Rectal Cancer: Signs, Symptoms and Treatment

Carcinoma Rectum

Aetiopathogenesis: Similar to carcinoma colon events such as adenoma—dysplasia and carcinoma.

However, a few precancerous conditions and risk factors are given as follows:

Precancerous Conditions

• Polyps in FAP, villous adenoma
• Ulcerative colitis
• Crohn’s disease

Carcinoma Rectum Risk Factors

• Smoking: Smokers are 30 to 40% more likely to die of colorectal cancer.
• Obesity: Obesity and lack of exercise are associated with rectal cancers.
• Alcohol: A definite increase has been found in breast and colon cancers. Alcohol damages the cells and prevents the repair of cells, thereby increasing the risk of malignancy.
• Genetic: Familial adenomatous polyposis gene: In hereditary forms of colorectal cancers such as Lynch syndrome mutation in one of the DNA mismatch repair genes is responsible.

Carcinoma Rectum Pathological Types

1. Annular: Annular variety is common at the rectosigmoid junction. It presents with constipation and intestinal obstruction. It takes about a year for the growth to completely encircle the lumen of the gut (napkin ring deformity).
2. Polypoidal: Polypoidal lesions are common in the ampulla of the rectum
3. Ulcerative: Ulcerative lesions can occur anywhere in the rectum with raised edges and growth occurs in the transverse direction.
4. Diffuse: Diffuse variety is similar to linitis plastica. It develops from ulcerative colitis. It has a poor prognosis.
5. Colloid: Colloid variety is rare  The tumour contents are gelatinous due to increased mucus production. This variety is seen in young patients. The cell is filled with mucus and nucleus is displaced. It is called ‘signet ring’ carcinoma. It is associated with poor prognosis.

Carcinoma Rectum Clinical Features

• Constipation: Constipation requiring increasing doses of purgatives due to annular growth at rectosigmoid junction. Always a sense of incomplete evacuation and altered bowel habits.
• Bleeding per rectum: Frank blood or mixed with stools is common. It is painless, never massive and is the earliest symptom of carcinoma rectum. Very often, it is confused for haemorrhoids.
• Early morning spurious diarrhoea:  Early morning spurious diarrhoea is due to accumulation of mucus overnight in the ampulla of rectum (dilated middle portion of rectum), which causes an urgency to pass stools but results in passage of only mucus with minimal stools. It is associated with a sense of incomplete defaecation.
• Tenesmus: Painful, incomplete defecation associated with bleeding is called tenesmus. This symptom is common with stricturous growths.
• Bloody slime: An attempt at defaecation results in mucus mixed with blood.
• Loss of appetite:  Loss of weight due to liver secondaries (cancer cachexia) and abdominal distension due to obstruction are late features

Carcinoma Rectum Correlation of Symptoms

• Symptom
• Constipation
• Bleeding
• Tenesmus
• Early morning spurious
• Bloody slime
• Sciatica-like pain
• Abdominal distension
• Loss of weight/  abdominal distension
• Strangury

Probable site of lesion/explanation:

• Rectosigmoid
• Cauliflower-like growth
• Rectosigmoid stricture
• Growth in the ampulla of diarrhoea rectum
• Sacral plexus infiltration
• Blood and mucus
• Large bowel obstruction
• Liver metastasis, ascites, etc.
• Infiltration of the bladder base anteriorly

ABCDEF of Rectal Carcinoma—Symptoms

• Altered bowel habits
• Bleeding per rectum and bloody slime—upper rectum.
• Constipation increasing—annular carcinoma at the rectosigmoid junction.
• Incomplete defaecation
• Early morning spurious diarrhoea—midrectum
• Fatigue, weight loss

Carcinoma Rectal  Clinical Examination

1. Rectal examination:

• In every patient with bleeding per rectum, rectal examination has to be done. More than 90% of cases of carcinoma rectum can be diagnosed by rectal examination.
• Always feel for the ulceror growth, nodularity, induration, and fixity to posterior sacrum, anterior bladder base and laterally to lateral ligaments.
• Look for the blood stains especially in ulcerative cases. It is also possible to feel the lymph nodes in the mesorectum in cases of lower third carcinomas.

2. Vaginal examination:

• When the growth is situated in the anterior wall of the rectum, accurate assessment of the growth can be done with one finger in the rectum and the other in the vagina
• Large Krukenberg tumours, if present, can also be felt by vaginal and rectal examinations.

