Breast cancer is one of the most common cancer and considered among the major reasons of cancer-associated mortality and morbidity in women. It is estimated that the global burden of this cancer will rise above 2 million cases every year by 2030. In India, it is the second most widespread cancer among women following cervical cancer.
Especially, the women who undergoes menopause after the age of 55 rather than 45 associated with higher risk of breast, ovarian and uterine cancers. The risk of breast cancer among such women is approximately increased by 30 percent.
This all is due to longer exposure towards estrogen. Estrogen is the natural hormone, essential for sexual development and other various body functions. It is generally produced in ovaries, but after menopause, its production in ovaries ceases. However, higher levels of estrogen in blood after menopause is significantly related to the higher risk of breast cancer.
Most of the breast cancer is come into existence due to luminal epithelial cells lined to mammary ducts. But, it is a heterogeneous disease and therefore, comprehends a diverse range of pathological existences. The present molecular classification of this cancer is premised on the gene expression profiles of various markers and receptors. One of those is hormone receptors (HR), for instance, estrogen receptor (ER), androgen receptor (AR) or progesterone receptor (PR).
To treat estrogen receptor-positive breast cancer, there can be two-way, either by lowering the estrogen levels in the body or by restricting estrogen from assisting in the progression of breast cancer.
Treatment for estrogen receptor-positive breast cancer
Inhibition of hormone reception has been seeking since the 1960s, primarily to develop contraceptives. However, in the 1970s, with the assessment of anti-tumours effects, the tamoxifen get approval for treating advanced stage. For over 20 years, this drug is present as the keystone of adjuvant endocrine therapy for hormone-sensitive early-stage breast cancer. However, over time patients develop resistance against this drug and a higher risk of thromboembolic events and endometrial cancer.
At present, evidence encourages upfront use of aromatase inhibitors (AIs) for treating this type of breast cancer, especially among the postmenopausal population.
Aromatase inhibitors (AIs) for ER-positive breast cancer
The novel FDA approved AI, anastrozole is a potent drug in the management of this breast cancer type.
The drug works on the principle of inhibition of protein aromatase. This blockage finally shut-downs the entire process involving activation of estrogen hormone, which is responsible for breast cancer.
As per FDA, Anastrozole is approved for,
First-line treatment of HR-positive or HR unknown locally advanced or metastatic breast cancer
Second-line treatment for disease progressed by tamoxifen treatment
Adjuvant therapy for HR-positive early breast cancer.
This all is due to significant efficacy and safety profiles of anastrozole:
According to a study presented in Frontiers in oncology, Anastrozole inhibits estrogen synthesis from non-ovarian precursor steroids. Furthermore, as compared to tamoxifen, this drug exhibits substantial superiority in progression-free survival, overall response rates and 10-year mortality rates.
Anastrozole also exhibits significantly lower recurrence rates. Furthermore, as per the outcomes of a recent meta-analysis, the switch trial from tamoxifen to anastrozole, patients get survival benefits concerning event- and disease-free survival rates.
The incidence of vaginal bleeding and thromboembolic events were also lower with anastrozole.
All these safety and efficacy profiles of anastrozole making this drug a potent choice of treatment for HR-positive breast cancer.