All patients underwent surgery according to the principles of TME[3]. APR was performed in cases where the tumor was too close (usually ≤ 2 cm) to the dentate line or where the differentiation of the tumor was poor (necessitating a longer distal resection margin). Low anterior resection (LAR) was adopted as often as possible, especially for tumors with a distance < 2 cm from the dentate line. To observe the effects of LAR with a colonic J-pouch, we performed a prospective clinical trial from 1998 to 2002 in which 16 out of 331 patients had a J-pouch created. In this study, LAR (with or without the creation of a J-pouch) and Bacon and Parks procedure were combined as SPS.

The Bacon pull-through procedure was performed for some patients with ultra low rectal cancers. In brief, in this procedure the mobilization of the sigmoid colon and the rectum is identical to that in LAR and APR. The anal sphincter is dilated to four to six finger breadths, and then the submucosa is infiltrated with 1:300  000 epinephrine. A circular incision is made in the mucosa at the anoderm at a point 5 mm from the dentate line. Isolation is performed upward beneath the rectal mucosa until reaching the upper limit of the internal sphincter; then the rectum is cut off and moved away from the abdomen. A 2-cm soft plastic pipe is inserted into the proximal colon. The colon is pulled through from the anus, and several sutures are made between the sigmoid colon and the anal canal. The second stage of the procedure is performed 14 to 21 days later. Excess bowel is amputated, and the anastomosis is completed. The Parks procedure is similar to the Bacon pull-through procedure, the difference being that the anastomosis between the colon and the anal canal is accomplished directly in the Parks procedure without the need to pull through the colon.

The CRM was not used at our institute during the study period. Instead, “resection margins” were adopted to record the status of the proximal, distal, and circumferential resection margins. Neoadjuvant chemoradiation therapy (CRT) was not extensively performed at our institute during the study period. Only 5 patients in the SPS group and 12 in the APR group received neoadjuvant therapy.

All of the patients were followed up every three to six months for the first two years, then every six months for the next three years, and then once a year thereafter. Digital palpation, abdominal and pelvic computed tomography (CT) scan, chest X-ray, total colonoscopy and carcinoembryonic antigen (CEA) were routinely measured to exclude local recurrence or metastasis.

Statistic analysis was performed using the SPSS 17.0 statistical package (SPSS, Inc., Chicago, IL, United States). The Student t-test and Chi-square test were used to analyze continuous and categorical variables, respectively. Overall survival, cancer-related survival and local recurrence rates were calculated using the Kaplan-Meier method. Potential prognostic factors were investigated using the log-rank test first, and then covariates with P-values < 0.05 were selected for backward multivariate Cox regression analysis. All P-values less than 0.05 with two sides were considered significant.

Patient characteristics and treatment details are summarized in Table 1. There were 211 male and 120 female patients with a median age of 56 years (range, 17 years-91 years). The median tumor size was 4.0 cm (range, 0.5 cm-15.0 cm). The median distance between the anal verge and the tumor was 4.0 cm (range, 1.0 cm-7.0 cm), and tumors in the APR group were significantly closer to the anus than those in the SPS group (median, 3.0 cm vs 5.0 cm, P < 0.001).

Of the 331 patients with low rectal cancer, 172 patients received the APR procedure and 159 underwent SPS, including 130 APR, 13 Bacon or Parks procedures, and 16 APR with a colonic J-pouch. Before 2001, only 40.9% (65 out of 166) of patients underwent SPS, while after 2001 more (59.1%, 94 out of 165) patients were able to undergo anus-sparing surgery (65/166 vs 94/165, P = 0.001). Combined resection of organs was performed for 35 patients, including 10 patients who underwent resection of solitary liver metastasis. Only 4 (2.5%) patients had a protective stoma after SPS.

Resection margins were microscopically positive in 33 (10%) patients. More patients in the APR group were diagnosed with “positive resection margins” than in the SPS group (13.4% vs 6.3%, P = 0.032). Data on tumor stage and tumor differentiation are presented in Table 1.

