Local failures most often result from inadequate surgical clearance of the radial margin. The concept of total mesorectal excision (TME) proposed by Heald et al has been shown to improve both disease-free and overall survival.3 TME in conjunction with an LAR or APR involves precise dissection and removal of the entire rectal mesentery, including that distal to the tumor, as an intact unit. Unlike conventional blunt dissection, which may leave residual mesorectum in the pelvis, TME involves sharp dissection under direct vision in the avascular, areolar plane between the fascia propria of the rectum, which encompasses the mesorectum, and the parietal fascia overlying the pelvic wall structures. This procedure emphasizes autonomic nerve preservation (ANP) and complete hemostasis and avoids violation of the mesorectal envelope. This results in a characteristic bilobed, smooth, glistening surface of the excised mesorectum.
Because rectal cancer spread appears to be limited to the mesorectal envelope, its total removal should encompass virtually every tumor satellite, thus improving the likelihood of local control. The excellent results with TME may be attributed to improved lateral clearance with removal of potential tumor deposits in the mesentery and decreased risk of tumor spillage from a disrupted mesentery.39 The completeness of the mesorectal excision influences local control, even if the surgical margins are uninvolved. In one report, both local (11.4 vs 5.5%) and distant recurrence rates (19.2 vs 12.2%) were higher in patients with an incomplete, as compared with a complete or nearly complete, mesorectal resection. These favorable results have led some to question the need for routine postoperative radiation in patients undergoing complete resection of rectal cancer with TME. However, the Dutch neoadjuvant trial that randomly assigned 1861 patients with resectable rectal cancer to TME alone or a short course of preoperative radiation (5 Gy daily for 5 days, in the “Swedish style”) followed by TME demonstrated a significantly decreased rate of local recurrence 8.2 versus 2.4% at 2 years.40
Of greatest importance is that improved local control appears to result in better overall survival. In one of the earliest reports, Heald et al noted a local recurrence rate of 3.6% and a survival rate of 86% after 9 years of follow-up.41 In 1994, the Norwegian Rectal Cancer Group was founded to improve the surgical standard by implementing TME on a national level and to evaluate the results; courses were arranged to teach surgeons the technique of TME. Optimized TME reduced the rate of local recurrence (6% TME vs 12% non-TME) and increased overall survival (73% TME vs 60% non-TME) within 2 years.42 This led to a strategic change in both Norway and the United States to initiate quality assessment in the surgical treatment of rectal cancer.
Guillem et al recently demonstrated an improved overall and disease-free survival in patients with T3 or N1 tumors who underwent TME after preoperative combined-modality therapy.43 With a median follow-up of 44 months, the estimated 10-year overall survival was 58% (Fig. 40-13) and 10-year recurrence-free survival was 62% (Fig. 40-14). On multivariate analysis, pathologic response greater than 95%, lack of lymphovascular invasion and/or perineural invasion (PNI), and lack of postoperative positive lymph nodes were significantly associated with improved overall and disease-free survival.
Five- and 10-year overall survival with 95% confidence intervals of rectal cancer patients following preoperative combined modality therapy and total mesorectal excision. (Used, with permission, from Guillem JG, Chessin DB, Cohen AM, et al. Long-term oncologic outcome following preoperative combined modality therapy and total mesorectal excision of locally advanced rectal cancer. Ann Surg. 2005;241:829–838.)
Five- and 10-year recurrence-free survival with 95% confidence intervals of rectal cancer patients following preoperative combined-modality therapy and total mesorectal excision (TME). (Used, with permission, from Guillem JG, Chessin DB, Cohen AM, et al. Long-term oncologic outcome following preoperative combined modality therapy and total mesorectal excision of locally advanced rectal cancer. Ann Surg. 2005;241:829–838.)
