Colorectal cancer patients who are obese or underweight may have a higher chance of recurrence of cancer, or of dying, in comparison with patients of a healthy weight. However, data from previous studies is inconsistent.
Part of this inconsistency may be explained by differences in the amount of fat and muscle between patients. In many studies, only body mass index (BMI) was measured and assessed, but this is simply a measure of height and weight so would not capture the amount of skeletal muscle or fat mass very well. Excess fat mass in combination with low muscle mass – sarcopenic obesity – has been related to worse survival in comparison with people who do not have a low muscle mass.
These findings underline the need to study the associations between muscle and fat mass both separately and combined with recurrence and survival. Moreover, in some studies, there is a large variation in the type of tumours that patients have and the stage of disease (early stage vs late stage disease). If those variations are not accounted for, results between different studies may seem inconsistent.
On the blog: do people change their lifestyle after a cancer diagnosis?
Aims and objectives
The main objective of this research was to assess the amount of muscle mass, abdominal fat (fat surrounding the organs) and subcutaneous fat (fat below the skin), and investigate whether these are associated with the chances of survival of early stage colorectal cancer patients.
How the study was done
For this study, three institutions collaborated: Wageningen University, Maastricht University, and the Netherlands Comprehensive Cancer Organisation. Together, these institutions created a large dataset with information on more than 2,000 colorectal cancer patients. CT scans from the time of diagnosis along with other data such as specifics of their disease, weight and gender were collected from the patient’s medical records. Before the study was conducted, the study was reviewed and approved by Medical Ethical Review Boards at the different institutions.
In this large study, men with a lower muscle mass had a higher risk of dying after a colorectal cancer diagnosis. However, among women there was no association between muscle mass and death.
In both men and women, low subcutaneous fat was associated with a higher chance of dying but there were no associations between abdominal fat and chances of dying. A higher amount of fat in the muscle was associated with a higher chance of dying, especially among patients who were also suffering from other diseases such as diabetes or hypertension. Moreover, we found that patients who had more fat in their muscle already showed higher levels of fatigue around the period of diagnosis, and those levels remained higher throughout and after treatment.
Our findings show that body composition is associated with chances of survival, and with fatigue. In future work, we will study what the best interventions are to change body composition.