Breast cancer, a life-altering diagnosis for millions of women globally, remains one of the most researched areas in oncology. Among the various treatment modalities, hormone-responsive breast cancer therapies have seen significant breakthroughs. Aromatase inhibitors (AIs) have revolutionised the management of hormone receptor-positive breast cancers. As a cornerstone of breast cancer treatment, these anticancer medicines have redefined the trajectory for postmenopausal women with estrogen-sensitive tumours, marking an era of tailored, precision medicine.

What is hormone-responsive breast cancer?

Approximately 70% of all breast cancers are hormone receptor-positive, meaning the cancer cells grow in response to hormones like estrogen and progesterone. These cancers are treated using hormone therapies that block or reduce the amount of estrogen in the body, thus inhibiting tumour growth.

Before the advent of aromatase inhibitors, tamoxifen was the go-to hormone therapy. However, while effective, tamoxifen’s mechanism of action involves blocking estrogen receptors, which still allows for the body's natural production of estrogen. Aromatase inhibitors, on the other hand, act on the enzyme aromatase, which is crucial in converting androgens into estrogen. By blocking this conversion, AIs significantly reduce estrogen levels in postmenopausal women, where the primary source of estrogen is through this conversion process.

Do aromatase inhibitors really work?

The enzyme aromatase is responsible for converting androgens (produced by the adrenal glands) into estrogen. Aromatase inhibitors block this enzyme, thereby reducing the overall production of estrogen in the body. Since estrogen fuels the growth of hormone receptor-positive breast cancers, lowering estrogen levels can effectively slow or stop the development of these cancers.

Anastrozole, the active ingredient in Arimidex 1mg Tablet, is one of the most commonly prescribed AIs. It is typically used in postmenopausal women as their ovaries no longer produce estrogen directly; instead, estrogen is generated from androgens through aromatisation. Blocking this process at the enzymatic level helps control cancer growth in hormone-responsive breast cancers.

What are the benefits of aromatase inhibitors?

Aromatase inhibitors have distinct advantages over older hormonal therapies like tamoxifen:

• Reduced Risk of Recurrence: Studies have shown that AIs minimise the risk of breast cancer recurrence by approximately 30% more than tamoxifen.
• Lower Risk of Blood Clots: Unlike tamoxifen, which increases the risk of blood clots and uterine cancer, AIs do not have these associated risks.
• Prolonged Disease-Free Survival: Aromatase inhibitors significantly prolong the time patients remain cancer-free after initial treatment compared to tamoxifen.

However, like any treatment, AIs come with their own set of challenges. Side effects such as joint pain, osteoporosis, and an increased risk of fractures must be managed. Nonetheless, with the right supportive care, many patients tolerate these side effects well.

What is the role of AI in breast cancer?

In cases of advanced or metastatic breast cancer, aromatase inhibitors continue to play a crucial role. They are often prescribed in combination with other treatments like CDK4/6 inhibitors, which further enhance their efficacy. This combination therapy has been shown to significantly improve overall survival and progression-free survival in patients with advanced hormone receptor-positive breast cancer.

The use of AIs in both early-stage and advanced breast cancer treatment underscores their versatility and effectiveness in managing the disease. As anticancer medicines continue to evolve, aromatase inhibitors remain a critical tool in the oncologist’s arsenal, offering hope for extended survival and improved quality of life.

What are the side effects of AI for breast cancer?

Aromatase inhibitors (AIs) are effective in treating hormone receptor-positive breast cancer, especially for postmenopausal women. However, like all treatments, they come with some side effects. Here’s a breakdown of the common and more serious side effects:

1. Joint Pain and Stiffness: This is one of the most frequently reported side effects, often referred to as AI-induced arthralgia. It can affect daily activities, but mild exercises, stretching, and pain relief options can help manage this discomfort.
2. Bone Thinning and Osteoporosis: AIs can lead to reduced bone density over time, increasing the risk of fractures. It’s essential to have regular bone density scans and take calcium and vitamin D supplements, or even consider bone-strengthening medications if advised by your doctor.
3. Hot Flashes: Many women experience hot flashes similar to menopausal symptoms. These are usually manageable but can be uncomfortable at times.
4. Fatigue: Some women report feeling more tired or experiencing low energy levels during AI treatment. Managing this often involves balancing rest with light physical activity.
5. Mood Swings: Changes in mood, including feelings of anxiety or depression, are sometimes seen. Staying connected with your support system and discussing emotional changes with your healthcare team can be beneficial.Heart and Cholesterol Concerns: Although rare, some AIs can slightly increase cholesterol levels and may pose a risk to heart health. Regular check-ups are key to monitoring these potential issues.