Treatment

Some form of excision of the rectum is essential, if at all pos­sible, because of the extreme suffering entailed if the neoplasm remains. However, before surgery is embarked upon, it is necessary to assess:

  the fitness of the patient for operation;

  the extent of spread of the tumour.

The findings will affect the surgical approach.

Assessment of spread should include ultrasonography or computed tomography (CT) of the liver, and a chest radio­graph to exclude distant metastases (Fig. 60.23).

Endoluminal ultrasound whereby a probe is placed in the rectal lumen can he used to assess the local spread of the tumour (Fig. 60.24), as can CT and, more recently, magnetic resonance imaging (MRI).

Principles of surgical treatment

Radical excision of the rectum, together with the mesorectum and associated lymph nodes, should be the aim. Even in the presence of widespread metastases a rectal excision should be considered, as this is often the best means of palliation. The presence of a solitary liver metastasis does not necessarily rule out the feasibility of a radical excision. Many instances have been reported where a presumed solitary liver metastasis has been resected either at the time of excision of the rectum or subsequently with long term survival being achieved.

When a tumour appears to be locally advanced, the administration of a course of preoperative radiotherapy may reduce its size and make it more amenable to radical excision. Indeed, recent evidence suggests that the administration of preoperative adjacent radiotherapy in all rectal cancer cases reduces the incidence of local recurrence significantly (Pahlman).

For patients who are unfit for radical surgery or who have widespread metastases, a local procedure such as transanal excision, laser destruction or interstitial radiation should be considered.

When a rectal excision is possible, whenever feasible, the aim should be to restore gastrointestinal continuity and con­tinence by preserving the anal sphincter. A sphincter-saving operation (anterior resection) is usually possible for tumours of the upper two-thirds of the rectum. Although removal of the rectum with a permanent colostomy (abdominoperineal excision) is often required for tumours of the lower third of the rectum, the introduction of the stapling gun has enabled many more of these patients to be treated by a sphincter-saving procedure. Provided a minimum distal margin of clearance of 2 cm can be secured, it is safe to restore gastro­intestinal continuity (Williams). Because of the much wider degree of local spread by anaplastic tumours and the high risk of local recurrence, it has been customary not to perform restorative operations when these carcinomas are in the lower third of the rectum. However, with the realisation that a preoperative biopsy is often inaccurate with respect to the degree of histological differentiation, coupled with the more widespread use of preoperative and postoperative radiotherapy, many more anaplastic lesions are being treated by sphincter saving procedures. Anterior resection is now applied to at least two-thirds of cases presenting with carcinoma of the rectum. The principles of the operation involve radical excision of the neoplasm, with at least a 2 cm margin of normal bowel below the lower edge of the tumour, removal of all the mesorectum, i.e. total mesorectal excision (TME) (Heald) and high proximal ligation of the inferior mesenteric lymphovascular pedicle. Once the rectum has been mobilised adequately, and the bowel washed out proximally and distally, it is removed. Restoration of continuity by direct end-to-end anastomosis (manually or by stapling) must be carried out by a meticulous technique to reduce risks of suture line breakdown. If a perfect union is achieved, a protecting colostomy is not necessary (see later).

Preoperative preparation of the alimentary tract

This is usually achieved by a combination of mechanical cleansing (purgatives, enemas or ‘whole-gut irrigation’) and antibiotics. The antibiotic regime must be active against both aerobic and anaerobic organisms. At present a suitable prescription would be cefuroxime 750 mg plus metronidazole 500 mg 1 hour before surgery, plus another two doses of each drug at 6 and 12 hours after the operation. If a patient comes to surgery with a loaded colon, perioperative wash outs can be performed provided the rest of the wound is scrupulously protected. Detergent preparations are available for this.

Blood and electrolyte deficiencies are corrected. Before commencing the operation, an indwelling catheter is inserted into the bladder.

Combined (abdominal and perineal) excision of the rectum. This operation is still required for large extensive tumours of the lower third of the rectum, which are unsuitable for a sphincter-saving procedure. It has the advantage for difficult tumours of the lower rectum of two surgeons operating from the abdominal and perineal approaches simultaneously. This considerably reduces the time expended in performing the operation, and obviates turning the patient. A large catheter is passed and with the patient in Trendelenburg lithotomy position, the legs being supported in special crutches designed by Lloyd-Davies, access is afforded to the abdomen and the perineum at the same time.

