Category Archives: Residual rectal adenocarcinoma

Predicting residual rectal adenocarcinoma in the surgical specimen: Conclusions

The addition of deep tissue needle biopsy of endosonographically suspicious residual intramural masses, using curvilinear EUS and fine-needle aspiration (FNA) technique, is a possible future solution to this problem, with or without polymerase chain reaction to look for micrometas-tases. However, a negative cytology would still not completely exclude the presence of residual tumour.

One limitation of this study is the poor sensitivity of EUS for N-staging. Nodal re-staging was not a primary endpoint ofthis particular study; we did not expect BT to alter lymph node status because of its limited depth of penetration and its lack of effect on N-staging, as shown in previous studies.

Predicting residual rectal adenocarcinoma in the surgical specimen: Discussion (Part 2)

urgently operatedAlthough higher stage tumours, in theory, could have been more urgently operated on and consequently missed their post-BT EUS, the high prevalence (89%) of stage T3 lesions in our cohort suggests this did not occur. Overstaging by EUS after BT was a significant problem: the inflammation that extends to the serosal edge, producing an irregular margin with small pseudopod-like projections, will likely remain indistinguishable from serosal invasion.

Predicting residual rectal adenocarcinoma in the surgical specimen: Discussion (Part 1)

Also, proportionally, nodal disease was more prevalent in the sterilized group than in the group with residual disease; however, the CI of the difference was wide (Table 2). These negative exploratory analyses lack the statistical power to be definitive. The accurate identification of patients with and without residual tumour after a BT protocol that promises a high tumour sterilization rate in rectal adenocarcinoma would be ideal and could, in theory, lead to less extensive surgical intervention.

Predicting residual rectal adenocarcinoma in the surgical specimen: Results (Part 4)

pathological T-stageIn eight patients (44%; 95% CI 21% to 67%), the pathological T-stage was exactly predicted on the post-BT EUS. Of the remaining 10, seven (70%; 95% CI 42% to 98%) were overstaged, but four of these (40%) were still within one T-stage of the pathological stage. This comparison is summarized in Table 1, with exact matches bolded. Again, the corresponding kappa was poor for agreement beyond chance (0.11). In the post-BT nodal assessments, there were four false negative and two false positive EUS examinations. These correspond to a sensitivity of 50% (95% CI 15% to 85%) and a specificity of 80% (95% CI 55% to 100%).

Predicting residual rectal adenocarcinoma in the surgical specimen: Results (Part 3)

Median follow-up was 6.5 months from the time of recruitment (range two to 14 months). One patient died at nine months without local tumour recurrence; this patient had residual post-BT T3N1 disease by both EUS and pathology and had undergone an anterior resection with negative margins. No other recurrences have been documented.

Performance of post-BT EUS in predicting residual tumour

Predicting residual rectal adenocarcinoma in the surgical specimen: Results (Part 2)

carcinoma in situOne additional patient had only carcinoma in situ. Three of the 11 patients (27%) with residual tumour only had tiny foci of malignant cells, seen in selected blocks. One of the 18 (5.6%) treated had residual T1 disease, one (5.6%) had stage T2 disease and eight (44%) had stage T3 disease. Significant downstaging occurred with significantly fewer patients having stage T3 disease after BT, in the surgical specimen (P<0.001; 95% Cl for difference: 17% to 72%). Mean MWT on EUS decreased from 14 mm to 9.2 mm (P<0.001).

Predicting residual rectal adenocarcinoma in the surgical specimen: Results (Part 1)

Factors predicting residual tumour were assessed from both the pre-BT EUS (proportion with stage T3 disease, proportion with nodal involvement, MWT) and the post-BT EUS (proportion down-staged, absolute reduction in MWT). Unpaired Student’s t tests were used for hypothesis testing involving continuous variables, and the %2 test (or Fisher’s Exact test where appropriate) was used for comparisons of proportions.

Eighteen patients underwent a post-BT EUS assessment for the presence of residual tumour and none had endoclips remaining at this assessment.

Predicting residual rectal adenocarcinoma in the surgical specimen: Surgery and pathological examination

The resected colorectal specimens were fixed in 10% buffered formalin for one to three days, then described and sectioned according to a uniform protocol: multiple longitudinal 5 mm-thick slices were made throughout the abnormal areas, either ulcerated or containing macroscopically visible tumour, and multiple tissue blocks were taken from all of these areas; in most cases, the entire abnormal-appearing regions were submitted for histological examination.

Predicting residual rectal adenocarcinoma in the surgical specimen: EUS

repeat EUS examinationPatients underwent a repeat EUS examination, performed by a single dedicated endosonographer, six weeks (range four to eight weeks) after completion of BT, and within two weeks before the planned surgical resection. The endosonographer was not blinded to the pre-BT EUS results. Patients with mild circumferential thickening of all wall layers, with layer blurring but without a focal hypoechoic mass, were considered to have inflammatory changes but no residual tumour; those thought to have residual tumour were re-staged according the American Joint Committee on Cancer (TNM) classification.

Predicting residual rectal adenocarcinoma in the surgical specimen: BT protocol

All patients were examined by flexible sigmoidoscopy and rectal EUS after completion of their MRI and CT; a pre-BT clinical staging was assigned using the American Joint Committee on Cancer TNM classification . During this examination, after the EUS was completed, endoclips (Olympus Co, USA) were endoscopically placed at the proximal and distal margins of the tumour mass to facilitate BT planning and imaging whenever technically possible.

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