Hormone Therapy — Endocrine Treatment for Cancer

Hormone therapy encompasses pharmacological and surgical strategies that modify the endocrine system to treat hormone-dependent malignancies. Certain tissues, notably those of the breast and prostate gland, depend on sex steroids like oestrogens and androgens for cellular proliferation and survival. When neoplasms arise from these tissues, they frequently retain sensitivity to these endogenous biochemical messengers.

Mechanistically, endocrine treatments act by either lowering circulating hormone concentrations or interrupting receptor-mediated signalling cascades. This is achieved through enzymatic blockade, receptor antagonism, receptor degradation, or surgical ablation of hormone-producing glands. Unlike cytotoxic chemotherapy, which targets rapidly dividing cells indiscriminately, hormone therapy specifically targets the physiological pathways that fuel hormone-dependent tumour proliferation.

Hormone therapy is a cornerstone in preventing cancer recurrence and controlling metastatic disease for millions of patients worldwide. Administered after primary surgery or radiation, it significantly reduces the likelihood of cancer returning. In advanced or metastatic scenarios, it provides durable disease stability while generally preserving a higher quality of life than traditional chemotherapy. Understanding how it functions helps patients manage common side effects, such as hot flushes or fatigue, and adhere to long-term regimens.

Before initiating hormone therapy, tumours must be confirmed as hormone-dependent through immunohistochemical staining of biopsy or surgical specimens. Pathologists assess tissue for oestrogen, progesterone, or androgen receptors. In prostate cancer, monitoring serum prostate-specific antigen (PSA) levels tracks disease response to androgen deprivation therapy. In neuroendocrine tumours, specialized imaging and biochemical markers assess receptor presence.

Hormone therapy is used most extensively in breast cancer (for oestrogen- and progesterone-receptor-positive tumours) and prostate cancer (which relies on androgens like testosterone). It is also utilised in endometrial cancer, certain ovarian stromal tumours, and well-differentiated neuroendocrine tumours, where somatostatin analogues are administered to suppress excessive hormone production and inhibit cellular growth.

Selection of therapy depends on the cancer type, menopausal status in women, and stage of disease. Modalities include selective oestrogen receptor modulators (tamoxifen), aromatase inhibitors (anastrozole, letrozole), luteinising hormone-releasing hormone (LHRH) agonists or antagonists (goserelin, leuprolide, degarelix), and androgen receptor pathway inhibitors (enzalutamide, abiraterone). Treatment duration often extends from five to ten years in early-stage curative settings.