From June 1995 to April 2008 two hundred and eighteen patients [120 male (55%), 98 female (45%); median age 58 years, range 19 to 88 years] with rectal cancer confined to the pelvis, without known distal metastasis, underwent surgical treatment at the North Colombo Teaching Hospital (Table ). Some one hundred (46%; 54 male, 46 female) had cancer > 6 cm from the anal verge (PRC) compared with 118 (54%; 66 male, 52 female) with cancer between 0 and 6 cm from the anal verge (DRC). We chose a limit of 6 cm from the anal verge to determine DRC because rectal cancer at this level would require complete removal of the rectum with a distal tumour-free margin of one to two cm with total mesorectal excision in all cases, unlike in some high PRCs, where it would suffice to remove only a part of the mesorectum[4
]. Also, in addition to mesorectal spread of rectal cancer as a cause for local recurrence, rectal cancer between 0 and 6 cm from the anal verge is likely to spread to internal iliac nodes as well as to mesenteric nodes, unlike in PRC which spreads proximally to the mesenteric group of nodes[8
Comparison of patients with proximal and distal rectal cancer
All patients were evaluated by comprehensive history and physical examination. Digital rectal examination was performed to assess tumour fixity and distance of tumour from the anal verge was also measured by rigid proctoscopy. Clinical assessment of the anal sphincter was performed by digital assessment of resting and squeezing anal tone. The proximal colon was examined to exclude synchronous polyps, tumour or polyposis syndromes and a biopsy of the tumour was obtained, morphology of the tumour documented and endoluminal ultrasound performed at the time of colonoscopy. Further investigation consisted of standard haematology and biochemical evaluation. Radiological investigations consisted of chest X-ray and trans-abdominal ultrasound and, from 2003, combined computerized tomography (CT) or magnetic resonance imaging (MRI) of the abdomen and pelvis. All patients were counseled by a stoma care nurse, stoma sites were marked preoperatively and the operation was performed after bowel preparation using polyethylene glycol 24 h preoperation, except in those presenting with obstruction or perforation.
Patients with T3 or T4 tumours, as judged by endo-luminal US or CT/MR, were given preoperative irradiation which consisted of 5040 cGy delivered in fractions of 180 cGy per day, 5 d per week. 5-Fluorouracil was given concomitantly in a 120 h continuous intravenous infusion at a dose of 1000 mg/m2 of body-surface area per day during the first and fifth weeks of radiotherapy. Surgery was performed 6 wk from completion of chemo-radiation following restaging of the disease. Those with PRC received preoperative c-RT on a selective basis: bulky tumours observed to involve the circumferential margin (CRM) on magnetic resonance scan and tumours that involved the circumference of the lumen.
Operations were performed under general anaesthesia with intermittent positive pressure ventilation. Patients were positioned in the modified Lloyd- Davies position with a 15o
to 30 reverse Trendelenberg tilt. Preoperatively, patients received prophylactic antibiotics, an urethral catheter was inserted and the rectum washed with 250 mL of 5% povidone iodine solution. The abdomen was incised in the lower midline to gain access to the peritoneal cavity. Proximal extension of the incision was necessary if mobilization of the splenic flexure was deemed essential at operation, particularly if the tumour was extra-peritoneal and an extended low anterior resection was planned, as in the case of most DRCs. We performed total mesorectal excision in all distal rectal tumours. Most tumours in the upper rectum, that is, rectum enveloped by peritoneum, were managed surgically by division of the rectum at least 2 cm distal to the tumour but with mesorectal excision 5 cm distal to the lower limit of the tumour. In all cases, we performed nerve sparing resections as described previously[10
]. In anterior wall rectal tumours we incorporated Denonvillier’s fascia in men or a cuff of posterior vaginal wall in women to ensure a curative resection. Postoperatively, after stabilization of vital signs and satisfactory postoperative pain control was achieved, all patients were managed either in an intensive care or high dependency unit for 24 to 48 h before transfer to a general ward.
