Rectal Cancer Overview

Rectal cancer develops in the last several inches of the colon near the anus (rectum). Most rectal tumors begin as noncancerous growths (polyps) that slowly progress and become cancerous. This progression usually occurs over many years.

Rectal cancer and colon cancer originate in the same way and share many risk factors and symptoms; however, the tumors may be treated differently. Although rectal cancer is much less common than colon cancer, it is still a significant health concern, particularly among older adults. As with most types of cancer, early detection is essential to achieve the best possible outcome and quality of life.

Rectal Cancer Types

Rectal cancer is classified based on the type of cells involved and the appearance of the cells when viewed under a microscope. The main types include:

• Adenocarcinoma – Develops in the mucus-producing glandular cells that line the inner surface of the rectum
• Gastrointestinal stromal tumors (GISTs) – Form in the blood vessels and connective tissues of the rectum
• Neuroendocrine tumors – Form in the hormone-producing cells of the rectum

Adenocarcinoma is by far the most common type of rectal cancer. GISTs and neuroendocrine tumors that form in the rectum are relatively rare.

Rectal Cancer Causes and Risk Factors

The precise causes of rectal cancer are not yet fully understood. However, researchers have identified several risk factors, including:

• A family history of colorectal cancer or polyps
• A personal history of colorectal polyps or inflammatory bowel disease, such as Crohn’s disease or ulcerative colitis
• A hereditary colorectal cancer predisposition syndrome, such as familial adenomatous polyposis (FAP) or Lynch syndrome
• Advanced age (most rectal cancers are diagnosed after age 50)
• Obesity or excess body weight

Rectal Cancer Signs and Symptoms

Precancerous polyps and early-stage cancer cells are often found in the rectum during a routine screening test, such as a colonoscopy, before symptoms develop. The first noticeable warning sign of rectal cancer may be a change in bowel habits.

What Does Rectal Cancer Feel Like?

Rectal cancer symptoms that can be felt include:

• More frequent or urgent bowel movements
• A feeling that the bowel does not fully empty during a bowel movement
• Persistent diarrhea or constipation
• An uncomfortable sensation of fullness in the abdomen
• Abdominal or pelvic pain
• Weakness and fatigue

What Does Rectal Cancer Look Like?

Rectal cancer symptoms that can be seen include:

• Narrow stools
• Bloody stools
• Rectal bleeding
• Abdominal bloating
• Unintended weight loss

Rectal Cancer Diagnosis

Routine screening tests can identify both precancerous polyps and early-stage cancerous tumors in the rectum. For this reason, many experts recommend periodic colorectal cancer screenings beginning around age 50 for individuals at average risk.

A colonoscopy is a commonly used screening test for colorectal cancer. During this outpatient procedure, a physician will guide a long, flexible instrument (colonoscope) into the anus, rectum and lower colon. Using a miniature camera attached to the end of the colonoscope, the physician will capture detailed images of the inner rectum and colon, which will be displayed on an external monitor in real time. Using the colonoscope, the physician can remove visible polyps and other suspicious tissues, which will be sent to a laboratory for microscopic examination by a pathologist. The lab testing results can help the physician confirm or rule out a diagnosis of rectal cancer.

Rectal Cancer Stages

Cancer staging provides important information that can help a physician plan treatment. To stage rectal cancer, many physicians use the TNM Staging System, which was developed by the American Joint Committee on Cancer (AJCC). “T” describes the size and extent of the primary tumor, “N” indicates whether the cancer has spread to nearby lymph nodes and “M” indicates whether the cancer has metastasized to distant organs.

Stage 1 Rectal Cancer

At stage 1, the rectal tumor has grown into the inner lining of the rectum but has not spread to nearby lymph nodes or metastasized to distant organs. Treatment typically involves surgery to remove the tumor, which may be followed by chemotherapy or radiation therapy to help prevent a recurrence. The prognosis for stage 1 rectal cancer is favorable, with a high likelihood of cure.

Stage 2 Rectal Cancer

At stage 2, the rectal tumor has grown through the wall of the rectum but has not spread to nearby lymph nodes or metastasized to distant organs. Like stage 1 rectal cancer, stage 2 rectal cancer is usually treated with surgery to remove the tumor followed by chemotherapy or radiation therapy to reduce the risk of recurrence. The prognosis for stage 2 rectal cancer is generally favorable, but it can vary depending on the specific characteristics of the tumor and the patient’s overall health.

Stage 3 Rectal Cancer

At stage 3, the rectal tumor has spread beyond the rectum to nearby lymph nodes but has not metastasized to distant organs. Treatment for stage 3 rectal cancer typically involves a combination of surgery, chemotherapy and radiation therapy. The prognosis for stage 3 rectal cancer can vary based on the extent of tumor spread, the patient’s response to treatment and other factors.

Stage 4 Rectal Cancer

At stage 4, the rectal tumor has metastasized to distant organs or tissues, making it more challenging to treat. Common sites of metastasis for rectal cancer include the liver, lungs, bones and brain. Treatment options for late-stage rectal cancer can include surgery, chemotherapy, radiation therapy and/or targeted therapy. The goals of treatment are to manage the symptoms, slow the progression of the cancer and improve the patient’s quality of life.

Rectal Cancer Treatment

Rectal cancer treatment can vary depending on the location, size and stage of the tumor. In some cases, benign rectal polyps and early-stage rectal tumors can be removed through the anus. Known as transanal minimally invasive surgery (TAMIS), this procedure is typically performed through a TAMIS port, a specialized device inserted into the anus. The TAMIS port provides a stable and controlled channel for the surgeon to access the rectum. To better visualize the targeted tissue, the surgeon may use an endoscope, a flexible tube with a light source and miniature camera attached to the end. To remove abnormal tissue, the surgeon can insert specialized surgical instruments through the port.

If a rectal tumor cannot be removed through the anus, a traditional open procedure may be considered, such as:

• Anterior resection – To remove a tumor in the upper rectum, the surgeon will remove the section containing the tumor and then reattach the colon to the remaining part of the rectum.
• Low anterior resection – To remove a tumor in the middle or lower rectum, the surgeon will remove the entire rectum, then perform a coloanal anastomosis to attach the colon to the anus and create a small pouch in the colon to collect stool.
• Abdominoperineal resection (APR) – To remove a tumor in the lower rectum, the surgeon will remove the lower (sigmoid) colon, rectum, anus and sphincter muscles. During APR surgery, the surgeon will create a stoma to bring the lower end of the colon outside the body through the skin in the lower belly, where a colostomy pouch will be worn to collect stool.

Chemotherapy or radiation therapy may be administered before or after rectal cancer surgery, depending on the stage of the tumor and other factors.

Benefit From World-Class Care at TGH

TGH’s colorectal oncology team includes fellowship-trained surgeons, medical oncologists, radiation oncologists, gastroenterologists, radiologists and interventional radiologists, as well as compassionate supportive care specialists. Working together, we provide comprehensive, individualized care for patients with rectal cancer. TGH performs more TAMIS procedures than any other hospital in West Central Florida, and our team has acquired unparalleled expertise as a result. For this reason and many others, we have been named One of the Nation's Best Hospitals for Cancer Care by U.S. News & World Report for 2024-25.

If you would like to learn more about rectal cancer, contact Tampa General Hospital at (800) 822-3627 to request an appointment with an expert in our Cancer Institute in Tampa, FL.