Understanding the differences between chemotherapy and hormonal therapy

Chemotherapy and hormonal therapy are well-known cancer treatments but how they work is different. Understanding that difference, i.e. what cancers they treat and why one may be recommended over the other, can help patients feel more informed about their treatment decisions.

What's chemotherapy and how does it work?

Chemotherapy kills rapidly dividing cells and, because cancer cells divide more quickly than most normal cells, chemotherapy can be effective across a wide range of cancers. 

Chemotherapy kills cancer cells but it can also impact healthy cells that also divide quickly, such as those in bone marrow, the digestive tract and hair follicles. There are ways to manage side effects, which our oncologists and doctors guide patients through as part of their treatment. 

Types of cancer commonly treated with chemotherapy

Chemotherapy can be used to treat lung cancer, colorectal cancer, ovarian cancer, lymphomas and leukemias, pancreatic cancer, and aggressive or fast-growing breast cancers. 

Chemotherapy can also be used in cancers that are hormone-sensitive, especially when the disease is high-risk, fast-growing or not responding to hormonal therapy alone. 

How chemotherapy is delivered

Chemotherapy is often delivered in cycles, which allows time for the body to recover between treatments. It can be given intravenously, orally, or by injection or infusion. Treatment duration is based on factors like the cancer type, cancer stage or the patient's response to treatment. 

What's hormone therapy and how does it work?

Hormonal therapy, which can also be called hormone therapy or endocrine therapy, is used for cancers that rely on hormones to grow. Rather than killing cancer cells directly, hormonal therapy removes or blocks hormonal signals that cancer cells depend on for their survival. 

Hormonal therapy can be used for breast cancer, prostate cancer and selected cases of endometrial (uterine) cancer. Hormone receptor testing can determine whether hormonal therapy will be effective, after which it can be decided if hormonal therapy is the right fit.

Types of hormonal therapy and how it works

Breast cancer

Breast cancer hormonal therapy targets estrogen pathways and includes Selective Estrogen Receptor Modulators (SERMs), e.g. Tamoxifen, which blocks estrogen from binding to cancer cells.

There’s also Aromatase Inhibitors (AIs). Examples include Anastrozole, Letrozole and Exemestane. These reduce estrogen production in postmenopausal women.

Lastly, ovarian suppression or Ablation - this temporarily or permanently stops estrogen production in premenopausal women. It's sometimes combined with other hormonal therapies in higher-risk disease.

Hormonal therapy for breast cancer can be prescribed for five to ten years, which is a long time - but this can significantly reduce the risk of recurrence.

Prostate cancer

Prostate cancer treatment aims to reduce testosterone levels or block its effects. This may include LHRH agonists or antagonists or anti-androgen medications that block testosterone from binding to cancer cells. Hormonal therapy can be used for advanced or recurrent prostate cancer and can be combined with radiation or chemotherapy, depending on the patient. 

Key clinical differences between chemotherapy and hormonal therapy 

Scope of treatment: Chemotherapy affects cancer cells throughout the body, whereas hormonal therapy works only in cancers driven by specific hormones.

Duration of treatment: Chemo is usually short-term (weeks to months) whereas hormonal therapy is often longer term.

Side effects: The side effects of cancer treatment will vary depending on the type of treatment received. At Harbour Cancer and Wellness, the consulting doctor discusses and provides support to each patient individually to determine the most suitable treatment programme and to manage side effects.

When are chemo and hormonal therapy used together?

In many hormone-sensitive cancers, chemo and hormonal therapy are used sequentially rather than simultaneously, e.g. Chemo may be used first to reduce cancer size, then hormonal therapy may be used to suppress long-term recurrence.

In advanced cancers, hormonal therapy may delay the need for chemotherapy or reduce overall treatment intensity.

How our oncologists decide on which treatment to use

Our treatment decisions are based on cancer type and stage, hormone receptor status, tumour, aggressiveness, genomic testing results; plus patient age, health, and preferences.

Our approach ensures patients always receive treatment that is both as effective and appropriate as possible for their situation. And most importantly it means our patients are also as comfortable as possible with their treatment plan. 

A final note

Both chemotherapy and hormonal therapy play a vital role in cancer care. They’re different but each has helped improve the survival and quality of life for countless patients. 

Facing cancer treatment is never easy, but what can help is knowing you are not going through this alone. Our team will answer your questions, help you manage your side effects as best as possible, and guide you through every step of your care.