The food that we eat, enters through our mouth and passes through our stomach and intestines. The intestine has two parts, the small intestines and the large intestines. The small intestine has the job of breaking down food and absorbing maximum nutrients. What remains of the processed food passes into the first part of large intestine or colon.
The colon has the job of absorbing water and the rest of the nutrients from the food and serving as a temporary storage for waste matter (stool). Stool then moves forward from the colon into the rectum, which is the last part of the digestive system’s large intestine and out through the anus, finally.
Anatomically THE RECTUM is the distal portion of the large intestine or the bowel, between the colon and the anal canal.
What are rectal cancers ?
Colorectal Cancers are basically tumours of either the colon or the rectum.
Because colon and rectal cancers are similar structures and their cancers arise from the same kind of cell, they are grouped collectively as “colorectal cancers”.
However, how we differentiate colon and rectal cancers is based on location and extent of the tumour from the anus. Tumours closer than 15 cm (as measured by a diagnostic test called rigid sigmoidoscopy) from the anus margins are RECTAL TUMOURS, and tumours further than 15 cm from the anus are COLONIC TUMOURS. This can vary a little based on patient parameters and individual anatomy. (for eg: taller people have longer rectums).
How does a rectal cancer develop ?
The cells lining the rectum can turn abnormal and start to divide rapidly. These cells can form either benign (non-cancerous) tumours or growths called polyps or later, malignant tumours.
It is not mandatory for all polyps to turn into rectal cancers, however rectal cancer almost constantly develops from a polyp. Over a long period, a polyp can experience a series of DNA mutations that make them malignant (cancerous).
What are the clinical features of rectal cancers ?
The symptoms of rectal cancer are not that specific, which means they can be caused by a variety of different diseases. Often colorectal or rectal cancers are asymptomatic, until the later stages and spread of the disease.
These symptoms MAY indicate rectal cancer and should be examined by a doctor:
- Long-standing diarrhoea or constipation
- The presence of blood in stools
- Feeling of incomplete bowel movement.
- A sudden loss of appetite or unexplained weight loss (seen in other cancers also)
- Fatigue & anemia
- Nausea & vomiting
- Feeling of pain or discomfort in the abdomen
How are rectal cancers diagnosed ?
- A complete physical examination of the body is mandatory.
- Faecal Occult Blood Test : Blood vessels in rectal cancers and polyps are more fragile and get damaged easily with stool passage, releasing a minimal, unseen amount of blood. A faecal occult blood test (FOBT) is able to identify occult (hidden) blood in faeces or stool.
- Blood Tests : Blood tests aid in diagnosis of rectal cancer. A test called a complete blood count (CBC) by seeing the red blood cells, can detect anemia (low red blood count) which many people with rectal cancer suffer from. This is because of long standing, undetected bleeding that occurs from a tumour.
- Another blood test is that for elevated levels of carcinoembryonic antigen (CEA). This is a protein frequently produced by rectal cancer cells, and may point to rectal cancer.
- Double Contrast Barium Enema :A double contrast barium enema (DCBE) is an X-ray test that provides imaging of the entire colon. A liquid containing barium sulfate is put into a patient’s rectum and colon. It can clearly define the appearance of the intestines on the X-rays. If a polyp is detected, then a colonoscopy will have to be undertaken.
- Colonoscopy : A colonoscopy is also done for rectal tumours. It is for checking of the entire colon and rectum length. A biopsy can also be performed simultaneously, if polyps or other abnormalities are seen in the colonoscopy.As this procedure is definitely more invasive, sedation has to be given to the patient. Colonoscopy is considered the best way to visualize a colorectal cancer.
- Biopsy : Removed tissue examined under a microscope by a pathologist is the only sure-shot way to make a colorectal cancer diagnosis.
- Imaging Tests : To determine the exact extent of disease, additional tests may need to be performed so doctors can view, assess and judge the cancer and determine how far it has progressed or spread. These tests may include the following such as X- rays, CT Scan, MRI Scan or PET Scans.
Endoscopic Ultrasound or rectal MRI are recommended for all tumours, including the earliest ones. Complete colonoscopy, both pre- or postoperatively is required.
Histopathological examination should include excised tumour with adequate margins of surrounding tissue with regional lymph nodes (at least 12 nodes are recommended to be examined).
How are rectal cancers staged ?
Rectal Cancers are staged same as colorectal cancers. Doctors will procure and analyze information from the physical examination, tissue biopsies and both blood as well as imaging tests to establish a stage of the cancer, known as the “clinical stage”. What staging does is describe the extent and spread of cancer judging by the layers of affected bowel wall, involved lymph nodes, or by spread to other organs, near or distant.
Clinical staging is important as it helps doctors decide on the first type treatment a patient should receive. Pathologic staging is done after study of tissues removed. Treatment depends on the stage of cancer primarily.
For most of the colorectal cancers, the first-line treatment is surgery to resect the tumour.
There are five basic stages of colorectal cancer, in progressive order. The greater the number, the more advanced the cancer.
0 — The cancer is restricted to the most inside layer of the colon or rectum. It is yet to invade the bowel wall.
I — The cancer has penetrated and involved more layers of the wall of colon or rectum.
II — The cancer has penetrated the entire wall of the colon or rectum and may spread into nearby tissue(s).
III — The cancer has spread to the neighbouring/regional lymph nodes.
IV — The cancer has metastasized and spread to distant organs, mostly the liver or the lungs.
How are rectal cancers treated ?
- Surgery : Surgery is the main treatment for both colon and rectal cancers. The standard operation, called a radical resection, involves an incision through the abdomen and removal of the tumour and surrounding bowel tissue, as well as the adjacent blood vessels and lymph nodes. The two ends of the remaining bowel are reattached.
- Radiation : High doses of external radiation from a machine are directed to the area of the tumour from outside the body. This is called therapeutic radiation. Radiation is more frequently used to treat rectal cancer.
- Chemotherapy : Chemotherapy involves the distribution of cancer-killing chemicals throughout a patient’s body to destroy fast-growing cancer cells that may be lingering after surgery. Chemotherapy can also be used to shrink a tumour before surgery, and treat advanced (Stage IV) disease.
- Targeted Therapies : Targeted therapies are newer intravenous medications used in advanced disease that target specific biological processes involved in cancer growth. These drugs are different from chemotherapy drugs which kill any fast growing cells in the body, including healthy cells.
What is the care to be taken after the removal of a rectal cancer ?
Metastatic diagnostic workup and monitoring post-treatment has to include imaging and scanning of the limbs, thorax, chest, retroperitoneum, and abdomen with radiography, MRI or CT scans. Adjuvant chemotherapy or radiotherapy may be required in cases wherein excision cannot be done completely.
How to find and reach cancer specialists for rectal cancer treatment ?
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Find, reach and choose a cancer specialist for rectal cancer treatment on Hinfoways. Make an informed choice.
Disclaimer: The content provided here is meant for general informational purposes only and hence SHOULD NOT be relied upon as a substitute for sound professional medical advice, care or evaluation by a qualified doctor/physician or other relevantly qualified healthcare provider.
