Evaluating the benefits of higher doses of fulvestrant in breast cancer patients

This review analyzed the results from several clinical trials which compared the benefits of the standard dose of 250mg of fulvestrant (Ful) once a month to higher doses in breast cancer patients. 

Some breast cancers need estrogen (a female sex hormone) to grow. Cancer cells respond to estrogen via their receptor (a protein found on the surface of the cells). These types of breast cancer are called estrogen receptor-positive (ER+). They may be treated with hormone therapy which blocks the estrogen supply to the cancer, thus stopping its growth. Ful (Faslodex) is such a hormone therapy drug called estrogen receptor antagonist and works by blocking the action of estrogen on breast cancer cells. Ful is currently used in the treatment of breast cancer patients at a dose of 250mg monthly.

The authors of this article have looked at the results of several good quality clinical trials which evaluated the standard dose of Ful versus higher doses in breast cancer patients. The reasoning behind looking at increasing the dose is that it takes 3 to 6 months at 250mg monthly for the drug to become effective. Higher doses researched include a high first dose of 500mg, then 250mg every two weeks and then every 28 days. This is called a loading dose strategy. Other studies compared the effects of Ful 250mg versus 500mg monthly. 

Results show that patients who received 500mg Ful monthly had higher response rates to therapy, with similar side effects compared to those treated with 250mg Ful. Also, patients treated with the higher dose of Ful had a 20% improved overall survival (the percentage of patients surviving for a defined period after the treatment) compared to those who received the standard dose. Additionally, another study showed that 500mg of Ful was beneficial in prolonging the time without disease progression to 23.4 months compared to 13.1 months with other hormone therapy drugs.