There has been some thought-provoking material published at the Natural News.com site about the ill-effects of chemotherapy on cancer treatment, that this does not get to the root of the cancer problem, but in the case of breast cancer, and maybe other cancers, may spread it:
https://www.naturalnews.com/2017-07-10-chemotherapy-found-to-spread-cancer-throughout-the-body-warn-scientists.html
https://www.naturalnews.com/2018-07-18-health-basics-quiz-which-kills-more-americans-cancer-or-chemotherapy.html
“A new study published in the journal Science Translational Medicine earlier this month proved what we have been saying for decades; conventional cancer treatments cause more cancer. A team of scientists at New York’s Albert Einstein College of Medicine has found compelling evidence that chemotherapy is only a short-term solution. Eventually, the drugs will make you sick again, pushing patients towards a second round of expensive treatments. Clever money generating trick: Instead of helping patients to get rid of the disease, they temporarily put it on hold so they can take the dollars twice. The New York scientists explained that while shrinking the tumors, chemotherapy simultaneously opens new doorways for tumors to spread into the blood system, triggering more aggressive tumors which often result in death. The researchers believe toxic chemo drugs switch on repair mechanisms in the body that allow tumors to grow back faster. Furthermore, Dr. George Karagiannis, lead author of the study, and his team found that two common chemo drugs increased the number of “doorways” on blood vessels which allowed cancer cells to spread to other parts of the body. The team also discovered that chemotherapy increased the number of cancer cells circulating the body and lungs of mice.”
The original paper is:
http://stm.sciencemag.org/content/9/397/eaan0026.full
with this abstract:
“Breast cancer cells disseminate through TIE2/MENACalc/MENAINV-dependent cancer cell intravasation sites, called tumor microenvironment of metastasis (TMEM), which are clinically validated as prognostic markers of metastasis in breast cancer patients. Using fixed tissue and intravital imaging of a PyMT murine model and patient-derived xenografts, we show that chemotherapy increases the density and activity of TMEM sites and Mena expression and promotes distant metastasis. Moreover, in the residual breast cancers of patients treated with neoadjuvant paclitaxel after doxorubicin plus cyclophosphamide, TMEM score and its mechanistically connected MENAINV isoform expression pattern were both increased, suggesting that chemotherapy, despite decreasing tumor size, increases the risk of metastatic dissemination. Chemotherapy-induced TMEM activity and cancer cell dissemination were reversed by either administration of the TIE2 inhibitor rebastinib or knockdown of the MENAgene. Our results indicate that TMEM score increases and MENA isoform expression pattern changes with chemotherapy and can be used in predicting prometastatic changes in response to chemotherapy. Furthermore, inhibitors of TMEM function may improve clinical benefits of chemotherapy in the neoadjuvant setting or in metastatic disease.”
In a nutshell, chemotherapy for breast cancer, may increase the entry of cancer cells into the vasculature, even after killing the initial cancer cells, thus enabling the cancer to spread.