J Clin Pathol 1985;38:385-389

Mucosal abnormalities at the anastomosis site inpatients who have had intestinal resection for coloniccancerJP SUNTER, MJ HIGGS,* WK COWAN

From the Departments ofPathology and *Surgery, Queen Elizabeth Hospital, Gateshead, and the DepartmentofPathology, University ofNewcastle upon TyneSUMMARY Twenty eight patients with colonic cancer, who were asymptomatic after intestinalresection and anastomosis, underwent colonoscopy as part of their routine follow up, and biop-sies were obtained from the anastomosis and several other sites. Sections were stained byhaematoxylin and eosin, several methods for mucin, and by the peroxidase-antiperoxidasemethod for carcinoembryonic antigen. Non-specific inflammatory changes were seen at the anas-tomosis in 11 of the 28 cases, apparent in several two years after operation; focal surfaceulceration was seen in over half these samples. Neither dysplastic nor adenomatous change wasdetected, but at seven anastomoses the so called transitional-change, which has been regarded asa preneoplastic change, was apparent. There was no consistent alteration in carcinoembryonicantigen reactivity.

It is concluded that there is morphological evidence of a continued stimulus to regenerativeactivity at some anastomoses and that this may represent a promoting factor enhancing furthercarcinogenesis.

Surgical resection is the only form of treatmentwhich offers any real hope of cure in cases of col-orectal cancer. More than half of all patients withthe disease present at a stage when a resectiondesigned at producing cure appears possible.' Butafter operation some of these patients will die of theeffects of metastatic disease not apparent at resec-tion, while others will succumb to the effects of localrecurrence. These local recurrences account for thedeaths of perhaps 10-15% of individuals who havehad "curative" resections' 2 and may develop in theperitoneum or in the abdominal wound, but are par-ticularly likely to arise at the site of the intestinalanastomosis. The development of carcinoma at theanastomosis has conventionally been regarded as

representing a true recurrence of the original prim-ary growth, due either to inadequacy of local resec-

tion in the first place or to implantation of exfoliatedbut viable tumour cells during the operation. Thereis no doubt that some anastomotic cancers must rep-

resent what is, in effect, a failure of surgical techni-que. There are, however, a number of reasons forconsidering the possibility that anastomotic cancersin fact represent second primary growths, thedevelopment of which has been promoted by some

abnormality at the anastomosis.In the first place large bowel cancer is not infre-

quently a multicentric disease, and both synchron-ous and metachronous carcinomas are not uncom-mon.34 It is perhaps not surprising therefore that

Accepted for publication 12 December 1984

385

generalised mucosal abnormalities have beendescribed in the non-neoplastic mucosae of patientswith ordinary large bowel carcinoma and that theseabnormalities have been regarded as havingsignificance as a preneoplastic state.5'7 If this is truethe promoting influences resulting from the pres-ence of an intestinal anastomosis might result inneoplastic development in the mucosa at that site, achange which would not occur in the absence of suchinfluences. It is noteworthy in this context that localrecurrence is more common in cases of carcinoma ofthe rectosigmoid treated by anterior resection thanin cases treated by abdominoperineal resection,regardless of the margin of clearance of the tumour.8While part of this difference may be accounted forby differences in the extent of clearance of perirectalsoft tissue, another important factor could well bethe presence in the anterior resection cases of ananastomotic line.

In the animal models of colorectal carcinogenesiswhich involve the administration of chemical car-cinogens there is a striking tendency for primarycolonic neoplasms to arise at sites of intestinal anas-tomosis. This is true regardless of whether the con-struction of the anastomosis precedes9 or follows'"carcinogen treatment, suggesting that some pro-liferative instability induced by the presence of theanastomosis may be a critical factor determining thesite at which successful neoplastic developmentoccurs. Perhaps of even greater interest, given theexceptional rarity of spontaneous intestinal car-cinomas in laboratory rodents, are observations

