Description of the condition
Based on worldwide statistics, ovarian cancer is the seventh most frequent cancer for both incidence and mortality with age-standardised rates (ASR) respectively of 6.3 and 3.8 per 100,000 women. Within these rates is significant geographical variation with an ASR of incidence of 9.3 per 100,000 in more developed regions and 4.9 per 100,000 in less developed regions of the world (GLOBOCAN 2008). Approximately 90% of ovarian cancers originate in the epithelial (or surface) layers of the ovary; other types of ovarian cancer can occur in the sex cord-stroma (inner structure of the ovary) and in the germ cells (where the eggs develop).
The presenting symptoms of ovarian cancer are often of a non-specific nature such as abdominal pain, abdominal bloating, changes in bowel habit, extreme fatigue or back pain and may be attributed to other reasons. As a consequence, patients may often be found to have advanced disease at the time of diagnosis. The treatment and prognosis of ovarian cancer are indicated by the staging of the disease classified using the International Federation of Gynecology and Obstetrics (FIGO) system (Benedet 2000). Staging may be evaluated from ultrasound, computerised tomography (CT) or other scanning techniques or from the finding of malignant cells in ascites (abnormal fluid collection in the abdomen); staging is confirmed when surgery occurs. The surgical treatment of ovarian cancer diagnosed at an early stage entails the removal of one or both ovaries and the uterus, depending on the extent of the disease and the need to preserve fertility. Where abnormal tissue is more widespread, for example in other pelvic organs, cytoreductive surgery is used with the aim of surgically removing all visible tumour tissue (optimal cytoreduction). If optimal cytoreductive surgery cannot be undertaken as a primary treatment, due to the presence of disease at inaccessible sites or poor performance status, chemotherapy may be commenced (neoadjuvant chemotherapy), prior to subsequent surgical reduction of the tumour (interval debulking) (Tangitgamol 2010). Surgical intervention may also be indicated where intestinal obstruction occurs as a complication of the disease.
Causes of malnutrition and weight loss in people with cancer have been described and these may include: tumour-induced anorexia; catabolic effects of the tumour; abnormal metabolism of nutrients; physical obstruction of the gastrointestinal tract by a tumour; reduced food intake as a side effect of radiotherapy or chemotherapy and diminished intake due to pain, anxiety or depression (Henry 2011). Specifically in ovarian cancer, common presenting symptoms include abdominal discomfort or pain, abdominal distension, nausea, dyspepsia, early satiety and constipation (Brooks 1994). In one UK study, more than 50% of 35 women recruited were reported to have a visibly distended abdomen due to ascites or ovarian mass (Balogun 2011).These factors are liable to influence food intake and consequently nutritional status within this patient group. Malnutrition in association with ovarian cancer has been identified as a problem for many years particularly in women with advanced cancer (FIGO stages III and IV) (Tunca 1983). Within a group of 33 women with ovarian cancer requiring an operation for a bowel obstruction, 75% were identified as having severe nutritional deprivation (Larson 1989).
A variety of methods have been used to identify malnutrition. Subjective global assessment (SGA) is a method of evaluating nutrition status combining weight change, diet history and physical examination. In a Brazilian study of women with gynaecological cancers, SGA identified malnutrition in four out of 14 (28%) women with ovarian cancer (Zorlini 2008), while the same method found 50% of 132 women with ovarian cancer in a US study were malnourished (Gupta 2008). In Australia, using the patient-generated SGA (PG-SGA), malnutrition was identified in two-thirds of 48 women with ovarian cancer in comparison with 12% of women with other gynaecological cancers. The mean body mass index (BMI) of the malnourished women (27.4 kg/m2) indicated that some women were overweight although their mean BMI was significantly lower than the mean BMI of well-nourished patients. Therefore, it was noted that the use of BMI and weight alone would not be sufficient to detect malnutrition in this patient group (Laky 2008).
Evidence of malnutrition in women with ovarian cancer has been related to outcomes from surgery. When surgery has been required for intestinal obstruction, poor nutritional status (identified either by weight loss, low serum albumin or low lymphocyte count) was a factor that significantly correlated with poor surgical outcome (Krebs 1983), poor postoperative survival (Clarke-Pearson 1988) and an increased incidence of postoperative infectious complications (Donato 1992). In a study of older women (aged 75 years or over) with ovarian and primary peritoneal cancer, serum albumin was used as a surrogate measure for nutritional status and was significantly associated with lower rates of optimal cytoreduction. Women with sub-optimal cytoreductive surgery had a lower median survival time in comparison with the women who underwent optimal cytoreduction (17 months versus 62 months) (Alphs 2006). Although serum albumin may reflect chronic protein deficiency, it is also an indicator of acute clinical stress, hydration status, liver dysfunction and inflammation, so requires careful evaluation. In a study where prealbumin was used as a nutrition assessment marker, a significant relationship was shown between low serum prealbumin and the risk of complications after primary radical cytoreductive surgery for ovarian cancer, with significantly greater risk of blood loss, morbidity and mortality where serum prealbumin was lower than 10 mg/dL (Geisler 2007).