3. Evidence of metastasis: Palpable nodular liver, paraaortic lymph nodes, ascites and enlarged left supraclavicular nodes (Troisier’s sign).

Histology: They are adenocarcinomas—well differentiated, moderately differentiated and poorly differentiated. However, a few special types of adenocarcinomas are colloid carcinoma rectum and signet ring carcinoma. In colloid carcinoma, colloid-like substance is produced which can be detected macroscopically. Signet cell cancer is a rare (less than 1%) type of cancer that starts in glandular cells.

Signet ring carcinoma and colloid carcinoma carry poor prognosis.

Carcinoma Rectal Differential Diagnosis

1. Villous adenomas (benign):

• Present as bleeding per rectum with occasional mass per rectum. They have a frond-like appearance. They are very friable, bulky and easily bleed on touch.
• Biopsy is a must. If it is benign, it can be removed through the rectum— submucosally.

2. Proctitis due to inflammatory bowel diseases:

Both ulcerative colitis and Crohn’s disease produce diarrhoea, blood in the stools and multiple nonindurated ulcers. Regardless biopsy is a must before doing a major surgical resection. Ulcers in ulcerative colitis are typically described as pinpoint ulcers. In Crohn’s, they are fissure type or patchy with a cobblestone appearance.

Rectal Ulcers:

• Carcinoma rectum
• Amoebic ulcers
• Ulcerative colitis
• HIV infection
• Solitary rectal ulcers
• Radiation proctitis

Rectum And Anal Canal Clinical Notes:

• A 22-year-old girl was treated with iron tablets for anaemia due to occasional bleeding per rectum. She was treated with metronidazole because she was passing mucus along with the stools. She developed intestinal obstruction after 6 months during which time a surgeon was consulted. Rectal examination revealed a large growth, fixed all around.
• She died 6 months later because of advanced disease. The case illustrates the importance of rectal examination and that carcinoma of the rectum often occurs in young patients also. Again to highlight the importance of rectal examination in a case of bleeding per rectum

3. Amoebic granuloma:

• It is not common nowadays. It presents with a soft mass at a rectosigmoid junction with or without obstruction.
• An ulcer over the surface will mimic carcinoma. Biopsy is mandatory because amoebomas are completely curable with antiamoebic treatment.

4. Tuberculous proctitis:

• Usually, patients have pulmonary tuberculosis. Submucosal abscess ruptures and results in ulcers with undermined edges.
• Hypertrophic tuberculosis with stricture can also occur. Biopsy is mandatory before resection.

5. Endometrioma:

• It presents as constipation, bleeding per rectum especially during menstruation. Typically young females between the age of 20 and 40 years are affected.
• It produces a constricting lesion in the rectosigmoid junction. Mucosa is intact as seen by sigmoidoscopy. Treatment is biopsy followed by treatment of endometriosis.

6. Solitary rectal ulcer syndrome (SRUS):

• Site: Commonly occurs in the anterior wall of lower rectum, an area of mucosal change.
• Mucosa: It is erythematous, heaped up and bleeds on touch.
• It is a single, depressed ulcer.
• The cause, even though not clear, is probably due to trauma by anal digitation. Today, it is believed that it is due to internal intussusception or anterior wall prolapse.
• Clinical features are passage of blood and mucus in stools. Mucosal prolapse may also be a feature.
• A biopsy must be done to rule out carcinoma rectum.
• Treatment is conservative: Avoidance of constipation and straining may treat the prolapse.

Carcinoma Rectum Spread

1. Local spread:
   • It takes 18 months for a growth to encircle the rectal lumen as in annular strictures at the rectosigmoid junction.
   • Then, it involves muscle coat and spreads into extrarectal tissues.
   • Anteriorly, it involves prostate, seminal vesicles and bladder base in males, vagina and uterus in females.
   • Posteriorly, sacral plexus gets involved in late cases and causes sciatica-like pain. Posterior sacral infiltration and anterior bladder base infiltration— surgery can be very difficult and dangerous (uncontrollable bleeding from sacral plexus of veins and prostatic plexus of veins in males.
   • Hence, preoperative chemoradiotherapy followed by surgery is done.
   • Involvement of mesorectum carries poor prognosis. Hence, the circumferential resected margin is important.
   • Lymphatic spread—chief nodes are para-aortic nodes.
2.  Haematogenous spread: It results in secondaries in the liver, lungs, etc. It is common in young patients with anaplastic variety and in colloid carcinoma.
3. Peritoneal spread: It results in ascites, carcinomatous nodules over the peritoneum, etc.