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relating to the development of adenocarcinomas incolostomy sites in rats not subjected to carcinogentreatment" and even occasionally in the colonicanastomoses of control animals being used in car-

cinogenicity studies.'2In view of these arguments it would seem prob-

able that at least some anastomotic recurrences inhuman patients do constitute metachronous sutureline primaries," and this has implications as far as

patient management is concerned. The investigationof patients with established carcinoma at the anas-

tomosis site can give information of only limitedvalue, since it is difficult to be sure on pathologicalgrounds whether the tumour is a recurrence or a

second primary even in the presence of some

unusual histological feature, and such a distinction isquite impossible in the case of more ordinarygrowths. Several morphological abnormalities oflarge intestinal mucosa have been described, how-ever, in situations associated with an enhanced riskof development of colonic cancer-56 and theirsignificance as preneoplastic phenomena implied,while the subsequent dysplasia-carcinoma sequence

is now generally accepted.'3 We have thereforeinvestigated by means of colonoscopy and biopsythe anastomosis site in a group of healthy patients,who had previously had surgical resection for col-onic cancer, in order to document any early mucosalchanges which might imply de novo tumorigenesis.

Material and methods

The study group consisted of 28 asymptomatic indi-viduals who were being routinely followed as outpa-tients after intestinal resection and immediate anas-

tomosis for tumours of the large bowel. None of thepatients suffered from inflammatory bowel diseaseor polyposis-in other words, their tumours hadbeen ordinary large bowel neoplasms. In every case

a "curative" resection had been performed andmargins of resection had been judged adequatepathologically. As part of the routine follow up eachindividual was subjected once to colonoscopicexamination. The colonoscopies were staggered so

that observations were included from about 6months after resection (an interval considered longenough to allow for normal mucosal healing), about12 months after resection, and about 24 monthsafter resection. Care was taken to ensure that thewhole colon was visualised, and any areas ofabnormality-for example, polyps-were biopsied;particular attention was paid to the state of the anas-

tomosis. Multiple mucosal biopsies (usually three or

four pieces) were obtained from the site of the anas-

tomosis and also from apparently normal colonicmucosa proximal and distal to the anastomosis (inleft sided resections) and distal to the anastomosis incases where right hemicolectomy and ileocolic anas-

tomosis had been performed.

Sunter, Higgs, Cowan

The biopsies were fixed overnight in neutral buf-fered formol-saline solution and then routinely pro-cessed and embedded in paraffin wax. Multiple dup-licate histological sections 4,um thick were preparedat several levels. One set was stained immediatelywith haematoxylin and eosin for diagnostic purposesand a histopathological assessment made. The restof the sections were retained unstained and subse-quently were batched for further staining proce-dures. These consisted of several stains for mucus-that is, the periodic acid Schiff reaction after pre-treatment with diastase, the high iron diamine/alcianblue (pH 2-5) technique'4 and Shikata's orceinmethod,'4 and a peroxidase-antiperoxidase method(Dako) for carcinoembryonic antigen.When all the histological material had been

assembled the slides, including the originalhaematoxylin and eosin stained sections, wereassessed blindly by two observers.

ResultsPATIENTSOf the 28 patients who comprised the study groupthere were 15 men and 13 women. The mean age atcolonic resection for the men'was 62 years (range27-78) and for the women 67 years (range 38-79).In 12 cases the tumour was situated in the caecum orascending colon and in one case the growth was inthe proximal transverse colon; these individualswere treated by right hemicolectomy and thus hadileo-colic anastomoses. Four patients with tumoursof the descending colon were treated by lefthemicolectomy and the 11 with growths of the sig-moid colon or upper rectum by sigmoid colectomyor anterior resection; these patients therefore hadcolonic anastomoses. In all cases the anastomoseswere fashioned by hand in two layers using routinelyblack silk sutures and catgut. Histologically, thetumours proved unequivocally to be primary colonictumours of epithelial origin. There were nine welldifferentiated adenocarcinomas, 12 moderately welldifferentiated adenocarcinomas, and six poorly dif-ferentiated adenocarcinomas; one lesion was finallyclassified as a large benign tubulovillous adenoma.In all cases resection was judged adequate and theoperations could therefore be considered "cura-tive." Synchronous tumours were seen in the resec-tion specimen, or were visualised and biopsiedendoscopically before the resection, in five patients.In one case the synchronous tumour was a secondcarcinoma, while in the other four the lesions weresingle small tubular adenomas. A further threepatie'nts had coexistent metaplastic polyps.

Following resection all the patients recovereduneventfully and appeared to be healthy on subse-quent follow up. None had any symptoms whichcould possibly have been related to abnormalities atthe site of the anastomosis when colonoscopy was

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Changes at colonic anastomoses

performed. This took place about 6 months afterresection in five patients, about 12 months afterresection in 12, and about 24 months after resectionin 11.