Despite the advent of TME and the addition of neoadjuvant chemoradiotherapy to the treatment of patients with rectal cancer, there is still a risk of local pelvic recurrence and the appearance of distant metastatic disease. Lateral nodal spread, especially in distal rectal cancers, is one possible culprit for treatment failures in rectal cancer. It is well established that distal rectal adenocarcinomas have a worse prognosis than more proximally based lesions. Most surgeons attribute this to three factors: (1) Distal tumors require a more difficult low dissection in a narrow pelvis; (2) there are probably biologic differences in tumors with the low-lying tumors probably having a poorer biology; and (3) the more distal tumors have a predilection to more complex lymphatic channels and the possibility of lateral spread into the systemic circulation as well as the portal circulation. Takahashi et al performed a retrospective analysis of 764 patients over a 20-year period (1975–1995) who underwent a curative three-space dissection. The three spaces are defined as follows: (1) The inner space is encircled by the visceral pelvic fascia posteriorly and Denonvilliers' fascia anteriorly, and laterally the three spaces unite near the pelvic nerve plexus; (2) the intermediate space is defined by the parietal pelvic fascia posteriorly and the internal iliac arteries and branches laterally and anteriorly; and (3) the outer space is lateral to the internal iliac arteries. Takahashi found that 66 of 764 patients (8.6%) had lateral nodal spread of their rectal cancer. More importantly, 16.4% of the low-lying rectal cancers had their lower margins less than 5 cm above the dentate line. Lateral nodal spread is outside the traditional TME resection plane but can be encompassed by a three-space lateral nodal dissection in appropriate patients. When this was achieved, they had a 42.4% 5-year survival in their subgroup of patients who had lateral spread and a curative three-space dissection.44
A comparative study of Japanese and Dutch patients examined local recurrence in Dutch patients who received TME-alone versus TME-plus preoperative radiotherapy and Japanese patients who were treated with TME-plus lateral nodal dissection (LAR or APR). Most Japanese patients did not receive neoadjuvant therapy. Local recurrence, lateral pelvic recurrence, and presacral recurrence rates were analyzed and are shown in Table 40-7.
Table 40-7: Analysis of Local, Lateral Pelivic, and Presacral Recurrence Rates ||Download (.pdf)
Table 40-7: Analysis of Local, Lateral Pelivic, and Presacral Recurrence Rates
|TME Alone (%)||TME + RT (%)||TME + Lateral Dissection (%)|
|Lateral pelvic recurrence||2.7||0.8||2.2|
In summary, both TME with radiotherapy and lateral nodal dissection without radiotherapy result in excellent local control and have improved local control over TME alone. The conclusion is that the radiotherapy sterilizes the lateral space that has microscopic tumor extension beyond the traditional TME resection plane.45 The major caveat is that patients who have TME alone have much better postoperative sexual and urinary function than those who have TME-plus lateral nodal dissection.46
Quality of life has improved with TME and ANP. Conventional rectal surgery is associated with a significant incidence of impotence, retrograde ejaculation, and urinary incontinence, presumably owing to damage to the pelvic autonomic parasympathetic and sympathetic nerves by blunt dissection.47 Postoperative impotence, retrograde ejaculation, or both are observed in 25–75% of conventionally treated patients compared with only 10–29% of patients after TME with its careful nerve-sparing dissection.47
Erectile capacity and normal ejaculation may be preserved in most male patients, especially those 60 years of age or younger. In one retrospective study of patients undergoing TME with ANP, 86% of male patients younger than 60 years and 67% of those 60 years or older were able both to engage in postoperative sexual intercourse and to achieve orgasm.47 In female patients, sexual activity was maintained in 86%, sexual arousal with vaginal lubrication in 98%, and the ability to achieve orgasm in 91%. With the advent of pelvic dissections that preserve autonomic nerves, postoperative sexual dysfunction rates have been reduced from greater than 50% to 10–28%.47
Isolated urinary dysfunction is uncommon with preservation of the pelvic autonomic nerves. In a prospective study of rectal cancer patients undergoing TME with ANP, only 2 of 35 had difficulty with bladder emptying and possessed evidence of bladder denervation on postoperative studies.
