Electronic cigarettes (vaping) not only promote tobacco addiction, contain toxic chemicals that have killed when swallowed, raise blood pressure and the risk of heart attacks and don’t lead to smoking cessation. A recent study published in Cancer Letters and carried out at leading US universities, including Yale, Princeton and John Hopkins have found for the first time that exposure to e-cigarette vapor produces a microenvironment that promotes the development of breast tumors and lung metastases. 

The Israel Cancer Association, which will in October mark Breast Cancer Awareness Month, disclosed the new research on the link between such cancers and vaping. The association noted that Young women represent a target of e-cigarette companies, raising concern for potential connections with breast cancer. 

In general, the immune system knows how to block the formation of malignant tumors. But in the case of chronic infections due to various factors, a condition can develop in the body that encourages the formation of tumors and leads to their progression, the formation of metastases and the inhibition of the immune system. This microenvironment consists of extracellular material (ECM), stroma cells and immune system cells, including those called tumor-associated macrophages (TAMs). 

TAM cells comprise up to half of the cells in the microenvironment of breast tumors, and it has long been known that they promote immune suppression, tumor proliferation and the spread of cancer cells to other parts of the body. In addition, in the present study, the researchers looked for the effects of e-cigarettes on the development of breast cancer and lung metastases, in addition to the mechanisms already identified.

They hypothesized that exposure to e-cigarette vapor activates monocyte-type immune system cells, which produce macrophages (cleanup cells that detect, engulf and destroy pathogens and dead cells.). Exposure changes the communication between the tumor cells in the breast and the macrophages, so that instead of identifying the tumor cells and destroying them, a micro-environment is created that encourages the growth of the tumor. 

As a result, there will be greater development and migration of the tumor cells in the breast as well as higher survival of these cells that have spread, which will eventually lead to metastases to the lungs. 

To test the hypothesis, the researchers conducted studies in female cells and laboratory mice. A group of 44 mice were divided into a study group and a control group. The study group was exposed to e-cigarette vapor two hours a day, five days a week for six weeks, while the control group was exposed to clean, filtered air and kept in a separate room. All groups were injected with breast cancer cells about a week after the start of exposure to induce breast cancer and/or lung metastases. The growth of the breast tumors and the metastasis to the lungs were monitored weekly 

They found that e-cigarette smoke has a far-reaching effect on the development of breast cancer: After four weeks of exposure to the chemicals, there was a significant acceleration of 2.27 times in the growth rate of cancer cells each week. This is compared to the group that breathed normal air, where there was a growth rate of 1.24 times per week. The cancerous growth area in mice that breathed e-cigarette vapor increased by almost 70%, compared with a 35.45% increase in the group that breathed normal air. Also, exposure to e-cigarette vapor was associated with the development of 100% of the tumors, whereas only 33% of the tumors developed in the group of mice that breathed normal air. 

In conclusion, the researchers note that the study findings show that exposure to e-cigarette vapor leads to an increase in breast cancer tumors and the transmission of tumor metastases to the lungs, as it alters the intercellular communication between the tumor microenvironment and the macrophages that are supposed to kill the tumor cells

The Israel Cancer Association, which encourages early diagnosis with awareness campaigns and promoting mammography in women of relevant ages and risks, said that 66% of cases are identified in the tumor’s early stages, thus increasing the rates of recovery. Breast cancer comprises a third of all new cancer cases in women (abut one percent of cases occur in men) andcause a fifth of all deaths from cancer among Israeli women. Survival rates are 90% in Jewish women and 84% in Arab Israeli women.

Adopting a healthful lifestyle, including maintaining normal weight, exercising, breastfeeding one’s babies, eating properly and avoiding smoking and alcohol significantly reduce the risk of contracting breast cancer, said cancer association director Moshe Bar Haim.