The abdominal surgeon makes a midline incision, extending it well above the umbilicus. The liver and the peritoneum are examined for metastases and the degree of fixity of the growth is established. The small intestine is packed away from the pelvis. A self-retaining retractor is placed in the wound and the pelvic colon freed by dividing any congenital adhesions on the left side. The peritoneum and the pelvic floor are divided with a knife by an incision which runs from the colon at the proposed site of division over the mesocolon and across the base of the bladder or near the cervix on the pelvic floor and then upwards on the right side of the mesocolon. The peritoneum is now raised, using the points of the scissors to expose the ureters and testicular or ovarian artery. The mesocolon is now divided at the site of the proposed division of the colon and the trunk of the inferior mesenteric artery (Fig. 60.25), is ligated and divided distal to the first branch. (Some surgeons emphasise ‘flush ligation’ of the artery at its origin from the aorta.) The rectosigmoid mesentery is further divided and separated from the sacrum by blunt dissection with the fingers. In this way, the sacrum is cleared almost down to the coccyx. The peritoneal incision anterior to the rectum is now deepened and the seminal vesicles or the vaginal wall are identified so that Denonvilliers’ fascia behind them is cleared by a dissection leading down to the prostate or perineal body. The middle rectal vessels usually lying anterior to the lateral ligaments on each side are now seized with clamps, divided and ligated. The site of division of the pelvic colon is cleared of fat and the colon divided between clamps with diathermy.

By this time, the perineal surgeon working from below has mobilised the anus and the lower rectum so that the whole of the bowel together with a clamp can be passed through the perineal wound by the abdominal surgeon. Haemostasis over the sacrum may be difficult, but it is achieved by diathermy and a hot saline pack left in position for a few minutes. The pelvic peritoneum is now united by continuous catgut stitches from the bladder right back over the promontory of the sacrum (Fig. 60.26).

The site in the left iliac fossa for the colostomy should have been marked preoperatively by the stoma care nurse in consultation with the patient. If this has not been possible it should be sited equidistant from the umbilicus and the left anterior superior iliac spine at the linea semilunaris about 2.5 cm above the spinoumbilical line. A circular piece of skin and fascia, about 3 cm in diameter, is excised and this hole deepened to excise similar layers of fascia and peritoneum. The protected end of the colon with the clamp is now passed through this incision and the colostomy performed by suturing the colon to the peritoneum and the mucosa directly to the skin. The paracolic gutter is closed with sutures — this will close the ‘lateral space’. The abdomen is closed and the layers of the incision are protected from the colostomy. An adherent plastic colostomy bag is then fitted in position and the dressings are placed on the abdominal wound.

When the abdominal surgeon has made certain that the condition is operable, the perineal surgeon closes the anus with pursestring sutures of stout silk. An elliptical incision between the tip of the coccyx and the central perineal point is made around the anus and deepened. The left forefinger is insinuated into the levator ani which is divided lateral to the finger first on one side and then on the other. The dissection is deepend posteriorly by incising Waldeyer’s fascia which is a thick condensation of pelvic fascia lying between the rectum and the sacrum. Contact is made with the abdominal surgeon. The apex of skin anterior to the anus is grasped in a haemostat, which serves as a retractor, and by scissors and gauze dissection the wound is deepened, when the catheter within the membranous urethra will be felt. In both the male and the female, a plane of cleavage will be found between the rectum and the prostate of the rectum and the vagina, respectively. This plane having been carefully determined, Denonvilliers’ fascia is divided, after which the rectum can be stripped from the prostate or the vagina. The posterior wall of the vagina is frequently excised with the rectum. When the abdominal surgeon has cleared the rectum laterally, the whole of the anus and rectum can be drawn downwards and removed. Haemostasis must be secured and the perineal wound closed anteriorly and posteriorly in layers around a large drainage tube or closed entirely around suction drains. Large dressings of gauze and wool are applied over the area and a triangular bandage is used to keep the dressing in place. It is usual to employ primary closure of the perineal wound, and to use laterally situated suction drains brought out through each ischiorectal fossa to keep the large perineal cavity from filling up with blood and serous exudate. These drains can be removed after 5 days.

After treatment. The patient is returned to bed, blood transfusion being continued as necessary. The catheter is connected to a closed drainage system and left in for 5 days. It may have to be reinserted if voluntary micturation is not re-established.

Reactionary haemorrhage from the perineal wound may demand return to the theatre to open and pack the wound with gauze. The colour of the colostomy must be watched to make sure that the blood supply is adequate. Small-bowel obstruction may occur by herniation through the lateral space of the colostomy or through the pelvic peritoneal closure line. Discharge of urine from the perineal wound demands immediate investigation for bladder, ureteric or urethral damage.

