Cancer survivors experience higher levels of fatigue even years after treatment, than people who have never had the disease. Being able to measure and monitor fatigability – the rate at which people tire – will help healthcare teams and advocacy groups to design helpful interventions that could improve quality of life.
In the past, the main aim of cancer treatment has been survival, but research is now seeking to understand how to improve survivors’ quality of life.
Fatigue is defined as a lack of physical and/or mental energy that interferes with normal activities. It is experienced by many cancer survivors and is often distressing. It has a negative impact on their state of mind and emotional wellbeing.
However, its subjective nature makes fatigue difficult to identify, measure and monitor. This means it may be underreported and makes it difficult to design effective interventions.
Fatigability is a relatively new concept that has been validated in gerontology – the scientific study of old age and aging. It assesses fatigue in relation to specific activities or situations. It is tested using standardized walk tests and measurable factors such as walking speed and ability.
Researchers from the Bloomberg School’s Department of Epidemiology at Johns Hopkins looked at data from the Baltimore Longitudinal Study of Aging (BLSA). The long-term study of aging required participants to take part in tests of fatigability at various intervals at and following enrollment.
A five-minute treadmill walk assessed perceived fatigability by asking people to rate their perceived exertion level on a scale between six and 20. A timed 400-meter walk tested participants for endurance.
Data from 1,665 people were included in the study, and 334 of these reported a history of cancer. The mean number of assessments per person was four. Factors such as age, sex, race, body mass index, smoking status, education and co-morbidities were also taken into account.
Overall, fatigability increased over time across the whole study population.
On average, people with a cancer history reported more fatigue in the treadmill tests which was associated with a 1.6 times greater risk of high perceived fatigability.
They were also slower on the endurance walks, by an average of 14 seconds, than those who had not experienced cancer.
On both measures, fatigability increased with age and with added comorbidities.
The researchers say the findings support the idea that a history of cancer is associated with higher fatigability and that this worsens with advancing age. What’s more, a typical 65-year-old will be living with two or more co-morbid conditions, which will also affect fatigability.
“The addition of cancer and associated symptoms, active cancer treatments and recovery from treatment to this burden increases the stress on an aging system, creating a need for more attention to effects that may persist long after the completion of treatment and may significantly impact on quality of life,” they add.
The research had several limitations, such as the study participants being healthier than the average population and the difficulties in looking at specific types of cancer, but the authors say it was a first step.
More research on fatigability, how it interacts with cancer treatments and its impact on quality of life will help the healthcare community to understand how best to integrate the concept into cancer care.
“The use of this methodology among those with a history of cancer may help illuminate potential causal and treatment pathways for managing fatigue in this population,” the paper concluded.
Gresham G, Dy SM, Zipunnikov V, Browner IS, Studenski SA, Simonsick EM, Ferrucci L, Schrack JA. Fatigability and endurance performance in cancer survivors: Analyses from the Baltimore Longitudinal Study of Aging. Cancer 2018; 124:1279-1287.