How Do Tumours Trigger Cancer Cachexia?

Cancer cachexia is a body-wide syndrome in which a person loses skeletal muscle and often fat while living with cancer. Eating more may help comfort and nutrition, but it usually cannot reverse the underlying process because the tumour and the body are changing inflammation, metabolism, appetite and tissue repair at the same time.

From a local tumour to a systemic problem

A tumour is surrounded by immune cells, fibroblasts, blood vessels and extracellular material. Together they form the tumour microenvironment. Cancer cells and neighbouring cells release cytokines, growth factors and metabolic signals that can enter the circulation or influence nerves. The liver may increase its inflammatory response, fat tissue may accelerate lipid breakdown and muscle may shift toward protein degradation.

Macrophages are especially important because they can adopt different states. Some support tissue defence, while others can be recruited and reprogrammed by a tumour. Cancer-associated fibroblasts also remodel tissue and release signals. A feed-forward loop forms when one cell population activates another and the response then strengthens the original signal.

Why location matters

Bulk sequencing averages gene activity across many cells. Single-cell sequencing separates cell types, while spatial transcriptomics also shows where their signals occur. Combining the two can reveal a small cellular neighbourhood that would otherwise disappear into the average.

The Cell study linked to NewTqnia Article 264 identified adjacent SEMA4A-positive tumour cells, AQP9-positive macrophages and LOXL2-positive fibroblasts in a cachexia-promoting niche. The researchers reported that the niche appeared before measurable tissue loss in experimental work. That makes it a candidate for further study, not a validated diagnostic test.

What a treatment would need to prove

A useful intervention would need to interrupt harmful signalling without weakening anti-tumour immunity, wound repair or other essential functions. Researchers must also show that the mechanism occurs consistently in people, predicts clinically important outcomes and adds value beyond existing measurements such as weight, muscle mass and inflammatory markers.

Future studies may test tissue biomarkers, imaging approaches or drugs aimed at one part of the loop. Until those studies are completed, cachexia care still depends on treating the cancer, supporting nutrition and physical function, and managing symptoms through a multidisciplinary clinical team.