What is Rectal Cancer: Causes & Symptoms

Rectal cancer is a cancer that originates in the rectum. Rectum is the lower part of the large intestine, which connects the colon to the anal canal. Rectal cancer, along with colon cancer, makes a large group known as colorectal cancer, which is the third most common malignancy diagnosed worldwide. Although they share similarities, rectal cancer is different in many diagnostic and therapeutic aspects.

The rectum has an essential position in the digestive system. It contains faeces, waiting until it's ready to remove the contents of the bowel system outside through the anus. Meanwhile, the remaining water content and the salt from waste are absorbed in the colon. 

Causes of Rectal Cancer

Like other cancers in different parts of the body, rectal cancer is also caused by the inappropriate growth of abnormal cells in the rectum. This uncontrolled growing mass or tumour can extend into the adjacent structures or can spread to regional lymph nodes or distant organs. The exact cause of rectal carcinoma is not always well-defined, as multiple factors contribute to an increased risk of developing the disease. These include:

• Age: The risk of cancer increases as the age increases. Most patients diagnosed with rectal cancer are over 50 years of age.
• Family History: A family history of colorectal cancer or some inherited conditions can increase the risk.
• Diet and Lifestyle: A diet rich in processed foods, red meats, and low in fibre, combined with sedentary behaviour, can increase the risk of developing rectal cancer.
• Chronic Conditions: For instance, inflammatory bowel disease (IBD) raises the risk of both colon and rectal cancers.
• Genetic Mutations: In rare cases, rectal cancer develops from inherited genetic mutations.

Symptoms of Rectal Cancer 

Rectal cancer symptoms differ with the staging of the disease and the location of the tumour within the rectum. The common symptoms are:

• Rectal Bleeding: Blood in the stool, which may appear bright red or darker, is a common sign.
• Changes in Bowel Habits: This may include altered bowel habits like constipation and diarrhoea.
• Unexplained Weight Loss: Sudden and unintended weight loss can be a warning symptom of cancer.
• Abdominal Discomfort: This can include cramping, bloating, or a feeling of fullness in the abdomen.

Keep in mind that these symptoms could be a result of some other conditions apart from cancer, like haemorrhoids and infections. Thus, if any symptoms persist, the individual should see a healthcare professional.

Diagnosis of Rectal Cancer

Diagnosis of rectal cancer usually starts with a medical history and physical examination. If a doctor suspects a case of cancer, then he or she might consider further tests, which are as follows:

• Colonoscopy: This procedure consists of the insertion of a long, flexible tube provided with a camera through the anus to examine the rectum and colon for abnormal growths.
• Biopsy: During a colonoscopy, if an abnormal growth or ulcer is seen, a tissue sample might be taken for laboratory analysis in order to confirm the presence of cancer cells.
• Imaging Tests: CT scans, MRI, and PET scans to determine the size and extent of the tumour and metastasis to other organs, are advised depending on the clinical case.
• Blood Tests: These determine levels of particular markers, including carcinoembryonic antigen (CEA), which is a marker raised in rectal cancer.

Treatment of Rectal Cancer

The treatment for rectal cancer varies with the stage of cancer and its location, along with the overall health of the patient. The main treatment modalities are:

• Surgery: Surgery is one of the most common treatment methods for rectal cancer, especially in the initial stages. 
• Radiation Therapy: Radiation therapy is done before surgery to decrease the size of the tumour or after surgery to remove any residual cancer cells.
• Chemotherapy: Chemotherapy drugs may either be used along with surgery or radiation therapy to treat cancer.
• Targeted Therapy and Immunotherapy: These newer treatments use drugs that specifically target cancer cells or stimulate the immune system to fight cancer.

Certain lifestyle changes may help to decrease the risk. These include a well-balanced diet that is high in fruits, vegetables, and fibre. Keeping a healthy weight and an exercise routine, avoiding excessive alcohol intake and tobacco use and regular screening, especially for people over 45 years old or with a family history of colorectal cancer, would be helpful. Rectal cancer is a serious condition, but when diagnosed early, it can be treated. By understanding its causes, symptoms, and available treatments, one can take steps towards prevention, early detection and treatment. Any persistent symptoms such as rectal bleeding, changes in bowel habits, or unexplained weight loss must be discussed with a doctor promptly. Early diagnosis and treatment increase the chances of successful outcomes considerably.