Guidelines for Complications of Cancer Treatment Vol VIII Part B

Time Course of Events: The onset may happen 6 months to10 years after the radiation therapy.Dose/Time/Volume: A rare event as it is and today much fearedby the Radiation Oncology community 12 , statistically accurateestimates are thus lacking. Much of the evidence is thus formsome patients treated in 1970-80s (see table) using high doseper fraction, animal studies, dose models and careful venturesin dose escalations.Author Year Doses Cases IncidenceEichhom et al. 13 1972 27 * 2.45 Gy Ca Lung 17.4% (8/46)Abramson et al. 14 1973 10 * 4 Gy Ca Lung 3.8% (4/103)Radical RTMiller et al. 15 1977 10 * 4 Gy Ca Lung 4% (4/97)Radical RTChoi et al. 16 1980 27 * 2.54 Gy Ca Lung 17% (8/46)PORTDische et al. 17 1981 6 * 5.8 Gy Ca Lung 11% (8/71)Radical RTFitzgerald et al. 18 1982 10 * 4 Gy Ca Lung 17%(6/45)The 5% probability of delayed radiation myelopathy in 5 years(TD5/5) and 50% in 5 years (TD 50/5) values were describedby Emami etal. 19 as:Volume 1/3 rd (5 cm.) ½ (10 cm) 3/3 (20 cm)TD 5/5 50 Gy 50 Gy 47 GyTD 50/5 70 Gy 70 Gy -This underlies the traditional prescriptions of keeping the corddose below 45Gy/ 23-25#/4.5-5 weeks. Few salient clinicalstudies that challenged these estimates when treated byconventional fractionation (1.8 to 2 Gy/#/day) found theincidence as:332