“But this must not be misinterpreted as meaning that all of them feel they should take a break, especially not during the first five years. The standard treatment is still continuous medication,” he continues. A hormone-sensitive breast cancer is curable, but a relapse is also common after five years if, from the beginning, the cancer has affected many lymph glands. Making the extended treatments more tolerable remains a challenge, however. There are many who do not persevere and thus lose the protection against relapse. Nearly 4,900 women from 22 countries took part in the study in total. All were post-menopausal and had already undergone about five years primary treatment with anti-hormonal drugs against hormone-sensitive breast cancer. The study covered five years of extended treatment, with or without a break, involving the drug letrozole. The fact that the drug reduces the risk of metastases was already known, but not how breaks in the medication might affect the growth of tumors and quality of life.
During a break in treatment the hormone levels begin to be normalized. Earlier tests on animals have shown that letrozole, following a break in the medication, can have a new and greater effect on the actual development of the cancer. The pause can possibly contribute towards a suppression of the resistance development that takes place during long-term treatment. This particular response was not, however, clear in the study in question. “Our primary hypothesis was that there could be fewer relapses with the pause, but it could not be demonstrated. It is possible that the pauses were too short and it was also possibly due to which drug the women had been given previously,” says Per Karlsson. “But it is good to know that the pause itself does not appear to be dangerous from a patient perspective. Relapses remained at the same level, with or without a pause; a point which is important to know for those who, because of problems, are considering taking a break in their anti-hormonal medication,” he points out.