Prognostic value of apoptotic index in cutaneous basal cell carcinomas of head and neck

Basal cell carcinoma (BCC) is the most common type of human cancer, often l ocally invasive, and following a benign clinical course. However, a proport ion of BCCs do recur after treatment, causing extensive local tissue destru ction, seldom metastasizing. Morphological methods to unequivocally disting uish the aggressive forms of these tumors (BCC2) from the ordinary ones (BC C1) have so far been lacking. Apoptosis, or programmed cell death, is thoug ht to be important for the death of tumor cells in various stages of carcin ogenesis. We analyzed the extent of apoptosis in BCCs of head and neck in a morphological, morphometric, and electron-microscopic study, to estabilish on a retrospective basis, the relative frequency of recurrence of tumors s howing different apoptotic rates. We found that BCC1 showed lower apoptotic index (AI) than BCC2 [BCC1: AI from 2.03 to 10.45% (mean value: 5.98%) BCC 2: AI from 21.91 up to 43.82% (mean value: 39.82%)]. The morphometric analy sis of both BCC1 and BCC2 revealed significant differences between the valu es concerning nuclear area, length, perimeter, and roundness of the apoptot ic cells with respect to the 'viable' neoplastic cells. Electron-microscopy confirmed that the features of morphological apoptotic cells were characte ristic of programmed cell death. We hypothesized that low apoptotic rates i n BCC1 could be indicative of a good prognosis. In fact, this corresponded to an 'expansive' but not still invasive neoplastic state. In this phase, h owever, the tumor cells may constitute the target for genetic changes trigg ered by enviromental physical or chemical mutagenic agents, such as UV rays . BCC2, then, could be the result of newly selected mutated neoplastic cell ular clones, with more aggressive biological behavior. The high apoptotic l evel found in BCC2 could thus be used as an indirect alarm signal from path ologists. This hypothesis seems to be supported by most of the current data in the literature and by the clinical outcome of BCC2 of our series. In ou r opinion, routine evaluation of apoptosis in BCCs could be proposed to fac ilitate their sub-classification, contributing toward the evaluation of the prospective outcome of the individual patients. (C) 1999 Elsevier Science Ltd. All rights reserved.