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ONCOLOGY


of muscle mass associated with increased body fat, occurs not only in cancer, but also in other diseases such as type 2 diabetes mellitus, COPD or post-organ transplants, especially in older patients. The term ‘obesity paradox’, which has been in use since 2002, is a hypothesis that suggests obese patients may have better outcomes in cancer treatment and lower all-cause and cardiovascular mortality, although obesity is associated with poorer health in most other cases. Body composition analysis using bioelectrical impedance analysis (BIA) contributes to a better understanding of the paradox as it shows that only the presence of FFM is a predictor of a better outcome. Cancer patients with high FM and low lean mass or SMM – the definition of sarcopenic obesity – have a significantly lower rate of survival than patients with isolated obesity (high FM and high FFM) or even isolated sarcopenia.


It is of utmost importance to identify these risk patients early and take measures to counter the adverse effects. The timing of the sarcopenia diagnosis is critical. Ideally, all patients would be screened for malnutrition and sarcopenia after being diagnosed with cancer but prior to being treated. At that point the patient could be advised to follow a healthy, protein-rich diet or take part in a rehabilitation programme to reduce the severity of the problems caused by sarcopenia. If the accompanying diagnosis of sarcopenia is made during cancer treatment, body composition should be closely monitored while the patient is treated for malnutrition. In severe cases, it may be necessary to interrupt cancer treatment and find a way to rehabilitate the patient and resume treatment. In recent decades, cancer research has expanded beyond survival rates to consider the patient’s quality of life. Supportive cancer treatment and nutrition therapy in particular


MARCH 2017


The dosage of chemotherapy has traditionally been based on body weight or body surface area (BSA).


play a major role since malnourished patients generally experience a severe reduction in quality of life. Modern medicine has excelled in the development of new anti-cancer drugs, which are expensive yet highly beneficial to the patient, but has not progressed in the diagnosis and treatment of something as basic as malnutrition.


Body composition as input for chemotherapy


The dosage of chemotherapy has traditionally been based on body weight or body surface area (BSA). The use of BSA, which is calculated from height and weight, has been used since 1958 when oncologists realised weight alone was an insufficient measure. They had observed that test subjects with the same weight had different metabolic rates, a status that influenced the effectiveness of the cytostatic drugs.


In recent decades, medical researchers have criticised the use of BSA by pointing out the lack of evidence of a correlation between BSA and pharmacokinetic parameters as well as the inadequacy of BSA for predicting drug exposure for the patient. The underlying problem is that small changes in dosages can lead to unacceptable levels of toxicity and potentially life-threatening adverse effects such as neutropenia or kidney and liver failure and poor effects on the tumour. The expected result is reduced survival rates and lower quality of life for patients. Although medicine has made such progress in the development of modern cytostatic and anticancer agents, cancer treatment still relies on outdated administration methods


from the mid-20th century that have been proven inaccurate, ineffective and sometimes harmful to patients.


The idea has merit that something other than weight or height can be used to calculate drug exposure. However, BSA is not an accurate parameter for determining metabolic tissue, which influences drug kinetics and drug exposure. The medical community needed to find a factor that defines metabolic differences among patients so that personalised therapy could be provided. Studies conducted during the past five years suggest lean body mass and sarcopenia as an independent determinant of chemotherapy-associated toxicity. The data imply the feasibility of using body composition parameters as potential new criteria for chemotherapy dosing and cancer treatment. Further studies on this topic with prospective, randomised controlled trials have not yet been made. Nevertheless it can be concluded that body composition tools should be used to identify risk patients early and measures taken to correct their body composition before they fall victim to manifest malnutrition.


Comparison of body composition tools


The range of tools used to assess body composition is broad and each has its advantages and limitations. One should keep in mind that not every tool is able to measure every body composition compartment. The following methods are listed because they are able to determine FFM, SSM and/or FM.


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