Hormones are proteins that influence growth and development in the body. Unfortunately, some cancer types, like those of the breast and prostate, also depend on hormones for their growth. Therefore, stopping or blocking the production of certain hormone in the body can help reduce the growth of these cancer cells. This is known as hormone therapy.

Hormone therapy is systemic; it only targets specific cells in our body which are hormone receptor positive. It works in a variety of ways like it prevents the hormone from attaching itself to cancer cells or altering the hormones so that they do not facilitate the growth of cancer, or it may block the production of the hormone.

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The effectiveness of hormone therapy depends on the type and spread of cancer. It is often used along with radiation therapy, chemotherapy, and surgery. It can be administered before surgery to reduce the size of the tumour (known as neoadjuvant therapy), after surgery or radiotherapy to avoid cancer recurrence (known as adjuvant therapy), or it can be used to treat recurrent cancers and metastatic cancers (known as palliative hormone therapy).

The uniqueness of hormone therapy lies in its ability to affect only the hormone-receptive cancer cells present in the body. For example, breast cancer grows due to oestrogen and/or progesterone. It can be treated through aromatase inhibitors, selective oestrogen receptor modulators (SERMS), fulvestrant (faslodex), and ovarian suppression. Prostate hormone grows due to androgen hormones. However, if the level of hormone is controlled and lowered through androgen deprivation therapy (ADT) and androgen blockers, there are chances of the tumour shrinking. For instance, in almost 85 per cent – 90 per cent cases of advanced prostate cancer, hormone therapy can shrink the prostate tumour.

The type of hormone therapy chosen is determined by several factors like the type of cancer, the stage of cancer, hormone receptor status, the risk of relapse, treatment-free interval before cancer recurrence, the types of cancer treatments one has already received or currently receiving, therapy’s side effects and menopausal status in case of women.

Hormone therapy can be provided to patients for a short or long period depending on the type of cancer the patient is suffering from. For patients with breast cancer, adjuvant hormone therapy is administered for 5 to 10 years. For patients with prostate cancer, hormone therapy is usually provided for the rest of their life. For those suffering from thyroid cancer, hormone replacement therapy needs to be provided on a daily basis and may even be given lifelong. Targeted hormone therapy has the potential to improve the survival rate and quality of life of a patient. Therefore, it should be discussed as a possible treatment option along with other cancer treatments.

(Dr. Satya Pal Kataria, Vice Chairman – Medical and Haemato Oncology, Cancer Institute, Medanta)