Rectal cancer

Diagnosis 

Investigations for diagnosing rectal cancer  

Screening tests to diagnose rectal cancer are as follows: 

• Colonoscopy.  A flexible tube with a camera is inserted into the rectum to the colon and inspects the structures inside. Colon examination on the affected area may be recommended if the doctor suspects cancer. 
• Biopsy.  During colonoscopy, the doctor will insert surgical instrument into the scope to take out tissue sample for examination under a microscope to examine the type of cancer cell, how aggressive the cancer is, which will know the prognosis of the disease and identify proper treatment. 

Investigations for evaluating severity of rectal cancer 

The next step after cancer diagnosis is to stage the cancer such as:  

• Complete Blood Count (CBC). Checks for various types of blood cells. Also, if the red blood cells have significantly decreased (anemia), it may indicate blood loss due to the presence of a tumor. Increased white blood cells also indicate infection which is harmful when the tumor is on the rectal wall. 
• Blood tests to measure organ function. High chemical levels in the blood may indicate that cancer has spread into the liver or kidney. 
• Carcinoembryonic Antigen (CEA). CEA testing is particularly useful in monitoring your response to treatment. CEA is a tumor marker which may be increased in people with colorectal cancer. 
• Computed Tomography (CT) scan of the chest.  A diagnostic imaging test that investigates whether the cancer has spread to other organs of the body.  
• Magnetic Resonance Imaging (MRI) of the pelvis. Shows more detailed images of the organs, muscles, lymph nodes and other tissues around the rectal tumor. 
• Positron Emission Tomography (PET) scan. This procedure uses special dye with radioactive tracers (by ingestion, intravenously or inhalation) to view a more detailed structure of the affected area.  

These tests will determine the stage of cancer which ranges from 0 (means the cancer is locally contained on the lining of the rectum only) to IV (means that the cancer is in its advanced stage and has spread to other parts of the body).  

Treatment 

A single or a combination of treatments may be suggested to manage and treat rectal cancer.

Surgery 

The following surgical options are available to remove rectal cancer:  

• Removing very small cancers from the inside of the rectum. Small sized rectal cancer may be removed using a colonoscope (trans-anal local excision). 
• Removing all or part of the rectum. If the rectal cancer is quite far from the rectal canal, all parts of the rectum including nearby tissue and lymph nodes can be surgically removed (low anterior resection). This procedure does not remove the anus so the body can still eliminate waste normally. The technique is based on the affected area. If the upper part of the rectum is removed, the colon will be re-attached back to the rectum that is left over (colorectal anastomosis). If the lower portion of the rectum is removed, the colon will be formed like a pouch that can be joined to the anus (colo–anal anastomosis). 
• Removing the rectum and anus.  An Abdominoperineal Resection (APR) may be performed to remove the rectum, anus, nearby lymph nodes and some parts of the colon. This procedure is done if the cancer has reached near the anus, damaging the nerves that control bowel movement. An opening will be created in the abdomen and attach the colon that is left (colostomy). A colostomy bag will then be attached to the opening to collect waste materials from the colon. 

Radiation therapy 

The body is exposed to a high radiation to eradicate cancer cells.  

Chemotherapy  

Chemotherapy medications are taken orally or intravenously to kill cancer cells. It is an option for cancers that has metastasized (spread to other parts of the body) or unresponsive to hormone therapy.  

Combined chemotherapy and radiation therapy 

A combination of chemotherapy and radiation may be used to eliminate a larger rectal cancer or if it has a high chance of recurrence. It can be done before or after the surgery or as a primary treatment for advanced cancer to control cancer growth. 

Immunotherapy  

Uses the body’s own immune system to fight cancer. Immunotherapy blocks the proteins produced by the cancer cells to hide from the body’s disease fighting immune system. 

Targeted drug therapy  

Medications are used to focus only on specific abnormalities in the cancer cells. Targeted therapy inhibits the abnormalities and kills the cancer cells.