The majority of women with ovarian cancer are diagnosed with the most advanced stage of the disease.

Less than a third of people diagnosed with the condition survive five years. According to a recent study, as the third most frequent type of gynaecological cancer, it caused more than 200,000 recorded deaths worldwide in 2020 alone.

In a study published this month in the Journal of Experimental & Clinical Cancer Research, University of Notre Dame researchers in collaboration with NeoGenomics Laboratories have shed new light on one key factor that can make ovarian cancer especially deadly: obesity.

Obesity, considered a non-infectious pandemic, is known to increase the risk of ovarian cancer and decrease the likelihood of surviving the disease.

A team of researchers led by M. Sharon Stack, the Ann F. Dunne and Elizabeth Riley Director of Notre Dame’s Harper Cancer Research Institute, and Anna Juncker-Jensen, senior scientist and director of scientific affairs at NeoGenomics, wanted to understand why obesity makes ovarian cancer more deadly.

The researchers analysed cancer tumour tissues from ovarian cancer patients. They were able to compare the tissues of patients with a high body mass index (BMI) to those with a lower BMI, and two important differences stood out.

In cancer patients with a BMI higher than 30 (the range for obesity determined by the Centers for Disease Control and Prevention), the researchers found a particular pattern in the type of immune cells surrounding cancerous tumours.

They found a change in the populations of a type of immune cells, called macrophages, infiltrating the tumour that is typically associated with more advanced cancer stages and poor survival.

The cancerous tumours in obese patients were also surrounded by more stiff, fibrous tissue known to help tumours resist treatment by chemotherapy.

The team was also able to confirm their findings by observing similar patterns in ovarian cancer-bearing experimental models fed a high-fat diet.

Stack, who also serves as the Kleiderer-Pezold Professor of Chemistry and Biochemistry in the College of Science at Notre Dame, emphasised that the study offers hope for better treatments as the prevalence of obesity increases worldwide.

“Our data give a more detailed picture of how and why obesity may affect ovarian tumour progression and therapeutic responses to cancer,” Stack said.

“We are hopeful that these findings will lead to new strategies for targeted therapies that can improve outcomes for ovarian cancer patients.”