Chemotherapy drugs could enhance the spread of cancer beyond a primary tumour site, scientists have established. In tests, researchers found that mice injected with cyclophosphamide, a popular chemotherapy drug, enabled breast cancer cells to squeeze through the blood vessel linings in the lungs and stick to cell walls. While chemotherapy remains an effective treatment for many, it could give cancer cells a "foot in the door," caution the authors.

To understand the impact of the chemotherapy drug cyclophosphamide on healthy cells, scientists injected a single dose into healthy mice. After four days, the same mice were injected with breast cancer cells. Studying the mice, researchers found the chemotherapy drug appears to have made it easier for the cancer cells to latch on to cell walls and avoid being carried away by the blood flow. This could lead to cancer spreading from its primary site to another, a process known as metastasis. The team found that chemo drugs can begin to affect non-cancer cells just three hours after the treatment was applied.

"The whole point of our pre-treatment model is to ask the question: Does chemotherapy affect normal cells in such a way that they will turn around and help cancer cells? The answer is yes," said senior author of the study Tsonwin Hai. 

Researchers found that cyclophosphamide increased the level of the enzyme MMP-2 in the blood. The increase in this enzyme allowed cancer cells to attach themselves to the lining of the blood vessels. "The effect of chemotherapy on non-cancer cells actually changes those cells, and those changes help cancer cells to progress," said Hai.

What was surprising was the speed of the body's reaction, Hai said. "Cancer cells' escape from a primary tumor is not a late event -- it can actually happen very early on. In fact, the cancer cells could begin to stick to the walls of the blood vessels within just three hours."

The paper furthers our understanding of the impact of chemotherapy drugs on the body, helping scientists to understand more about the hidden mechanisms at work. Chemotherapy remains a safe and effective treatment for many, but it's not risk-free, caution the authors. 

The findings strengthen the need for those with a cancer diagnosis to remain vigilant. At RGCC, we offer a range of genetic tests including tests that monitor cancer following diagnosis and treatment. 

Our Metastat RGCC test can identify blood-borne biomarkers (called circulating tumour cells (CTCs)) that can help to identify whether a secondary cancerous tumour is developing and provide information as to its potential location. You can learn more about RGCC's range of advanced genetic tests here

You can read the full paper, Chemotherapy-Induced Changes in the Lung Microenvironment: The Role of MMP-2 in Facilitating Intravascular Arrest of Breast Cancer Cells, here.