In 1963 Professor Huggins! wrote "more than one half of the male population over the age of 50 suffer from benign tumors known as prostatic hypertrophy. Often an enlarged prostate is the only difficulty to cloud an otherwise tranquil old age". This statement emphasizes two important features of benign prostatic hypertrophy (BPH); the frequency with which it occurs and its association with increasing age. The true incidence is difficult to determine as most data relate to selected groups of patients; moreover, the diagnostic criteria of prostatic hypertrophy are not clearly defined. Normality merges imperceptibly into abnormality, for even in men who are clinically normal, rates of urinary flow decrease with 2 increasing age . Despite these inaccuracies, incidence figures show the magnitude of the problem; Flocks (1963) 3 reported that 65% of American men over 60 years suffer from it and in a selected group of Danish men 43% had symptoms of the 4 disease ; similar figures are reported for the U ni ted Kingdom 5. At present most patients with BPH, who need treatment, undergo surgical prostatectomy which may be considered the usual treatment. The frequency of the disease alone, creates certain problems, for annually more than 30000 men are admitted to hospital in the United States with this as a primary diagnosis and with an ageing population the figures can be expected to increase.

An immunological approach to the treatment of cancer has many theoretical features to commend it. There should be specificity, so that tumour cells alone are destroyed whilst normal tissues are unaffected. Provided the tumour is uni form and all of the cells have appropriate antigens, every malignant cell should be destroyed and even distant metastases dealt with. So far these speculative advantages are unfulfilled and the initial optimism that surrounded im munotherapy has not been sustained. Acceptance of the precepts of tumour im munology continues but these disappointing observations had led to increasing scrutiny of certain aspects. The purpose of this chapter is to review the prin ciples which underly tumour immunology and immunotherapy, so that the more detailed studies that follow can be considered in perspective. TUMOUR ANTIGENS (Chapter 2) For a tumour to initiate an immunological response, it must possess distinctive antigens. Much of the early work in tumour immunity was confused because it was not appreciated that tumours, like other tissues, exhibit transplan tation antigens. Only when syngeneic tumours are used can tumour antigens alone be studied and it was the introduction of inbred mouse strains which allowed Foley in 1953' to produce the first evidence for specific an tigenicity of experimental tumours. Demonstration of these antigens requires that pretreatment with syngeneic tumour will influence the growth of a sub sequent challenge with the same neoplastic cells."

Immunology is a rapidly developing subject. The contributors in this book present some components of immunological knowledge which relate to the present and the possible future practice of surgery. Aspects of cellular and humoral immunity necessary for understanding are described and considera tion given to the mechanisms underlying immunological diseases. Whilst the original interest in immune response was related to microbial resistance, the recent impetus to surgical immunology has been the resurgence of organ grafting. Separate sections of the book deal with clinical organ transplanta tion, the allograft reaction, graft rejection and immunogenetics. A pre-requi site of successful organ grafting is suppressive control of immune responses. Approaches to conventional immunosuppression and specific non-reactivity are therefore considered. One method of cancer therapy is strengthening of the host's immune responses. Both experimental and clinical immunotherapy are discussed and components of tumour immunology necessary for their rational understand ing are dealt with separately. Successful immunotherapy requires monitoring of immune responses but another method for improving results of cancer treatment is earlier diagnosis by immunological methods. The book is aimed at practising surgeons who want to know the relevance of immunology to clinical surgery and laboratory scientists needing to understand the applications of their basic concepts. I am very grateful both to the authors for their contributions and the editorial staff of MTP Press Limited, for their considerable help."