Some studies, however, have demonstrated impaired quality of life owing to LAR with TME in part because of a temporary loop ileostomy or preoperative radiotherapy. Yet cost-utility analysis estimates that improved survival outweighs impaired quality of life.48
Technique of Total Mesorectal Excision
Prior to the procedure, all patients receive a full mechanical and antibiotic bowel preparation. The patient's abdomen is marked preoperatively by the enterostomal therapy nurse for potential stoma sites. An epidural catheter is placed by the anesthesia team for postoperative pain control. Sequential compression devices are applied to the lower extremities before general anesthesia is induced for deep vein thrombosis (DVT) prophylaxis. One dose of 5000 units of heparin is administered subcutaneously. Cefazolin and metronidazole are infused. After anesthesia is induced, the patient is brought down on the table so that the buttocks are at the edge; a gel pad placed under the buttocks facilitates access to the anus. The patient is placed in a modified lithotomy position using Allen or Yellow Fin stirrups (Fig. 40-15). The hips are minimally flexed and abducted. The feet are positioned flat in the stirrups; an imaginary line is visualized keeping the ankle, knee, and contralateral shoulder in a straight line. Care is paid to having no pressure on the peroneal nerve or bony prominences; a hand should be able to be placed easily between the posterolateral aspect of each lower leg and its respective stirrup. If the patient has had previous pelvic surgery or evidence of hydronephrosis on CT scan, consider bilateral ureteral stent placement. A Foley catheter is placed and is draped over one leg. A nasogastric tube is inserted by the anesthesia team. A DRE is performed. If there is any question regarding the distal or proximal limits of the tumor, rigid proctoscopy may be performed at this time. Preoperatively, the lesion may have been marked by an injection of India Ink. The surgeon should wear a headlight to help with visualization in the lower pelvis. Most surgeons stand on the patient's left, which allows them to operate more efficiently with their right hand in the lower pelvis. A low midline incision is made between the umbilicus and the pubis, keeping in mind potential stoma sites; cephalad extension may be necessary to mobilize the splenic flexure. The abdomen is explored to search for metastatic disease in the liver or peritoneal surfaces. The rectum is palpated to assess the primary mass. The colon is palpated for any synchronous lesions.
Position of patient for surgical treatment of rectal cancer allows access to both the abdomen and the perineum.
The abdominal self-retractor is set up. The patient is placed in slight Trendelenburg's position. The sigmoid is mobilized laterally by scoring the white line of Toldt (Fig. 40-16A). The left ureter is identified by several ways: visualizing it cross over the bifurcation of the common iliac artery, palpating the external iliac artery and pinching the tissue above it, locating it at the level where the sigmoid turns, or incising the peritoneum over the psoas muscle and finding the ureter on the medial aspect of the peritoneum (Fig. 40-16B). If it is clear that much length will be necessary for reconstruction, the splenic flexure is mobilized. Tension on the colon should be gentle but firm; too much traction on the colon or omentum can cause splenic injury. The transverse colon is freed from the omentum by sharp dissection along the avascular plane between the two structures. The bowel is packed into the upper abdomen. The sigmoid is held up in the air at the junction between the descending colon and sigmoid. Both sides of the mesentery are scored from this point down to the sacral promontory. The right ureter is identified. The colon usually is divided at the sigmoid-descending colon junction using a linear stapler (or may be divided between two bowel clamps, which would require a hand-sewn anastomosis). The sigmoidal vessels are isolated and divided using large Kelly clamps, two proximally and one distally. Metzenbaum scissors are used to divide the vessels. The vessels are doubly ligated. The colon is packed cephalad, out of the field. The superior hemorrhoidal artery is then divided at the junction with the left colic artery (Fig. 40-16C). A more proximal ligation of the inferior mesenteric vessel can also be performed if extra length on the colon is needed, but it is not necessary to ligate the IMA flush with the aorta for oncologic reasons. One usually suture-ligates the superior hemorrhoidal vessels so as to ensure hemostasis.
Mobilization of the left colon. A. Incision line around the left colon. B. Left colon reflected medially, exposing the ureter and gonadal vessels. C. Superior hemorrhoidal artery is divided close to the aorta to result in a high arterial ligation. The arcade of Riolan is preserved, and the left colon and mesentery are divided at the junction of the descending and sigmoid colon. D. Proximal ligation of the inferior mesenteric vein adds extra mobility.
