A new research has found that talcum powder has the ability to control cancer growth by cutting the flow of blood to metastatic lung tumors.
The study, published in the European Respiratory Journal in April, showed that talc arouses healthy cells to generate endostatin, a hormone considered the magic bullet for treating metastatic lung cancer. The UF researchers say talc is a stimulating new therapeutic agent for a cancer which is largely considered incurable.
"We found, to our surprise, that talc causes tumor growth to slow down and actually decreases the tumor bulk. Talc is able to prevent the formation of blood vessels, thereby killing the tumour and choking off its growth. The tumors appeared to grow much slower and in some cases completely disappeared," said Veena Antony, MD, a professor of pulmonary medicine and chief of pulmonary and critical care medicine at UF's College of Medicine.
Scientists have only recently discovered that talcum powder checks tumour growth, though the mineral has been used for almost 70 years to treat the respiratory problems that come with metastatic lung cancer.
About half of all patients amass fluid around the surface of the lungs, a condition known as malignant pleural effusion.
"That fluid can press down upon the lung, impair the breathing of the patient and cause the patient to feel very short of breath," said Antony.
"Shortness of breath is a horrible way to die. The procedure spares the patient and the family the misery of watching their loved ones suffer. It's been used very extensively in Europe but it's had slower acceptance (in the United States), perhaps because of the need to learn a new technology," Antony added.
The Food and Drug Administration approved talc for use in medical thoracoscopy in
2003, but UF is one of just a handful of US institutions that carry out the outpatient procedure on a regular basis.
Doctors have noticed that patients who endure medical thoracoscopy with talcum powder live up to 18 months longer than expected. To comprehend why, Antony compared lung fluid from 16 patients with malignant pleural effusions before and after doctors dusted their lungs with talc and the results were shocking.
"We were surprised to find that talc has added benefits besides causing scarring and taking away the fluid that surrounds the lung," Antony said, adding, "The cells that cover the lining of the lung are stimulated by the presence of talc to produce a factor that inhibits the growth of blood vessels and kills the tumor cells themselves."
Less than one day after treatment with talc, patients began producing 10-fold higher levels of endostatin, a hormone released by healthy lung cells. Endostatin prevents new blood vessels from forming, slows cell growth and movement, and even induces nearby tumor cells to commit suicide. All of these make it hard for tumors to grow and spread into healthy lung tissue.
When endostatin was first discovered in 1997, doctors hoped its tumor-fighting properties would show the way to a cure for cancer. But clinical trials have been disappointing, possibly because most clinicians have injected the hormone directly into patients. The hormone breaks down in the body before it has a chance to slow the spread of cancer, Antony said.
"It was there, it had a very short half life, it was gone," Antony said, adding, "What we have done is caused the normal pleural mesothelial cells to continue to produce endostatin. Talc doesn't go away. Talc stays in the chest cavity, constantly causing the normal cells to produce this factor that inhibits the growth of the tumor."
The anti-tumor effects of talc appear to be long-lasting, said Antony, who is continuing to examine the long-term outcomes of patients who have undergone talc pleurodesis.
"It surprised us that such a cheap, easily available product, such an old-fashioned product, can have benefits to the patient and perhaps prolong the patient's life," Antony said.
Yossef Aelony, MD, a clinical professor of respiratory and critical care medicine at the Harbor-University of California at Los Angeles Medical Center, said the UF findings are an important milestone.
"This work will undoubtedly have a significant influence on future clinical trials dealing with the treatment of pleural malignancies, including lung cancer, mesothelioma and metastatic adenocarcinoma involving the pleural surfaces," Aelony said.
