| Citation | The log-rank test for comparing sets of censored data (e.g. time of death) in randomised trials was discovered independently by Peto and 3 others. Peto, however, demonstrated its optimal qualities and the clarity of his exposition has led to it becoming the method of choice in the analysis of clinical trials and, increasingly, in animal experiments. He has extended the test for use in experimental oncology to allow the efficient use of data relating both to tumours diagnosed in life or as the cause of death and to those found incidentally at necropsy. More than anyone else he has convinced clinicians that clinical trials need to be large, if small, but important, differences in treatment effects are to be recognized, and has shown that trials on several thousand patients are practicable.
Using Fletcher's data, he showed that chronic bronchitis consisted of two independent processes one of which (hypersecretory/infective) was related to infection and irreversible, though progressing more slowly when smoking was stopped. He devised and analysed large scale studies of skin carcinogenesis in mice, which demonstrated the importance of duration of exposure, the unimportance of ageing, and a decrease in promoting activity with age. Precise quantification of human observational data combined with an understanding of biological mechanisms has enabled him to present new perspectives on the environmental hazards of cancer. |