Colorectal cancer, which includes both colon and rectal cancers, begins in the large intestine or the rectum—the final part of the digestive tract. It is the third most common form of cancer globally and the second leading cause of cancer-related deaths. Alarmingly, cases are rising among individuals under 50 years old in the United States.

When detected early, colorectal cancer has a five-year survival rate of approximately 90% with surgery being the primary treatment. The goal of treatment is to eliminate all cancer cells and reduce the chances of recurrence. Treatment typically involves a multidisciplinary medical team that includes a gastroenterologist, colorectal surgeon, surgical oncologist, medical oncologist, and radiation oncologist.

Surgery

Surgery is the frontline treatment for all stages of colorectal cancer and may be the only treatment needed for stage 0. Surgical techniques include:

  • Excision: Tumors are removed using an endoscope, typically in very early-stage cancers.

  • Resection with anastomosis: The tumor and surrounding tissues are removed, and healthy portions of the colon are reconnected.

  • Resection with colostomy: An external stoma is created to allow waste to exit into a bag when reconnection of the colon isn't possible.

Side Effects of Surgery

  • Bleeding

  • Infection

  • Blood clots

  • Abdominal pain or swelling

  • Scar tissue causing adhesions

  • Temporary or permanent colostomy

Radiation Therapy (Radiotherapy)

Radiation therapy uses high-energy waves to destroy cancer cells and is commonly used for rectal cancer. It can be applied:

  • Before surgery to shrink tumors

  • After surgery to eliminate residual cancer cells

  • During surgery to target cancer areas

  • For patients who are not candidates for surgery

  • To relieve symptoms or treat cancer that has spread

Types

  • Internal radiation: Delivered via implanted radioactive materials

  • External radiation: Delivered by machines targeting the cancerous area

Side Effects of Radiation Therapy

  • Skin irritation

  • Nausea

  • Bladder or rectal irritation

  • Fatigue

  • Bowel incontinence

  • Scarring

Ablation or Embolization

These are local treatments, especially useful for tumors that have spread to the liver or lungs. Imaging guides a probe through the skin to target the tumor.

Types of Ablation

  • Radiofrequency ablation (RFA)

  • Microwave ablation (MWA)

  • Ethanol ablation

  • Cryotherapy

Types of Embolization

  • Arterial embolization: Blocks blood flow to the tumor

  • Chemoembolization: Combines chemotherapy with blocked blood flow

  • Radioembolization: Delivers radiation via tiny beads

Side Effects

  • Abdominal pain

  • Fever

  • Liver infection

  • Abnormal liver tests

  • Bleeding or clots

Chemotherapy

Chemotherapy is a systemic treatment targeting cancer cells throughout the body. It can be administered:

  • Before surgery

  • After surgery

  • For advanced or metastatic cancer

Administration

  • Systemic: Injected into veins or taken orally

  • Regional: Directed to specific arteries near the tumor

Side Effects of Chemotherapy

  • Hair loss

  • Nausea

  • Diarrhea

  • Appetite loss

  • Skin and nail changes

  • Infection risk

  • Fatigue

Targeted Therapy

This treatment uses drugs that act on specific cancer cell mechanisms. It may be used alongside chemotherapy or when chemotherapy is ineffective.

Types

  • EGFR inhibitors: Block proteins aiding cancer growth (e.g., cetuximab)

  • Anti-angiogenesis drugs: Inhibit blood vessel formation in tumors (e.g., bevacizumab)

Side Effects

  • Fatigue

  • Nausea

  • Diarrhea

  • Appetite loss

  • Headache

  • Heart, liver, or lung complications

Immunotherapy

Immunotherapy enhances the immune system’s ability to target cancer cells. It is particularly beneficial for advanced or metastatic cancers. Common agents include pembrolizumab and nivolumab.

Side Effects

  • Fatigue

  • Nausea

  • Diarrhea

  • Appetite loss

  • Joint pain

  • Infusion reactions

  • Autoimmune complications

Palliative Care

Palliative care focuses on improving quality of life for those with advanced cancer. Services may include:

  • Nutritional support

  • Pain management

  • Exercise guidance

  • Reducing hospital visits

  • Psychological support

  • Chemotherapy for symptom control

Treatment by Cancer Stage

Colon Cancer

  • Stage 0: Surgery

  • Stage 1: Surgery

  • Stage 2: Surgery, possibly with chemotherapy or radiation

  • Stage 3: Surgery and chemotherapy, possibly with radiation

  • Stage 4: Surgery (if feasible), chemotherapy, targeted or immunotherapy

Rectal Cancer

  • Stage 0: Surgery

  • Stage 1: Surgery or chemoradiation if necessary

  • Stage 2 & 3: Combined surgery and chemoradiation

  • Stage 4: Surgery, chemotherapy, targeted or immunotherapy

Recurrent Colorectal Cancer Treatment

If cancer returns, treatment depends on whether it can be surgically removed:

  • Localized recurrence: Surgery with chemotherapy or radiation before and/or after

  • Metastatic recurrence: Systemic chemotherapy, targeted therapy, or immunotherapy

  • Symptom control: Radiation therapy

Living With Colorectal Cancer

Monitoring after treatment is crucial. Factors affecting prognosis include tumor spread, lymph node involvement, metastasis, and biomarkers like CEA levels.

Managing treatment side effects and having continued support is key to living with colorectal cancer. Early detection through regular screenings, such as colonoscopies starting at age 45, greatly improves survival outcomes.