Cancer Cachexia and Nutrition in Oncology
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Direct answer
Cancer cachexia is a multifactorial syndrome of ongoing weight loss, muscle wasting and anorexia that feeding alone cannot fully reverse. Systemic inflammation, with cytokines such as IL-6 and TNF-alpha, drives muscle protein breakdown and reduced appetite. Management combines screening, dietary counselling, exercise and, where needed, appetite-stimulating drugs such as megestrol acetate or olanzapine.
What you must remember
- Consensus definition: more than 5 per cent weight loss over six months, or a body mass index below 20 with more than 2 per cent loss, or sarcopenia with ongoing loss, in a patient with cancer.
- Cachexia versus starvation: starvation reverses with adequate intake, whereas cachexia persists because inflammation-driven catabolism continues despite feeding.
- Mechanisms: IL-6, TNF-alpha and proteolysis-inducing factor activate the ubiquitin-proteasome pathway, and hypermetabolism and anorexia add to the loss.
- Screening: the Patient-Generated Subjective Global Assessment is widely used to detect malnutrition at diagnosis and at regular intervals.
- Feeding route: oral nutritional supplements come first, enteral feeding when the gut works, and parenteral nutrition only when the gut cannot be used.
- Exercise: resistance training is the most supported non-drug measure for preserving lean mass.
- Appetite drugs: megestrol acetate and olanzapine are options, with megestrol carrying a risk of venous thromboembolism.
A stepwise plan for a patient losing weight
Cachexia is managed by addressing what can be reversed first and what the patient wants from treatment. The sequence below moves from measurement to goals of care, and each step decides whether the next is needed.
- Screen and grade. Record the weight trend, oral intake and muscle mass, and classify nutritional status with a structured tool such as the PG-SGA.
- Treat reversible causes. Mouth sores, nausea, constipation, dysphagia, low mood and infection are corrected, because each one reduces intake.
- Counsel the diet. Small, frequent, high-protein and high-energy meals are advised, and oral nutritional supplements are added when intake falls short.
- Offer exercise. Resistance and aerobic exercise preserve lean mass, even when total weight looks stable.
- Escalate the feeding route. Enteral feeding is used when the gut works, and parenteral nutrition is reserved for when it does not.
- Consider drugs and goals. Megestrol or olanzapine may be tried for appetite, with thrombosis risk weighed, and in advanced disease the plan is refocused on comfort.
Where the exam tries to catch you
Questions test whether the cause of weight loss is identified before a remedy is chosen.
- Trap: Cachexia is treated with high-calorie feeding alone. Correct: inflammation-driven catabolism means calories alone do not restore muscle, so exercise and anti-catabolic measures are added.
- Trap: Megestrol acetate builds muscle mass. Correct: it improves appetite and weight largely through fat rather than lean muscle, and it raises the risk of thrombosis.
- Trap: Artificial nutrition prolongs life in every advanced cancer. Correct: in terminal disease it does not prolong survival and may add burden, so comfort and patient wishes decide.
Cost often limits supplements in Indian oncology, so affordable, locally available protein foods are the practical first step.
Frequently asked questions
What is the consensus definition of cancer cachexia?
Cancer cachexia is defined by weight loss of more than 5 per cent over six months, or a body mass index below 20 with more than 2 per cent loss, or sarcopenia with ongoing weight loss, in a patient with cancer. It is a syndrome of muscle wasting and not simply low body weight.
How does cancer cachexia differ from simple starvation?
Starvation is reversed by adequate calorie and protein intake, whereas cancer cachexia persists because of inflammation-driven muscle breakdown and anorexia. Feeding alone therefore rarely restores lean mass in cancer cachexia.
Which screening tool is used for malnutrition in oncology patients?
The Patient-Generated Subjective Global Assessment, or PG-SGA, is widely used to screen oncology patients for malnutrition and to guide intervention. It combines patient-reported weight change, intake and symptoms with a clinician assessment.
Which appetite stimulant is used in cancer cachexia and what is its main risk?
Megestrol acetate is a progestogen used as an appetite stimulant in cancer cachexia, and it improves appetite and weight. Its main risk is venous thromboembolism, and the weight gain it produces is largely fat rather than lean muscle.
When is parenteral nutrition appropriate in advanced cancer?
Parenteral nutrition is appropriate when the gut cannot be used adequately, such as in intestinal failure or obstruction. It is not routinely beneficial in terminal disease, so the decision is guided by goals of care and the patient's wishes.