Tumor implantation on colonmucosa

Synchronous polypectomy during endoscopic diagnosis of colorectal cancer - is the risk of tumour implantation at the polypectomy site significant?

Background

Synchronous polypectomy in colonic malignancies is contentious due to the perceived risks of tumour implantation at polypectomy sites (PS). We assess the risks of tumour implantation after synchronous polypectomy.

Methods

An analysis of all endoscopies for cancer that were accompanied by synchronous polypectomies from 2005 to 2009 was performed. The incidence of metachronous colorectal cancers located at the same segment of a previous PS was the surrogate for tumour implantation. Data on patient demographics, tumour and polyp location(s) and follow-up outcomes were extracted. The rate of metachronous lesions at the same segment of a previous PS between patients who had all synchronous PS resected (Group A) and patients with PS left in-situ (Group B) were compared.

Results

Two hundred and eighty-four patients had synchronous polypectomy performed during their initial endoscopy for cancer. Three patients were lost to follow-up and, in the remaining 281 patients, 87 (31.0%) were in Group A while 194 (69%) were in Group B. Median age, gender, tumour location, tumour stage, and pathological characteristics were similar between both groups. 2 (0.7%) patients developed local recurrences. Six (2.1%) patients developed metachronous lesions, four of which were located at the same segment where synchronous polypectomy was previously performed. The rates of metachronous lesions at the PS in groups A and B were similar at 1.1% (1/87) and 1.5% (3/194), respectively (p = 0.795).

Conclusion

Malignant implantation after synchronous polypectomy in the setting of a newly diagnosed cancer remains unproven. Even if tumor implantation did occur, the incidence is likely low.

Operative vectors, anatomic distortion, fluid dynamics and the inherent effects of pneumatic insufflation encountered during transanal total mesorectal excision

BACKGROUND

Transanal total mesorectal excision (taTME) is an altogether different approach to rectal cancer surgery, and the effects of carbon dioxide (CO₂) on this dissection remain poorly described.

METHODS

This article critically examines the effect of carbon dioxide insufflation and the workspace it creates during the process of taTME. The unique aspects of insulation with this approach are governed by the laws of physics, especially the principles of fluid dynamics, an area that remains poorly described for laparoscopy and not at all described for taTME.

RESULTS

A summary of established factors which affect the operative field of the taTME surgeon is delineated and further explored. In addition, new concepts regarding gas delivery, such as insufflation vectors, anatomic distortion, hyper-dissection, and workspace volume rate of change as a function of taTME dissection time, are addressed. Collectively, these factors pose important challenges which increase case complexity and are thus essential for taTME trainers and trainees alike to understand.

CONCLUSIONS

Although an invisible gas, CO₂ insufflation with taTME produces markedly visible effects which are imposed upon the operative field. This can result in anatomic distortion and misperception of operative planes. Thus, practicing taTME surgeons should be cognizant of these effects.

Critical concepts and important anatomic landmarks encountered during transanal total mesorectal excision (taTME): toward the mastery of a new operation for rectal cancer surgery

Over the past 3 years, colorectal surgeons have begun to adapt the technique of transanal total mesorectal excision. As international experience has been quickly forged, an improved recognition of the pitfalls and the practical details of this disruptive technique have been realized. The purpose of this technical note was to express the various nuances of transanal total mesorectal excision as learned during the course of its clinical application and international teaching, so as to rapidly communicate and share important insights with other surgeons who are in the early adoption phase of this approach. The technical points specific to transanal total mesorectal excision are addressed herein. When correctly applied, these will likely improve the quality of surgery and decrease morbidity attributable to inexperience with the transanal approach to total mesorectal excision.

Endoscopic excision of synchronous large bowel polyps in the presence of colorectal carcinoma: is the fear of malignant cell implantation justified? A systematic review of the literature

AIM

A systematic review of the literature was performed to establish evidence to support the practice that in the presence of a colonoscopically diagnosed colorectal cancer immediate endoscopic excision of synchronous polyps should not be performed due to the risk of malignant cell implantation at the polypectomy site.

METHOD

A systematic literature search was performed using Medline, Embase and the Cochrane Central Register of Controlled Trials to identify studies comparing the rate of implantation of colorectal cancer cells in normal and damaged colonic mucosa and reports of colorectal cancer cells seeding into sites of damaged mucosa after polypectomy.

