Impact of obesity in breast cancer: the FATLAS study

In this video, Josephine Van Cauwenberge, a gynaecology resident and PhD student at the Laboratory for Translational Breast Cancer Research, highlights research on the impact of obesity in breast cancer. With obesity rates rising worldwide, and increasing numbers of patients with breast cancer also living with overweight or obesity, understanding how excess adiposity influences tumour biology, treatment, and clinical decision-making has become increasingly important.

The Belgian, mono-centre, prospective FATLAS study includes treatment-naïve patients with hormone receptor-positive, HER2-negative breast cancer scheduled for upfront surgery. The study assesses global adiposity using routine clinical markers such as BMI and waist circumference, alongside more detailed measures like body fat percentage. It also evaluates local adiposity in breast tissue by analysing adipocytes from both the tumour and macroscopically normal breast tissue at a distance.

A key finding is that fat cells in normal tissue (distant adipocytes) are consistently larger than those close to the tumour (cancer-associated adipocytes). This suggests that cancer-associated adipocytes may act as an energy source for cancer cells by supplying lipids and shrinking in size. Secondly, BMI and waist circumference correlate well with other indicators of global adiposity in most patients, confirming that these routine clinical tools remain informative. Finally, adiposity was linked to inflammation and metabolic changes, with stronger associations observed in premenopausal patients compared to postmenopausal patients.

Overall, this research underlines the biological differences between normal and tumour-associated adipocytes and supports the continued clinical value of standard obesity markers, while also offering a rich framework for future studies on obesity-related mechanisms in breast cancer.