Chemotherapy is an effective treatment for breast cancer, but some patients still have metastases. Can chemo cause cancer spread?
The study reveals the previously unrecognized effect of chemotherapy
A new study mainly done in mice suggests that chemotherapy given before surgery for breast cancer may cause changes in cells inside and around the tumor that are associated with an increased risk of cancer spreading to other areas of the body. However, the study also identifies experimental therapy that can potentially reduce this risk.
Working with mouse models of breast cancer, researchers have shown that several chemotherapeutic drugs commonly used to treat localized and advanced breast cancer increased the number of microscopic structures in breast tumors metastatic tumor microenvironment (TMEM) as well as the number of circulating cancer cells in the blood.
Why can cancer come back?
Cancer may come back some time after the first treatment. This idea can be scary. There are various reasons why cancer can come back.
One reason is that the original treatment did not get rid of all the cancer cells, and the remaining ones have grown into a new cancer. Another is that some cancer cells have spread to other parts of the body and have started to grow there, forming a tumor.
After cancer treatment or radiation therapy
Cancer can sometimes come back after cancer treatment or radiation therapy, which can happen because the treatment did not destroy all cancer cells.
Drugs used in chemotherapy kill cancer cells, attacking cells that double up to form 2 new cells. But not all cancer cells divide simultaneously. Normal cells go into a long period of rest between divisions. Cancer cells do this too, although the rest period can be much shorter.
Giving chemotherapy in a series of treatments helps to catch as many dividing cells as possible. Cells that rested during the first treatment may divide when you have the next cells, so the probability of death will be higher.
Radiation therapy causes small breaks in the DNA inside cells. These interruptions stop the growth and division of cancer cells and often cause their death. Normal cells close to cancer can also be damaged by radiation, but most of them return to normal and return to normal work. If radiation does not kill all the cancer cells, they will grow in some future moment.
Tumors may become refractory to treatment
Sometimes cancer can become refractory to cancer treatments. Tumors develop from normal cells that have changed or mutated and become cancerous. The mutation happens in cell genes. These gene changes cause a cell to behave differently than a normal cell. Cancer cells can still mutate, making them more and more abnormal.