In 1987, we published a case series of a newly-described, highly malignant neoplasm, termed sinonasal undifferentiated carcinoma, in which treatment results were poor. In this updated study, we report the followup for the original three surviving patients and for six additional cases whose tumors were diagnosed between January 1987 and October 1991. These data suggest that the prognosis for patients with localized disease may be better than originally described.

This paper supplements an earlier paper which explained how to calculate the probability distribution of the number of mutants that would be observed in a fluctuation test experiment. The formulas in that work give the distributions to be expected under a wide variety of experimental conditions, but the method it uses when only a fraction of the mutants will produce visible colonies are clumsy and inefficient. Here I describe efficient procedures for dealing with that case, provided that the mutation rate per cell division remains constant during the experiment.

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