A lesion comprised of “cancer cells,” but with those cells limited to the lining mucosa and without evidence of extension to adjacent structures. In other words, there is no sign of invasion beyond the mucosa. Carcinoma in situ (CIS) is typically a localized and highly curable precursor to invasive cancer. CIS is sometimes called intraepithelial carcinoma.
In laryngology, CIS is found primarily on the vocal cords themselves, where a tiny, early lesion can change the quality of the voice. In other locations, CIS would ordinarily be “silent.”