Offering a fascinating preview of the coming age of molecular medicine in dentistry, a report by Tsui, et al appeared in the American Journal of Surgical Pathology (November 2009) on the topic of oral cancer and the old concept of “field cancerization.” Better known today as cancer fields, the concept encompasses 4 general ideas: (1) abnormal tissue surrounds the tumor that may not be apparent clinically, (2) potentially cancerous cells can arise at multiple locations simultaneously, (3) oral cancer can consist of several independent lesions that can coalesce into one tumor, and (4) the incomplete removal of clinically occult abnormal tissue after surgery may explain recurrences.
National Institute of Dental and Craniofacial Research (NIDCR) grantees and colleagues unravel the underlying biology of an oral cancer field in a 52-year-old male smoker with a 1.5-cm nodular tumor on his tongue. By shining the blue light from a hand-held device (VELscope) directly on the tumor and the surrounding area, the normal tissue absorbs the light and re-emits a pale green, while abnormal tissue appears dark or dark brown. Using this device, they identified a 25-mm lesion outside the clinically visible margin of the tumor. Three 5-mm biopsies were taken from and around the affected area and they performed a series of molecular and genomic analyses. The results revealed 2 distinct clonal populations of tumor cells within the same cancerous field. Each had different characteristic genetic alterations, or signatures, suggesting each might respond differently to treatment. The authors note, “This is a key example of using whole genome technologies to determine the clonality between samples of a single patient.”
.
