Fasting for Cancer Patients
Dr. Abdul Rahman Jazieh
Consultant Oncologist
Dr. Mahmoud Charif
Consultant Oncologist
Dr. Tahir Latif
Consultant Oncologist
Introduction:
Cancer is a very common disease affecting millions of people every year. According to one estimate, approximately 40% of people (1 in 3 individuals) will develop cancer in their lifetime. (1) For most patients it has a huge impact on their well-being, not only physically but also mentally, socially, and financially. Cancer comes in many varieties and affects individuals very differently depending upon the age and gender of the individual, the organs affected, stage at diagnosis and speed of cancer growth. Even the same cancer can affect two individuals very differently as far as the type and severity of symptoms as well as from one time in the disease course to another. Over the last few decades, our understanding of cancer and how to treat these patients has improved significantly. Multiple treatment modalities are available, and each treatment can impact patient quality of life differently. We currently have surgery, radiation therapy, and several types of drug treatments including chemotherapies, immunotherapies, targeted therapies, and hormonal therapies. Each of these treatments come with their own complications and side effects which may differ from one patient to another. Moreover, over time the severity of the symptoms may improve with good disease control, or it may worsen if the disease progresses.
Fasting, with some variation, is an act of worship for many religions. Islam obligates daily fasting (no food or drink from sunrise to sunset) every year for the month of Ramadan for individuals who are able to fast. There is emerging evidence that intermittent fasting may have health benefits including anticancer effects (2). It is becoming much more common for patients dealing with cancer to seek medical advice regarding the safety of fasting as they are either suffering through symptoms of cancer or treatment adverse effects. Due to differences in symptoms related to cancer and complications related to treatment, there are different situations that can affect fasting. Considering many individuals’ strong desire to fulfill their religious obligations, and potential health benefits of fasting, it is not prudent for us to provide an overarching decision of recommending no fasting to all cancer patients. Although it is very difficult to cover all possible scenarios in this chapter, we will address some common situations and make recommendations regarding the safety of fasting. These recommendations in no way substitute personalized medical advice, and individual patients should always seek advice from their physicians.
Effects of Fasting on Patient Health:
Cancer patients may be at risk of malnutrition or dehydration due to decreased oral intake, increased use of nutrients by cancer, and loss of fluids. Already decreased intake may result from cancer, causing loss of appetite or direct involvement of the GI tract. Chemotherapy may also lead to a decrease in appetite or cause nausea. Increased fluid loss may occur from increased sweating, vomiting or diarrhea. The loss of fluids combined with decreased oral intake may lead to dehydration, low blood pressure and eventually kidney damage. There are chemotherapy agents that require increased hydration to protect the kidney.
Considering the above-mentioned facts, we can broadly divide cancer patients into three categories based on health risk associated with fasting.
Safe Conditions:
Conditions that do not present increased risk of fasting to patients more than the general population.
Conditions with Uncertain Risk:
These conditions vary in their risk based on the individual patient and treatment,and require individual advice from physicians.
Likely Harmful Conditions:
These conditions have a clearly increased risk of harm with fasting, and if adequate hydration and caloric intake are not maintained, patients can develop organ failure. Additionally, these conditions often require frequent administration of medications, making fasting impossible.
Table 1. The categories of risk of fasting in patients with cancer
General Recommendations and Precautions
Nutrition and Hydration:
Unintentional weight loss in cancer patients can negatively affect quality of life and survival. There are multiple reasons for weight loss in cancer patients including lack of appetite, nausea, vomiting, diarrhea, and tumor growth. Supportive care of cancer patients often includes nutritional support to make sure patients have adequate calorie intake and can maintain hydration by drinking enough fluids. It is essential for patients with cancer to have adequate amounts of food and fluids. If the patient going through cancer treatment chooses to fast after discussion with their physician, it is very important that patients are able to meet nutrition and hydration goals between Maghrib (Iftar, sunset) and Fajer (Imsak, sunrise).
Medication Administration:
After open discussion with your physicians some medications can be safely modified to accommodate fasting. Table 2 provides some general guidelines in this regard.
Parenteral Nutrition:
Total Parenteral Nutrition (TPN, intravenous administration of all nutrition) is the only way to provide some patients with nutrition and hydration due to inability to tolerate food orally while they are going through cancer treatment. Although it is usually provided over 24 hours, many patients can be on cyclic TPN where it is infused overnight. If the volume of fluids can be limited during the time between Iftar and Imsak, then it will be safe to do that and fast. If that is not possible either due to the fluids’ volume or nutritional/mineral needs, then it should be infused as required and the patient should not fast.
Tube Feeding
A similar principle applies if the patient has a feeding tube If the nutritional needs and fluid volume can be infused during nighttime between Iftar and Imsak without exposing the patient to increased risk, then the patient can fast that day If this is not possible and the patient cannot tolerate receiving all nutrition at night, then the patient should not fast.
Radiation Therapy
Patients receiving radiation therapy generally can fast unless they have gastrointestinal complications or symptoms such as nausea, vomiting, diarrhea and stomatitis/mucositis. They may require medications, oral hydration, and pain killers and therefore, they may not be able to fast.
Stem Cell Transplant and Other Cellular Therapy Patients
The recommendations regarding fasting for patients undergoing stem cell transplant have to be individualized by the treating physicians as there are many factors to consider. These include but are not limited to: type of transplant, autologous (your own stem cell) or allogeneic (someone else’s stem cell), timing of the transplant, i.e., within a month, 3 months ago, or a long time ago, need for infection prophylaxis, nutritional status, symptom burden of graft vs host disease, need for immunosuppressive medications.
Available Resources and References
https://www.cancer.org/content/dam/cancer-org/research/cancer-facts-and-statistics/annual-cancer-facts-and-figures/2023/2023-cancer-facts-and-figures.pdf
Faiza Kalam, PhD and others, Intermittent fasting interventions to leverage metabolic and circadian mechanisms for cancer treatment and supportive care outcomes, JNCI Monographs, Volume 2023, Issue 61, June 2023, Pages 84–103, https://doi.org/10.1093/jncimonographs/lgad008
