Problems in histological diagnosis of cancer associated with chemo- and/or radiotherapy

This special report discusses problems relevant to histological diagnosis of cancer after chemo- and/or radiotherapy. One of the issues relates to pitfalls, i.e. over-, under- or misdiagnosis or oversight, stemming from a lack of concern or awareness of therapeutic effects on tumors or normal tissues. Another set of questions concerns inadequacy or insufficiency in the evaluation of therapeutic effects stemming from practical difficulties. In view of the importance of this area, we should set out a comprehensive research programme with close cooperation among clinicians, pathologists and molecular biologists to overcome these problems.