Carcinoma of the colon and rectum

In Europe, carcinoma of the large gut is commoner than all the other carcinomas, except for those of the lung in men and the breast in women. It is not uncommon in India, but it is still uncommon in Africa, especially in the rural areas, where a high fibre diet is still the rule. If Schistosoma mansoni is endemic in your community, you will see the adenocarcinoma of the rectum that it causes. You will probably never see diverticulitis.

Carcinoma of the large gut is usually a slow-growing adenocarcinoma, which may not penetrate a patient's gut until he has had symptoms for about 18 months, although it tends to grow faster if he is young. It may project into the lumen like a cauliflower, or it may form a stricture (long or short), or an ulcer (if so it is likely to penetrate early). It invades locally, spreads to his regional nodes or his liver (usually late), or through to his peritoneal cavity (late and uncommon). Tumours of the rectum spread upwards, those of the anal canal (less common) spread to the inguinal nodes.

He is usually over 45, but is occasionally a young adult, who presents with the following symptoms: (1) Blood and mucus in his stools. (2) An alteration in his bowel habit. (3) A sense of incomplete defaecation. (4) Colicky abdominal pain (incomplete obstruction). (5) Intestinal obstruction. (6) A fixed mass. (7) A faecal fistula which appears spontaneously (rare).

You are most likely to meet carcinoma of the large gut when you operate for obstruction, and have to relieve it. Otherwise, avoid operating, and refer him.

Carcinoma of the rectum usually presents late, because it causes little pain in the early stages. Rectal bleeding is the important symptom, sometimes with disturbances of bowel function, increasing constipation, subacute obstruction, abdominal distension, cramps, and a feeling that there is something left to pass after a bowel evacuation. You can feel most rectal carcinomas with your finger[md]either as a firm raised plaque, or an ulcer with hard rolled edges, leaving blood on your glove afterwards.

Try to: (1) Remember the possibility of carcinoma of the large gut and rectum, and alert your paramedical staff to it also. (2) Do a rectal examination, proctoscopy, and sigmoidoscopy when these are indicated (22.1). (3) Stage a patient and assess his operability. (4) Do a colostomy or Hartmann's operation (9.5, 10.10, 10-16) if he presents in obstruction. (5) If you cannot refer him, you may have to do a right (66-20), or left hemicolectomy, or you can resect the gut supplied by his middle colic vessels (all difficult operations). An abdominoperineal resection, or an anterior resection for a rectal or low sigmoid carcinoma, is an expert's task. Management is essentially surgical. Chemotherapy is palliative only.

CARCINOMA OF THE LARGE GUT [s8]AND RECTUM HISTORY and EXAMINATION. The patient is likely to have had symptoms for several months. Look for: (1) Signs of loss of weight and anaemia. (2) A primary mass, secondaries in his liver, and ascites. (3) A rectal mass (75% of rectal tumours can be felt on rectal examination in Europe). Send a specimen for histology from the edge of the lesion. (4) Occult blood in his stools (90%). (5) A tumour at sigmoidoscopy (all rectal, and 25% of sigmoid, tumours can be seen with a rigid sigmoidoscope).

X-RAYS. If the above investigations are negative, do a barium enema. This is not easy, but it can be done in a district hospital. Use barium and air phase contrast (34.5). Avoid a barium enema with complete or partial obstruction.

THE DIFFERENTIAL DIAGNOSIS includes: (1) Other causes of blood in the stools (piles, amoebiasis, and S. mansoni dysentery, 22.3). (2) Other causes of altered bowel habit (gut infections, poor food supply, upper abdominal malignancy). (3) Other causes of acute-on-chronic obstruction (acute volvulus, amoebic stricture, in South America Chagas' disease). (5) Other causes of strictures of the rectum or sigmoid (amoebic strictures, or lymphogranuloma venereum, especially in women).

The frequency of different presenting symptoms varies with the site of the lesion:

Suggesting a lesion in the right colon[md]anaemia, a mass, caecal pain, weight loss, obstruction.

Suggesting a lesion in the left colon[md]colicky abdominal pain, alteration of bowel habit (diarrhoea alternating with constipation), blood mixed with stools, obstruction.

Suggesting a lesion in the rectum[md]rectal bleeding, diarrhoea, a feeling of incomplete evacuation.

