What are lymph nodes?
Spreading to lymph nodes helps cancer metastasize
Many studies have looked at the interplay of immune cells and cancer cells inside tumors, but these findings highlight“ action happening somewhere else, outside of the metastatic and primary tumors,” said Hannah Dueck, Ph. D., of NCI’ s Division of Cancer Biology. It highlights the role of the lymph nodes in the overall immune response to cancer, she said.
With some exceptions, the study was mostly carried out in mice implanted with melanoma, so additional studies are needed to see if the same phenomenon happens in people and with other kinds of cancer, Dr. Dueck noted.
What are lymph nodes?
“ Lymph nodes are the heart and soul of the immune system,” Dr. Engleman said. But they haven’ t gotten as much attention as they deserve, he added.
Lymph, a watery mixture of immune cells and fluid, flows through our bodies via a network of veinlike pipes. Hundreds of lymph nodes are dotted along this network.
Lymph nodes are like sophisticated training centers. Inside, immune cells learn how to fight infections and cancer. Once fully trained, the immune cells leave the lymph nodes to monitor the body for intruders.
To metastasize, cancer cells break off from the primary tumor and travel through the blood or lymph to other organs. If someone is found to have cancer in their lymph nodes, it’ s usually a bad sign that the cancer has or will soon spread to other parts of the body. Most cancer deaths are caused by metastatic cancer.
But it’ s never been clear what cancer cells are actually doing in the lymph nodes.
“ One of the theories is that, in the lymph node, [ cancer cells ] gain traits that make them metastatic. And then, from there, they go to the distant organ,” Dr. Dueck explained.
“ There is another theory that some cells from the tumor go to the lymph nodes, and some go to the distant organ,” she said. With this view, the lymph nodes don’ t play a critical role in metastasis, she added.
With the necessary models and tools at their disposal, Dr. Engleman’ s team set out to address the long‐standing debate about these two theories.
Spreading to lymph nodes helps cancer metastasize
The researchers first asked whether cancer in the lymph nodes of mice helps tumors metastasize to the lungs, one of the most common places cancer spreads to.