After dividing the superior hemorrhoidal artery, it is important to find the proper plane of dissection at the sacral promontory. One first locates the sympathetic nerves along the pelvic brim. The rectum is retracted anteriorly. Electrocautery with a long Bovie tip is used to develop the loose areolar plane of avascular issue posteriorly (Fig 40-17B). The nerves are visualized and kept posterior to the plane of resection. The presacral fascia is incised down to Waldeyer's fascia, and the dissection is carried inferiorly to the coccyx. The St. Mark's abdominal retractor facilitates the deep pelvic dissection.
The anterior and lateral dissections are then started after the posterior dissection has been partially completed. The peritoneum is incised on each side and then across the anterior midline to meet at the deepest point in the cul-de-sac, the groove between the rectum and the anterior structures (uterus/vagina in women, seminal vesicles in men) (Fig. 40-17A). The mesorectum is separated from the pelvic sidewall using the cautery to divide the thin areolar tissue that is found when one is dissecting in the proper plane. The dissection is carried down anterolaterally to the lateral ligaments or “stalks” (Fig. 40-17C). Only 25% of patients have distinct branches of the middle rectal vessels in these ligaments. They can be divided flush with the pelvic sidewall, but care should be taken to preserve the hypogastric plexus that lies on the pelvic sidewall just lateral to the seminal vesicles in men or just lateral to the cardinal ligaments in women. Preservation of the plexus helps with avoiding postoperative potency or urinary problems, and resection of the plexus is rarely helpful for oncologic reasons. Throughout the lateral dissection, one should be aware of the nerves and vessels along the pelvic sidewall. Too lateral a dissection causes bleeding from the pelvic sidewall.
Mobilization of the rectum. A. Peritoneal incision of the pelvis. B. Rectum reflected anteriorly and posterior avascular plane entered between the presacral fascia of Waldeyer and the fascia propria of the rectum. C. Division of lateral stalks. D. Projected line of dissection in pelvis through Waldeyer's and Denonvilliers' fascia.
Anteriorly, the planes are less distinct, and the fat of the mesorectum is thin. The vaginal wall or seminal vesicles are elevated anteriorly using the lipped St. Mark's retractor while the surgeon places posterior traction on the rectum. In the male patient, the dissection is continued through or anterior to Denonvilliers' fascia (Fig. 40-17D). This fascia is often two layers of a thin membrane. When performing a cancer resection, one should take both layers of this membranous fascia off the seminal vesicles and upper prostate if possible.
For middle to low rectal cancers, TME involves removing the entire mesorectum with its enveloping fascia as an intact unit. For tumors in the upper rectum (>10 cm from the anal verge), TME is extended to 5–6 cm below the level of the tumor, dividing the rectum and mesorectum at the same level. A number of pathologic studies demonstrate that tumor spread within the mesorectum rarely extends beyond 4 cm distal to the caudal edge of the tumor; usually most nodes or mesorectal implants are within 3 cm of the distal edge of the tumor.6,12 However, multiple studies have shown that a 2-cm margin is adequate on the mucosa. Fewer than 2–4% of tumors will have mucosal or submucosal spread beyond 2 cm distally. Rigid sigmoidoscopy may be used to identify the appropriate site for transection if the cancer is not palpable, especially after neoadjuvant therapy.
Once the rectum has been mobilized, a tumor measured at 5 cm by rigid proctoscopy often may be moved to 8 cm from the dentate line, a distance that permits an adequate resection margin and sphincter preservation (Fig. 40-18).
Tumor position relative to the dentate line after mobilization of the rectum. This may permit a sphincter-preserving resection.
When the distal extent of the tumor and the site of transection have been established, electrocautery is used to dissect the mesorectal fat away from the rectum. Vessels require ligation with 2-0 Vicryl ties. It is important to keep the dissection of the mesorectum perpendicular to the site of transection. “Coning in” as one divides the mesorectum prior to transection should be avoided.
