Cancer’s Hidden Circles: How Extra DNA Helps Tumors Survive

by Dr. Stephen Pelsue
Fri, Oct 17th, 2025 11:48 am

When Cancer Keeps Finding a Way

It seems like cancer cells are always one step ahead of us. In many cases whatever we throw at them, they can adapt and survive.  Don’t get me wrong, we have made tremendous progress in targeting specific cancer cells and holding the disease at bay, but in some cases, the ability of the cancer cells to mutate and dodge everything that we have in our arsenal is both admirable and frustrating. 

The Frustrating Genius of Cancer’s Survival Tactics

Our understanding of cancer development and progression has been able to define several mutations and genetic alterations that can promote this behavior through two separate opposite actions:

  • activation of oncogenes (cancer promoting genes)
  • and inhibition of tumor suppressor genes (genes that block cell division). 

As cancer cells mature, they often accumulate more mutations that make them even more insidious and harder to control but understanding the mechanisms behind this has been lacking.

The DNA Loophole Behind Tumor Survival

A recent study has shed some light on one way that cancer cells are able to adapt and resist treatments.  Extra chromosomal DNA has been found to accumulate in advanced and aggressive tumors.  It turns out that in many cases, these circular fragments of DNA, that are not part of the normal chromosomal compartment, contain genetic elements that assist in the survival of the cancer cells.  They are known to carry

  • oncogenes
  • regulatory elements
  • immunomodulatory genes
  • as well as genes that impact genome instability and mutational processes. 

Sometimes the extrachromosomal DNA will have dozens of copies of these cancer genes, which make them very difficult to target and kill.  The more advanced the cancer is, the more extrachromosomal DNA they are likely to carry, which indicates that it accumulates over time.  There is also tremendous variation within a cancer cell population, making it very difficult to target. 

Outsmarting Cancer: Insights for Future Research

These recent findings have highlighted an area of research that needs immediate attention, as well as a method for better characterizing tumors.  Perhaps the more that we understand the cancer playbook, the more likely we are to be able to disrupt its strategy and stop cancer in its tracks.

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