Cancer-related fatigue: why it lasts, and what helps

If you are exhausted months after treatment finished, you are not failing to recover properly and you are not imagining it. Cancer-related fatigue is a recognised clinical problem with recognised management. The counter-intuitive part is that the best-evidenced treatment is graded physical activity — not rest — which is difficult to hear when getting up the stairs is hard.

Cancer-related fatigue is usually described as a persistent sense of physical, emotional or cognitive exhaustion that is out of proportion to activity, is not relieved by sleep, and interferes with normal functioning. People describe it as heaviness, as wading, or as a battery that never charges past half.

• It commonly continues for months after treatment and, for a minority, for years.
• It fluctuates: a good day is often followed by a flat one, especially if the good day was overdone.
• It has cognitive and emotional components as well as physical — see chemo brain.
• It is worse when combined with poor sleep, low mood, pain, deconditioning or anaemia — all of which are treatable.

Before accepting fatigue as "just recovery", ask for the treatable contributors to be looked for. Guidelines recommend assessing these explicitly.

A meta-analysis comparing pharmaceutical, psychological and exercise treatments for cancer-related fatigue found exercise and psychological interventions were effective, while drug treatments were not, on average, better than the comparison. Guidelines from ASCO and the international exercise roundtable reach the same practical conclusion: activity is first-line.

1. Start below what you think you can do. Five to ten minutes of walking, most days, is a legitimate starting point.
2. Increase by about ten per cent a week, and only when the previous level feels sustainable.
3. Add resistance work twice a week — sit-to-stands, wall push-ups, resistance bands. Muscle loss is a major driver of fatigue and is reversible.
4. Keep going on flat days at a reduced level rather than stopping. Consistency matters more than any single session.
5. Aim, over months, towards roughly 150 minutes of moderate activity a week plus two strength sessions — the general guidance for adults, including cancer survivors.

Keeping a simple energy diary for two weeks — activity, energy out of ten, sleep — usually reveals a pattern people had not noticed, and makes planning possible. My Journey includes a wellbeing log that stays on your device.

Most people improve substantially over six to twelve months after treatment, with the steepest change in the first three to six. A minority have fatigue that persists for years, particularly after intensive chemotherapy, stem cell transplant, or where other long-term effects are present.

Fatigue that is worsening, sudden, or accompanied by breathlessness, chest pain, dizziness or bleeding is different — that needs assessment rather than pacing.