The recommended period of time for taking preventative drugs such as tamoxifen or those in the newer class of anti-hormone drugs after breast cancer treatment is five years.
The research, by the University of Glasgow and the University of Dundee and funded by the charity Breast Cancer Campaign, looked at the anonymised data for almost 3,400 women prescribed tamoxifen or other aromatase inhibitors in the Tayside area of Scotland to see how often they had collected their prescription, considering this a good indication of their compliance with the drug regime.
Writing in the British Journal of Cancer, the researchers revealed that 90% of women collected their medication in the first year but those figures dropped over the following years until by the end of the fifth year, only 51% of prescriptions were being picked up.
A common complaint from many women was of the side effects from taking hormonal drugs, particularly hot flushes and sweating. Other side effects were weight gain, nausea, depression, headaches and blood clots.
However, the most dramatic effect of not taking the medication was a recurrence of the cancer. The study revealed that those women who stopped or reduced their medication were three times more likely to die of recurrent breast cancer than the women who stuck to the prescribed medication for 80% of the five-year period.
The study noted that women needed more support from clinicians to deal with the side effects so they stuck to the medication to give themselves a greater chance of surviving breast cancer for longer.