Guidelines for Complications of Cancer Treatment Vol VIII Part B

With these doses, the rate of necrosis is less than 1%. Tolerancedoses of the upper vagina and surface of the distal vagina are140 Gy and 100Gy, respectively. Threshold doses reportedfor vesico-vaginal fistula is 150Gy and for recto-vaginal fistulais 80 Gy (4). Hence a combination of external andbrachytherapy is offered to cervical cancers. The radiationinduced side effects and their manifestations depend on thetype of tissues receiving radiation i.e. early or late respondingnormal tissues and the radiation tolerances. Early respondingtissues like, the skin and intestinal mucosa have a high cellturnover rate and they express radiation injury earlier, at about2 to 3 weeks. Conversely, late responding tissues, like spinalcord, rectum, bladder, or kidneys have a slow cell turnover ornon-proliferating, thus expressing radiation injury many yearslater after treatment.Classification of Radiation Induced ReactionsBroadly, reactions may be divided into acute, subacute andlate. Acute reactions are those which manifest while ontreatment or within 3 months, subacute reactions arise between3 to 6 months and late reactions become apparent after 6months of treatment. Adverse event (AE) reporting in oncologyhas evolved from unceremonious metaphors to a highlysystematized method. The Common Terminology Criteria forAdverse Events (CTCAE) is the principal system fordescribing the severity of AE’s commonly encountered inoncology clinical studies. CTCAE clinical descriptors havebeen developed empirically during more than 30 years of use.The method of data collection is clinician based. Limitationsof the CTC system include potential for incomplete reportingand limited guidance on data analysis and presentationmethods.Early reactions manifest clinically during the course ofradiotherapy, and are generally due to mitotic-linked cell deathin rapidly dividing tissues and secondary impaired tissue265