Rectal Cancer - Symptoms, Causes, Diagnosis, Treatment

The rectum is the last part of the large intestine that temporarily stores the stools. Rectal cancer involves the growth of cancer cells in the rectum. It occurs in both men and women. However, men are more likely to get rectal cancer than women. In most cases, it occurs in people above 50 years. Approximately 5% of people may have rectal cancer during their life. Out of these, 11% are below 50 years of age.

Many patients do not experience symptoms of rectal cancer at an early stage. However, some patients may have signs, such as:

1. Blood in stools
2. Diarrhoea and constipation
3. Change in bowel habits
4. Narrow stools
5. Abdominal pain
6. Weakness and fatigue
7. A feeling of incomplete bowel emptying
8. Increased frequency of bowel movements
9. Change in appetite
10. Abdominal discomfort due to cramps, bloating, and gas
11. Back pain, pelvic pain, and urinary symptoms (later stage)

There is no knowledge about the actual cause of Rectal cancer but:

1. It may occur due to several factors, such as Environmental and Genetic factors. Cancer develops when the DNA of the healthy rectal cells abruptly changes.
2. It results in uncontrolled cell division, forming a tumour. As cancer advances, it starts damaging the nearby healthy cells. In the advanced stage, the cancer cells spread to other organs. 
3. Some genes also play a vital role in the development of rectal cancer. Two genetic conditions that may cause rectal cancer are Lynch syndrome and familial adenomatous polyposis.

Several factors increase the risk of rectal cancer. Some of them are:

1. Age more than 50 years
2. History of polyps or colorectal cancer
3. Inactive lifestyle with very little exercise
4. Presence of diabetes, inflammatory bowel disease or obesity
5. Radiotherapy as a part of cancer treatment
6. A high-fat, low-fibre diet
7. High consumption of alcohol and smoking
8. Presence of genetic syndromes
9. A pro-inflammatory diet like red and processed meat

The doctor may diagnose rectal cancer through the following techniques:

1. Patient History: The doctor assesses the history of the patient. If the patient has a history of polyps, they may have a high risk of rectal cancer. Further, the doctor diagnoses the condition based on the symptoms, such as abdominal cramps and sudden changes in bowel habits.
2. Clinical Examination: The doctor may advise the patients to undergo a clinical examination. It includes colonoscopy and biopsy. The doctor inserts a long and flexible tube, having a camera, in the rectum during the colonoscopy and views the rectum and colon. If the doctor finds abnormal cells, he may examine the tissue samples.
3. Laboratory Tests: The doctor may advise several laboratory tests to analyse blood and organ function. Persistent loss of blood may result in anaemia. Further, abnormality in the liver function test may indicate that cancer has spread to the liver. The doctor may also suggest a stool test to determine the presence of blood in the stool. 
4. Imaging Techniques: The doctor also utilises imaging techniques to determine the presence and extent of cancer. The imaging techniques include CT scan, PET scan, and MRI. 

Disease Progression

Rectal cancer progresses through the following stages:

1. Stage 0: At this stage, the cancer cells are present on the inner lining of the rectum.
2. Stage 1: As cancer progresses, abnormal cells spread to the rectal wall.
3. Stage 2: In stage 2A, the cancer cells spread to the muscle wall of the rectum. In stage 2B, the cancer cells spread to the lining of the abdomen.
4. Stage 3: The cancer cells spread to the lymph nodes at this stage.
5. Stage 4: The cancer cells spread to the distant organ. It is known as cancer metastasis.

How to prepare for doctor's consultation?

The following measures help the patients to prepare for doctor consultation:

1. Book an appointment to avoid any waiting time.
2. The doctor will ask you about the symptoms, past medical history, and the reports of tests done if any. Make sure to explain the signs in detail. It will help your doctor to diagnose the problem. 
3. If there is already a diagnosis, make a list of questions you need to ask the doctor in your next appointment. It may include questions regarding treatment options, disease progression, and recovery. 

There is no way to prevent the risk of rectal cancer completely. However, several measures may help reduce the risk of rectal cancer. Some of them are:

1. Regular screening for rectal cancer, especially in the elderly and those at high risk.
2. Staying active and exercising at least 4-5 days a week.
3. Maintaining a healthy weight
4. Incorporate whole grains, fruits, and vegetables into the diet
5. Quit smoking
6. Consume a limited quantity of alcohol. Men should take not more than two drinks, and women should not take more than a drink daily.

The doctor develops the treatment strategy according to the stage of cancer. In most cases, the doctor suggests a combination of therapies. Some of the treatment options for rectal cancer are:

1. Surgery: Surgery is the most common method for managing rectal cancer. The type of surgery depends upon the stage and location of the tumour. The doctor may remove tissue or a part of the rectum if the rectal cancer is small. The doctor may either remove the complete rectum or both rectum and anus in advanced cancers.
2. Radiation Therapy: Radiation therapy involves the use of high-energy radiation. These radiations kill the cancer cells. In some cases, where there is no option for surgery, the doctor uses radiation therapy to relieve symptoms.
3. Chemotherapy: Chemotherapy involves using drugs that kill cancer cells. The doctor generally uses chemotherapy if cancer has spread to distant organs and surgery is not an option.
4. Combination Therapy: The doctor may use chemotherapy, surgery, or radiation therapy simultaneously. Radiation therapy, along with chemotherapy, shrinks the tumour. The doctor then removes the tumour through surgery. The doctor may also use chemotherapy to kill the remaining cancer cells after surgery.
5. Targeted Therapy: The doctor prescribes targeted therapy for advanced rectal cancer. It uses drugs that target a specific abnormal process inside the cancer cells. 
6. Immunotherapy: Immunotherapy assists the immune system in fighting against cancer cells. Cancer cells evade the immune system through several mechanisms, such as immune suppressive effects. Immunotherapy interferes with these mechanisms and makes the cancer cells more vulnerable to killing action of the immune system.

Ignoring warning signs and not treating rectal cancer at an early stage may progress to the advanced stage, resulting in complications. The complications include:

1. The tumour may grow to such an extent that it may cause bowel obstruction. 
2. Significant loss of blood may result in iron deficiency anaemia. 
3. Cancer may also spread to other organs making it difficult to treat.

When to see a Doctor?

1. Do not ignore any signs of rectal cancer. For example, if you have persistent abdominal pain or cramps and blood in your stools, immediately consult your doctor.
2. Avoid making assumptions of your own. If you also notice any sudden changes in your bowel habits or have constant constipation or diarrhoea, visit the doctor.
3. Patients with a high risk of rectal cancer can ask the doctor about the screening schedule and measures to reduce the risk.