RESULTS

No randomized controlled trials were identified. Three studies involving mammalian models of colonic mucosal damage were included. Pooling relevant results revealed that out of 59 exposed mammals only one developed tumour cell implantation at a site of colonic mucosal damage. This equates to a mammalian in vivo experimental risk of malignant cell implantation of 1.6%.

CONCLUSION

The topic of colorectal cancer seeding following endoscopic procedures has received little attention. This review suggests that in the presence of a proximal colonic carcinoma there is a negligible risk of malignant implantation if a more distal polyp is endoscopically excised.

Intersphincteric resection and coloanal anastomosis in treatment of distal rectal cancer

In the treatment of distal rectal cancer, abdominoperineal resection is traditionally performed. However, the recognition of shorter safe distal resection line, intersphincteric resection technique has given a chance of sphincter-saving surgery for patients with distal rectal cancer during last two decades and still is being performed as an alternative choice of abdominoperineal resection. The first aim of this study is to assess the morbidity, mortality, oncological, and functional outcomes of intersphincteric resection. The second aim is to compare outcomes of patients who underwent intersphincteric resection with the outcomes of patients who underwent abdominoperineal resection.

Options for sphincter preservation in surgery for low rectal cancer

BACKGROUND

Abdominoperineal excision of the rectum with a permanent end-sigmoid colostomy was the classical operation for cancer of the distal third of the rectum. A number of factors have recently led to a more conservative approach, allowing sphincter preservation when excising tumours that are not invading the anal sphincter.

METHODS

The review is based on the published literature of the treatment of low rectal cancers accessed by searching Medline and other online databases. It includes a description of all the surgical options currently available for low rectal tumours, and a discussion of the advantages and disadvantages of the types of anastomosis and reconstruction.

RESULTS AND CONCLUSION

It is now technically possible to remove rectal cancer that is extending into the anal canal with preservation of the anal sphincter mechanism and with a satisfactory oncological outcome. Ultra-low colorectal and coloanal anastomosis, together with a colonic pouch or coloplasty, produces acceptable function in many patients. However, there is still controversy about the risk of tumour implantation, the place of downsizing neoadjuvant therapy, and true long-term functional outcome. Despite these concerns, surgeons should strive to perform rectal resection with sphincter preservation for low-lying rectal cancer whenever possible.

Model of implantation of tumor cells simulating recurrence in colonic anastomosis in mice

PURPOSE

Local recurrence after colorectal cancer surgery is usually perianastomotic. An experiment was designed to investigate whether free intraluminal cells can penetrate through a colonic anastomosis and thereby cause local recurrence.

METHODS

BALB/c and C57/BL mice underwent ascending colotomy followed by watertight anastomosis. Thereafter, CT-26 murine colon carcinoma cells were injected into the cecal lumen 2 cm proximal to the anastomosis of syngeneic BALB/c mice, whereas B-16 murine melanoma cells were injected in the same fashion into C57/BL mice. Control animals without anastomosis received similar injections. Animals were killed 24 hours, 72 hours, and 30 days after surgery and were checked for tumorigenesis.

RESULTS

Results of peritoneal fluid cytology were negative after 24 hours, whereas after 72 hours cancer cells were identified in the peritoneal fluid of 80 percent of mice with colotomy and anastomosis compared with 20 percent of control mice. Thirty days after surgery, 11.1 percent of the control BALB/c mice developed pericecal tumor growth, similar to the overall rate of murine melanoma in C57/BL. In mice with anastomoses, perianastomotic tumor growth was observed in 47.5 percent of BALB/c mice (P < 0.001) and was correlated with the number of injected cells. Tumor growth reached approximately 75 percent tumor take with high cell densities, whereas in C57/BL mice no difference was found between the experimental and control groups.

CONCLUSIONS

The findings suggest that free intraluminal cancer cells of colonic origin may penetrate through watertight anastomoses and implant on the anastomotic or peritoneal surface and initiate tumor growth. This anastomotic penetration is cell-mass dependent. The reported experimental model is simple, reproducible, and advantageous for studies of colonic anastomosis.

A laparoscopic triple stapling technique that facilitates anterior resection for rectal cancer

A new technique that facilitates laparoscopic anterior resection is described. The technique is a modification of a triple stapling technique that the authors currently use for conventional anterior resection of the mid- and low-rectal cancers. The new laparoscopic technique may reduce the risk of staple line or port site recurrence.

