Positive effect of immune reaction to hormone-negative breast cancer less strong in obese patients

10 July 2020

The body of patients with a hormone-negative breast cancer often develops a strong immune response. This reaction is beneficial for the patient and has a positive effect on the chemotherapy's efficacy. KU Leuven and UZ Leuven researchers have recently published the results of a trial which shows that the degree in which this beneficial effect manifests itself, is dependent on the body mass index (BMI). In obese patients the effect is less strong and the chemotherapy clears away the tumour less efficiently.

Research shows that the positive effect of the immune response often seen in hormone-negative breast cancers is less prominent in obese patients. 

The body's immune reaction that presents itself for some types of breast cancer is caused by tumour-infiltrating lymphocytes (TILs), cells that are part of the immune system. They attack the tumour and try to clear away the cancer cells. Especially in hormone-negative breast cancers which do not grow under the influence of female hormones, the immune reaction can be strong.

The presence of TILs leads to better results of a chemotherapy treatment in hormone-negative breast cancers. When there is a large presence of TILs, the breast tumours will disappear more easily from the breast and the lymph nodes when administering chemotherapy, and also in combination with immune therapy.

Influence of body weight

Leuven researchers have now shown that the positive effect of the immune reaction on the efficacy of the chemotherapy, given prior to breast surgery, is less strong in women with a high body mass index (BMI). They found that especially in patients with a normal BMI, the breast cancer with high TILs disappeared completely as a result of the chemotherapy. These findings were then later confirmed by a large number of hormone-negative breast tumours in the Institut Curie in Paris.

The trial is an important contribution to the breast cancer research into the influence of the immune system. In addition, it stresses how extensive the negative impact of overweight and obesity is for the end-result of breast cancer, before, during as well as after the therapy. A healthy weight is an important factor for success treating breast cancer.

About the trial

This trial was published in the Journal of the National Cancer Institute and is the work of the multidisciplinary breast centre (coordinator prof. dr. Hans Wildiers) under the supervision of prof. dr. Giuseppe Floris (pathological anatomy) and prof. dr. Christine Desmedt (head of translational breast cancer research KU Leuven) as a result of a finding during the doctoral research of Lynn Jongen (promotor: prof. dr. Patrick Neven).

Read the full article in the Journal of the National Cancer Institute.

Last edit: 15 July 2020