The Human Immunodeficiency Virus and Opportunistic Cancers

Abstract

It has been known for many years that immunosuppressed patients have a diathesis to cancer. Thus in retrospect it is no surprise to find that many patients with human immunodeficiency virus (HIV) infection develop opportunistic cancers. Moreover, the parallelsbetween the acquired immunodeficiency syndrome (AIDS)and cancer are striking both in the laboratory and at the bedside. Much of the fundamental work on AIDS is emerging from cancer research laboratories. The research overlaps at the molecular level. The AIDS virus is closely related to the T-cell leukaemia virus, and discovery of both viruses is claimed by Dr Robert Gallo. The similarity in the viruses is at first sight surprising, for ~IDS and cancer have opposing effects. Whereas vrralleukaemia entails the uncontrolled proliferation of T-cells, AIDS leads to the death of T-cells and crippling of the immune system. The pathogenic human retroviruses have been called 'molecular pirates'P, Five different types have so far been described. The first to be discovered was HTLV-I. This virus can be carcinogenic in its own right and probably initiates viral oncogenesis by affecting the cellular genes that regulate growth. The virus may be latent for many years or the patient may develop adult T-cell ~eukaemia. This may be accompanied by malignant infiltration of the skin in some cases, with the clinical picture of mycosis fungoides or Sezary syndrome. The disease may be further complicated with hypercalcaemia. The precise clinicalsyndromes associated with the laboratory variants and sub-strains require further clarification. In the case of HTLV-III, now called HIV-1 infection, Kaposi's sarcoma (KS) and non-Hodgkin's lymphomas (NHL) are commonplace, involving up to one-third of all patients. The AIDS epidemic is thus being accompanied by a mini-cancer epidemic. These opportunistic cancers probably stem from viral derangement of immune surveillance. Production ?f growth factors in the tissues may also be Involved. At present HIV-1 is not by itself thought to cause malignant transformation. K~ was first described over 100 years ago by Montz Kaposi. The sporadic occurrence of the tumour in older men of Eastern European origin and