For the clinical staging of the tumour, necessary for correct planning of the therapeutic approach, the information supplied by the two methods are: the macroscopic appearance of the tumour; its size; its occlusive character; its distance from the anus and exact location (intra- or extraperitoneal).
As for the first, the main forms have already been described. The evaluation of the size plays a major role, particularly with the introduction of protocols of combined and neoadjuvant therapies which necessitate a precise definition. In fact, for a correct assessment of the effects of radiation and/or chemotherapy, the size of primary tumour is required for pre-and post-treatment comparison.
For this purpose, the longitudinal length of the tumour as well as the circumferential involvement, expressed as quarters of circumference, should be defined.
Finally, the diagnostic findings should supply information on the degree of stenosis (expressed as per cent of residual lumen) caused by the tumour and on the short-term risk of intestinal occlusion. These data may be used for the indication for preventive diverting colostomy, when the features of the tumour, after complete staging, suggest pre-opera-tive neoadjuvant treatment.
Similarly important in the planning of surgery is the assessment of the distance from the anal sphincter. For uniform criteria of assessment and for useful information for the surgeon who must decide on the type of surgery, we believe that the most important parameter is the distance between the inferior margin of the tumour and the internal anal orifice. This represents exactly the rectal length that can be used for a conservative operation of the sphincter, excluding the length of the anal canal, which varies from case to case and does not represent a useful segment for intestinal anastomosis. Differential criteria for the diagnosis of intra- or extraperitoneal location are also very important to plan pre-operative treatment. A comparison of double contrast radiology vs. rec-toscopy was carried out in 23 patients with rectal cancer based on the above-described parameters.
In 7 patients (30%) the assessment of the length of tumour was impossible because of the obstacle represented by the neoplastic stenosis across which the endoscope could not be passed. Fifty per cent of these cases were shown to have a circumferential involvement on double-contrast enema and in the other 50% 2/4 of the circumference were involved. Most likely the vegetating component of the tumour hindered the advancement of the instrument. In 16 patients (70%) comparison of results was as follows: in 9 patients (56%) they were concordant; in 7 patients (47%) there was a difference of 1-2 cm and endoscopy tended to indicate a shorter length as compared to the enema.
The assessment of the circumferential involvement of the rectal lumen by the tumour is expressed in quarters of circumference: 18 patients (78%) showed concordant results while discordant results were observed in 5 patients (22%). Rectoscopy in discordant cases assessed 1/4 more than the enema. In the 9 patients with 4/4 circumferential involvement the two methods were fully concordant.
As for the important parameter of the distance of tumour from the internal anal sphincter in the 23 patients under study, in 6 (26.7%) the results were concordant while in 8 patients (34.7%) the results were discordant by only 1 cm. In 9 patients (39.1%) the results were discordant by 2-3 cm and in most cases the tumour was located in the mid-rectum. Rectoscopy tended to exceed the measurement by the enema.
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