Current DateSeptember 17, 2021

Breast cancer: how tumors spread in the lymph nodes

Inserm researchers (France) have discovered that cancer cells are able to bypass the immune system to spread better.

When a woman has breast cancer, the tumor can spread throughout the body through cancer cells. The axillary nodes are often affected (these organs are located in the armpits and belong to the lymphatic system). The latter is part of the immune system. Eliane Piaggio, director of the “Translational Immunotherapy” team of the Inserm “Immunity and Cancer” unit at the Curie Institute and her team wanted to understand how these lymph nodes can be affected. They published the results of their work in the specialized journal Nature Communications.

Regulatory T cells involved in the spread of cancer cells

The French researchers analyzed lymph nodes that were invaded and others that were not invaded by cancer cells and tumors from women with breast cancer. They highlighted the role of regulatory T cells (Treg). “This T-cell subpopulation is essential for homeostasis of the immune system,” said Eliane Piaggio in a statement. Concretely, this means that it controls and regulates immune reactions. “It prevents the runaway of other immune cells,” she adds. “But in the case of cancer, we have found that it weakens tumor immunity and promotes the spread of cancer.”

Hijacking the immune system

It seems that the tumors have managed to upset the immune system: the Tregs promote cancer cells instead of destroying them. When affected, their activity becomes excessive and they prevent white blood cells from destroying these cells. “As soon as the lymph node is metastatic, there is an increase in regulatory T lymphocytes,” underlines Eliane Piaggio. “We even discovered that the cells present in the tumor and those found in the lymph nodes are from the same clone, which means that they share common information but above all express unique molecules.” The researchers notably identified the CD80 marker. “This protein could become an interesting therapeutic target and open the way to the development of a new immunotherapy. The objective would then be to eliminate regulatory lymphocytes to unblock the immune system’s action against the tumor,” they said.

Screen early to avoid complications

Breast cancer is the second most common among women in the United States. In 9 out of 10 cases, the disease can be treated if diagnosed early. To detect it as quickly as possible, examinations are recommended: a palpation performed by a health professional every year in people over 25 years old and a mammography every two years for women aged 50 to 74, without risk factors or symptoms. If you are considered at risk, the doctor will suggest a specific monitoring system which may be similar to that of organized screening.

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