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
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.