Care of the colostomy. This is much the same as the care of an ileostomy (Chapter 57). Within a very short time, the colostomy acts once or twice a day. The patient soon learns which foods cause diarrhoea and therefore avoids them. Many patients are now taught to empty their lower colon by irrigations through the colostomy: this has many advantages for the patient who requires an inactive colostomy while at work. Occlusive caps ate also available which fit in the end of the stoma and allow some degree of continence.

Stenosis of colostomy is usually avoided by the removal of the circle of skin and subcutaneous tissues at the colostomy site. Dilators may be necessary if there is any tendency for stenosis to occur.

Laparoscopic abdominoperineal excision. Recently, it has been demonstrated that the operation can be carried out laparoscopically. The rectum is mobilised completely from above using the laparoscope. A small circular perineal incision is made around the anal canal, and via a limited perineal dissection the rectum and anal canal are completely mobilised. After transecting the mid-sigmoid colon with an Endo GIA instrument, the specimen containing the carcinoma is delivered through the perineal wound. A trephine incision is made in the left iliac fossa and the sigmoid colon is brought out as an end colostomy. Although the operative technique has been shown to be quite feasible and reduces postoperative pain and time in hospital, there is concern that it may not be as curative as the standard ~open’ technique. The concern surrounds the degree of clearance that can be achieved via the laparoscope, and the risk of free cancer cells being disseminated around. the peritoneal cavity and implanting, particularly at the ‘port’ sites. Controlled trials will be needed to determine whether the laparoscopic approach is safe.

Anterior resection

In cases of carcinoma of the rectum situated above the peritoneal reflection, lymphatic spread is virtually confined to the upward path. Here a wide resection of the bowel with its lymphatic field, followed by end-to-end anastomosis and preservation of the sphincter mechanism is both justifiable and highly desirable.

As discussed previously, in the last two decades there has been a move to extend sphincter-saving operations to treat most tumours of the middle third of the rectum, and indeed many of the lower third. The introduction of the stapling instruments, particularly the new Premium CEEA instrument with its detachable head, has made such procedures far more feasible.

The operation of low anterior resection proceeds in the same manner as the abdominal part of abdominoperineal excision. The rectum is mobilised to such an extent that a right-angled clamp can be placed at least 2 cm below the tumour. The rectal stump can then be stapled transversely, using a TA instrument. After the rectum and sigmoid colon have been excised, continuity is re-established by the method depicted in Fig. 60.27. Some surgeons are concerned that the anastomotic leakage rate will be increased if the technique of cross-stapling of the rectal stump is used. They prefer to place a pursestring suture in the rectal stump lumen, as well as in the proximal colon. After the stapling gun is fired and removed, it is essential that the head of the instrument is detached and the ‘doughnuts’ are examined. A break in the circumference of one or both ‘doughnuts’ signifies a defect in the anastomosis, and the latter should be sought and repaired with interrupted sutures. In these circumstances, a covering stoma will also be required to allow safe healing of the anastomosis. Some surgeons believe that such a stoma is required for all colorectal and coloanal anastomoses which are constructed below the penitoneal reflection.

Occasionally, although the rectum, together with its tumour, can be removed adequately, continuity cannot be restored by a stapling technique. In such cases, it may still be possible to restore continuity by bringing the colon down to the anal canal and constructing a coloanal anastomosis via the transanal route (Fig. 60.28) (the so-called abdominotransanal—coloanal operation first described by Parks).

In each of the procedures, it is essential to ensure that any free tumour cells released by mobilisation of the rectum are destroyed by irrigation of the colonic and rectal lumens with a cancercidal solution such as 1 per cent centrimide. By so doing, the implantation of such cells and subsequent local recurrence is prevented. However, it should be realised that, although a small percentage of local recurrences is due to implantation of shed cells, the majority is due to inadequate removal of the tumour at the time of the initial operation. Although it is usual for the surgeon to remove all macroscopic tumour, he or she is often unable to remove all microscopic tumour. Particular interest has recently focused on local microscopic spread. It is now known that micrometastases are present in the mesorectum, and these are the most likely cause of local recurrence after rectal excision (Quirke). Heald has emphasised how important it is to remove all of the mesorectum during anterior resection or abdomino­penineal excision. TME is now being practised world-wide and appears to reduce the risks of local recurrence substantially (Fig. 60.29). However, it is unlikely that surgery alone will deal adequately with the micrometastases in the pelvis. Consequently, adjuvant radiotherapy may have added benefit (see below).

Laparoscopic anterior resection

It is now possible to perform a high anterior resection using the laparoscope, the anastomosis being performed intraperitoneally using a slightly modified circular stapling gun. Laparoscopic anastomoses below the penitoneal reflection are feasible, but are much more difficult. However, with improvements in technology such procedures may become more commonplace. Nevertheless, like laparoscopic abdominopenineal excision, there is concern that these operations may be less curative than the standard operations.