Effect of fibrin sealant on perianastomotic tumor growth in an experimental model of colorectal cancer surgery

Viable intraluminal tumor cells can penetrate a clinically intact rodent colonic anastomosis and give rise to perianastomotic tumor growth. The aim of this study was to determine whether transanastomotic cell migration can be prevented by fibrin-based tissue sealant. Following distal colonic transection and reanastomosis with 5/0 silk sutures, Fischer F344 rats were randomly allocated to three experimental groups. In Group A, a circumferential ring of tissue sealant was placed around the serosal surface of the anastomosis; in Group B, sealant was limited to 50 percent of the anastomotic circumference; and, in Group C, no sealant was applied. All rats then had 10(5) Mtln3 carcinoma cells injected into the proximal colonic lumen via a rectal catheter. The incidence of perianastomotic tumor at 21 days was significantly lower in Group A (3 of 14 animals) than in Group B (11 of 16 rats) (P = 0.012; Fisher's exact test) or Group C (10 of 14 rats; P = 0.011). A further experiment demonstrated that sealant did not protect the anastomosis when tumor cells were instilled directly into the peritoneal cavity. A topical carcinocidal action therefore appears unlikely, but our results suggest that a circumferential anastomotic ring of fibrin sealant forms an effective mechanical barrier preventing intraluminal tumor cells from reaching the peritoneal cavity.

Local recurrence after anterior resection for rectal cancer using a double stapling technique

Fifty-five patients of mean age 69 (range 41-96) years with rectal cancer (Dukes' A:B:C, 11:24:20) underwent anterior resection using a double stapling technique under the care of one consultant surgeon between 1983 and 1988. The mean distance of the anastomosis from the anal margin was 7.2 (range 4-13) cm. The clinical leak rate was 9 per cent (five patients). There were three postoperative deaths from pulmonary embolism, lower limb ischaemia and renal failure. On prospective follow-up, 35 patients had no evidence of local or systemic cancer a median of 32 (range 24-84) months after operation; seven have died from unrelated diseases and ten from metastatic cancer. Pelvic recurrence, in four patients at 9, 11, 12 and 50 months, has occurred only in association with widespread metastasis. These results suggest that the theoretical risks of an increase in the local recurrence rate of rectal cancer after resection using a double stapling technique are not substantiated.

Sutureless intestinal anastomoses

Sutureless intestinal anastomoses can be achieved either by compression, where two inverted rings of bowel are compressed by a hollow circular device that subsequently sloughs away and is passed anally, or by the use of tissue glues or laser welding. Compression devices used clinically with success are the Valtrac biofragmentable anastomotic ring, the polypropylene rings described by Rosati and the AKA guns. Glued anastomoses have only been used in animals and seem to be unsafe. However, laser-welded intestinal anastomoses appear highly promising in experimental studies and further development of this technique is warranted.

Importance of the omentum in the development of intra-abdominal metastases

Areas of trauma are preferred sites for metastatic tumour growth. In extensive intra-abdominal tumour recurrence the omentum is invariably involved. The importance of the omentum in the development of tumours at sites of intra-abdominal trauma has been investigated. Colonic anastomoses were performed in Hooded-Lister rats with and without omentectomy. Animals received intraluminal or intraperitoneal injections of a syngeneic tumour. With intraluminal injection, tumour occurred at the anastomosis and in the omentum in 38 and 43 per cent of animals respectively but following omentectomy the values were 14 and 9 per cent (omental remnant). With intraperitoneal administration tumour occurred in 53 per cent at the anastomosis and in 79 per cent in the omentum compared with 16 and 29 per cent (in omental remnant) following omentectomy. In this model a reduced ability of an anastomosis to support 'seeded' tumour following removal of the omentum is demonstrated and the development of local recurrence from spilled tumour cells during operation may be enhanced by, or be dependent on, the proximity of the omentum.

