Rectal Cancer: Symptoms, Causes, and Much More

Rectal cancer is a type of cancer that develops in the cells of the rectum. The rectum is located below the sigmoid colon and above the anus.

Your rectum and colon are both parts of the digestive system, so rectal and colon cancers are commonly referred to together as colorectal cancer.

In the United States, colorectal cancer is the third most common cancer. It is the second leading cause of cancer-related deaths, making early detection and treatment very important.

Worldwide, according to the 2020 Worldwide Cancer Research Fund data, colorectal cancer is the second most common cancer among women and the third most common among men.

A report by the American Cancer Society estimated that in 2022, 44,850 new cases of rectal cancer would be diagnosed in the United States. In comparison, 106,180 new cases of colon cancer were expected.

✅ What are the symptoms of rectal cancer?
In the early stages, rectal cancer may have no symptoms.

As the cancer progresses, the most common symptom is bleeding from the anus. There may also be changes in bowel habits lasting more than a few days. Unexplained weakness and fatigue may also be experienced.

According to the CDC (Centers for Disease Control and Prevention), common symptoms of colorectal cancer include:

• Bleeding from the anus

• Changes in the frequency or habits of bowel movements

• Feeling of incomplete bowel evacuation after defecation

• Pain during bowel movements

• Diarrhea or constipation

• Blood or mucus in the stool

• Unexplained weight loss and loss of appetite

• Unexplained fatigue

• Frequent abdominal pain, gas, cramps, or discomfort

Another possible symptom is iron-deficiency anemia, which may result from slow blood loss.

✅ What causes rectal cancer?
The exact cause of rectal cancer is not fully known. Cancer occurs when cells divide uncontrollably, becoming cancerous and attacking healthy tissue.

The reasons for this process are not always clear, but some genetic mutations can increase this risk.

👉 Common hereditary causes:
Hereditary Nonpolyposis Colorectal Cancer (HNPCC), also known as Lynch syndrome, increases the risk of various cancers including colon cancer. In some cases, doctors may recommend preventive colon removal.

Familial Adenomatous Polyposis (FAP) is a rare genetic disorder where many polyps form in the lining of the colon and rectum. Though initially non-cancerous, these polyps can turn cancerous, often before age 50. Preventive removal of large intestine sections may be advised.

✅ How does rectal cancer spread?
Like other cancers, rectal cancer spreads when cancer cells invade healthy tissue and spread to other parts of the body.

Initially, rectal cancer may be confined to the lining of the rectum but can spread to the entire rectum.

It can spread to:

• Nearby lymph nodes

• Adjacent organs, with the liver being the most commonly affected

Other possible sites of metastasis include:

• Abdomen

• Brain

• Lungs

• Ovaries

✅ What are the risk factors for rectal cancer?
While there is no single cause, certain risk factors increase the likelihood of rectal cancer:

• Age (usually diagnosed after 50, though rates are rising in younger people)

• Race (Black Americans have a higher risk, possibly due to disparities in healthcare)

• Family history of colorectal cancer

• Genetics (Lynch syndrome and FAP)

• Previous radiation therapy in the abdomen or pelvis

• Other health issues like ovarian cancer, polyps, inflammatory bowel disease (especially if lasting 8 years or more), obesity, and uncontrolled type 2 diabetes

• Lifestyle and diet: low vegetable and fiber intake, high consumption of red and processed meat, lack of exercise, smoking, and drinking 3 or more alcoholic beverages daily

✅ How is rectal cancer diagnosed?
Tests and procedures include:

1. Physical exam and screening: Medical history, digital rectal exam to feel for lumps or abnormalities. Possible tests include:

• FIT (Fecal Immunochemical Test)

• Sigmoidoscopy; if positive, colonoscopy is done

2. Colonoscopy: A thin tube with light and camera examines the rectum and colon; polyps can be removed during this. Tissue samples are taken for lab analysis and genetic testing.

3. Blood tests: Carcinoembryonic Antigen (CEA) protein levels may indicate cancer.

4. Imaging tests: To check spread of cancer:

• Endorectal ultrasound

• CT or PET scan

• MRI for staging

✅ How is rectal cancer staged?
Staging shows how far cancer has progressed and guides treatment:

• Stage 0 (Carcinoma in situ): Abnormal cells only in the innermost layer of the rectum

• Stage 1: Cancer cells have grown beyond the inner layer but not reached lymph nodes

• Stage 2: Cancer has spread through the muscle layer but not to lymph nodes

  • 2A: Cancer up to outer layer of rectum

  • 2B: Cancer reached abdominal lining

• Stage 3: Cancer spread to lymph nodes (subdivided into 3A, 3B, 3C by number of lymph nodes)

• Stage 4: Cancer spread to distant organs like liver and lungs

✅ Treatment by stage:
Treatment depends on tumor size, spread, patient age, and health:

• Stage 0: Removal of tissue during colonoscopy or surgery

• Stage 1: Local excision or resection, sometimes radiation or chemotherapy

• Stage 2 & 3: Surgery, radiation, chemotherapy

• Stage 4: Surgery, radiation, chemotherapy, targeted therapy (like monoclonal antibodies or angiogenesis inhibitors), cryosurgery, radiofrequency ablation, stent placement, and palliative care for quality of life

✅ Clinical trials:
Discuss with your doctor if clinical trials are suitable. Trials can involve new drug combinations, repurposed drugs, or new therapies. Costs may be covered by insurance or sponsors. Trials offer access to new treatments and help advance science.

✅ Complications:
Rectal cancer can spread to tissues outside the rectum, lymph nodes, and other organs. Post-treatment, there is risk of second cancers in anus, colon, kidneys, lungs, small intestine, or vagina.

✅ Prevention:
Early detection before spread improves survival. According to CDC and American Cancer Society, the best prevention methods include:

• Starting regular screening at age 45, earlier if high risk

• Routine colonoscopy or stool tests for early detection

• Lifestyle changes like physical activity, quitting smoking, and reducing red/processed meat intake

✅ Prognosis:
Thanks to medical advances, many patients recover successfully. The 5-year survival rate for rectal cancer is about 67%.

By stage:

• Localized: 89%

• Regional: 72%

• Distant/metastatic: 16%

(These stats are from 2010–2016; current outcomes may be better.)

Personal prognosis depends on cancer spread, bowel obstruction, tumor removal, age, health, new or recurrent cancer, and treatment tolerance. Your doctor can provide the best information for your case.

✅ Summary:
Rectal cancer, often called colorectal cancer, is common worldwide including the US.

• Early stages may show no symptoms

• Regular screening is very important

• Treatment and screening methods are improving

• Lifestyle changes can reduce risk

• See a doctor if you notice abnormal bowel symptoms or have concerns about rectal cancer.