Just been diagnosed with colorectal cancer? You're not alone, and there is a plan ahead.

Colorectal cancer starts in the colon (large bowel) or the rectum. Hearing the word cancer can make everything feel like it's spinning. Take a breath. Colorectal cancer is one of the most studied cancers, and there are many good ways to treat it. Here you'll find clear, friendly guides for you and your family about tests, treatment and everyday life, one step at a time.

Updated September 30, 2026

In an emergency, call 9-1-1 or your local emergency number.

Start here

Your first 30 days: a checklist

Save the phone number of your cancer centre's 24-hour line, and a nurse or navigator you can call with questions.
Bring a family member or friend to appointments, and write down questions before each visit.
Ask what stage your cancer is, whether it is in the colon or rectum, and what the plan is for your treatment.
Ask whether your cancer was tested for mismatch repair (MMR) or MSI, and what the result means for you and your family.
Keep an up-to-date list of all your medicines, vitamins and supplements, and bring it to every visit.
If you are having chemotherapy, get a working thermometer and learn when to call about a fever.
If you may have an ostomy, ask to meet an ostomy (stoma) nurse before surgery.
Tell your team if you feel low, worried or can't sleep for more than two weeks. Ask about social work and support groups.

Your first weeks after a cancer diagnosis: A calm, step-by-step guide to the first weeks after being told you have cancer: getting organized, understanding your diagnosis, planning treatment and finding support. (6 min read)

Understand it

Colorectal Cancer, Explained: a longer guide for you and your family (video coming soon)
How Your Digestive System Works: from first bite to last (video, 4:46)
Cancer Screening, Explained: finding problems before they start (video, 4:39)

Understanding colorectal cancer: What colorectal cancer is, how colon and rectal cancer differ, what the stages mean in plain words, and the tests used to plan your treatment. (6 min read)

Your treatment

Cancer Surgery, Explained: removing the cancer, and getting ready (video coming soon)
Chemotherapy, Explained: medicines that travel through your body (video coming soon)
FOLFOX and CAPOX: what to expect from this chemotherapy (video coming soon)
Radiation Therapy, Explained: focused energy aimed at cancer cells (video coming soon)
Targeted Therapy and Biologics: medicines aimed at a cancer's weak spots (video coming soon)
Immunotherapy and Checkpoint Inhibitors: helping your immune system fight cancer, and side effects to report (video coming soon)

Treatment options for colorectal cancer: How colon and rectal cancer are treated: surgery, ostomies, chemotherapy, radiation, targeted therapy and immunotherapy, and how your team tailors a plan to you. (6 min read)
Clinical trials explained: What cancer clinical trials are, how the phases work, what randomization and placebos mean, how you are protected, and how to find a trial that might suit you. (6 min read)

Living well

What Exercise Does for Your Body: and how much you really need (video, 4:38)

Managing side effects of cancer treatment: Practical, friendly tips for common side effects of cancer treatment: tiredness, nausea, mouth sores, hair loss, numbness and tingling, skin changes, low blood counts and "chemo brain." Report them, don't just endure them. (7 min read)
Eating well during cancer treatment: Practical tips for eating well during cancer treatment: getting enough protein and energy, coping with poor appetite, nausea and taste changes, food safety, and what to know about supplements. (6 min read)
Your feelings matter: emotional health and support with cancer: Fear, sadness, anger and worry are common after a cancer diagnosis. Practical ways to cope, when to ask for help, crisis support (9-8-8), talking with family, and support for caregivers. (6 min read)
Work, money and practical matters: Practical help after a cancer diagnosis: telling your employer, time off and benefits, fertility preservation before treatment, getting to appointments, and keeping paperwork in order. (6 min read)

When to get help

Call 9-1-1 now

Trouble breathing, or chest pain or pressure
Fever with feeling very unwell, confusion, fainting or trouble breathing while on chemotherapy
Heavy bleeding from the bottom or the stoma, throwing up blood, or black, tarry stool with dizziness
Severe belly pain, a hard swollen belly, or throwing up with no stool or gas passing (signs of a blocked bowel)
Sudden swelling of the face, lips or throat, or trouble breathing after a treatment (a severe allergic reaction)
Sudden weakness on one side, trouble speaking, or a seizure
Someone collapses, doesn't respond, or isn't breathing normally: call 9-1-1 and start CPR

Call 9-1-1 or your local emergency number. Don't drive yourself.

Call your cancer centre now

A temperature of 38 °C (100.4 °F) or higher, or shaking chills, during chemotherapy: call your cancer centre's 24-hour line right away. If you can't reach them, go to the nearest emergency department.
Diarrhea that doesn't settle with the medicine your team gave you, or 4 or more extra bowel movements a day than usual
You can't keep food or fluids down, or you feel dizzy and are peeing much less than usual
Your stoma turns dark red, purple or black, or it stops working for more than a day and you feel sick or bloated
Redness, swelling, warmth, pus or opening at a surgery wound
Red, sore, peeling or blistering hands or feet, or mouth sores that stop you eating or drinking
Numbness or tingling in your hands or feet that is getting worse or making it hard to do up buttons or walk
Pain, swelling, warmth or redness in one leg or arm (a possible blood clot)
On immunotherapy: new diarrhea or belly pain, a new cough or shortness of breath, a rash, yellow skin or eyes, or feeling very tired
Low mood or worry that lasts more than two weeks

Use the 24-hour line. Don't wait for your next appointment. If you can't reach anyone and you're worried, go to emergency.

