Cancer cells emanate in the tissues of the rectum causing rectal cancer. Colorectal cancer can occur either in the rectum or in the colon. Colon and rectal cancer extensively comprise of adenocarcinomas (about 98%). Rectal cancers are also inclusive of carcinoid, sarcoma and lymphoma. Both colon and rectal cancers may undergo similar screening recommendations. Squamous cell carcinomas are anal carcinomas that develop in the area commencing from the rectum to the anal verge. Every 6 days the mucosa in the large intestine regenerates during which time the crypt cells migrate to the surface. Their ability to replicate is lost when they encounter differentiation and maturation.

Causes and risk factors
The development of colorectal cancer is sporadic and the exact etiological factors are unknown.

• Family and medical history: Women with a history of breast, uterus or ovarian cancers are at a high risk of developing the disease. If an individual’s first-degree relatives such as siblings, parents and children have had colorectal cancer, then the person is more likely to develop it themselves.
• Genetic disorders: Genetic components play a significant role in the development of colorectal cancer. 2% of all colorectal cancers occur due to the alteration of the HNPCC gene. FAP or familial adenomatous polyposis is caused due to alterations in the APC gene.
• IBD or inflammatory bowel disease: Crohn’s disease causes inflammation of the colon increasing the risk of the development of colorectal cancer.
• Lifestyle and environmental factors: High ingestion of alcohol, smoking and consumption of high-fat foods increase the risk of colorectal cancer.
• Cholecystectomy: The cholecystectomy procedure allows the free flow of carcinogenic bile acids and their byproducts enhancing intestinal degradation due to bacteria.

Signs and Symptoms

• Prolonged rectal bleeding – this could also be due to the presence of hemorrhoids
• Blood mixed with the stool
• Anal bleeding
• Bowel obstruction
• Presence of a large rectal mass disallowing the normal passage of stools resulting in severe constipation and pain
• Narrow size of stool – pencil-thin stools are a result of obstruction due to rectal cancer
• Sensation of incomplete evacuation of stools
• Unexplained weight loss

Diagnosis

• Physical examination will check for metastatic lesions, enlarged lymph nodes, the size and location of cancer.
• DRE or digital rectal examination is done to detect the presence of abnormal lesions. The size, ulceration and existence of pararectal lymph nodes of rectal tumours are assessed.
• Laboratory tests will include CBC, serum chemistry, carcinoembryonic antigen test and cancer antigen 19-9 assay. Screening techniques conducted are:
  • FOBT – Guaiac-based fecal occult blood test
  • SDNA – Stool DNA screening using polymerase chain reaction
  • FIT – Fecal immunochemical test using monoclonal antibody assay
  • Rigid proctosigmoidoscopy to estimate the size of the lesion and degree of obstruction
  • FSIG – Flexible sigmoidoscopy
  • DCBE – Double-contrast barium enema
  • CTC – CT Colonography or virtual colonoscopy
  • FFC – Fiberoptic flexible colonoscopy

Treatment and Medication
Surgery and radiotherapy are options to be considered for the treatment of rectal cancer. Medication with antineoplastic agents helps to induce remission and downstage cancer thus preventing complications.
We conduct laparoscopic surgery for the complete excision of rectal cancer. Met the chief gastro specialist in Chennai and get resolved from the rectal cancer.