The researchers found that cells from parts of the kidney tumor behaved differently and that they were more aggressive in the center with a higher chance of spreading.

They found that cells in the center of the tumor had a less stable genome and were more likely to spread to secondary areas, whereas cells at the end of the tumor had lower growth rates.

Cancer cells in the central zone of the tumor face harsh hypoxic environmental conditions, as there is a lack of blood and oxygen supply. A subclonal phenotype of more aggressive growth was observed in the center of the tumor, with an increased load of copy number changes, higher necrosis and proliferation.

These cells must adapt to survive, which makes them stronger and more aggressive and can spread. The results underscore the need to pay close attention to the center of the tumor to understand how the cancer is spreading and to find the cancer cells that pose the greatest threat to the patient.

The observations shed light on the kind of environmental conditions that promote the emergence of aggressive behaviors.

 Conclusion: The metastatic subclones preferably originate from the center of the tumor.

SOURCE: Inst. Francis Crick, Royal Marsden, UCL and Nos. Cruces {Nature    Ecology and Evolution 17/5/2021}