COLONOSCOPIC FINDINGSColonoscopy was usually easy in these patients,especially those who had had left sided resections,and an adequate view of the colorectal mucosa andthe anastomosis site was obtained in all patients.The anastomosis was discernible as a region of

attenuation of the normal pattern of mucosal folds,and in some cases a puckering of the mucosa wasevident. Black silk sutures were quite often visiblethrough mucosa which was obviously intact, but insome five cases there was clear evidence ofinflammation; in two cases small polypoidal masses,apparently of granulation tissue, were seen. In onlyone case was there the suggestion of any tumourrecurrence and this was in fact negative histologi-cally (see below). There was no evidence of stenosisat any anastomosis.

In most patients the general colonoscopic findingswere essentially negative, although so calledmelanosis coli was common. In five individualssingle small polyps remote from the site of the anas-tomosis were visualised and biopsied; these provedto be benign tubular adenomas. Three more indi-viduals had several simple metaplastic polyps.MICROSCOPICAL CHANGES AT THEANASTOMOSISNo appreciable technical difficulties in obtainingmucosal biopsies from the anastomosis site wereexperienced, the samples from the anastomosisbeing similar in size and state of preservation tothose obtained from other sites in the bowel. Inspec-tion of haematoxylin and eosin stained sections ofthe latter showed no evidence of any generalisedmucosal abnormality in any case.The haematoxylin and eosin preparations of the

anastomoses showed that in most cases the mucosawas perfectly normal and indistinguishable from thesamples obtained from other parts of the bowel. In11 cases, however, they showed clear evidence ofmucosal inflammation. In some fragments this evi-dence consisted merely of a slight increase in thenumbers of mononuclear cells in the lamina propria(Fig. 1), but in most cases the changes were morestriking. They were apparent in two of five patientsexamined 6 months after resection, six of 12 at 12months, and three of 11 at 24 months, and weretherefore not related merely to a short postoperativetime interval. In a number of cases showinginflammation at the anastomosis there was also evi-dence of ulceration (Fig. 2) or even the formation ofexuberant granulation tissue (Fig. 3). Occasionally,the formation of granulation tissue was obviouslyrelated to the presence of suture material; taken

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Fig. 1 Mucosa from an anastomosis site 12 months aftercolonic resection showing minimal inflammatory changeevidenced by a slight increase in the numbers ofmononuclear cells present in the lamina propria.Haematoxylin and eosin. x 300.

overall there was evidence of mucosal ulceration atthe anastomosis in two of five patients seen at 6months, three of 12 at 12 months, and two of 11 at24 months. Those cases with more florid inflamma-tory changes corresponded with those which had

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As :,, A es* 4W,I*'

Fig. 2 Mucosa from an anastomosis 12 months afterresection showing active inflammatory change includingsuperficial mucosal ulceration. Haematoxylin and eosin.x 150.

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Sunter, Higgs, Cowan

Fig. 3 Exuberant granulation tissue present at ananastomosis at 24 months after resection. Haematoxylin andeosin. x 150.

been abnormai endoscopically, and both right andleft sided anastomoses were affected.

In several of those cases in which inflammatorychanges were apparent there were accompanyingdisorders of crypt architecture. These abnormalitiesincluded areas of crypt elongation or dilatation andexamples of distorted or branched crypts. In twocases, one of which is illustrated (Fig. 4), somechanges were sufficiently conspicuous as to warrantconsidering the possibility of transitional change onthe strength of haematoxylin and eosin stained sec-tions alone. There was no evidence in any case ofeven mild dysplastic change, however, and no evi-dence of recurrent or de novo carcinoma in any ofthe samples. No fibrosis of the lamina propria wasapparent.

