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  • Writer's pictureSurviving Breast Cancer

Understanding and Managing GI Issues Caused by Breast Cancer Treatment

Although they can be lifesaving, breast cancer treatments can lead to various gastrointestinal (GI) issues. These side effects can vary in intensity from mild to severe and can significantly affect a person’s quality of life. Understanding GI issues’ causes, symptoms, and management strategies can help individuals navigate their treatment experience more comfortably.

While GI issues can be a challenging side effect of breast cancer treatment, various techniques can help you manage these symptoms and improve your quality of life. It’s essential to communicate with your healthcare team about any GI symptoms you’re experiencing so they can provide appropriate care and support. Continue reading for an in-depth look at the causes, symptoms, and management strategies of GI issues related to breast cancer treatments.


The GI issues experienced during cancer treatment can include a range of symptoms, including:

  • Nausea and vomiting

  • Diarrhea

  • Constipation

  • Abdominal pain or cramping

  • Bloating

  • Loss of appetite

  • Changes in bowel habits

What Causes GI Issues in Breast Cancer Patients?

The primary treatments for breast cancer — chemotherapy, radiation therapy, hormone therapy, and targeted therapy — can all contribute to GI issues. Here’s a closer look at how each treatment can affect the digestive system:

  • Chemotherapy: Chemotherapy targets and kills rapidly dividing cancer cells. Unfortunately, it also targets healthy cells in the body, such as those in the digestive tract, potentially leading to a range of GI issues:

    • Nausea and vomiting: Chemotherapy can trigger signals to the brain that activate the vomiting center, leading to these symptoms.

    • Diarrhea: Damage to the cells lining the intestine can disrupt water absorption and nutrients, resulting in loose or watery stools.

    • Mucositis: An inflammation and ulceration of the digestive tract lining can cause pain and increase the risk of infection.

  • Radiation Therapy: Radiation treatment uses high-energy rays to target and kill cancer cells. The radiation field, including the abdomen or pelvis, can affect the GI tract.

    • Inflammation: Radiation can irritate and inflame the intestinal lining, known as radiation enteritis or colitis.

    • Pain and cramping: The inflammation can cause abdominal pain and cramping.

    • Altered bowel habits: Individuals may experience changes in bowel habits, including diarrhea or, less commonly, constipation.

  • Hormone Therapy: Hormone therapies are used to treat breast cancers that are sensitive to hormones. They can indirectly affect the digestive system by altering hormone levels:

    • Bloating and gas: Changes in hormone levels can affect digestion and increase gas and bloating.

    • Constipation: Hormone fluctuations can slow the digestive process, leading to constipation.

  • Targeted Therapy: These treatments focus on specific molecules and pathways more active in cancer cells. However, they can also affect similar pathways in normal cells:

    • GI symptoms: Depending on the specific targeted therapy, patients might experience various GI symptoms, such as diarrhea, abdominal pain, or liver function changes.

  • Surgical Treatments: Surgical interventions for breast cancer may not directly target the digestive system, but when surgeries involve the abdominal area, they can impact GI function:

    • Direct impact: Surgery can physically alter the structure and function of the GI tract, particularly if parts of the digestive system are removed or altered.

    • Indirect impact: Surgery can affect surrounding tissues, nerves, and blood supply, indirectly influencing GI function and leading to issues like altered bowel habits or digestion.

Understanding these potential side effects can help patients and healthcare providers anticipate and manage GI issues during and after breast cancer treatment, improving the quality of life for people undergoing these treatments.

Managing GI Issues During Breast Cancer Treatment

Dietary Changes

Making specific changes to your diet can significantly reduce GI discomfort:

  • Eat small, frequent meals: This approach can lessen the burden on your digestive system, reducing symptoms like nausea and bloating.

  • Stay hydrated. Dehydration can exacerbate symptoms like constipation and fatigue. Aim for clear fluids and consider oral rehydration solutions if you are dealing with diarrhea.

  • Choose bland, easy-to-digest foods: Simple, non-spicy, and low-fat foods can prevent exacerbating GI symptoms.

  • Avoid irritating foods: Foods that are overly spicy, greasy, or high in fiber can aggravate your symptoms. Identifying and avoiding your personal trigger foods can be beneficial.


Various medications can help manage specific GI symptoms:

  • Anti-nausea medications: These can be crucial to prevent nausea and vomiting, especially during chemotherapy cycles.

  • Anti-diarrheal medications: Essential for managing diarrhea, these medications can improve your quality of life during treatment.

  • Laxatives and stool softeners: These can provide relief from constipation, a common side effect of specific breast cancer treatments and medications.

Lifestyle Changes

Lifestyle adjustments can also play a significant role in managing GI symptoms:

  • Rest and relaxation: Stress can exacerbate GI symptoms, so incorporating relaxation techniques like deep breathing or gentle yoga can be beneficial.

  • Gentle exercise: Physical activity can stimulate digestion and alleviate symptoms like constipation and bloating.

Professional Support

Don’t hesitate to seek professional advice for managing GI issues:

  • Consult a dietitian: A dietitian specializing in oncology can provide tailored dietary advice to manage your specific symptoms.

  • Talk to your oncologist: Your oncologist can adjust your treatment plan or prescribe medications to alleviate severe or persistent GI symptoms.

Count On Us for Information, Resources, and Support 

Whether you’re newly diagnosed with breast cancer, are navigating survivorship, or are the loved one of someone experiencing breast cancer, you can count on to keep you informed. We provide educational information to help you better understand symptoms, testing, treatment options, surgery, etc., and podcasts that feature professionals, advocates, and caregivers who share valuable information.

Your donations enable to offer resources and support every day, every month, and every year. 

Note: This article is designed to provide general information and not replace professional medical advice. Always discuss your options with your healthcare provider.

Learn More:

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