Blood transfusion and recurrence of colorectal cancer: the role of platelet derived growth factors

Efforts to explain the possible effects of blood transfusion on the recurrence of colorectal cancer have been based entirely on the immunosuppressive effects of blood transfusion. However, the relationship between solid tumour development and the immune system is inconclusive. We have investigated an alternative mechanism involving the potential role of growth factors in this phenomenon. Using a human fibroblast: [125I]deoxyuridine uptake mitogenesis assay, the relative amounts of growth factor in the plasma of stored blood were measured. There was a progressive increase in mitogenesis from day 0 (n = 6) to day 28 (n = 6; P less than 0.001, Mann-Whitney U test). The effect of growth factors on the development of liver and intraperitoneal metastases was studied in Hooded Lister rats. Following an intraportal injection of 10(5) MC28 tumour cells, the experimental group (n = 25) received 2 ml of syngeneic serum intravenously for 4 days. Likewise, colonic anastomoses were performed on omentectomized rats and the peritoneal cavity seeded with 10(3) cells. The experimental groups (n = 20) received either 2 ml serum intravenously repeatedly or 3 ml serum intraperitoneally (n = 19). There was no significant increase in liver metastases or peritoneal disease following intravenous infusion of serum but serum delivered intraperitoneally resulted in a significant increase in tumour from 22 per cent in the controls to 89 per cent in the study group (P less than 0.01). Growth factors released from platelets following blood loss into the peritoneal cavity may be important in enhancing local recurrence of colorectal cancer.

Anastomotic suture materials and implantation metastasis: an experimental study

Suture implantation of viable exfoliated malignant cells may be responsible for local recurrence (implantation metastasis) of colorectal cancer. In this study, four anastomotic materials (braided polyamide, braided polyglycolic acid, monofilament polypropylene and monofilament stainless steel) were compared with respect to their ability to entrap and transfer free Mtln3 carcinoma cells from the colonic lumen of a rat. The braided materials transferred greater numbers of cells than did the monofilament sutures (P less than 0.001), but significant differences were also observed between polyglycolic acid and polyamide (P less than 0.001) and between polypropylene and stainless steel (P less than 0.05). Secondly, the firm adherence of tumour cells to the suture materials was assessed by an in vitro technique. The Mtln3 cells were found to adhere in significantly greater quantities to the braided sutures than to the monofilaments (P less than 0.001) and this was supported by in vivo tumour growth studies. These findings may have implications for colorectal cancer surgery in man.

Serum dependent variability in the adherence of tumour cells to surgical sutures

Five commonly used surgical sutures were tested for their abilities to adhere tumour cells by an in vitro adherence assay. Adherence was quantified in vitro using radiolabelled tumour cells after standard incubation with a set length of the differing sutures. Tumour cells consistently adhered least to Prolene. All suture materials tested adhered significantly more tumour cells than Prolene (P less than 0.002 for chromic and less than 0.0001 for nylon, silk and Vicryl when compared with Prolene, with increasing cell numbers adhering to the sutures tested in that order). These differences in adherence were dependent upon an as yet unidentified macromolecule(s) in serum. All of the suture materials supported tumour growth in vivo after pre-incubation with tumour cells. Rapidity of in vivo tumour growth, however, correlated well with the in vitro tumour adherence characteristics of the different suture materials. The clinical significance of these findings is discussed.

The effect of inadvertent intraoperative perforation on survival and recurrence in colorectal cancer

Inadvertent perforation of the bowel during curative resection for colorectal cancer has serious consequences. In 174 curative resections with spillage, five-year survival was 29 per cent. In 67 patients where the cancer itself was disrupted during dissection, five-year survival fell to 14 per cent in the colon and to 9.3 per cent in the rectum. Local recurrence developed in 65 per cent of spillage cases. In Dukes' C tumors that were perforated during surgery, local recurrence occurred in 87 per cent. As surgeons, our efforts must be directed toward preventing injury to the bowel during definitive resection of colorectal cancers. The instillation of tumoricidal solutions within the bowel lumen and the application of bowel ligatures prior to dissection may help toward preventing recurrence, should inadvertent perforation and spillage occur.

Differences in potentiation of melanoma growth by absorbable and nonabsorbable suture

This study demonstrates that various suture materials have different influences on tumor take and growth. When used in an area containing 10(5) or greater tumor cells, all suture types studied potentiated tumor growth. At subclinical tumor cell doses- that is, 1,000 or fewer cells that do not normally grow to a clinically detectable tumor- silk and steel increased tumor occurrence. In comparison, monofilament nylon, polyglycolic acid, and chromic suture did not potentiate tumor growth. This phenomenon of increased tumor growth associated with certain suture types appears to be related to the physical characteristics of the suture involved, although the interaction of the chemical breakdown products of the suture material with the local tumor cells is under investigation. The type of suture material used may play a significant role in the subsequent development of local recurrence of cancer.

Tumor recurrence in colon anastomoses: prevention by coagulation and fixation with formalin

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