Microsatellite instability as a predictor of survival in head and neck cancer -- is there a link with colon cancer?

Objective: A reliable genetic marker to predict outcome for head and neck cancer is needed. In colon cancer, microsatellite instability (MSI) predicts response to therapy and improved prognosis. Colon cancer patients with MSI have a 60% improvement in survival as compared to patients without MSI. To assess whether MSI is a predictor of improved prognosis in head and neck cancer we used our tumor registry to find 8 patients treated between 1995 and 1998 with head and neck squamous cell carcinoma and either a history of colon cancer or a parent who had colon cancer. As a control, 15 T(2) or T(3) oral cavity cancers were used.

Methods: The tumor specimens were obtained and laser capture microdissected for analysis using the following microsatellite markers: BAT25, BAT26, BAT40, D1S2883, D2S123, D3S1611, D5S346, D7S501 and D8S25.

Results: All 8 patients with head and neck cancer and a colon cancer history exhibited MSI or loss of heterozygosity (LOH) at 1 or more of the markers tested. Three patients had 2 abnormal markers, 1 patient had 3 abnormal markers and 1 had 7 abnormal markers. Only 1 of the patients with a colon cancer history, all of whom had MSI, developed recurrent head and neck cancer. Of the 15 control patients, 5 had MSI or LOH and 1 had MSI or LOH at 2 markers. Three of the 5 patients with MSI or LOH had a recurrence; hence MSI and LOH at these markers were uncommon, and there was no relation between MSI and outcome in patients without a history of colon cancer.

Conclusions: These results support a possible alternative mode of carcinogenesis in patients with head and neck cancer and a history of colon cancer and, most significantly, that these cancers are a subgroup of head and neck cancer that may have a better prognosis.