STAGING. A tumour can be mobile, tethered to surrounding structures, or fixed. Assess a rectal tumour digitally, and those elsewhere at laparotomy. A carcinoma is resectable unless: (1) It is fixed to his pelvic wall, his abdominal wall, or his bladder (fixity is a difficult and misleading sign). (2) He has palpable masses in his liver, or malignant ascites, or metastases in his lungs, or superficial lymph nodes. Ascites, jaundice, or a hard, irregular liver all indicate an incurable tumour for which no surgery is possible; palliate him.

If his tumour and its associated mesentery can be excised, the following staging (Dukes) will give a more accurate prognosis. In the UK 15% are in Stage A, and 50% in stages C or D. Overall only 20% of patients with carcinoma of the large gut survive 5 years in the UK.

Stage A. The tumour is confined to the wall of his gut. 85% chance of surviving 5 years.

Stage B. The tumour spreads through his gut wall, but his lymph nodes are not involved. 50% chance of surviving 5 years.

Stage C. His lymph nodes are involved. 25% chance of surviving 5 years.

Stage D. Distant or liver metastases, nobody survives 5 years.

MANAGEMENT. See Section 9.3 about ''Which parts of the gut you can anastomose to which and when'. Management depends on: (1) Where the tumour is. (2) If it is resectable or not. (3) If his gut is obstructed or not. (3) How skilled you are.

If his gut is not obstructed, only operate if you cannot refer him and you are experienced. Definitive operations in Stages A and B have a good prognosis. Palliation to remove obstruction, or prevent it, in Stages C and D will help him much.

If his gut is obstructed (much the most likely occasion on which you will meet this tumour), you will have to relieve the obstruction yourself by doing a colostomy, or an anastomosis, as these are practicable.

If possible, avoid resecting at the initial operation: (1) The contents of his gut will not have been ''sterilized'. (2) A primary anastomosis in the large gut is apt to leak when it is full of faeces, especially if it is obstructed.

CAUTION ! (1) The contents of the large gut are always loaded with bacteria, so always prepare the gut before an elective operation (see below). (2) When you have to operate in an emergency for obstruction avoid: (a) contaminating his peritoneal cavity, and (b) remember that the only safe anastomosis is one between his ileum and his colon, never colon to colon! (3) When you anastomose the ileum to the transverse colon, remember to save as much ileum as you can, because its last few centimetres are the site of absorption of vitamin B[,12].

Fig. 32-15a CARCINOMA OF THE LARGE GUT. Carcinomas in various sites: the ascending colon (A), the descending colon (B), the sigmoid colon (C), the rectosigmoid junction (D) and the lower rectum (E).

F, a right hemicolectomy with an end to side anastomosis. G, a side to side ileocolic bypass anastomosis. H, excision of a tumour from the left colon with a protective colostomy. I, excision of the tumour followed by a sigmoid colostomy. J, a colostomy to relieve obstruction by a tumour in the descending colon. K, Hartmann's operation. L, exteriorization of a tumour in the sigmoid colon. M, never do this! Never make an anastomosis of the distal colon unprotected by a proximal colostomy. N, anastomoses of the caecum are especially dangerous.

If his tumour is proximal to his mid transverse colon (A, in Fig. 32-15a):

If his gut is unobstructed or only partly obstructed, try to refer him. If you cannot do this, prepare him first and operate.

If his tumour is resectable, resect his caecum, ascending colon, and associated mesentery, and anastomose his ileum to his transverse colon. This is major surgery (F, in Fig. 32-15a, and the second part of Fig. 66-20). The ileum has a good blood supply, and when it is dilated it matches the size of the empty transverse colon. F, shows the anastomosis end to side. You can also do it end to end. If his ileum is not the same size as his colon, you can make a nick in it to enlarge it, as in Fig. 9- 7.

If it is not resectable, bypass the obstruction with a side to side ileotransverse anastomosis (G, also Fig. 9-12). He may obstruct at any time.

If he is obstructed: (1) If his condition is good and you are fairly experienced, do a left hemicolectomy at the time of the obstruction (F). (2) If his condition is poor and/or you are inexperienced, make a bypass (G). This is safe, but he may be unwilling later to undergo the resection which might cure him.

If his tumour is between his mid transverse colon and his sigmoid colon (B):

If he is unobstructed or partly obstructed, try to refer him. If this is impossible, prepare him first and operate.

