Numerous trials have been done over the years to evaluate the oncological merits of the two operations and no difference in the pelvic recurrence rate or disease-free survival has been demonstrated. There are no randomised studies to confirm this and such a study will probably not ever be done. So, the general opinion held is that a correctly performed AR for a rectal cancer should not decrease the curative potential when compared to an APR, and should give as good a long-term cure as the APR.
The appearance of a local pelvic recurrence both after an AR or an APR has been a disappointing event over the years but the recent introduction of total mesorectal excision (TME) - a proper anatomical dissection technique advocated by Heald et al. , has been a great step forward by reducing the recurrence rate considerably. Special attention is directed towards the importance of a TME - which rests on the recognition of the distal mesorectum as a possible site of tumour spread - and on the recognition of an inadequate circumferential margin outside the mesorectal fascia . Subsequently the removal of the distal mesenteric tongue has been considered excessive as a standard procedure. Therefore - in its present form properly defined - the TME with complete excision of the visceral mesorectal tissue down to the level of the levators is recommended mainly for distal mid- and lower rectal cancer (at or below 12-13 cm above the pectinate line); whereas for the upper third or rectosigmoidal cancer a tumour-specific mesorectal excision (TSME) should be preferred, which means a precisely perpendicular and circumferential excision of the mesorectum to the level of an appropriate resection margin distal to the tumour. The current most popular view is that the distal intramural spread below the tumour is a rare event and a free distal margin of 2 cm below the tumour is considered adequate .
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