Technique of inter-sphincteric resection
Inter-sphincteric resection was performed through the anus with the aid of a ‘Lone Star’ (Lone Star Medical Products, Inc., Stafford, Texas, USA) retractor. The lower limit of the tumour was visualized trans-anally and a distal margin of at least 1 cm was marked by electrocautery. The incision at this predetermined site was deepened to enter the inter-sphincteric space. Inter-sphincteric dissection, usually commenced at or below the dentate line and incorporated part of or, sometimes, the whole internal anal sphincter, approached the lowermost limit of anorectal mobilisation to reach the pelvic floor by abdominal dissection in the inter-sphincteric space, wide of the tumour. The mobilized rectum with the tumour was then delivered via the anal canal. Reconstruction was achieved by handsewn trans-anal, colo-anal anastomosis with 3/0 polyglactin 910 sutures. A diverting loop ileostomy was performed: in all patients with DRC who underwent restoration of intestinal continuity; in those with PRC, after pre-operative c-RT, where there was a positive air leak test during insufflation of the anastomosis under water in the pelvis; or where the surgeon deemed it necessary because of excessive bleeding during the operation.
Definition of level of anterior resection
The levels of resection employed in this study are as described previously[11
]. Accordingly, high anterior resection is defined as resection where the level of anastomosis is proximal to 10 cm from the anal verge. Anterior resection is where the anastomosis is less than 10 cm from the anal verge but above the level of the pelvic floor where a part of the distal rectum is left in place. A low anterior resection is defined as an anastomosis at the level of the pelvic floor. It is an extended low anterior resection, when a colo-anal anastomosis followed inter sphincteric resection in which the anastomosis was within the anal canal. Thus, PRC was treated either by high anterior resection or anterior resection whilst all DRC patients received either a low anterior resection or an extended low anterior resection. A proportion received either Hartmann’s resection or an abdomino-perineal resection of the rectum.
All patients were followed up at the outpatient clinic at 2 wk, 4 wk and at 3 monthly intervals for 3 years. Subsequently, patients were followed at 6 monthly intervals up to 5 years and in the absence of recurrent cancer, annually thereafter. Serum CEA was measured at each follow-up visit. Chest X-ray, CT scan of the abdomen to evaluate the liver and colonoscopy were undertaken at the end of the first and the second year. Thereafter, patients were advised to follow standard colonoscopy protocols for those at average risk of colorectal cancer[12
]. Those who had had restorative proctocolectomy with an ileal pouch were assessed by pouchoscopy.
Local recurrence in the pelvis was confirmed if there was histologically proven cancer present in the pelvis either by fine needle aspiration, trucut biopsy or histopathological examination of a resected specimen. Median follow up after operation was 35 mo (range 12 to 126 mo). In cases of loss to follow up, survival was evaluated up to the time of the last documented visit.
The endpoints of our study were: mortality at 30 d post-operation, morbidity (anastomotic leakage, pelvic sepsis, wound infection, chest infection and urine retention); curative resection, where all margins (proximal, distal and CRMs) were histologically free of tumour (R0) vs resection with at least one margin involved by tumour (R1); local recurrence in the pelvis; and overall survival. Concerning CRM of resection, we evaluated resection rates in a microscopic margin free of tumour for > 1 mm but <
2 mm and > 2 mm separately. Also, the rate of permanent stomas was compared between operations for PRC and DRC.
Data have been presented as either median and range or mean and standard deviation. Differences between PRC and DRC have been compared using the χ2 test and Fisher’s exact test in case of a number less than 5. Operative data have been compared with one way ANOVA using SPSS version 16 (SPSS, Chicago, USA). Significance was assigned to a P-value of less than 0.05. Survival was analysed using Kaplan-Meier curves. The study was approved by the National Research Council and the University of Kelaniya.