Staining by the diastase-periodic acid Schiffmethod made clear the presence of so calledmelanosis coli in most cases, but the extent of thisabnormality was similar in the anastomoses and inthe bowel as a whole. No obvious change in thepattern of mucin production at the anastomosis wasseen in the section stained by diastase-periodic acidSchiff and Shikata's orcein method. Changes were,however, often demonstrable in the sections stainedby the high iron diamine/alcian blue method. Inseven cases one or more mucosal samples from theanastomosis showed the overwhelming predomi-nance of sialomucins characteristic of the transi-tional mucosa. And in other samples a mixed pat-tern of mucin production was apparent, the picturebeing neithler that of normal left colon nor that of

Fig. 4 Abnormal mucosa oftransitional patern present atan anastomosis 12 months after resection. Haematoxylinand eosin. x 150.

normal right colon. This mixed pattern of mucinproduction was seen elsewhere in the bowel in ninepatients, and it is thus difficult to regard it as particu-larly important, but transitional change did appearto be confined to the site of the anastomosis. Inorder to exclude the possibility that change mayhave been present at the time of the original surgicalresection-that is, that it was not acquired subse-quent to anastomosis-sections from the line ofresection blocks from the original surgical resectionswere stained by methods for mucin. Transitionalchange was not apparent in this material.The intensity of epithelial carcinoembryonic anti-

gen positivity varied from case to case, but no con-sistent change in the pattern of expression at theanastomosis site was discerned.DiscuWsonFor the reasons outlined previously it is quite poss-ible that suture line tumours represent metachron-ous primary growths, but this hypothesis is difficultto prove. In view of the obvious difficulties in inter-preting the changes apparent in established sutureline malignancies this study was designed to investi-gate whether any preneoplastic alteration in thecrypt cells could be detected at the site of healthyanastomoses. It is now generally accepted thatmalignancies of the large bowel arise as a result of aprogre-ssion from various abnormalities described as

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dysplasias, both in the case of ordinary large bowelcancer'3 and in the setting of carcinomas complicat-ing inflammatory bowel disease.'5 But dysplasticchanges were not seen at the anastomoses, and itwould thus appear that fully acceptable evidence ofthe earliest changes of de novo tumorigenesis is lack-ing. Other changes at the anastomosis site werecommon, however, and, given the small numbers ofpatients included in this study and the relativelyshort follow up period, these may well be of impor-tance in indicating the possibility of an enhancedrisk of tumour development at the anastomosis.

Perhaps the most striking of these changes was theemergence at the anastomosis in seven cases ofpatchy transitional change, with a switch from adominance of sulphomucin production within thecrypt to almost entirely sialomucin production. Thischange has long been recognised in the vicinity ofprimary colonic carcinomas both in man'6 and inexperimental colonic cancers in rats'" and its impor-tance as a preneoplastic change has been sug-gested.'8 While transitional change has recentlybeen described in situations not obviously related tothe development of cancer and its significance as apreneoplastic phenomenon has been questioned,'9 20debate continues.2' It may well be that in the presentmaterial transitional change is merely a regenerativeeffect and that this is what accounts for its localisa-tion to the anastomosis; but the alternative interpre-tation is still possible. Those cases in which it wasmanifest were not conspicuously those withadenomas, which is another index or risk of meta-chronous cancer development;22 nor was itspresence related to Dukes' stage of differentiationof the original tumour.

Inflammatory changes at the anastomosis wereseen in 11 cases, often with associated ulceration,and these changes were apparent up to 24 monthsafter resection, indicating a degree of chronicity.Since it is generally accepted that any stimulus tocontinued cell proliferation can act as a promotinginfluence in the process of neoplastic development,this inflammation could certainly act to localise thedevelopment of a metachronous tumour to the anas-tomosis. The precise cause of the inflammation andulceration is not clear, but it may well be related tothe presence of sutures.

In conclusion, we have found no definite evidenceof precancerous change at the sites of large intestinalanastomoses; there are, however, often quite strik-ing morphological abnormalities which suggest thatthe anastomosis is especially vulnerable to de novotumorigenesis. More intensive study is required,using greater numbers of patients, and perhaps

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especially looking at anastomoses which have beenpresent for several years before we can be sure thatlarge bowel anastomosis in patients with cancer doesnot in itself present a significant cancer risk.

We thank the technical staff of the HistopathologyLaboratory, Queen Elizabeth Hospital, for theirexpert assistance; Mrs A Hogarth and Miss D Scottfor typing successive versions of the manuscript; andMr S Brabazon for preparing the illustrations.

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Requests for reprints to: Dr JP Sunter, Department ofPathology, Queen Elizabeth Hospital, Sheriff Hill, Gates-head, Tyne and Wear NE9 6SX, England.

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