If his tumour is resectable, resect the involved gut 5 cm clear of the tumour with its associated mesentery. Do an end to end anastomosis with a proximal colostomy (H). The bowel ends must have a good blood supply. If not, resect more gut, but not more mesentery. The extent of this operation varies from being a local resection to being a left hemicolectomy. Beware of: (1) His left ureter, which is easily reflected with his descending and his sigmoid mesentery (10-16). (2) His spleen, if you need to mobilize his splenic flexure. Make the anastomosis in 2 layers, as for small gut, preferably with a non-absorbable suture for the outer layer. Make sure the anastomosis is not under tension. This operation is less often necessary than the corresponding operation on the right, but the principles are the same (66- 20).

If his gut is obstructed, immediate anastomosis of his distal colon is dangerous because of its poor blood supply, its fluid contents which easily escape, and the great difference in size of the gut ends. So, excise the tumour if you can. Bring the two cut ends out as separate colostomies (I). Join them up electively later. Or, merely do a proximal defunctioning colostomy (J), and, if his tumour is resectable, refer him for a definitive operation as soon as he recovers.

Alternatively, when his left colon is obstructed, you can do an ileo-descending, or an ileo-rectal anastomosis (not shown). This is reasonably safe, but it is a big operation, and he may have diarrhoea afterwards. Most surgeons prefer a colostomy with or without immediate resection, depending on the circumstances.

If the tumour is in his sigmoid or upper rectum (C or D):

If his gut is unobstructed and the tumour is likely to be resectable, refer him. If this is impossible, prepare him, and do a two-stage Hartmann's operation (K).

If the tumour is not resectable, as judged by fixity to his abdominal wall, do a double-barrelled colostomy of his transverse colon (J).

If his gut is obstructed, contributors differ as to which of these alternatives is best. You can: (1) If the tumour is suitably placed in his upper sigmoid, resect it and make a colostomy proximally and a mucous fistula distally which someone else can repair (I). (2) Resect it, close the distal end of his colon, and bring the cut proximal end out as a colostomy (K, Hartmann's operation). (3) Bring his sigmoid colon out through a pelvic colostomy, and exteriorize it as if it were a loop of gangrenous gut (L); this helps to avoid contaminating his peritoneal cavity. The difference is that you need to mobilize much more mesentery, so watch his ureter (see C, Fig. 10-16). To resect gut, mobilize his colon well on both sides of the lesion. If possible, divide his inferior mesenteric artery flush with his aorta, and resect a V-shaped piece of mesentery. Bring the carcinoma out as a ''double-barrelled' loop colostomy, and resect it when you have closed his abdomen, and the operation is nearly over. Leave 1.5 cm of gut above the skin when you resect it. Three months later refer him to a specialist for a joining- up operation; if if this is impossible, do it yourself (9.5).

If the tumour is in his middle or lower rectum (E), do a biopsy through a proctoscope or sigmoidoscope. If he is not obstructed and is likely to be operable, refer him for an anterior resection, or an abdominoperineal resection. If he is obstructed, you have a choice between: (1) A transverse colostomy (J), which is best if he is going to have further surgery, because it makes this easier. (2) A double barrelled sigmoid colostomy (I), which is best if he is inoperable, because he retains the absorptive properties of his descending colon. A rectal tumour rarely causes obstruction; if it does, it will certainly be inoperable.

CAUTION ! If he has liver metastases or a fixed tumour, think hard before you do a colostomy. He may live a few more months, but dying with a colostomy will be miserable, especially if colostomy care is poor. If his tumour is not resectable, it is better to do a bypass operation, an ileotransverse (9-11, 66-20) or colo-colic anastomosis. This is possible for lesions of the ascending, transverse, or descending colon, but not the distal sigmoid or the rectum. If a bypass is impossible, a colostomy is better than dying in obstruction.

PREPARATION. If he is not obstructed, you will be able to do an elective operation, so empty his colon first. Enemas only clear its left side, so give him enough magnesium sulphate or castor oil to give him diarrhoea, meanwhile giving him plenty of fluids to avoid dehydration. For 2 days preoperatively, give him metronidazole 400 mg 8-hourly and neomycin 1 g 8 hourly, or ampicillin 500 mg 6-hourly, together with a nutritious fluids- only diet.

LAVAGE. When the operation is over, wash out his peritoneal cavity with warm saline, and then leave tetracycline 1 g or chloramphenicol 1 g in 500 ml of saline in his peritoneal cavity; don't insert drains.