Is it the cancer or its treatment

One of major unresolved issues is the extent to which fatigue is caused by the tumour and its effects (for example cachexia (Plata-Salaman 1996)), the treatments used (for example chemotherapy, radiotherapy, or surgery), or an interaction between the two. Fatigue is a common presenting symptom of many different types of cancer (see Chapters 1 and 2) with little apparent difference in the incidence (except perhaps for haematological malignancies associated with severe anaemia), suggesting some commonality of mechanism associated with substances produced by, or in response to, the tumour (for example cytokines). In a study of 499 patients with cancer, Glaus (1998) found that reported fatigue was related to tumour type, with individuals with gynaecological cancers reporting more fatigue than patients with testicular cancer, who in turn reported more fatigue than patients with breast cancer. Fatigue was also influenced by stage of disease, with patients with metastatic disease reporting more fatigue than patients with localized disease, and those with localized disease reporting more than individuals in remission.

In a retrospective study of 50 consecutive patients (men and women) receiving radiotherapy for lung cancer, 39 individuals (78%) reported fatigue during the course of treatment, with the proportion of patients with fatigue increasing linearly over the course of therapy (Hickok et al. 1996). Fatigue frequency did not vary significantly by demographic variables such as age, gender, race, work, or marital status of the patients, or by disease or treatment characteristics, such as disease stage, radiation dose, and previous chemotherapy. A study of 183 men with prostate cancer (Stages 1,2, or 3), receiving external beam radiation therapy extended these findings (Morrow et al 2001). Results presented in Table 3.1 show 75% feeling fatigued during treatment, and in 50% the fatigue was described as moderate or severe. This table also shows that approximately one-third had sleeping difficulties.

Taken together, these studies indicate that some patients with cancer have a degree of fatigue prior to treatment but that the incidence and severity of the fatigue is increased during radiotherapy. Studies of treatments have focused on radiotherapy and chemotherapy, and, as far as we are aware, the possible impact of surgery as an independent variable has not been examined. Many patients will have surgery at some point in their treatment and studies in patients undergoing elective surgery for diseases other than cancer have revealed fatigue as a sequela to surgery (Christensen et al. 1989; Zeiderman et al. 1990) (see also Chapter 2).

For obvious reasons it is not possible to study the effect of therapy in subjects who do not have a tumour in order to evaluate the relative contributions of cancer and its treatment to overall fatigue. Data collected from the victims of accidental nuclear fallout exposure show that they experience fatigue and that the incidence falls within the range of that found for radiotherapy patients (Anno et al. 1989). Although sparse and uncontrolled, these observations demonstrate that radiation is capable of inducing fatigue, and that the presence of a tumour is not an essential cofactor. However, it is not known whether the fatigue induced by radiotherapy in cancer patients has the same characteristics and mechanism(s) as that induced by nuclear fallout exposure.

To summarize, the sparse evidence available indicates that cancer, cytotoxic therapy, and surgery are all independently capable of inducing fatigue, although its characteristics and underlying mechanism(s) may differ. Some patients with cancer report fatigue at diagnosis, and this increases in incidence and severity with treatment.

Table 3.1 Frequency and severity of adverse effects in 183 men receiving external beam radiation treatment for prostate cancer

Adverse effect


Intensity (moderate or severe)


N = 121 (74%)

N = 60 (50%)

Urinary problems

N = 118 (72%)

N = 72 (61%)


N = 105 (64%)

N = 49 (47%)

Difficulty sleeping

N = 52 (32%)

N = 25 (48%)

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