Biological reproduction of cancerous cells.
Breast cancer is the most common single cause of death in women aged between 35-45 years. In the UK alone there are approximately 20,000 new cases every year and over 15,000 deaths. From these startling facts it is obvious that the successful treatment of the disease would be considered a significant advancement in medicinal science. Cancer has been hailed as many ( and rightly so in my opinion ) as one of the great plagues of the 21st Century. The actual mechanism of growth and development of breast cancer is still unknown. However there seems to be a direct link between the female growth hormone oestrogen and related cases of breast cancer. The probability of developing breast cancer also increases with age, hence at one time in a women's life there is a high probability that she will be diagnosed as having breast cancer. (See graph below which shows a survey of America women conducted by America College of Surgeons)
It is an important fact that like most other diseases not all types of breast cancer are identical. Tamoxifen is only really effective against malignant cells who's mechanism for reproduction is mediated via oestrogen. However Tamoxifen has shown in some cases to reduce symptoms of other types of cancer ( not mediated by oestrogen.) Therefore the following discussion is concerned with oestrogen mediated cancer only.As a result Tamoxifen's impact has been mainly in the field of female related cancers.Oestrogen in the female body promotes growth and regulation in cells. This process occurs via cells which contain certain proteins capable of accepting the oestrogen and then using it to promote the growth of cells. Such cells containing the correct proteins for this task are known as the oestrogen receptors sites. Hence for this process to occur efficiently we require both oestrogen and the oestrogen receptor sites to be fully functional. Many cancers are thought to develop as a result of over production of some cells.It therefore follows that if we can oppress the rate at which cells reproduce we can limit the chances of cancer forming. This can be achieved by effecting the above system in some way.Evidence for these conclusions lie in the fact that when females have there ovaries removed there risk of developing breast cancer drops enormously. This is due to the fact that this removes oestrogen from the system. (Important Note : Oestrogen is produced in female ovaries.)
Tamoxifen can have the desired effect of mediating such a mechanism. The Tamoxifen molecule has the ability to bind to the oestrogen receptor sites and hence deprive the cells of oestrogen. This has the desired effect of reducing the formation of cancerous cells.
Huw Tanner.Undergraduate Year 2 .Imperial College of Science,Technology and Medicine.
Study of Tamoxifen.