Scientists from Rockefeller University have found that cancer metastasis may not be due to mutations in the tumor itself, but to individual genetic features of the body. The results of the study are published in the journal Cell. It was previously thought that it was in the DNA of tumors that malignant mutations, which allow cancer cells to detach from the primary tumor and spread through the bloodstream and lymphatic system, developed. However, a new study suggests that critical mutations may occur in a person's genes rather than in the tumor itself. Scientists studied the genetic characteristics of breast cancer patients and found that a common variant of the PCSK9 gene, which is present in germ cells in 70% of white women, may be associated with an increased risk of metastasis. Women with this variant had a lower survival rate and a significantly higher risk of developing metastases - 22% compared to 2% in women without the variant. To confirm these findings, the research team conducted a study in patients with early-stage breast cancer, which also showed an increased risk of metastasis in women with the PCSK9 variant. The scientists hypothesized that PCSK9 affects the LRP1 receptor in cancer cells, which triggers a cascade of gene activation that promotes metastasis. The same receptor has previously been linked to metastasis in melanoma, suggesting similar mechanisms between different cancers. However, the researchers caution that the presence of the PCSK9 gene does not mean that metastases will inevitably develop. Most patients with this variant will not experience metastatic disease, and the risk remains relatively low for most women with early breast cancer.