November 19, 2009
Case studies rarely rise to the level of news. But a brief report in the November issue of the American Journal of Surgical Pathology offers a fascinating preview of the coming age of molecular medicine in dentistry. The topic is oral cancer and the old concept of “field cancerization.” Better known today as cancer fields, the concept encompasses four 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.
In the case study, NIDCR grantees and colleagues unravel the underlying biology of an oral cancer field – and its clinical implications for future molecular medicine – in a 52-year-old male smoker with a 1.5 centimeter nodular tumor on his tongue. They began by shining blue light from a hand-held device directly on the tumor and the surrounding area. Normal tissue absorbs the light and re-emits a pale green, while abnormal tissue appears dark or dark brown. Using this device, called a Velscope®, they identified a 25-millimeter lesion outside the clinically visible margin of the tumor. They took three five-millimeter biopsies from and around the affected area and performed a series of molecular and genomic analyses. The results revealed two 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. As the authors note, “This is a key example of using whole genome technologies to determine the clonality between samples of a single patient.”
- A Dynamic Oral Cancer Field: Unraveling the Underlying Biology and Its Clinical Implication. Tsui, IF, Garnis, C, Poh, CF. Am J Surg Patho. 2009 Nov; 33 (11): 1732-8.