Once the bowel has been cleared of mesorectal fat, a 30-, 45-, or 60-mm TA linear stapler is used to staple the rectum (Fig. 40-19A). This is the first staple line in the “double-stapling technique.” The bowel is clamped just proximal to this point. A no. 10 blade on a long handle is used to transect the bowel. The specimen is handed off the field.
Colorectal anastomosis: double-staple technique. A. Transection of the distal rectum with a linear stapler. B. Stapling instrument introduced through rectum. C. Descending colon purse-string suture is tied around shaft of anvil. After the trocar of the circular stapler penetrates behind the staple line, the trocar is removed before reconnecting the anvil to the shaft. D. The circular stapler is reconnected, reapproximated, and fired. E. The anastomosis is complete. F. The proximal and distal staple lines are examined for intact inner “donuts.”
Reconstruction: Double-Stapling Technique
The proximal colon is unpacked, and the length required for a tension-free anastomosis is determined. If more colon is needed, the splenic flexure is mobilized further. This may require an extension of the incision cephalad. Proximal ligation of the inferior mesenteric vein also adds extra mobility (see Fig. 40-16D). The proximal bowel is cleaned by resecting residual fat and small vessels approximately 1 cm proximal to the staple line. The staple line is excised with Bovie electrocautery. Sizers may be inserted to select an end-to-end anastomosis (EEA) stapler diameter (25, 29, or 31 mm). A circular stapler is then chosen. The anvil is placed within the opened bowel. A 3-0 Prolene is used to take full-thickness, 1- to 2-mm bites to fashion a purse-string stitch around the anvil. The purse-string suture is tied gently but firmly around the shaft so that the shaft is completely encircled by bowel (Fig. 40-19C). If there are any gaps, an additional 3-0 Prolene suture can be used to take another full-thickness bite, and this suture may be tied around the shaft as well. The serosa of the bowel is cleaned further of fat and small vessels within 1 cm of the shaft of the anvil to optimize bowel-to-bowel contact when the circular stapler is applied. One can also perform a similar placement of the anvil on the antimesenteric side of the colon for a side-to-end anastomosis. The optimal placement of the anvil in this case is such that only a small blind end of colon remains distal to the anastomosis (1–5 cm).
Attention then is turned to the pelvis, which is irrigated and inspected for hemostasis. This is one's truly last opportunity to inspect this area because one's exposure will be compromised once the anastomosis is completed.
One member of the team then stands between the patient's legs. The circular stapler tip is coated with lubricant on the outside of the stapler; we do not place lubricant on the staples themselves. The tip is retracted fully. A rectal examination is performed, and the anus is dilated gently with two to three fingers in order to accommodate the stapler. The circular stapler is inserted gently following the curve of the rectum—initially straight in and then the stapler is tilted posteriorly. Using close communication with the surgeon overlooking the abdomen, the assistant positions the circular stapler tip so that the trocar will exit either 2–3 mm anterior or posterior (we elect to do this posteriorly in women in order to avoid the vaginal wall) to the staple line (Fig. 40-19B). The trocar then is advanced slowly; the bowel continues to be adjusted as necessary. When the trocar protrudes through the bowel wall, be sure that the trocar is fully advanced so that its bottom is visualized (see Fig. 40-19C). The trocar is removed. Ensuring that the proximal bowel is not twisted and that the remaining bowel, mesentery, and epiploicae are held away, the anvil is brought down gently to the stapler and connected. The colon is inspected again to verify that no adjacent tissue is entrapped. The stapler is closed slowly until both pieces of colon are fully approximated (Fig. 40-19D). The stapler is fired, opened slightly, and gently removed as directed according to the type of stapler. This is the second staple line in the double-stapling technique (Fig. 40-19E). The stapler is opened, and the tissues from the proximal and distal bowel are inspected to make sure that the two rings of tissue, or “donuts,” are intact (Fig. 40-19F). If they are not intact, additional sutures are placed if a visible gap is apparent. All anastomoses are checked for integrity. The surgeon fills the pelvis with saline and clamps the bowel proximal to the anastomosis gently with the hands; the assistant introduces a rigid sigmoidoscope through the rectum and insufflates air. If bubbles cannot be detected, one can be confident that the anastomosis is intact. If bubbles are detected, additional sutures are placed in suspected areas, and a diverting loop ileostomy is constructed. If the anastomosis is disrupted completely, it must be refashioned.
