Heterogeneity of immunostaining for tumour markers in non-small cell lung carcinoma

Lung carcinoma is a leading cause of death. However, there are few indicators that can aid in prediction and prognosis. Many tumour markers are available, but their reliability is questionable. For example, Ki-67 expression has been associated with increased as well as decreased survival or with no clinical significance. The varying results have been attributed to the methodology, relative intensity of staining, variety of marking and statistical methods. To determine whether differential expression of markers within tumours may be a contributory factor to this lack of agreement, we used two marking methods to evaluate the level of expression of Ki-67, p53 and bcl-2, in addition to the apoptotic index, in serial sections of non-small cell carcinoma. All stains exhibited a degree of heterogeneity. This small study highlights the importance of standardisation of marking methods and interpretation of results if tumour markers are to be used as predictive or prognostic factors.