Experts at Stanford University believe that cancer drug therapy triggers natural selection that makes metastases resistant to drugs. This is evidenced by the results of a large-scale study published in the scientific journal Nature Genetics.
For the experiment, the scientists took samples of primary tumors and metastases from 136 patients with breast, rectal and lung cancer. After that, the biomaterial was divided into two groups, one of which was exposed to drugs, and the second was left untouched.
As a result, a strange pattern was discovered: it was the drugs that were used to treat primary cancer that triggered the evolution of metastatic cells in the first group. At the same time, the formed secondary foci of tumors were initially weakened: the use of drugs made them more aggressive and immune to therapy.
Metastases are one of the leading causes of death in cancer patients. According to staff at Stanford University, they can appear in the body 2-4 years before diagnosis. At the same time, this occurs most rapidly in colorectal cancer and lung cancer.
The authors of the study note that where metastasis occurred earlier, secondary foci of tumor growth are more similar to primary ones and consist of cancer cells with a small number of unique mutations. Whereas in people who have been treated, they are most often formed by drug-resistant cells.
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