Colorectal cancer- The large intestine, also known as colon is a five feet long tubular structure. After the small intestine, large intestine begins starting with caecum, ascending, transverse and descending colon, sigmoid colon, rectum and anus. It has four linings. It absorbs water from the liquid stool and making it solid.
WHAT IS COLON CANCER?
Abnormal and unrestricted growth of normal colonic cells which tends to invade the adjacent structures and spread through lymph and blood. It grows into a mass/ tumour, as an ulcer or as a constricting ring in the lumen. It can arise from any component of tissue, however commonest one is adenocarcinoma which arises from the glands of the lining.
WHO IS AT RISK OF GETTING COLONIC CANCER?
- Classic or attenuated Familial Adenomatous Polyposis (FAP/aFAP)
- Hereditary non polyposis colorectal cancer or Lynch syndrome (HNPCC)
- Juvenile polyposis syndrome
- Peutz Jeghers syndrome
- Turcot’s syndrome
- Cowden syndrome
Certain risk factors identified in non-inheritable cases long standing ulcerative colitis, obesity, high consumption in processed foods and processed meats, smoking, alcohol abuse.
WHAT ARE THE SYMPTOMS OF COLONIC CANCER?
- Blood in stools/ black tarry stools
- Changing bowel habits
- Unexplained weight loss
- Emergency presentation : Signs of intestinal obstruction or perforation of intestine
- Lump in abdomen/ Abdominal distension
- Unexplained anaemia
Early colonic cancer may have no signs or symptoms. Some may be diagnosed incidentally during endoscopy.
WHAT ARE THE TESTS TO DIAGNOSE COLONIC CANCER?
1. Colonoscopy and biopsy: it is done for visualising the entire colon from within and taking specimen from any suspicious areas for pathological testing.
2. Studies to decide stage of cancer: Computed Tomogram (CT scan), PET scan. Detailed imaging of the colon and surrounding structures, to detect spread of the disease and planning for surgery.
3. Tumour markers: Sr. CEA and CA 19-9 levels, though not diagnostic in itself, can be used for treatment monitoring.
WHAT ARE THE STAGES OF CLORECTAL CAnNCER?
There are four stages
- Stage I: When cancer is within the lining of the colon
- Stage II: When cancer has involved the entire thickness of colon and regional lymph nodes
- Stage III: When cancer has involved adjacent organs and considerable lymph nodes
- Stage IV: When cancer has spread to distant organs (mostly liver and lungs)
WHAT ARE THE TREATMENT OPTIONS FOR COLONIC CANCER?
Treatment depends on various factors, most important being stage of the cancer, location and general health of the patient.
1. Early tumours can be treated by endoscopic techniques like polypectomy and endoscopic resection. These therapies avoid a major surgery and removal of the colon. But they require strict follow up and repeated endoscopies to pick up the recurrence if any.
2. Surgery: This means removal of a part or entire colon and subsequently maintaining the continuity by joining to the colon. This also involves removing the lymph nodes. This can be done as an open surgery or minimally invasive techniques (laparoscopic or robotic surgery). After this surgery additional treatments may be required in form of chemotherapy or radiation depending on the pathology of the tumour. Sometimes, surgery is also done for staging the disease (staging laparoscopy). In emergency settings of obstruction of perforation, the intestinal opening might have to be brought out on the abdominal wall (stoma).
3. Radiation: Radiation given to kill the tumour cells, either as treatment for advanced/ inoperable cases, before or after surgery or as part of combination therapy.
4. Chemotherapy: Injectable drugs are given either before or after surgery, or as a part of combination therapy
After any modality of treatment, a strict follow up with your oncologist is important to pick up complications or recurrence of disease as early as possible.