Dissection
What is required for good pathological reporting? Dissection should be by protocol using the method described here which is consistent with the MRC Clasicc trial , the updated Royal College guidelines and the UKCCCR booklet (1997). Reporting should be by TNM 5 (UICC) and Dukes. The specimen should have the front and back surfaces digitally photographed (preferably prior to inking of any non-peritonealised surfaces) to allow audit of the quality of surgery. The specimen should then be opened down to just above the tumour but not through the tumour. The anterior surface in the area of the tumour should be preserved to allow assessment of this surface for direct and peritoneal spread
Preparation of specimen
The specimen is opened except for the area of the tumour to preserve assessment of the anterior aspect where peritoneal involvement may be seen. Anterior and posterior non-peritonealised surfaces are painted with ink. It should be remembered that the circumferential margin only applies to the surgically incised mesocolic planes and not the peritonealised surfaces. After the resection surfaces have been inked, and the specimen fixed in formalin for a minimum of 2 days, it should then be described and the tumour thinly (3-5mm) sliced transversely from 2 cm below to 2 cm above. The slices should also be photographed as a valuable demonstration of the quality of the surgery and copies of the slides forwarded to the trials office. Three views are required front back and slices with a scale. An assessment of the quality of surgery should be made by the reporting pathologist. A second assessment will be made centrally to identify inter-observer agreement. This will be done on the digital photographs which will be data based.
Not opening the specimen facilitates comparison with MRI/CR imaging.
The distance of direct spread outside the muscularis propria and the distance of spread to local lymph nodes should be recorded. The area in which the tumour spreads closest to the mesocolic surgical margin should be identified. Large blocks should be taken from the area closest to the circumferential margin and any area where the tumour extends to within less than 3 mm from the margin. Any area identified as interesting by the radiologist should also be large blocked. Other blocks should be taken to allow at least 5 blocks of tumour to confirm presence or absence of extramural venous invasion. The number of any large blocks containing tumour can be subtracted from these 5. Likewise the peritoneal surface should be sampled by a minimum of 2 blocks if the tumour impinges on it.
The local lymph nodes should be identified and embedded as should all the lymph nodes above and below the tumour. The tumour should be staged by both Dukes’ and TNM 5 methods. Dukes’ allows easy communication between surgeons and the clinical team whereas TNM 5 gives more prognostic information especially with respect to early tumours and local spread, e.g. peritoneal and direct spread. It is mandatory to fill out the trial proforma to be returned to the trial office. This ensures complete data capture which would otherwise be incomplete. Between 10 and 20 plus blocks will need to be taken. The circumferential margin is considered involved if the tumour extends to within 1 mm of the circumferential excision margin. No distinction is currently made between the various modes of involvement, e.g. direct spread, lymph node spread, vascular, etc. Although all are associated with an increased local recurrence rate, this is lower in the case of involvement by tumour within a lymph node. A measurement of tumour at 1mm or less from a resection margin is considered an incomplete excision. Measurement is best made by using a sheet of graph paper that is photocopied onto a sheet of acetate and cut to size. This will be provided. This is more easily used than the Vernier scale.
Dissection of abdominoperineal resections