Current guidelines recommend the use of nutrition screening in hospital to identify individuals at risk of malnutrition. Identification of patients found to be malnourished or at risk of malnutrition should be linked to further assessment and implementation of an appropriate nutrition care plan, which may include nutrition support (ASPEN 2011; Kondrup 2003; NICE 2006). Women with ovarian cancer may have co-existing excess weight or obesity with or without ascites, therefore appropriate screening and assessment methods are required to ensure that malnutrition is identified and treated.
Description of the intervention
In this context, nutrition interventions include nutrition screening, nutrition assessment or nutrition advice, which may be combined with nutrition support (additional or alternative provision of nutrients), with the intention to improve or maintain nutrient intake. Nutrition support may be provided as supplementary foods and drinks, fortified foods or oral nutrition supplements; also nutrition formulations given by tube into the gastrointestinal tract (enteral feeding) or given by infusion intravenously (parenteral feeding or PN). Nutrition support may compensate in part or in full for inadequate food consumption. In this review, nutrition interventions do not include the use of nutrition formulations given routinely in 'Enhanced Recovery after Surgery (ERAS)' programmes, which have been recently reviewed in the context of gynaecological oncology (Lv 2010). Nutrition interventions may occur at any stage in the perioperative period with the intention to identify, prevent or treat malnutrition. It is important that the risk of adverse effects associated with the provision of nutrition support are considered. Risks associated with nutrition support interventions may range from minor effects such as taste dislike or nausea to life-threatening effects such as PN catheter-related sepsis.
How the intervention might work
Nutrition screening and assessment may identify women at risk of malnutrition and enable nutrition support to be implemented. Nutrition support may improve the nutrient intake of women undergoing surgical intervention for the investigation or treatment of ovarian cancer or associated complications. The nutrition intervention may prevent further nutritional losses at a time of increased metabolic requirements due to the stresses of surgery and the requirement for postoperative wound healing.
Nutrition interventions may improve quality of life (QoL) as perceived by the patient. In other patient groups undergoing radiotherapy for cancer treatment, randomised controlled trials (RCTs) have shown that nutrition counselling improved nutrition intake, nutritional status and QoL (Ravasco 2005; Ravasco 2005a).
Nutrition interventions may reduce the length of hospital stay. Malnutrition has been identified as a factor contributing to prolonged length of stay following surgery for gynaecological cancer (Laky 2010).
Nutrition interventions may affect clinical outcome by reducing postoperative complications. Parenteral nutrition has been successfully used to raise prealbumin levels above 10 mg/dL in women with ovarian cancer; this reduced the incidence of surgical complications, which occurred in women when prealbumin levels were lower than 10 mg/dL. Prealbumin levels were subsequently used to determine the prescription of nutritional support and the timing of surgical intervention (Geisler 2007).
Women who are unable to eat due to ovarian cancer-related intestinal obstruction can be given nutrients by an alternative route (PN) either pre- or perioperatively (Rubin 1989). Nutrition support techniques may be used as an alternative to normal food intake where gastroparesis has occurred as a side effect of cytoreductive surgery in ovarian cancer (Caprino 2006).
The identification of malnutrition may provide useful prognostic information. Mean survival time has been shown to be longer in well-nourished women than in malnourished women with similar cancer staging (Gupta 2008). Nutrition status can improve. Some women with ovarian cancer identified as being malnourished at diagnosis, were subsequently noted to be nourished three months later and they had a median survival time similar to that of women who were identified as well nourished both at diagnosis and at three months. Nutritional interventions may have contributed to improved nutritional status (Gupta 2010).
Why it is important to do this review
Malnutrition has been shown to be a significant risk in women with ovarian cancer and therefore requires purposeful identification and treatment. Nutrition interventions may positively improve clinical outcomes, nutritional status or QoL measures in women with ovarian cancer. There is a need to develop practical guidance on the use of nutrition interventions derived from a systematic review of high quality studies undertaken in this patient group.