Search Results for “cancer”
There are 32 results.
- You are currently searching All Media
Video:
even though they're chemically similar, marijuana smoke is less likely than tobacco smoke to cause cancer, according to one expert review of the literature.
the review, by dr. robert melamede of the university of colorado, colorado springs, noted that tobacco and marijuana smoke differ in a number of ways, particularly in the fact that marijuana smoke contains tetrahydrocannabinol (thc), while tobacco smoke contains nicotine. nicotine increases the cancer-promoting effects of smoke, while thc reduces those effects, he explained.
and even though thc and nicotine act on related cellular pathways, they bind to different receptors to activate these pathways, the review found. cells in the lungs and respiratory passages are lined with nicotine receptors but these cells don't appear to have thc receptors. this may explain why smoking marijuana has so far not been linked with lung cancer, a major cause of death from cigarette smoking.
research has also shown that marijuana kills cancer cells and reduces tumor growth. this is, in part, because marijuana reduces the formation of blood vessels that nourish tumors.
however, the review warned that the effects of marijuana are complex and sometimes contradictory. it also noted that many people use marijuana and tobacco together, and the two drugs may interact in complex ways.
while some governments are reluctant to approve marijuana for medicinal use, the review noted that there's increasing evidence that marijuana can improve the lives of patients with a broad range of health problems, including insomnia, aids, multiple sclerosis and alzheimer's disease.
the review will be published in an upcoming issue of the journal harm reduction.
yahoo
Video:
tumours put up a protein "smokescreen" to escape the body’s immune system, and blocking those proteins helps kill cancer cells in mice, a new study has found. the work also offers new insight into why some inflammatory diseases increase a person’s risk of cancer.
the immune-system protein that appears to help tumours escape attack is called cytokine interleukin 23 (il-23). high levels of il-23 were found in the human tumours studied by martin oft at the schering-plough institute in palo alto, california, us, and his colleagues. the team also found that mice deficient in il-23 did not develop as many tumours as normal mice.
under ordinary circumstances, il-23 contributes to the recruitment of cells known as neutrophils. these play an important role in the early immune response to an infection, targeting foreign particles in the body.
but the tough task of infiltrating diseased tissues and rooting out the source of an illness belongs to another kind of immune cell called cd8 t-cells, oft explains. and it is these cells that il-23 appears to repel. in the case of cancer, excess il-23 prevents the cd8 t-cells from eliminating a tumour.
in one part of the experiment, mice received an antibody molecule that blocks il-23. these animals developed fewer tumours and eliminated injected cancer cells more quickly than control mice. the researchers think the antibody holds promise as a future tool to fight cancer in humans, but they stress that it remains in the pre-clinical phase of development.
the team's work also addresses the link between chronic inflammation and cancer, which doctors have suspected for more than a century. for example. some inflammatory illnesses – such as psoriasis and inflammatory bowl disease – are associated with an increased cancer risk.
the team's work explains this link because earlier work has shown that excess il-23 in the body appears to drive chronic inflammatory disease.
journal reference: nature (doi: 10.1038/nature04808)
