What is Rectal Cancer? What Are the Symptoms of Rectal Cancer?

The rectum is the last 15 cm of the muscular channel called the colon, which is an important part of the digestive system. Tumor cells that develop in this 15 cm area may lead to rectal cancer once they reach a certain number. It is a type of cancer with a high mortality rate, which is why early diagnosis and treatment are critical. Rectal cancer may develop without symptoms in some cases. Some patients may experience symptoms such as rectal bleeding, diarrhea, constipation, and unexplained weight loss. A family history of rectal cancer and certain hereditary disorders may increase the risk of rectal cancer. Treatment procedures may vary depending on the stage of the cancer. The general treatments include surgery, chemotherapy, radiation therapy, and targeted therapy.

What is Rectal Cancer?

Rectal cancer is a type of cancer that develops in the inner lining of the rectum and grows slowly. It typically starts as clusters of abnormal cells known as adenomas. These cell clusters, called polyps, may take 10-15 years to turn into cancer. Cancer screenings, such as colonoscopy, can detect polyps that may potentially become cancerous. Regular health screenings to detect and remove polyps can help reduce the risk of developing rectal cancer.

In some cases, rectal cancer may develop together with colon cancer, which is known as colorectal cancer. Rectal cancer ranks second among the most common cancers in the general population, making it a serious public health issue. If left untreated, rectal cancer can spread to other organs, such as the liver and lungs.

What Are the Symptoms of Rectal Cancer?

Rectal cancer may grow and develop inside the body for years without causing any symptoms, particularly in the early stages. Therefore, it is essential for individuals to undergo regular screenings for cancer based on their age, medical history, and other risk factors. Significant changes in bowel habits that last for several days should not be ignored, as these may be a sign of rectal cancer. The symptoms of rectal cancer include:

• Rectal bleeding
• Diarrhea (loose stools)
• Constipation
• Changes in bowel habits
• The feeling of incomplete bowel evacuation
• Dark red or bright red blood in the stool
• Sudden changes in how and when bowel movements occur
• Extremely thin stools
• Fatigue
• Weakness
• Frequent gas pains, bloating, fullness, and cramps that can lead to abdominal pain
• Unexplained weight loss

What Causes Rectal Cancer?

Cancer occurs due to mutations in the DNA of healthy cells in the rectum. These mutations lead to uncontrolled cell growth, and the cells accumulate. Over time, cancerous cells grow and invade healthy tissues. Cancer cells can break apart and spread to other parts of the body, causing metastasis. While the exact cause of mutations leading to rectal cancer is not known, there are several risk factors that can increase the likelihood of these mutations. There may be one or multiple factors involved in the onset of the disease. The risk factors and causes that increase the risk of rectal cancer can be summarized as follows:

• As with almost every type of cancer, the risk of rectal cancer increases with age.
• Inflammatory bowel diseases, such as ulcerative colitis and Crohn's disease, can increase the risk.
• Consuming excessive processed meats is known to contribute to rectal cancer.
• Having a family member diagnosed with rectal cancer doubles the risk of developing the disease.
• Men are more likely to develop rectal cancer compared to women.
• Hereditary conditions such as Lynch syndrome and familial adenomatous polyposis can increase the risk of rectal cancer.
• People who are obese are at a higher risk of developing rectal cancer compared to individuals without obesity.
• A diet high in red meat and low in vegetables, combined with little physical activity, can pose a potential risk for rectal cancer.
• Previous treatments involving radiation therapy to the abdominal region for other cancers can also be a risk factor.

How Is Rectal Cancer Diagnosed?

When rectal cancer is suspected, doctors may use various screening tests to both diagnose and determine the stage of the cancer. The methods doctors may use to diagnose rectal cancer can be summarized as follows:

• Physical Examination and Screening Tests: Doctors start by learning about the patient's family history and health background. The physical examination includes a manual examination of the rectum to detect any swelling or abnormalities.
• Blood Tests: Various blood tests may be used to investigate cancer symptoms. These tests include a complete blood count to check for signs of anemia, comprehensive metabolic tests to assess kidney and liver function, liver enzyme tests to check for the presence of rectal tumors in the liver, and tumor marker tests to identify antigens released by cancer cells into the bloodstream.
• Colonoscopy: This method provides images of the colon and rectum using a small camera attached to a long, flexible tube and a monitor.
• Biopsy: If suspicious findings are detected in other tests, doctors may use a biopsy to collect tissue samples or remove polyps for examination.
• Fecal Occult Blood Test: One of the most common symptoms of cancer is the presence of blood in the stool. However, this test is not enough for a cancer diagnosis and further investigation is necessary.
• Bowel Imaging: The lining of the colon can be evaluated using contrast imaging techniques, which are particularly effective for detecting large polyps.
• Other Imaging Methods: Special ultrasounds, magnetic resonance imaging (MRI) of the lower abdomen, and positron emission tomography (PET) may also be used.

How Is Rectal Cancer Treated?

Treatment for rectal cancer typically involves a combination of methods, and surgical intervention may be used to remove the cancerous tissue when possible. In some cases, radiation therapy or chemotherapy may be needed after surgery to eliminate any remaining cancer cells and reduce the chances of recurrence. If there are concerns regarding the risks of surgery, such as damage to nearby organs and tissues, chemotherapy and radiation therapy may be used first to shrink the cancer, making it easier to remove through surgery. For very small rectal tumors, colonoscopy and a procedure called transanal local excision may be used.

Chemotherapy involves the use of chemotherapeutic agents to destroy cancer cells. Chemotherapy may also be used to alleviate symptoms of cancers that cannot be removed by surgery or have spread. In radiation therapy, X-rays and high-energy protons are used to kill cancer cells. When surgery is not an option, radiation therapy can be used to relieve symptoms. Chemotherapy and radiation therapy are often used together. Targeted drugs that detect and kill cancer cells by recognizing specific chemicals released by the tumor may also be used in combination with chemotherapy.

Rectal cancer is a highly risky cancer with symptoms that develop in a complex and subtle manner. Therefore, early diagnosis is critical for rectal cancer. If you or your loved ones have concerns or questions about rectal cancer, it is recommended to consult a medical specialist. Consulting with a doctor will help understand the risks of rectal cancer and aid in prevention and treatment.