Guidelines for Complications of Cancer Treatment Vol VIII Part B

therapy (3D-CRT) and intensity modulated radiation therapy(IMRT) in contemporary oncologic practice. The incidenceof RAM is hypothesised to increase with the use of newtechniques compared to conventional RT due to followingreasons:(a) More number of beams is used for treatment in 3D-CRTand IMRT which resulting in a more conformal dosedistribution to target but at the expense of low-doses tomore normal body volume outside target area.(b) The beam ON time is longer with these techniquesresulting in is higher total body low-dose exposure dueto more leakage and scatter.At the same time it is expected that 3D-CRT/IMRT may resultin irradiation of smaller volumes which may possibly reducethe whole-body integral dose that might reduce incidence ofRAM. Therefore exact risk modelling with 3D-CRT/IMRT isdifficult as the spatial distribution of dose, sensitivity of variousirradiated organs and leakage are variable. Studies with longerfollow up of patients treated with conformal techniques willprobably answer these questions (7).Disease-specific SMNs:Hodgkin’s disease: Long-term survivors of Hodgkin’s disease(HD) are at increased risk of leukaemia, non-Hodgkin’slymphoma (NHL) and solid tumor which have been correlatedwith carcinogenicity of alkylating agents of chemotherapy andradiotherapy. In a study of 1319 patient of HD (majoritypatients with early stage disease) treated at Dana Faber CancerInstitute between 1969 to 1997 with a median follow up of 12years, 15 and 20 years cumulative incidence of SMN was 14%and 23% respectively. Relative risk (RR) for leukaemia, NHLand solid tumor were 82.5, 16.5 and 3.5 respectively whichcorresponds to excess absolute risk of 14.2, 14.3 and 59 per10,000 person-years. RR was significantly higher for combined285