to cancer
The top causal diagram shows exposure 1 leading to cancer directly without passing through a known precancer step. The bottom causal diagram shows exposure 2 leading to cancer indirectly by causing the precancer, from which the cancer eventually emerges.
Figure 2
Figure 2. Different Precancers might distinguish two pathways for head and neck squamous cell carcinomas (HNSCC)
Leukoplakia and erythroplakia are precancerous lesions for HNSCC caused by alcohol (EtOH) and smoking. No precancer lesions of other HNSCCs, mostly caused by HPV are known. Easily detectable precancers could be the basis for effective screening programs to prevent HNSCC or could indicate different management strategies for patients after diagnosis.

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