What is Rectal Cancer?

The rectum is the last 12–15 cm segment of the large intestine (colon). Rectal cancer develops from the cellular lining (mucosa) that covers the inner surface of the rectum. Colorectal cancers are the second most common cause of cancer-related deaths in both men and women in the United States. Among all diagnosed cancer patients in Turkey, colorectal cancers rank third in both men and women. The general population has a 5% lifetime risk, while those with a family history of colorectal cancer face a 10–15% risk. In individuals with ulcerative colitis or specific genetic mutations within the family, the risk exceeds 50%. According to GLOBOCAN data, colorectal cancer ranked as the third most common cancer (10%) and the second leading cause of cancer-related deaths (9%) worldwide in 2018. Among women over 75 years old, colon and rectal cancers have surpassed breast cancer as a leading cause of cancer-related death.

Who Is at Risk for Rectal Cancer?

The exact cause of rectal cancer remains unknown. However, the likelihood of developing rectal cancer increases with age; 90% of patients are over the age of 50 at diagnosis. The most common risk factors include a family history of colorectal cancer (especially in first-degree relatives), a personal history of inflammatory bowel disease (ulcerative colitis or Crohn’s disease), and colon polyps.

Can Rectal Cancer Be Prevented?

Yes, rectal cancer can be prevented. In most cases, it develops when benign polyps located on the rectal wall gradually turn into cancer. Detecting and removing these polyps during colonoscopy significantly reduces the risk of developing rectal cancer. Screening colonoscopy is recommended for individuals aged 45 and older in the general population. Depending on personal and familial risk factors, earlier screening may be advised.

What Are the Symptoms of Rectal Cancer?

Rectal cancer often progresses silently without causing noticeable symptoms and may be detected incidentally during a routine colonoscopy. The most common symptoms include changes in bowel habits (constipation or diarrhea), narrow stools, or blood in the stool. Additional signs may include pain in the lower abdomen, unexplained weight loss, or persistent fatigue. Hemorrhoids (piles) do not cause cancer but can produce similar symptoms.

What Tests Are Used to Diagnose Rectal Cancer?

  • Physical examination and medical history

  • Digital rectal examination

  • Proctoscopy: evaluation of the rectum using a small illuminated device inserted through the anus

  • Colonoscopy: assessment of the entire colon with an illuminated scope to detect polyps, abnormal areas, or cancer

  • Biopsy: removal of tissue or cells from a suspicious area of the rectum for microscopic pathological examination

What Determines the Prognosis of Rectal Cancer?

  • The stage of the cancer (extent of spread)

  • Presence of obstruction in the colon

  • Whether the tumor is surgically removable

  • The patient’s overall health and ability to tolerate additional treatments (chemotherapy, radiotherapy)

  • Whether the cancer has recurred

How Is Rectal Cancer Staged?

Distant Staging

Computed tomography (CT) scans can identify most masses formed by cancer cells that have spread beyond the rectum. PET-CT scans are used to evaluate metastasis to distant organs such as the lungs, liver, or bones. A CEA blood test can help assess tumor activity.

Local Staging

Magnetic resonance imaging (MRI) is the most frequently used method to evaluate local tumor spread. It determines whether the tumor has extended beyond the rectal wall or invaded adjacent organs, and whether lymph node involvement around the rectum is present.
Endoscopic ultrasonography (EUS) can assess the depth of tumor invasion starting from the inner surface of the rectum, making it particularly useful in early-stage cases.

How Is Rectal Cancer Treated?

Today, the gold standard in treatment is the surgical removal of the rectum along with its vascular and lymphatic network. In certain cases, chemotherapy and radiotherapy may eradicate detectable tumor tissue, but non-surgical management of these patients remains controversial. When the rectum is surgically removed, accurate pathological staging can be performed, greatly improving disease control. In non-surgical management, frequent follow-ups with imaging and endoscopic evaluation are required, and surgery becomes necessary if the tumor recurs. In such situations, preserving anal sphincter function may not be possible.

During rectal cancer surgery, part or all of the rectum, along with surrounding lymph nodes, is removed depending on the tumor’s location. In most cases, it is possible to preserve anal function by reconnecting the remaining colon to the residual rectum or the anus. These procedures can be performed using laparoscopic or robotic techniques, avoiding large abdominal incisions and allowing for a less painful recovery, earlier bowel function, and faster return to daily activities.
Depending on factors such as the tumor’s size, location, relationship with surrounding tissues, and stage, chemotherapy and/or radiotherapy may be administered before (neoadjuvant) or after surgery.

What Are the Most Important Factors Affecting the Course of the Disease?

The stage of cancer at diagnosis is the primary determinant of prognosis. The less deeply the tumor invades the rectal wall, the higher the chance of successful treatment. Therefore, screening colonoscopy and removal of polyps at an early stage remain the most effective preventive measures.

What Does Follow-Up Look Like After Treatment?

According to the disease stage, follow-up includes regular blood tests (CEA), computed tomography scans, digital rectal examinations, and colonoscopies to monitor for recurrence or metastasis to distant organs.