Our study was about the association between adiposity and overall survival in older adults with gastrointestinal malignancies.

What was the rationale of this study?

The rationale behind this study was mainly two things. First of all, we know that in literature we have seen that lower muscle mass, or sarcopenia, is associated with worse outcomes and worse overall survival in particularly older adults with malignancies. But there is paucity of literature with regards to adipose tissue mass in these individuals and how it affects the overall survival.

That got us interested to study this association. And, secondly, we know that obesity is a known risk factor for GI malignancies, especially colorectal cancer, hepatobiliary cancer and pancreatic cancers. Obesity is measured by BMI. BMI, or the Body Mass Index, is really a calculation of weight upon height squared. We know weight could be contributed by muscle, body fat, as well as bones. So maybe you and I have the same BMI but may not have the same fat content. Therefore we wanted to study the body composition of these individuals and we utilised CT scan data and validated segmentation methods to study the body composition of individuals.

What was the study design?

It was an observational study. We included older adults who were 60 years or older and had a newly diagnosed GI malignancy. They were followed up in our clinics and we used validated segmentation methods to calculate the areas on the CT scan and with these areas of the visceral adipose tissue, subcutaneous adipose tissue, and skeletal muscle we created an index just like BMI. So we created a visceral adipose tissue index which was area upon height squared and so forth with the subcutaneous adipose tissue as well as the skeletal muscle tissue.

Thereafter we created a multivariable Cox model and we kept in mind the confounding factors that would be age, sex, cancer type, cancer stage, frailty status and other confounding factors that could have been affecting the individual overall survival.

What were the results?

In our study we included 484 older adults who were diagnosed with GI malignancies and 57% of these adults were males, 72% were non-Hispanic white and a majority of our patients had colorectal cancer followed by pancreatic cancer as their main diagnosis. So when we ran our data through the multivariable Cox regression models we saw that the visceral adipose tissue index was directly correlated with worse overall survival in this cancer population. We concluded that overall the more the visceral adipose tissue in our body it is correlated with worse overall survival.

The limitations of the study mean that it is done for older adults in particularly gastrointestinal malignancies. That has been done at a single institution so more work has to be done further moving forward.

What do you think the clinical significance is of these results?

The significance of our study is that we can use CT scan data to analyse the body composition in our individuals and this data can be used further to determine the prognosis of cancer patients. So we are working on creating scales that could help us analyse this data and use this data along with other demographic data and frailty to create a scale that would be able to tell us the prognosis of cancer.