Rectal Cancer: Causes, Symptoms, and Treatment
Medically reviewed by Achuta Uppu, MD, Internal Medicine. Last reviewed: October 23, 2026.
What kind of doctor treats Rectal Cancer?
A colorectal surgeon, a surgeon who treats the colon and rectum, usually leads the care of rectal cancer. A medical oncologist treats cancer with medicines. A radiation oncologist treats cancer with radiation. They are often part of the team. A direct primary care or concierge doctor can be a first stop for an evaluation and can refer you to a specialist when needed.
What is rectal cancer?
Rectal cancer is a type of cancer that forms in the tissues of the rectum. The rectum is part of the body's digestive system. Together, the rectum and anal canal make up the last part of the large intestine. Rectal cancer is one kind of colorectal cancer, which starts in the large intestine (colon) or the rectum.
Symptoms
Signs of rectal cancer include blood in the stool or a change in bowel habits. Other conditions can cause the same signs, so a doctor needs to check them. Signs can include:
- Blood in the stool, either bright red or very dark.
- Diarrhea or constipation.
- A feeling that the bowel does not empty completely.
- Stools that are narrower or have a different shape than usual.
- General belly discomfort, such as frequent gas pains, bloating, fullness, or cramps.
- A change in appetite.
- Weight loss for no known reason.
- Fatigue, which means feeling very tired.
Causes and who gets it
Colorectal cancer is caused by changes in how colorectal cells work. The changes are especially in how the cells grow and divide into new cells. Nearly all colorectal cancers begin as noncancerous lumps called polyps in the lining of the colon and rectum. A risk factor is anything that increases the chance of getting a disease. Risk factors for colorectal cancer include:
- Having a parent, brother, sister, or child who had colon or rectal cancer.
- Having had colon, rectal, or ovarian cancer yourself.
- Having inherited gene changes that cause familial adenomatous polyposis (FAP) or Lynch syndrome.
- Having ulcerative colitis or Crohn disease for 8 years or more.
Having one or more risk factors does not mean that you will get colorectal cancer.
How doctors diagnose it
Your doctor will ask about your personal and family health history and do a physical exam. Tests that examine the rectum and colon are used to diagnose rectal cancer. Your doctor may use:
- A digital rectal exam. The doctor or nurse inserts a gloved finger into the lower part of the rectum to feel for lumps.
- A colonoscopy. A thin tube with a light and a lens is used to look inside the rectum and colon for polyps, abnormal areas, or cancer.
- A biopsy. Cells or tissue are removed so they can be viewed under a microscope for signs of cancer.
After rectal cancer is diagnosed, imaging tests are done to find out if the cancer has spread. This process is called staging.
Treatment
Surgery is the most common treatment for all stages of rectal cancer. The cancer is removed using one of several types of surgery. Which one is used depends on how far the cancer has spread.
After the cancer is removed, the surgeon will either sew the healthy parts back together or make a stoma. A stoma is an opening from the rectum to the outside of the body for waste to pass through. Radiation therapy or chemotherapy may be given before surgery. This can shrink the tumor, make it easier to remove, and help with bowel control after surgery. Some patients are given radiation therapy or chemotherapy after surgery to kill any cancer cells that are left. Chemoradiation therapy combines chemotherapy and radiation therapy to increase the effects of both. Targeted therapy and immunotherapy are also used to treat rectal cancer. Your treatment plan depends on the stage of the cancer, your overall health, and your preferences. Treatment for rectal cancer may cause side effects.
When to see a doctor
Check with your doctor if you have blood in the stool or a change in bowel habits. Also check if you have belly discomfort, a change in appetite, weight loss for no known reason, or fatigue. Call 911 or go to the emergency room if you have bleeding that will not stop, severe belly pain, or fainting.
How a direct primary care or concierge doctor fits in
A direct primary care doctor charges a flat monthly fee instead of billing insurance, while a concierge doctor usually charges more and often works alongside insurance. Either kind of doctor can review symptoms such as blood in the stool, arrange first tests, and refer you to the right specialists. They can also help coordinate care and follow-up during and after treatment.
Common questions
What are the signs of rectal cancer?
Signs of rectal cancer include blood in the stool or a change in bowel habits. Other signs can include weight loss for no known reason and fatigue. These signs can also be caused by other conditions, so check with your doctor.
Is surgery the main treatment for rectal cancer?
Yes, surgery is the most common treatment for all stages of rectal cancer. Radiation therapy and chemotherapy may also be given before or after surgery.
Does rectal cancer surgery always mean a stoma?
No. After the cancer is removed, the surgeon will either sew the healthy parts back together or make a stoma. A stoma is made if the cancer is too close to the anus.
Sources
- National Cancer Institute - Rectal Cancer Treatment (PDQ) Patient Version
- MedlinePlus - Colorectal cancer
Medical Disclaimer
This content is for general educational and informational purposes only and is not medical advice. It is not a substitute for professional medical advice, diagnosis, or treatment, and reading it does not create a doctor-patient relationship. Always seek the advice of your physician or another qualified health provider with any questions about a medical condition, and never disregard or delay seeking professional advice because of something you read here. If you think you may have a medical emergency, call 911 (or your local emergency number) immediately.
