Radiosensivity of Tumor Cells: The Predictive Value of SF2

Abstract

Early the history of radiation therapy, clinicians recognized that some tumor entities can be controlled considerably more easily by radiation therapy than others (Wetterer 1913–1914; Holthusen 1936; Paterson 1948.) Table 8.1 summarizes the ranking of the radiosensitivities of selected tumor histologies. The judgment of the responsiveness of different tumors has changed little from Paterson’s textbook, published in 1948, to recent reviwes such as Wang’s textbook from 1988. Today, knowledge of the relative radiosensitivities of tumors of given histologies and grades, together with careful assessment of tumor size, stage, location, and patient characteristics such as sex, age, hemoglobin level, and Karnofsky score, forms the basis of prediction of the outcome of radiation therapy in individual patients (Peters et al. 1986, 1988; Suit and Walker 1988; Bentzen et al. 1991). Typical examples of radiosensitive tumors are seminomas and lymphomas, with total doses of 30–45 Gy being highly effective in achieving local tumor control (Rubin etal. 1974; Perez and Brady 1992). Adenocarcinomas and squamous cell carcinomas are generally considered moderately radiosensitive: if not too large, these tumors are radiocurable by doses between 50 and 75Gy (Rubin etal. 1974; Perez and Brady 1992). A uniquely radioresistant tumor is glioblastoma multiforme: This entity is almost never controlled permanently by radiation doses between 60 and 80 Gy (Davis 1989), and in-field recurrences have been reported even after doses as high as 115 Gy (Loeffler et al. 1990a, b).