Kohn: Cure rates vary with the type of cancer and with the stage of the disease at which treatment is initiated. To make comparisons yuM#stongbetween different cancers, or different stages of cancer, it is necessary to make statistical comparisons. Likewise when seeking to improve the cure rate by some change in the treatment schedule, for example, by increasing the dose by ten per cent or by giving five treatments a week instead of three. Berge; How did they establish a dose, originally, for example, five times a week? Kohn: like Let's say it was five times aweek. especially by the German schoo. In the early days of radiation therapy it was generally held, 4 that the biggest dose (tolerated) given as fast as possible was the best treatment. During the period, roughly 1920-30, Claude Regaud of Paris argued that the differential effect of x-rays on cancer and normal tissues could (befbest obtained by giving the treatment slowly. For example, healing was very much better when skin cancer was treated over a period of a week than in one day. Originally they used a radium applicator, strapped, say, to the arm. When the x-ray machine was introduced in about 1920, they fractionated the treatment - one brief exposure per day for seven days. aynthanbome I began training in 1949, treatment schedules had gradually been improved and become more or less standardizedy For example, treating over the course of five weeks in the case of many types of cancer. a aai PereaLeeEELS oP a nmonearcmneandmeasmsmagen PAGE @ 24 pe ae eeneeerry