Why does cancer keep mutating even after treatment at 50?

Question

Hello doctor,

My father is 50 years old and has been undergoing treatment for lung cancer for the past year. Initially, his scans showed a good response to therapy, but recently the doctor mentioned that the cancer appears to be changing at the molecular level, possibly developing resistance to the current medication.

We were informed that repeat molecular testing might help identify new mutations that could guide the next line of treatment. We are finding it difficult to understand how cancer cells can continue to change even while treatment is ongoing.

Why does cancer keep mutating despite treatment, and does this mean the disease becomes harder to control over time?

Please help.

Thank you.

Answer 1

Hello,

Welcome to icliniq.com.

I have gone through your query and understand your concern.

I understand how confusing and difficult this situation can feel, especially after seeing an initial good response to treatment.

Cancer cells are not stable like normal cells. They have a natural tendency to develop new genetic changes over time. Even while treatment is working, a small group of cancer cells may already have or gradually develop changes that allow them to survive.

When treatment is given, it destroys the sensitive cancer cells, but the resistant ones remain. These surviving cells then grow and become the dominant type, which is why the cancer appears to change at the molecular level.

This is the reason your doctor has advised repeat molecular testing (a precise laboratory method that analyzes biological markers in tissue or fluid samples to detect genetic changes, infections, or diseases like cancer).

It helps identify these new changes so that the next line of treatment can be better targeted. This does not necessarily mean that the disease cannot be controlled, but it does mean that treatment often needs to be adjusted over time as the cancer evolves.

I hope I have answered your question.

Let me know if I can assist you further.

Thank you.