Hartmann’s operation. This is an excellent procedure in an old and feeble patient who would not stand a lengthy anterior resection or an abdominoperineal procedure. Through an abdominal incision the rectum is excised, if possible, to within 2.5 cm of the anus, the anorectal stump is transected usually with a stapler, a colostomy is performed and the peritoneum oversewn to cover the pelvic defect in the usual way. In an old patient, where the neoplasm is usually slow growing and spread is late, this is a most useful operation.

Palliative colostomy. This is indicated only in cases giving rise to intestinal obstruction, or where there is gross infection of the neoplasm. It is often possible to resect the growth later, and in some cases cure, rather than palliation, is achieved.

Local operations. For small, low-grade mobile lesions, which are often Dukes’ A tumours, local removal should be curative. For these tumours, especially in the unfit or patients who will not accept a colostomy, local removal has been used. Such operations are only suitable for lesions within 10 cm of the anal verge. Turnbull advocated local diathermy removal while York-Mason developed a trans-sphincteric approach, but a peranal approach is usually possible, with full-thickness excision of the lesion. More recently, the TEM technique has been used for these tumours. There is considerable doubt whether such techniques should be used for potential curable lesions as they do not deal with the mesorectal or lymphatic spread of the tumour.

More extensive operations. When the carcinoma of the rectum has spread to contiguous organs, the radical operation can often be extended to remove these structures. Thus in the male, where the spread is usually to the bladder, a cystectomy and resection of the rectum can be effected. In the female, the uterus acts as a barrier preventing spread from the rectum to the bladder. Accordingly, a hysterectomy should be undertaken in addition to excision of the rectum. Should the bladder base be involved, then pelvic exenteration must include that structure. Pelvic evisceration for carcinoma of the rectum is justifiable only when the surgeon is reasonably confident that the growth can be removed in toto.

Pelvic exenteration (Brunschwig’s operation). The aim is to remove all of the pelvic organs, together with the internal iliac and the obturator groups of lymph nodes (Fig. 60.30). The Trendelenburg lithotomy position facilitates the procedure, and ligation of both internal iliac arteries diminishes the blood loss. The small intestine fills the empty pelvis. Special care must therefore be taken to suture accurately the perineal skin, and to avoid pressure necrosis of the perineal incision by nursing the patient on alternate sides. Some form of urinary diversion is necessary (Chapter 65), usually an ileal conduit.

Radiotherapy. With modern techniques (MV cobalt therapy or neutron beam irradiation) some adenocarcinomas now respond to radiotherapy. Various controlled trials have recently been performed to investigate the effect of adjuvant radiotherapy given either preoperation or postoperatively. The overall results of these trials suggest that provided an adequate dose is given (4000—5000 Gy) adjuvant radiotherapy can reduce the incidence of local recurrence; however, long-term survival is not affected. Surprisingly, with modern techniques morbidity from the radiation is not a major problem. Another advantage of preoperative radiotherapy is often its ability to reduce the size of a large tumour and make its subsequent removal easier. Palliative irradiation can be given for inoperable primary tumours or local recurrence, especially when painful. Papillon perfected a technique of intracavity radiation which applies the treatment direct to the tumour from the rectal lumen. In a selected series of early cases, the results were good (more than 70 per cent 5-year survival rates). Intraoperative irradiation is also being evaluated.

Chemotherapy and immunotherapy. A variety of drugs has been tried both as an adjuvant therapy and for the treatment of disseminated disease. The most frequently used drug is 5-fluorouracil (SFU). Up until recently, the results of various trials using SFU either alone or in combination were disappointing. However, some optimism has recently been aroused by studies which have infused SFU into the portal vein during and immediately after the primary operation (Taylor). Such adjuvant therapy is thought to kill malignant cells which are released into the circulation during operative manipulation of tumour, and thus prevent the formation of metastases. Initial results suggest that such therapy does reduce the incidence of metastases and can prolong survival.

There is also evidence that systemic folinic acid (Leucovorin) has an effect as an adjuvant therapy when used in combination with 5FU. Similarly, studies from both the UK and the USA suggested that the combination of SFU and levamisole (a nonspecific stimulator of the immune process) was effective as an adjuvant therapy for Dukes’ C carcinomas. A variety of studies is now being conducted world-wide to examine which are the best forms of adjuvant therapy that should be used for both rectal and colon cancer. At the present it is generally accepted that the combination of SFU and folinic acid given for a 6-month period in patients who are at high risk of recurrence can reduce cancer specific mortality.

