Occurrence of field cancerization in clinically normal oral mucosa: A systematic review and meta-analysis

In the general adult population, oral squamous cell carcinoma (OSCC) is the sixth most common cancer in developed countries and the third most common cancer in developing countries (Chen et al., 1990, Farhadieh et al., 2004, Franco et al., 1991, Hande et al., 2015). Two years post complete treatment of OSCC, the risk of developing a recurrence of this cancer or a second primary tumor (SPT) is significant (Angadi et al., 2014, Kim et al., 2002, Thomson, 2002).

SPT is based on mutations; some mutations may be caused by the environment, deleterious habits (ultraviolet radiation and cigarette), others by the cell itself, and its genetics. These cancer cells can cause SPTs or multiple primary cancers. Their occurrence may be a result of a phenomenon called field cancerization (FC), first described by Slaughter, Southwick, and Smejkal (1953), who found separate foci of in situ cancer or isolated islands of invasive squamous-cell carcinoma, based on the analysis of serial sections of tumor (1 cm or less in diameter). FC is characterized by genetic tissue alterations, scattered throughout the oral mucosa, which occur in response to carcinogenic factors and may lead to SPTs. Multiple carcinogenic foci could explain the linear superficial growth of SPTs (Slaughter et al., 1953).

This theory is supported by a previous report on oral cancer by the Medical Research Council of Great Britain. They reported that radiotherapy results in the elimination of all tumor cells; however, the behavior of potential malignant disorder areas is different, persisting despite radiation and leading to the appearance of a SPT in the treated area. In this report, one-third of treatment failures were due to the persistence of potential malignant disorder lesions. Thus, the success of radiotherapy may be limited by the condition of the tissue surrounding the oral carcinoma (Wood & Boag, 1950).

The concept of FC explains the occurrence of SPTs, which may result from the initial primary tumor that is removed by radical surgery; however, the normal tissue adjacent to the tumor has certain preneoplastic genetics. The expansion of preneoplastic daughter cells over several years may lead to tissue malignancy (Bansal et al., 2020). Considering that it is essential to understand the concept of field cancerization of OSCC to increase the survival rate of patients, the objective of this systematic review was to describe whether there are FC indicators in clinically normal mucosa opposite to primary OSCC.

留言 (0)

沒有登入
gif