Low Breast Cancer Pill Use Ups Death
Women Who Fail to Take Tamoxifen as Prescribed Have Increased Death Risk
Sept. 6, 2007 -- Women who fail to take the breast cancer drug tamoxifen as
prescribed may be placing themselves at substantially increased risk of dying,
a study of more than 2,000 women shows.
"Our most significant finding was that women who filled 70% or fewer of
their tamoxifen prescriptions had a significantly -- 16% -- increased risk of
death [compared with women who filled all their prescriptions]," says
Alastair Thompson, MD, professor of surgical oncology at the University of
Dundee in Scotland and one of the researchers.
In the study, one in 10 women filled 70% or fewer of their tamoxifen
prescriptions, he tells WebMD.
Refills are a well-accepted surrogate for how many pills a person actually
takes, as it is rare for people to buy medication if they still have some
The research is being presented here this week at the 2007 Breast Cancer
Symposium, co-sponsored by the American Society of Clinical Oncology and four
other cancer care groups.
Findings Apply to Newer Hormone Drugs, Too
Doctors have been using tamoxifen to fight tumor growth in women with breast
cancer who have tumors that are fueled by estrogen for over 25 years.
More recently, newer hormone drugs known as aromatase inhibitors, such as
Aromasin, Arimidex, or Femara, have been shown to shrink tumors better, with
fewer side effects.
While tamoxifen deprives breast cancer cells of the estrogen they need to
grow, aromatase inhibitors actually block an enzyme needed to make estrogen,
thereby slashing the body's production of estrogen altogether.
Nonetheless, tamoxifen still has an important role in breast cancer
treatment, says Julie R. Gralow, MD, an associate professor of medical oncology
at the University of Washington School of Medicine in Seattle, and moderator of
a press briefing on the findings.
Aromatase inhibitors can only be given to postmenopausal women, leaving
tamoxifen as the cornerstone of hormone therapy in younger women, she points
Plus, the less expensive tamoxifen is still more commonly prescribed in many
other parts of the world, Gralow says.
The new findings also have implications for women taking aromatase
inhibitors, she says.
"The study clearly shows that you need to take the majority of your
pills to really get benefit. As we move toward greater use of aromatase
inhibitors, which do not stay in the body as long, taking the drug as
prescribed becomes even more important," Gralow tells WebMD.
Less Than Half of Women Took Tamoxifen for 5 Years
For the study, the researchers reviewed the records of 2,080 women treated
for breast cancer between 1993 and 2002 in Scotland. Of the total, 79% were
prescribed tamoxifen to reduce the risk of breast cancer returning after
Thompson notes that in Scotland, every patient has a unique 10-digit health
number. This allowed the researchers to link data on each person's health
status to pharmacy records.
Among the results:
- Although a 5-year course of tamoxifen is typically recommended, women took
the drug for an average of 2.42 years.
- 37% of women stopped taking tamoxifen before 5 years, with 19%
discontinuing its use 2 years into therapy.
- Less than half of women, 49%, took tamoxifen for 5 years.
- Women who didn't take tamoxifen at all had a 50% increased risk of dying,
compared with women who took the drug.