A diverting loop ileostomy should be considered in any low anastomoses (<5 cm) from the dentate line, which are associated with anastomotic leak rates of up to 17%. Other risk factors for anastomotic breakdown include a history of radiation, perioperative steroid use, malnutrition, elderly women with a thin rectovaginal septum, or elderly patients undergoing preoperative combined-modality therapy with planned postoperative chemotherapy. Additionally, if there is any question regarding the integrity of the anastomosis, an ileostomy should be created.
Ileostomies can be closed within 8 weeks but often are left in place until the patient completes adjuvant chemotherapy. A Gastrografin (diatrizoate meglumine) enema is used to check the patency and integrity of the anastomosis prior to takedown of the anastomosis.
Most surgeons continue to advocate routine use of drains after pelvic anastomoses. One prospective, randomized trial of 100 patients to receive either no drains or closed-suction drains demonstrated that the presence or absence of a drain did not influence the rate of morbidity and mortality. Although there is no evidence for the use of drains when an anastomosis has been made outside the pelvis, pelvic drainage may be important after anterior resection. We recommend placing a drain in extremely low resections, especially where the anastomosis was hand sewn or in patients who undergo an APR. For all other resections, placement of a drain may be determined on a case-by-case basis.
We prefer to close the abdominal fascia with a looped no. 0 PDS suture starting at the cephalad and caudad ends and to run the suture toward the middle. The deep dermal layer is closed with 3-0 Vicryl. The skin is closed with either staples or a 4-0 Vicryl subcuticular suture followed by benzoin and Steri-Strips. A 4 × 8 gauze dressing is applied and covered with Tegaderm (3M, St. Paul, MN).
The nasogastric tube is removed at the end of the procedure or on postoperative day 1, and the patient can drink sips of clear liquids. The diet is advanced to low residue after flatus is passed. Cefazolin and metronidazole are continued for 24 hours postoperatively. Heparin is administered subcutaneously at a dose of 5000 units BID or TID depending on the patient's weight. Low-molecular-weight heparin also can be used in appropriate doses. Sequential compression devices are worn by the patient unless the patient is ambulating well. Most patients ambulate on postoperative day 1. The Foley catheter is kept in place for 3–5 days. If an epidural has been used for postoperative pain control, it is usually left in place until the patient is started on oral pain medication when he or she is tolerating clear liquids well.
Anastomoses at or just above the anorectal ring often result in increased frequency of stool, incontinence or soilage, and impaired quality of life owing to an insufficient reservoir. Diet restrictions and time after surgery usually will improve these symptoms, but two alternative techniques of reconstruction address these postoperative problems and often allow for improved function to be attained more quickly.
A 6-cm limb of sigmoid or descending colon is folded, and the apex is brought down to reach the rectal stump without tension. The splenic flexure may require additional mobilization. A colotomy is made at the apex with Bovie electrocautery, and a no. 75 GIA linear cutter is used to staple the pouch on itself to create a common lumen. A second fire of the stapler may be necessary. This pouch now serves as the neorectum. A double-stapled anastomosis as described or a hand-sewn anastomosis then is performed. A diverting loop ileostomy is used routinely for these ultralow anastomoses.
Multiple prospective, randomized studies have demonstrated superior function of a coloanal J-pouch over a straight coloanal anastomosis, especially in the first 6 months after ileostomy takedown.
When the pelvis is too narrow for a J-pouch or the length of the pouch is inadequate, a transverse coloplasty may be fashioned. This is performed by placing the anvil of a 29- or 33-mm circular stapler into the cut end of the sigmoid as described under the section Low Anterior Resection. The colon should be mobilized to the level of the middle colic vessels. Beginning 2 cm proximal to the anvil, a 7- to 8-cm longitudinal colotomy is made. This colotomy then is closed transversely. The anastomosis is completed as described under Low Anterior Resection. A diverting loop ileostomy is created.