There was no mortality. Anastomotic leakage occurred in 6 (3.8%, 6 out of 159 SPS) patients, all of whom did not have a protective stoma before, and these patients were treated conservatively. In total, 63 (19.0%) patients received adjuvant chemotherapy with 5-fluorouracil plus leucovorin or FOLFOX (oxaliplatin, 5-fluorouracil, and folinic acid).

Patients were followed up with a median follow-up time of 61 mo (range, 1 mo-194 mo). At the last follow-up in November 2010, 177 patients (53.5%) were alive, and 154 (46.7%) were dead.

A total of 97 (27.3%) patients experienced recurrence, including 34 (10.3%) local, 58 (17.5%) distant, and 5 (1.5%) combined recurrence. Seventy-five patients died of cancer recurrence. The median disease-free interval for the 35 patients with local recurrence was 15.5 mo (range, 4 mo-104 mo). For the 51 patients with distant metastasis, the median time to metastasis was 25 mo (range, 4 mo-123 mo). The overall 5-year cumulative local recurrence rate was 10.9%. The estimated local recurrence rate at 5 years was 14.7% for APR and 6.8% for SPS (P = 0.041, Figure 1A).

Open in New Tab   Full Size Figure   Download Figure

Figure 1 Surgical outcomes among 331 patients who underwent abdominoperineal resection and sphincter-preserving surgery. A: Cumulative local recurrence rate; B: Overall survival rate; C: Disease-free survival rate. APR: Abdominoperineal resection; SPS: Sphincter-preserving surgery.

The five-year overall (OS) and disease-free survival (DFS) were 60.6% and 59.1%, respectively. The five-year OS was 54.6% after APR and 66.8% after SPS (P = 0.018, Figure 1B). The 5-year DFS was 52.9% after APR and 65.5% after SPS (P = 0.013, Figure 1C).

In univariate analysis, OS and DFS were both significantly influenced by tumor size, type of surgery, resection margins, tumor histopathologic grade, pT stage, and pTNM stage (Table 2).

Multivariate analysis was performed for those factors which were statistically significantly associated with OS and DFS in the univariate analysis. In backward multivariate Cox regression analysis, poor OS was significantly related to positive resection margins [hazard ratio (HR) = 1.644, P = 0.031], pT3-4 (HR = 1.781, P = 0.003), and pTNM III-IV (HR = 2.153, P < 0.001). Positive resection margins (HR = 1.728, P = 0.012), pT3-4 (HR = 1.669, P = 0.006), pTNM III-IV (HR = 1.839, P < 0.001), and poor tumor differentiation (HR = 1.665, P = 0.034) were significantly associated with poor DFS (Table 3).

Risk factors for survival in low rectal cancer patients still need to be clarified. There is evidence that the type of surgery, sphincter-preserving surgery (SPS) or abdominoperineal resection (APR), may influence the prognosis in low rectal cancer.

A retrospective, consecutive cohort study was conducted, attempting to demonstrate the oncologic outcomes of low rectal cancer and to clarify the risk factors for survival. Univariate and multivariate Cox regression analyses were performed to determine whether gender, age, tumor size, distance of the tumor from the anal verge, operative procedure, resection margins, histopathologic grade, pathologic stage, mucin production, and adjuvant therapy were associated with the prognosis of low rectal cancer.

A higher risk for positive resection margins and local failures were observed in APR. The survival outcome after APR is inferior to that after SPS. However, after adjustment for other covariates, the type of surgery was not identified as an independent risk factor for survival.

To reduce positive resection margins and local recurrence, there has been a call for a change in the approach to APR.

Total mesorectum excision (TME) is the standard technique for the treatment of rectal cancer. It was devised some 20 years ago by Professor Bill Heald at the Basingstoke District Hospital in the United Kingdom. TME is accomplished by precise sharp dissection under direct visualization with the true pelvis around the integral mesentery enveloping the entire mid-rectum and with preservation of the hypogastric plexus.

This is an important paper, comparing the outcome of low mesorectal anterior resections for carcinoma of the rectum with abdominoperineal resections.