Colon Cancer
Dr.Satheesh Kumar.P.K  BHMS,MD(Hom)
Medical Officer, Dept. of Homoeopathy, Govt. of Kerala
 

Cancer of the colon and rectum is the most common cancer of the gastrointestinal tract. In women colorectal cancer is second only to breast cancer as a cause of cancer related death. In man it is the third most common lethal cancer preceded by carcinoma of the lung and prostate. 
Colorectal carcinoma is the third  leading cause of death among malignancies all over the world
Rectal carcinoma slightly more common in men where as there is a slight predominance of colon cancer in woman. 

Most cases of colorectal carcinoma are diagnosed in patient over the age of 50 and the incidence of the disease rises steadily after that age. Despite the clear relationship with the aging, colorectal cancer is not strictly a disease of elderly; between 6 and 8 % of cases can occur in individual under the age of 40. the onset of familial and hereditary forms of the disease occurs at a much earlier age typically around the 3rd decade. 

ETIOLOGY: 
Etiology is unknown. Villous adenoma, congenital polyps of the colon, chronic ulcerative colitis and rarely adenomatous polyp may develop in to malignant lesion. 
Genetics play a major role in colorectal carcinoma. Risk of developing colorectal carcinoma is higher in person who have first degree relative with colon cancer. 

PATHOLOGY: 
Microscopically the neoplasm is a columnar celled carcinoma, originally in the epithelial cells that line the colon. 
Macroscopically the growths are 4 types.
1. Annular
2. Tubular
3. Ulcerative
4. Cauliflower
The annular variety carries a relatively good prognosis. Not give rise to early obstructive symptoms and there for is often extirpated before metastases have occurred. 
SITE:
Most frequent site is towards the termination of the colon. About 75% of tumors are seen in the descending colon, recto sigmoid and rectum. 
Cecum and ascending colon are affected in 15%.
Transverse colon 10%  
SPREAD: 
It is a comparatively slowly growing neoplasm, and if removed thoroughly at a reasonably early stage a cure can be hopefully anticipated. 
Local spread
It spreads round the intestinal wall and to a certain extend longitudinally- and usually causes obstruction before it has penetrated adjacent structures. 
Lymphatic spread
Lymph node draining the colon are a) Epicolic lymph node
b) paracolic lymph node
c) Intermediate lymph node
d) The main lymph node 
 (The intermediate lymph node arranged along the iliocolic, right colic, mid colic, left colic and the sigmoid artery.)
 ( The main lymph node aggregated around the superior and inferior mesenteric vessels- where they arise from aorta) 
Blood stream spread 
Are carried to the liver via the portal system. 

CLINICAL FEATURES: 
Signs and symptoms of colorectal carcinoma are varied and nonspecific. The symptoms that most often compel the patient to seek medical attention include rectal bleeding, a change in bowel habit and abdominal pain. Nature of the symptoms depends on the location of tumor and the extend of the disease. 
Presentation of signs and symptoms – two types 
1) sub acute presentation: 
Right colon - Growth in the cecum or ascending colon ( right colon) are usually flat and they remain silent for long periods. [ Tumors in the right colon typically do not cause changes in bowel habits – although large mucous secreting tumors may cause diarrhea] 
Patient might notice dark or tarry stools but more often these tumors cause truly occult bleeding which is not detected by the patient. Blood stained stool is the presenting complaint in 25% of right sided lesion. Such chronic blood loss may cause iron deficiency anemia; with resultant fatigue, dizziness and palpitation. 
When a post menopausal woman or an adult man develops iron deficiency anaemia- colorectal carcinoma should be suspected and appropriate diagnostic studies must be performed. Because the bleeding associated with colon tumors tends to be intermittent- then a negative tests for occult blood in the feces do not rule out the presence of a large bowel carcinoma. 
Non specific symptoms like anaemia, weight loss, anorexia or malaise may be the presenting symptoms in some cases. 
Left colon - 75% of the neoplasm situated on left side of the colon. Left sided lesion cause obstruction early, since the contents are solid and the lumen of the bowel comparatively narrow (lesion- stenosing variety). 
Lower abdominal pain is more often associated with tumors located in the narrow left colon. Pain is of a cramping in nature and may be relieved by bowel movements. These patients are more likely to notice a change in bowel habits and the passage of bright red blood. These patients may have diarrhea which is alternating with constipation.
When the affected region is of sigmoid colon- then there is tenesmus while passing stool (bloody or mucus).
A palpable lump felt on abdominal, rectal or abdomino-rectalal examination- it may be the growth or impacted feces above it. 
Septicemia is rare but can occur with any stage of large bowel tumor. 
2) Acute presentation: 
Acute symptoms reflecting obstruction or perforation of the large bowel. ( colonic obstruction highly suggestive of cancer particularly in older patients) 
Complete obstruction occurs in less than 10% of patients with colorectal carcinoma but it is an emergency, that requires immediate diagnosis and surgical treatment. Patient with complete obstruction complain of inability to pass flatus or feces, cramping abdominal pain and abdominal distension.
Examination reveals a distended , tympanitic abdomen occasionally t he obstructing tumor can be palpated as an abdominal mass. 
If the obstruction is not relieved and the colon continues to distend, the pressure in the intestinal wall exceeds the capillary pressure and the oxygenated blood will not reach the bowel wall resulting in ischaemia and necrosis. In such situation the patient will complain of severe abdominal pain and the abdominal examination will reveal rebound tenderness and decreased or absent bowel sounds. If not treated immediately, the necrosis will progress to perforation with fecal peritonitis and sepsis. 
The large bowel can also perforate at the tumor site probably because a transmural tumor loses its blood supply and become necrotic. Inflammatory process may be continued to the site of the perforation. In some cases perforation leads to generalized peritonitis. In rare cases, perforation in to the adjacent organ occurs ( usually the bladder and vagina) and is manifested by pneumaturia, fecaluria or feculent vaginal drainage. 
Unfortunately in many cases the first sign of colon cancer may be caused by metastasis.
Massive liver metastasis-- pruritus and jaundice.
Ascitis, enlarged ovaries and scattered deposit in lung detected in a chest  x-ray can be caused by an otherwise asymptomatic colon cancer. 

