Letter: Cancer viruses

Sir: Dr Milton Wainwright suggests (letter, 20 August) that government agencies and charities are misguided in directing research funding into viral infections as potential causes of cancer.

This policy is based on the facts that virus infections are known to account for about 15 per cent of all human cancers and that there are well-established mechanisms by which viruses cause cancer. The only link which has been convincingly demonstrated between bacterial infection and cancer is that between Helicobacter pylori and certain rare forms of stomach cancer. The mechanism is well understood and has no relation to the "pleomorphic bacteria" which Dr Wainwright proposes as significant human carcinogens.

A five-year national study into the causes of childhood cancer has just been completed and the results will soon be reported. This study, funded by a consortium of cancer charities, including the Leukaemia Research Fund, is investigating, among other possible causes, the significance of infections of all types. It is inaccurate to suggest that research into possible infectious mechanisms is confined to viruses alone.

KENNETH CAMPBELL

Clinical Information Officer

Leukaemia Research Fund

London WC1