Apoptosis in squamous cell carcinoma of the lung: correlation with survival and clinicopathological features

Aims-Apoptosis is recognised as a physiological mechanism for controlling c ell numbers and its subversion is thought to contribute to carcinogenesis. The aims of this study were to measure the apoptotic index (AI) in a series of squamous cell carcinomas (SCCs) of the lung using standard histological staining and confirm this by immunohistology using an antibody to an apopt osis specific protein (ASP), and to seek to correlate the AI with clinicopa thological parameters. Methods-Sections of 134 SCCs were stained by haematoxylin and eosin (H&E) f or counting apoptotic bodies to determine the Al (number of apoptotic bodie s/10 000 tumour cells); 26 of these were also stained with anti-ASP antibod y and the proportion of ASP positive cells counted. Clinical data were obta ined from hospital notes. Results-The mean Al obtained by H&E staining of all 134 SCCs was 30.3 (SD, 24.75). Anti-ASP staining allowed identification of apoptotic bodies, gener ated a somewhat higher index (mean, 51.4; SD 39); this was not a result of the selection of tumours because the Al by H&E in the subset stained with a nti-ASP was 31.1. Regression analysis showed that the correlation between t he two values of AT was highly significant (Rs = 0.9760; p < 0.001), indica ting that the two methods were both reliable measures of apoptosis but that the anti-ASP staining is the more sensitive method. The tumours were group ed into high AT (> 50) and low Al (< 50) and survival analysis was carried out. The mean survival of the high AT group was 109 weeks and of the low Al group 72 weeks (p = 0.036). Conclusions-Anti-ASP staining is a reliable, easy, and sensitive method for assessing apoptosis in tumour sections and confirms the validity of the AI obtained by H&E staining. Al is a guide to the behaviour of SCCs of the lu ng.