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Anorexia is the lack or loss of appetite and interest in food.
During the cancer process, anorexia can be induced in three different ways:
premature satiety: the person is unable to eat more than a few mouthfuls,
nausea: the person feels like vomiting as soon as food arrives,
- loss of or change in sense of taste and smell: no food is pleasant to eat, the smell of meat, pork, ham becomes unpleasant. Due to this discomfort, the person is unable to prepare meals and forgets to eat.
During cancer, anorexia may be due to cancer itself, its treatment or the psychological consequences of cancer (depression).
Biological anomalies related to cancer are sometimes observed:
elevation of serum lactate, related to the tumour mass,
ketosis due to fasting,
hypercalcaemia (paraneoplastic syndrome or due to bone metastases),
anatomical alterations and mechanical consequences related to cancer of the digestive tract: cancer of the oro-pharynx, oesophagus, stomach, pancreas, liver, peritoneum,
abnormal secretion of bombesin (a neuropeptide produced by small cell lung carcinoma) or serotonin (produced by carcinoid tumours),
elevation of serum tryptophane due to abnormal tumour metabolism,
- production by the tumour cells of cytokins like TNFα (Tumor Necrosis Factor α), IL1 (Interleukin-1) or IFN-γ (Interferon γ), which seem to possess a direct effect on the satiety centre of the brain (hypothalamus).
Most therapies do promote anorexia, at least during the first days:
- taste modifications and alimentary difficulties after a surgical procedure,
- vomiting and nausea induced by radiotherapy, often associated with mucitis (lesion of the mucosae), dryness of digestive mucosae, such as the disappearance of salivary secretion,
- chemotherapy induced nausea, vomiting and mucitis.
Anorexia may also be the consequence of psychological disorders induced by cancer:
transitory loss of appetite after the announcement of the disease,
psychotic depression favoured by cancer, with its major weight loss and necessitating anti-depressive treatments.
Cachexia or general state alteration including major weight loss is the consequence of both anorexia and evolution of the cancer process. Various factors have been incriminated:
- diversion of the normal metabolism by the growing tumour,
- mass effect of the tumour itself as well as secretion of cytokines with a necrotic effect (see above),
- direct effect on the digestive tract (sub-occlusions, absorption disorders),
- previous poor alimentation or under nourishment due to alcoholism and smoking,
- liver metastases (poor metabolism of normal nutriments).
The easiest way to measure cachexia is to weigh the patient although the weight loss may be masked by oedema or effusion (like ascites). A loss of 10% to 20% of normal weight can be observed in cancers of the stomach or the oesophagus. There is a clear correlation between the weight loss observed before treatment and poor cancer prognosis.
Severe under nourishment may be observed during complicated treatment (such as radiotherapy for head and neck cancers or poorly tolerated chemotherapy). These therapies may have to be temporarily stopped in order to take corrective measures (such as hyperalimentation by nutritive components or IV feeding).
Severe cachexia is frequently observed at the end of life. Major emaciation is due to the disappearance of all muscular and fat masses. The skin becomes very fragile like parchment, dentures become too big for the mouth, the patient becomes skeletal. In such a state of under nourishment, complications arise very quickly: a dry mouth further reduces feeding, the body support zones are the target of necrosis process (decubitus bedsore).
Biologically, such cachexia induces an increased metabolism of lipids and proteins, anaemia (without any clear aetiology), hypo-albuminemia (further inducing oedema), hyponatremia.
Fever is a very frequent symptom at the end of life in cancer patients.
An infection should always be investigated (cf. chapter on emergencies), but generally is not proven (no germ).
Some cancers specifically involve fever during their evolution (Hodgkin’s disease, acute leukaemia, kidney cancer, osteogenic sarcoma, atrial myxoma), with sweating episodes, probably related to cytokine production.
More frequently, fever is observed with major tumour mass (almost the same mechanisms as for cachexia), with tumour necrosis (and the risk of anaerobic super infection).
Major liver metastases are often complicated by a moderate fever which can be notably reduced by anti-inflammatory drugs like cortisone.