A total of 11–12000 patients with gynaecological, urological and rectal cancer undergo radical pelvic radiotherapy annually in the UK. This reflects about 20% of patients diagnosed with pelvic malignancy (Moller et al, 2003). More than 70% develop acute inflammatory small intestinal changes (Resbeut et al, 1997), leading to gastrointestinal symptoms during treatment partly because healthy bowel tissue is encompassed in the radiation field.
Acute symptoms include diarrhoea, abdominal pain, tenesmus or nausea that usually start during the second or third week of a course of radical radiotherapy and resolve within a fortnight of completion of radiotherapy (Ajlouni, 1999). The incidence of chronic bowel damage is difficult to assess, as patients may be lost to follow-up, may not report any changes to their clinician or may not be identified by scoring systems historically used in clinical trials. In 5–10% of patients, serious gastrointestinal problems may occur (Ooi et al, 1999; Denton et al, 2000; Nostrant, 2002). These include bowel obstruction, fistulation, intractable bleeding or secondary cancers. A further 6–78% of patients develop less severe symptoms, which nevertheless detrimentally affect quality of life (Kollmorgen et al, 1994; Potosky et al, 2000; Gami et al, 2003). These may include urgency, frequency, faecal incontinence, diarrhoea, steatorrhoea, tenesmus, pain, constipation and weight loss (Andreyev et al, 2003). The severity of acute bowel toxicity may predetermine the degree of chronic bowel changes (Donaldson et al, 1975). Therefore, early intervention to prevent or reduce acute toxicity may be worthwhile in the long term.
A number of radiotherapy techniques are used to treat cancers within the pelvis. These may influence the dose that is delivered to the tumour and surrounding structures. Radiotherapy damages tissue because energy dissipated from ionising radiation generates a series of biochemical events inside the cell. Free radicals are formed and disrupt DNA, preventing replication, transcription and protein synthesis. When given in combination with chemotherapy, the risk to normal tissues may be enhanced. The small intestine is particularly susceptible to damage because its cells are usually rapidly proliferating, and bile acid and pancreatic enzymes may potentiate damage to the mucosal glycocalyx (Sullivan, 1962; Mulholland et al, 1984).
Consideration of nutrition before, during and after radiotherapy to the pelvis may be important for several reasons. Nutritional risk describes patients who are likely to develop malnutrition as a result of their illness, but the prognostic significance of nutritional risk is not clear. Malnutrition per se is an independent adverse prognostic factor in many cancers (Bozzetti, 2001). It may occur due to physiological, metabolic, psychological or iatrogenic processes, which exist as a result of malignancy and may affect morbidity, mortality and response to treatment (Argiles and Lopez-Soriano, 1999).
Specific therapeutic nutritional intervention before and during radiotherapy may induce a radio-protective effect for healthy tissues, for example, elemental diet by various mechanisms including attenuation of biliary and pancreatic secretions (McArdle et al, 1974, 1985; Pageau and Bounous, 1977; Mester et al, 1990) or nutritional intervention may be used for its radio-enhancing effect on malignant tissues, for example, polyunsaturated fatty acids (Conklin, 2002).
Manipulation of habitual diet after radiotherapy may help to reduce or eliminate chronic, undesirable changes in bowel habit once they have occurred. A number of dietetic interventions such as lactose restriction, fat restriction, reduced intake of motility stimulants such as caffeine and a decrease in fibre-containing foods (Classen et al, 1998) have been suggested.
This review has two aims. First, to assess the incidence and significance of malnutrition in patients undergoing pelvic radiotherapy and those with chronic bowel side effects resulting from pelvic radiotherapy and second, to examine the efficacy of therapeutic nutritional interventions used to manage gastrointestinal side effects of pelvic radiotherapy.