For women with breast cancer who take adjuvant Tamoxifen daily for 5 years, their risk of dying from the disease drops by one third, compared to their chances without the drug, researchers reported in The Lancet today. They referred specifically to women with estrogen-receptor positive breast cancer, also known as hormone-sensitive breast cancer.
After effective breast cancer surgery, various treatments can be given to prevent recurrence of the disease and possibly death. The authors explained that several trials have been conducted in this area of medicine.
Every five years, the EBCTCG (Early Breast Cancer Trialists’ Collaborative Group) has gathered all the evidence worldwide from all trials. The latest report has data on over 20,000 females with early breast cancer in 20 randomized studies – the women were on approximately 5 years of Tamoxifen therapy compared to no Tamoxifen. About 80% of those on Tamoxifen complied fully with the treatment regimen. The majority of the 5 years Tamoxifen trials started in the 1980s. Data today can reveal what the additional effects might be for patients 10 years after treatment began, including mortality data.
The authors found that among patients with estrogen-receptor positive breast cancer (ER-positive disease), 5 years of daily Tamoxifen therapy reduced their 15-year risk of recurrence and death considerably, regardless of whether they received chemotherapy. Moreover, Tamoxifen significantly reduced the risk of recurrence even among those with weekly ER positive disease.
For a period of 15 years from the beginning of treatment, Tamoxifen was found to reduce the risk of death from breast cancer by one third. This considerable reduction in breast cancer mortality was maintained not only during years 0 to 4, and 5 to 9, but also 10 to 14.
A newer class of drugs – Als (aromatase inhibitors) – are effective for some women as an alternative to Tamoxifen, however, only for post-menopausal patients. Approximately half of all new breast cancer diagnoses globally involve women under 55 years of age. The authors wrote:
“. . . . especially for pre-menopausal or peri-menopausal women who have had a breast cancer removed that is ER-positive, 5 years of Tamoxifen remains a major hormonal treatment option.”
The uncommon but potentially dangerous side effects linked to Tamoxifen therapy, such as venous thromboembolic events (blood clots) and uterine cancer tend to affect patients over the age of 55. Hence, the risk when giving Tamoxifen to younger women is minimal.
Lead EBCTCG investigator, Christina Davies, concluded:
“Breast cancer is a nasty disease because it can come back years later. This study now shows that Tamoxifen produces really long-term protection. For ER-positive disease, Tamoxifen reduces 15-year breast cancer mortality by at least a third, whether or not chemotherapy has been given.
Tamoxifen was developed 50 years ago and is long out of patent, but even if costs are ignored it remains a major first-line treatment option, especially for women whose ovaries are still functioning.”
Dr Stephen K Chia, British Columbia Cancer Agency, University of British Columbia, Vancouver, Canada, and Dr Antonio C Wolff, The John Hopkins Kimmel Comprehensive Cancer Centre, Baltimore, MD, USA , wrote:
“We can confidently and clearly state that Tamoxifen is an important treatment option for early-stage ER-positive breast cancer, whether or not chemotherapy is also given… Breast cancer is the most common female cancer worldwide. ER-positive phenotype is the most common, and half of the 1•4 million diagnoses worldwide every year occur in premenopausal or perimenopausal women for whom aromatase inhibitors are ineffective.
Therefore, access to accurate ER testing, and to Tamoxifen (a relatively inexpensive drug) or other endocrine therapies is a public health imperative for all women with breast cancer.”
Written by Christian Nordqvist