AIM: To analyze oncological outcome of intersphincteric resection (ISR) in ultra-low rectal cancer with intent to spare colostoma.

METHODS: From 1995 to 1998, patients with a non-fixed rectal adenocarcinoma (tumor stage T2) preserving the lower margin at 1-3 cm above the dentate line without distant metastasis was enrolled (period I). ISR was practiced in eight patients, and their postoperative follow-up was at least 5 years. In addition, from 1999 to 2003, another 10 patients having the same tumor location as period I underwent ISR (period II). Among those, 6 patients with T3-4-staged tumor received preoperative chemoradiotherapy.

RESULTS: All patients received ISR with curative intention and no postoperative mortality. In these case series at period I, local recurrence rate was 12.5% and metastasis rate 25.0%; the 5-year survival rate was 87.5% and disease-free survival rate 75.0%. There was no local recurrence or distant metastases in 10 patients with a median follow-up of 30 (range, 18-47) mo at period II.

CONCLUSION: As to ultra-low rectal cancer, intersphincteric resection could provide acceptable local control and cancer-related survival with no permanent stoma in early-staged tumor (tumor stage T2); moreover, preoperative concurrent chemoradiotherapy would make ISR feasible with surgical curative intent in more advanced tumors (tumor stages T3-4).

In earlier ages, tumors within 7-8 cm above the anal verge were treated by abdominoperineal resection (APR), especially when the rectal tumor could be easily palpated by an examiner’s finger.

Along with the recent development of circular stapling devices, it facilitates the feasibility of ultra-low anterior resection of rectal tumor. Recent studies have shown that a distal clearance margin greater than 1.5 cm is sufficient when tumor histological differentiation is not poor to achieve curative resection of low rectal tumors[1]. These have established the feasibility of ultra-low anterior resection for tumors at level as low as 3 cm from the dentate line.

For the ultra-low tumors, i.e., tumor with lower margin situated within 1-3 cm above the dentate line, the mandatory surgical procedure is still controversial. It is hardly practical to apply conventional ultra-low anterior resection with autosuture instrumentation to achieve an adequate section margin, because of the extreme difficultly in placing a stapler across the optimal distal rectal margin. While most surgeons insist in performing APR in these cases, intersphincteric resection (ISR) has drawn increasing attention as it provides anus preservation and more clear vision for resection.

Many retrospective studies have pointed out that there is a good local control after sphincter-saving resection for rectal cancer[2-11]; however, the majority of studies did not carry more than the 5-year follow-up interval and they examined all rectal tumors, many of which can be removed by low/ultra-low anterior resection. This study assessed the oncological outcome of patients with very low rectal cancer by intersphincteric resection to determine whether abdominoperineal resection could be abolished.

The distal section margin of 1-2 cm would be currently considered sufficient for ultra-low rectal cancer in most instances[1,5,7,8]. Parks et al[12] reported that long-term survival and local recurrence rate after ISR were similar to those after APR. Several specialized studies have investigated ISR for low rectal cancer, and their local recurrence rates ranged from 0% to 12%[2-11]; however, some studies reported that the patients with the location of rectal cancer at 5 cm more proximal to anal verge and did not always carried more than a 5-year follow-up interval. In this study, the local recurrence rate was 12.5% for T2-staged ultra-low rectal tumor after at least a 5-year follow-up. However, the number of patients in this study is small because of the highly selected criteria, size of the tumors smaller than 5 cm and the lower margin of tumors within 1 to 3 cm from the dentate line.

The radial involvement of a tumor is another critical predictive factor for local recurrence after rectal cancer resection. In most instances, patients with T3-4 carcinomas of the low-third rectum require APR. Recently, by using a multimodal approach, intersphincteric resection was practical in patients with T3-4 carcinomas of the lower third of the rectum[7,10,11,13-15].

Preoperative CCRT reducing tumor volume, causing tumor down-staging, and further facilitating surgical resection of malignancy have been proposed. Recent studies concerning preoperative chemoradiotherapy have demonstrated that it improves local control and cancer-related survival. Rullier et al[10] reported only 2% (1/43) local recurrence rate if combining preoperative CCRT and successive ISR for ultra-low rectal cancer were attempted (median follow-up was 30 mo)[10]. Luppi et al[13] reported 94% local control rate for T3-4 rectal cancer using preoperative chemoradiotherapy[13]. Saito et al reported similar results for local control and acceptable anal function in a series of 35 patients (median follow-up: 23 mo), these patients had T3-staged ultra-low rectal cancer and were treated by preoperative CCRT with consecutive ISR[7].

In the past 4 years, 10 patients with ultra-low rectal cancer were managed in this study by multimodality treatment and no distant metastasis was disclosed during the follow-up period. Preoperative CCRT was applied to six T3-4 staged patients, and this treatment enhanced tumor shrinkage more than 25% in five patients; it is inspiring that no residual cancer was identified in 2 patients among these 5 patients. After a median follow-up of 30 mo, there was no local recurrence or distant metastasis developed.

Cluster defecation associated with tenesmus, urgency, and incontinence are not uncommon in straight coloanal anastomosis. The colonic pouch could convert the functional deficiencies associated with the loss of rectal capacity and reduced compliance resulting from straight coloanal anastomosis. Lazorthes et al[16] and Parc et al[17] conducted a colonic J pouch anastomosing at the dentate line, and they assumed superior functional outcome compared to straight anastomosis[16,17]. A number of clinical series have evidence to support that utilizing a colonic pouch anal anastomosis could enhance the functional results and postoperative quality of life of patients after rectal cancer resection[16-19,21,22]. The functional advantages of a colonic pouch anal anastomosis have been achieved within a shorter period than straight coloanal anastomosis after surgery. This superiority in J pouch groups remains evident when compared with the straight coloanal anastomosis 2 years after the surgery as reported by Joo et al[21] and Sailer et al[22].

Optimal pouch size remains unclear. Numerous J pouch sizes have been attempted, ranged from 5 to 12 cm in length. Increasing pouch length is always associated with incomplete evacuation and requires suppositories or enemas to rescue such sufferings. Parc recommended an adequate limb length of 8-10 cm[17]. Hida et al[20] proposed that a 5-cm pouch could function as adequate reservoir, and it is technically easy with requiring not too long a segment of bowel for construction[20]. Clinical experience to date favors that the optimal pouch is achieved by employing two 6-7 cm limbs of the colon. In this study, a 6-8 cm pouch was constructed and harvested proper functional outcome. During the time the colonic Jpouch was constituted, the distal colon must be mobilized and adequate perfusion should be preserved to prevent complications such as mobilized colon ischemic change or anastomotic insufficiency. We believe that these standard surgical issues have facilitated the achievement of tolerable functional results.

In conclusion, ISR could achieve acceptable local control, cancer-related survival and avoid permanent stoma in patients with early staged ultra-low rectal cancer. Preoperative CCRT facilitates intersphincteric curative resection in patients with T3-4 staged ultra-low rectal cancer. Longer follow-up of these patients should be recommended, especially for those receiving preoperative chemoradiotherapy.

Presented in part at the 10th Congress of Asian Federation of Coloproctology, 2005, Singapore.