IN SEARCH OF A DOSE-RESPONSE RELATIONSHIP WITH RADIOTHERAPY IN THE MANAGEMENT OF RECURRENT RECTAL-CARCINOMA IN THE PELVIS - A SYSTEMATIC REVIEW

Purpose: A systematic review of the literature was undertaken to addre ss the question: ''What is the most effective dose fractionation sched ule for the relief of symptoms in patients with pelvic recurrence from rectal or colorectal carcinoma?'' Methods and Materials: Cancerlit/Me dline-computerized databases were searched between the years 1966-1996 . Studies that explored the response to radiotherapy in patients with pelvic recurrence from rectal/rectosigmoid carcinoma were included, Fa ctors that may contribute to differences in results were postulated in advance and the variations encountered between articles were presente d, Articles with data applicable to recurrent disease only were includ ed in the primary analysis, The effect of including articles that repo rted outcomes of recurrences with unresectable primaries and residual disease was presented as a sensitivity analysis. Results: Only retrosp ective series (level V evidence) were available, The many sources of p otential bias inherent in retrospective analyses make the data suitabl e for hypothesis generation only, Comparison of response was made betw een ''lower'' vs, ''higher'' doses, using 45-50 Gy as the dividing dos e, base on the primary analysis, There were no significant differences observable in terms of initial response and the proportion maintainin g a response at 6 months, within the range of doses employed, When dat a from articles that reported outcomes of recurrent disease with prima ry untreated cancers and postoperative residual disease were included, there was a suggestion for a more favorable response with higher dose s, This requires cautious interpretation within the methodological lim itations of the data, Conclusion: The optimal dose fractionation sched ule for the palliation of pelvic recurrence from rectal carcinoma rema ins undefined, Well-designed randomized studies, with study arms that are sufficiently diverse biologically to allow the detection of a dose -response relationship if one existed, equipped with suitable symptom control end points, are necessary to provide a clinically relevant ans wer, (C) 1998 Elsevier Science Inc.