There is considerable interest at present in immunotherapy for the treatment of disseminated colorectal cancer. Various monoclonal antibodies to carcinoembryonic antigen have been developed, which theoretically can be targeted to malignant deposits. When these antibodies are conjugated to cancercidal agents, they have the ability to destroy the cancerous cells. Unfortunately, the antibodies are not sufficiently specific and, therefore, normal tissue is likely to be damaged. Nevertheless, the search continues for more selective antibodies.

Results of surgery for rectal cancer. In specialised centres, the resectability rate may be as high as 95 per cent, with an operative mortality of less than 5 per cent. Overall, 5-year survival rates in these centres is about 50 per cent, but the rate falls to approximately 25 per cent when the results of nonspecialised centres are included. The most likely reason for this difference is the higher proportion of advanced and emergency cases treated in nonspecialised hospitals. However, another contributing reason is that in specialised centres there is a concentration of expertise which is not readily available in district hospitals. Survival rates are influenced by Dukes’ stage, with C eases doing worse than A and B lesions (Fig. 60.31). The degree of mobility also influences survival, with fixed lesions having a worse prognosis than mobile lesions. The lower the tumour is in the rectum, the worse the outlook. Histological grade also influences outcome, anaplastic lesions having the worse prognosis. Interestingly, despite the more frequent use of sphincter-saving resection compared with abdominoperineal excision, survival has not been affected.

Local recurrence. Local recurrence after rectal excision is a major problem. The patient often presents with persistent pelvic pain, which radiates down the legs if sacral roots have been involved. Bladder problems may occur. If recurrence develops after abdominoperineal excision, a swelling or induration may be present in the perineum, or an abscess or discharging sinus may develop. Occasionally, the presence of a large recurrence in the pelvis may lead to bilateral leg oedema, from either from pressure or invasion of lymphatics or veins. After sphincter-saving resection, local recurrence may produce a change in bowel habit, or the passage of blood per rectum. Sigmoidoscopic examination after sphincter-saving resection may reveal friable tissue at the anastomosis which, when biopsied, confirms the diagnosis. However, usually the recurrence is situated extrarectally, and is detected either as induration on digital examination or by endoluminal ultrasonography or CT. These investigations can also detect recurrence before it causes symptoms. Local recurrence rates vary between 2 and 25 per cent and seem to occur with equal frequency after sphincter-saving resection an abdominoperineal excision. The most common cause is inadequate removal of all the tumour at the initial operation. This is due to the presence of microscopic tumour deposits in the tissues surrounding the rectum. Heald has shown that if the mesorectum is removed in its entirety, the local recurrence rate can be reduced to less than 5 per cent.

Other possible causes for local recurrence include implantation of viable cells on the suture line and the development of a new primary tumour. Although both mechanisms may occur, inadequate removal of the tumour is by far and away the most important reason for recurrence. Eighty per cent of all local recurrences develop within 2 years following surgery and are very difficult to treat. The best prospect of salvage is by surgical resection. However, it is only possible to achieve apparent complete removal in a minority of cases. It was hoped that serial measurements of carcinoembryonic antigen might identify those patients who might benefit by early radical surgery, but this has been found not to be the case (Northover).

The mainstay of therapy for local recurrence is radiotherapy, which is invariably palliative. Occasionally, a neodymium: yttrium-aluminium-garnet (Nd:Yag) laser can be used to deal with an obstructing or bleeding lesion.

Carcinoid tumour. Carcinoid tumour of the rectum, as far as its lethal properties are concerned, can be looked upon as a gradation between a benign tumour and a carcinoma. A latter-day aphorism is ‘keep carcinoid in mind when an atypical neoplasm (ulcer) of the rectum is encountered’. Like benign lymphoma, carcinoid tumour originates in the submucosa, the mucous membrane over it being intact. Consequently, it seldom produces evidence of its presence in the early stages, when it presents as a small plaque-like elevation. The incidence of clinical malignancy, i.e. the occurrence of metastases, is 10 per cent. This is much less than that for carcinoid tumour of the small intestine, but it is greater than that of carcinoid tumour of the vermiform appendix. Multiple primary carcinoid tumours of the rectum are not infrequent. The neoplasm is of slow progression, and usually metastasises late. Large carcinoids (over 2 cm) are almost always malignant.

Treatment. Local excision is sufficient treatment. Resection of the rectum is advisable if the growth is more than 2.5 cm in diameter, if recurrence follows local excision or if the growth is fixed to the perirectal tissues. Even when metastases are present, resection may prolong life.