Guidelines for Complications of Cancer Treatment Vol VIII Part B

function. In general, with conventionally fractionatedradiotherapy, the acute normal tissue reactions are withintolerable limits. However, with development of newerstrategies of delivering radiation like, concurrent chemoradiotherapy,accelerated fractionation, and hyperfractionation,the chances of severe acute radiation toxicityare increased manifold.Variables affecting normal tissue toleranceVariables impacting normal tissue tolerance maybe classifiedinto host, organ, tumor, and treatment related factors.Host-related factors include age, individual response toradiation, and comorbid conditions like, collagen vasculardisease and diabetes mellitus.Organ-related variables include pre-radiation organ functioncompromise or loss, volume of organ irradiated, geographicalvariation in the radiosensitivity within the organ, and thefunctional organization of the organ (i e, whether it is a serialor parallel type and if damage to one part affects only thatportion or has more widespread effect).Treatment-related variables include total dose, fraction size,overall treatment time, beam energy and volume irradiated.In a classic pelvic radiation field, the small and large bowelmainly recto-sigmoid, and urinary bladder are at an increasedrisk of treatment-related complications.The common complications encountered in routine clinicalpractice have been discussed in subsequent paragraphs.Gastrointestinal toxicity:A : Small BowelAt the start of pelvic radiation therapy, most patients will havenormal gastrointestinal functions. While on therapy, the normaltissues around the tumour will undergo radiation effects. The266