If you have any of the emergency signs, call 9-1-1 or your local emergency number right away. Keep your cancer centre's 24-hour phone number in your phone and on your fridge, and share it with your family. If you are on chemotherapy or immunotherapy, tell any emergency team what treatment you are on. Don't wait to see if a fever goes away on its own. If you're not sure, call.

Fever and when to get help during cancer treatment: Clear lists to help you decide: a fever of 38.0 °C (100.4 °F) during chemotherapy is an emergency. Plus when to call 9-1-1, when to call your cancer centre's 24-hour line, and immunotherapy side effects to report. (6 min read)

Questions to ask your team

A printable list of questions to bring to your next appointment.

Go deeper

Written for clinicians and students. More technical material from Hibbert Medical, for readers who want more detail.

Podcast summaries

Cancer podcasts, summarized: Cancer podcasts with written summaries, including colorectal cancer research.
Gastroenterology podcasts: Bowel specialists on colonoscopy, screening and gut health.
Nutrition podcasts: Researchers and dietitians on eating well, including during illness.

Lectures

Colorectal Disorders: Medical school: polyps, colorectal cancer and other bowel conditions.
Colorectal Cancer: Surgical Principles: How colon and rectal cancer operations are planned.
Rectal Cancer: Total Neoadjuvant Therapy and Organ Preservation: Radiation and chemotherapy before surgery for rectal cancer.
Rectal Cancer Staging: MRI-Based Assessment: How MRI scans are used to stage rectal cancer.
Colorectal Liver Metastases: Treating colorectal cancer that has spread to the liver.
Lynch Syndrome: An inherited cause of colorectal cancer, and what it means for families.
Colorectal Cancer Screening and Polyp Management: Screening tests and follow-up after polyps.
Chemotherapy-Induced Peripheral Neuropathy: Numbness and tingling from chemotherapy, and what helps.

Seminars

Colorectal Surgery: Clerkship seminar: bowel cancer surgery and recovery.

Clinical cases

Colon Cancer: From diagnosis to surgery for colon cancer.
Rectal Cancer Requiring Neoadjuvant Therapy: Why some rectal cancers are treated before surgery.
Colorectal Cancer: Symptoms, tests and staging in one patient.
MSI-High Colorectal Cancer Responding to Immunotherapy: When immunotherapy works for colorectal cancer.
Lynch Syndrome: An inherited risk, and testing for relatives.

Oncology regimen tutorials

FOLFOX (modified FOLFOX6): Oxaliplatin, leucovorin and infusional fluorouracil: doses, toxicities and monitoring.
CAPOX (XELOX): Oxaliplatin with oral capecitabine, including 3- vs 6-month adjuvant treatment.
FOLFIRI ± bevacizumab or anti-EGFR antibody: Irinotecan-based treatment for metastatic colorectal cancer, with the biologic chosen by RAS status and sidedness.
Monoclonal antibodies and biologics in oncology: Special tutorial: mechanisms, antibody–drug conjugates, bispecifics and class toxicities.

Common questions

What is the difference between colon cancer and rectal cancer?

Both are part of the large bowel, so they are often grouped together as colorectal cancer. The colon is the long first part, and the rectum is the last 12 to 15 centimetres or so before the anus. They grow in a similar way, but treatment can be different. Rectal cancer sits in a tight space in the pelvis, so it is more often treated with radiation and chemotherapy before surgery.

Will I need a colostomy or ileostomy bag?

Many people with colorectal cancer do not need one. Some people need an ostomy for a short time while the bowel heals, and it is closed later with a smaller operation. A small number of people, most often with cancer very low in the rectum, need a permanent one. Ask your surgeon what is likely for you. An ostomy nurse can help you prepare and learn to live well with one.

What is MMR or MSI testing, and why does it matter?

Mismatch repair (MMR) and microsatellite instability (MSI) tests look at how well the cancer cells fix mistakes in their DNA. A small number of colorectal cancers are MMR-deficient (dMMR) or MSI-high. These cancers often respond well to immunotherapy. The result can also be a clue to Lynch syndrome, an inherited condition, so your team may suggest genetic counselling for you and your family.

Did I do something to cause my cancer?

No one deserves cancer, and most people never learn exactly why it started. Colorectal cancer is linked to many things, including age, family history and inherited conditions, and much of it is out of anyone's control. What matters now is getting the right treatment and support. Your team is there to help, not to judge.

Is it normal to feel scared or overwhelmed?

Yes. Fear, sadness, anger and worry are all common after a cancer diagnosis, and they often come in waves. These feelings are real, and help is available. Ask your team about social workers, counsellors and support groups. If you are thinking about suicide, call or text 9-8-8 in Canada or the U.S., or call 9-1-1.

Sources for this page

Back to Cancer: types of treatment, side effects and support for any cancer

General information, not medical advice. It does not replace your own care team. If you think you or someone else is having a medical emergency, call 9-1-1 or your local emergency number. If you are in crisis or thinking about suicide, call or text 9-8-8 (Canada and the US).

All After a Diagnosis guides