Staging of head and neck cancer

To the Editor: Brennan et al. (Feb. 16 issue)¹ are to be commended for their important and well-executed study. This is an excellent example of the use of emerging molecular-biology techniques to address important clinical questions. The clinical usefulness of the study would have been augmented, however, if the authors had provided details of the radiotherapy administered. Because radiation kills cells exponentially, its success is inversely related to the log of the clonogenic cells within the treated volume.² The tumor-cell burden is higher in patients with positive margins, and it is for this reason that radiation decreases the rate of.