Russian scientists have found that 23 percent of breast cancer patients who had undergone chemotherapy were back to square one with new formation of tumors.
The neoadjuvant chemotherapy in patients with breast cancer can stimulate evolution of the new tumour, said Nicholay Litvyakov of Cancer Research Institute.
The scientists analyzed biopsies of women with breast cancer and preparing for operation and in each biopsy, researchers examined the genetic landscape – chromosomal abnormalities that are present in it.
Before the operation, the women received 2-4 courses of neoadjuvant chemotherapy (NAC). Repeated analysis was done after surgery to see the therapy effect on the tumor.
The scientists have found that chemotherapy fully or partially destroyed the tumor clones in the majority of patients, but 23% of women surveyed showed new tumor formation under the influence of NHT.
Some chromosomes doubled in these clones, and the tumor cells became more resistant in a phenomenon called amplification, and is a negative consequence of chemotherapy. Almost all of these patients experienced development of metastases, while the remaining patients had not metastases in the five-year period of observation.
“We have preliminary results indicating that chemotherapy may cause the appearance of mutations which had not been observed before in the form of amplifications of chromosomal regions. In some cases it was a reason for occurrence of hematogenous metastasis,” said Marina Ibragimova, a TSU researcher.
Their study has been published in “Siberian Journal of Oncology.” These results will help to personalize treatment process for woman with breast cancer. For now chemotherapy is one of the main tumor treatment instruments for the oncologists. Report on this topic was held at the plenary session of the 19th Russian Cancer Congress.