Cancer-related fatigue (CRF)

This is different from the fatigue of daily life and many studies have shown a clear linkage between cancer and fatigue.   It is more severe than regular fatigue and is often described as an overwhelming exhaustion that cannot be overcome with a good night’s rest. Some people may also describe it as constantly feeling physically weak, drained or have difficulty concentrating (“brain fog”). If you look at many cancer sites, fatigue is listed as a symptom but for many different cancers, there may in some cases be different causal effects. I intend to open that up more below to cover some of the main issues related to NETs.

Below are some signs of CRF that you should pay close attention to. If more than one of the following symptoms apply to you, I recommend visiting your doctor.

• Weakness or tiredness that lasts for longer than 2 weeks
• Weakness or tiredness accompanied by a loss of weight
• Tiredness that remains even after rest or sleep, it keeps coming back, or is getting worse.
• You are continually finding yourself more tired than usual or breathless during or after an activity.
• You’re spending extra time in bed and/or sleeping for unusual amounts of time.
• You are finding it significant difficulty to concentrate and becoming confused more easily.

The causes of cancer-related fatigue (CRF)

I found the site OncoLink.com very useful in this part of my research.  This award-winning site is maintained by a group of oncology healthcare professionals, so they know what they are talking about.

According to them, the most common reason for CRF is anaemia, something which will be of interest to many NET patients.  As I said above, I was actually diagnosed via iron deficiency anaemia signalled by low haemoglobin results. Anaemia prevents bone marrow from efficiently producing red blood cells. Since red blood cells contain ‘haemoglobin’, which carries oxygen from the lungs to the body’s cells, a deficiency of red blood cells means there is less oxygen being carried around the body.  Your body’s cells use the oxygen to fuel the combustion of sugar and fat, which then produces the body’s energy, and so, without oxygen, the body cannot function properly, and this leads to the feelings of extreme tiredness.  The other causes listed by OncoLink are included below alongside anaemia (some entries supplemented from ASCO):

Medical conditions that can cause fatigue

• Anaemia.  Many NET patients will have anaemia as a side effect their NET type e.g. Gastric NETs are known to be associated with pernicious anaemia. Small Intestine NETs with iron deficiency anaemia. There are many other anaemia related scenarios.
• Pain.  The physical and emotional energy you use trying to deal with pain can make you feel fatigued including loss of sleep, and it can also force you to be less mobile.
• Infection.  e.g. You sleep a lot when you have flu. SIBO in small intestine NETs or those who have had bowel surgery, might contribute.
• Cardiac (heart) or pulmonary (lung) disease.   Can affect blood flow in the body or cause inflammation and may lead to fatigue.
• Medication side effect.  As one example, I always feel sleepy if I take antihistamines and certain cough medicines.  I know fatigue is listed as a short-term side effect of somatostatin analogues (in my own experience that improved over time).  Treatments, including chemotherapy, immunotherapy, targeted therapy and radiation therapy; are known to cause fatigue, mostly while undergoing treatment.
• Endocrine disorders. Not having enough thyroid hormone can slow down a person’s metabolism and lead to several adverse symptoms. This is a very common issue in the general population, but somatostatin analogues are known to affect thyroid levels in some NET patients (or exacerbate an existing comorbidity).  Diabetes can contribute to fatigue and is a common issue in the general population.  Many functional pancreatic NETs can succumb to diabetes (or exacerbate an existing comorbidity) due to their cancer type and some NET treatments can influence blood glucose levels, including but not limited to, somatostatin analogues.
• Nutritional deficiency.  Nutrition is a huge issue for many NET patients, particularly those who have had surgery and have known functional tumours where the oversecretion of hormones is causing these deficiencies. NET patients are known to be at risk for several vitamins and minerals many of which are related to low energy for tiredness and might have been caused by malabsorption. ASCO added this could be an issue with electrolyte imbalances, such as abnormal levels of sodium, potassium, calcium, and magnesium.  You may need to involve a registered dietitian in helping to assess and then treat these causes of fatigue.
• Renal (kidney) failure. Can lead to a build-up of toxins and impurities in the blood causing people to feel tired, weak and can make it hard to concentrate.  This issue can also cause anaemia.

But it’s not just medical conditions according to OncoLink and ASCO. Psychosocial conditions that can cause fatigue

• Lack of family, friends, and community social supports.
• Poor coping skills.
• Sedentary lifestyle.
• Anxiety.
• Depression.
• Sleep problems; especially a lack of sleep or disrupted sleep patterns.

There’s a useful article from American Society of Clinical Oncology (ASCO) entitled Cancer-Related Fatigue: What People With Cancer and Their Loved Ones Should Know | Cancer.Net

How can we help relieve or prevent cancer-related fatigue?

I am far from qualified to advise you on this but according to OncoLink, ” …………. only two interventions have been proven truly effective in large clinical trials to relieve or prevent fatigue: correction of anaemia and exercise. One reason it has been difficult to evaluate new therapies is due to a lack of understanding of the exact cause of CRF, as well as the lack of an animal model in which to do preliminary studies. You can’t exactly ask a mouse to rate his fatigue!”.  In addition to anaemia and exercise, OncoLink does discuss some other ways to manage fatigue that have been shown to be helpful (the link is below).

I also liked the page from the American Society of Clinical Oncology (ASCO) “8 Ways to Cope With Cancer-Related Fatigue” – read more here.