STAGING:
 The factors that are most closely related to staging of tumor are
1. The depth of tumor penetration in to the bowel wall
2. The involvement of regional lymph node
3. The presence of distant metastasis
 
Stage of the T N M system
Stage 0
T is
N 0
M 0
Stage 1
T1 / T2
N 0
M 0
Stage 2
T3 / T4
N 0
M 0
Stage 3
Any T
N1 /N 2 / N3
M 0
Stage 4
Any T
Any N
M1
T is- Tumor in situ
T 1 – Limited to mucosa and sub mucosa
T 2 – Invasion in to but not beyond muscularis propria
T 3 – Penetration of full thickness of bowel wall
T 4 – Perforate the visceral peritoneum or directly invades other organs or structures
N 0 – No regional lymph node metastasis
N 1 – One to three pre colic lymph node
N 2 - Four or more lymph node
N 3 - Any lymph node
M 0 – No distant metastasis
M 1 - Distant metastasis 

Duke’s classification of large bowel cancer 
Stage Percentage prognosis( 5 yr. Survival)
A – Spread not beyond muscularis. No lymph node metastasis  
4 %  
80 %
B – Spread is beyond muscularis into pericolic tissues but no lymph node metastasis  
28 % 
58 %
C – Spread to lymph node
27 %
36 %
D - metastasis present
41 %
6%

Diagnosis : 
1. By digital examination of the rectum
2. Stool – occult blood- indicative of ulcerative growth
3. Definitive diagnosis is usually established by endoscopy  Endoscopy - - - flexible sigmoidoscopy or
    Colonoscopy – most accurate
4. Barium enema – seen as filling defect or distortion of the colonic mucosa or as an ulcer.
5. Plain film of the abdomen reveal dilated colon in colonic obstruction
6. Chest x- ray – pulmonary metastasis
7. C T scan – asses the extend of invasion of the primary and to guided for intra abdominal metastasis
8. Liver function test- elevation of alkaline phosphatase, lactate dehydrogenase, bilirubin and transaminase enzyme are suggestive of liver metastasis ( these are useful in post operative follow up and if elevated can suggest the need for C T scan to search for hepatic secondaries)
9. Serum level of C E A. ( C E A is an antigen present in embryonic and fetal tissue and in colorectal carcinoma but is absent in normal adult colonic mucosa.) In patient with cancer that has not penetrated the bowel wall, the serum C E A is usually not elevated. It is not a specific test- since it is increase in tumors of the lung, breast, stomach and pancreas. It may also be elevated in smokers and patients with cirrhosis, pancreatits, renal failure and ulcerative colitis. The elevated C E A does have a high correlation with tumor recurrence and with the presence of secondaries from colorectal carcinoma. If the C E A elevated before operation, the recurrence rate is elevated regardless of the disease stage. Post operative C E A level may indicate the completeness of surgical resection or the presence   of occult metastasis. When used alone the C E A assay is 70% accurate in predicting the development of liver secondaries with in one year. In combination with ct accuracy increases to up to 90 % 

Treatment : 
Surgical –
Preoperative treatment- wound infection and intra abdominal abscess are two  common problems after colorectal surgery. So steps must be taken before operation to reduce the bacterial population as much as possible. 
Emergency for operation –
Obstruction-when a colon or rectal cancer causes complete obstruction, immediate surgical treatment is necessary. The entire colon proximal to the obstruction should be resected and the terminal ileum then anastomosed to the remaining normal colon. Obstruction by a left sided cancer presenting more difficult problems.
Perforation- cancer causing a perforation of the colonic wall represent a life threatening surgical emergency. 
Operation-
Remove the cancer segment of the bowel, its mesentery that contain the lymphatic drainage and any organ that has been directly invaded by the tumor.
Hepatic metastasis - solitary- can be resected as uninvolved lobe can be preserved.
Multiple painful secondaries can be palliated by hepatic artery ligation 

Differential diagnosis : 
 Ulcerative colitis
Polyps
Diverticulitis
Intestinal tuberculosis
Chronic amebiasis
Lymphoma
Endometriosis 
Complication :  
Secondaries
Obstruction
Intussusceptions
Volvulus
Perforation
Local peritonitis
Massive hemorrhage
Spread to neighboring organs –ureters, bladder etc. 

Prognosis:
Since most cases are detected late, either when the growth is fixed or has metastasized the prognosis is poor.
5 year survival for the patients undergoing radical surgery is about 50%

Prophylaxis : 
Preventable if premalignant condition such as ulcerative colitis and colonic polyposes are regularly followed up with annual endoscopic examination. 

Homoeopathic medicines :
Hydrastis,Alumina, Ars alb, Kali carb, Nitric acid ,Carbo veg, Graphitis, Lycopodium, Muriatic acid, Ruta, Sepia, Spigelia.