The prostate is a hormone-dependent gland, primarily influenced by testosterone, which regulates its function and growth. In prostate cancer, this hormonal dependence can be exploited to slow disease progression, especially in advanced stages.

This is the principle behind hormone therapy, which aims to reduce or block the action of androgens—particularly testosterone—that stimulate the growth of prostate cancer cells.

However, other non-hormonal treatments may also be used depending on the disease profile, such as PARP inhibitors, which act on different cellular mechanisms.

In this article, you will learn about:

• Traditional hormone therapy, how it works, and its side effects
• New hormone therapies targeting the androgen receptor pathway (ARATs or ARPIs), their mechanisms, and side effects
• PARP inhibitors, how they work, and their side effects
• Strategies to better manage treatment side effects

Medical review by uro-oncologist Dr. Paul Toren, December 2025

Traditional hormone therapy or ADT

Hormone therapy, also known as androgen deprivation therapy (ADT), is a commonly used treatment for prostate cancer. Reducing testosterone levels helps control the disease, but also causes significant hormonal changes with side effects that can impact daily life:

• Reduced libido and sexual dysfunction: Lower testosterone often leads to reduced sexual desire and sometimes erectile difficulties, which can be emotionally and intimately challenging.

• Hot flashes and night sweats: Hormonal drops can trigger sudden feelings of heat and disrupt sleep, similar to menopause.

• Mood changes: Irritability, anxiety, or sadness may occur, as testosterone also affects brain neurotransmitters.

• Loss of muscle mass and weight gain: Testosterone helps maintain muscle strength; its suppression can cause fatigue, weakness, and noticeable body changes.

• Bone fragility (osteoporosis): Lower hormone levels reduce bone density, increasing fracture risk.

New hormone therapies: ARATs or ARPIs

New hormone therapies, called ARATs (Androgen Receptor Axis-Targeted therapies) or ARPIs (Androgen Receptor Pathway Inhibitors), represent significant advances in prostate cancer treatment.

They more precisely block androgen action, such as testosterone, on cancer cells and often provide better disease control, even in advanced stages. As with any hormone treatment, side effects can occur due to hormonal changes. Knowing them helps patients prepare:

• Persistent fatigue: One of the most common side effects, gradually appearing and affecting daily activities. This is not just ordinary tiredness but a symptom linked to hormonal and cellular changes.

• Reduced libido and sexual issues: Blocking hormone action can lower sexual desire and cause erectile problems.

• Weight gain and fat redistribution: Often noticeable around the abdomen, sometimes accompanied by reduced muscle mass.

• Hot flashes: Less frequent than with traditional ADT but may still occur, sometimes with sweating or sudden discomfort.

• Mood changes or difficulty concentrating: Irritability, low mood, or concentration problems can arise due to hormonal fluctuations.

PARP inhibitors: a targeted approach

PARP inhibitors are an important advancement in treating prostate cancer, particularly for patients with genetic mutations such as BRCA1 or BRCA2.

They exploit a weakness in cancer cells by blocking their ability to repair DNA, while preserving healthy cells as much as possible. Like all treatments, they may cause side effects:

• Severe and persistent fatigue: Often the most significant side effect, affecting all daily activities.

• Anemia: Some men may develop anemia, reducing oxygen delivery to tissues and causing fatigue and shortness of breath.

• Nausea and vomiting: May occur early in treatment and persist. Medications can help prevent these effects in many patients.

• Diarrhea: Usually mild to moderate; may require dose adjustment or temporary interruption if persistent.

• Reduced libido: Even though these drugs do not directly target sex hormones, fatigue, stress, or other concurrent treatments may reduce sexual desire.

• Sleep disturbances: Difficulty falling asleep, frequent awakenings, or poor-quality sleep can occur, exacerbating hormonal and emotional impacts.

• Mood changes: Anxiety, irritability, or sadness may appear due to the overall impact of treatment on the nervous system and hormonal balance.

• Muscle loss: Often indirect, worsened by fatigue and inactivity, affecting self-image and vitality.

Living better with side effects from hormone therapy and PARP inhibitors

Although the side effects of these treatments can be challenging, they are well-known, taken seriously, and manageable. To better cope, it is important to:

• Adopt healthy lifestyle habits: balanced nutrition, appropriate physical activity, quality sleep, and stress management
• Report any side effects promptly to your healthcare team so treatment can be adjusted if needed
• Avoid facing symptoms alone: support treatments and resources exist to preserve your quality of life

Hormone therapy and targeted therapies like PARP inhibitors have evolved significantly.

Each treatment affects the body and hormones differently. Understanding these mechanisms helps patients and their families anticipate side effects and adapt more effectively.

At PROCURE, we believe that better understanding leads to better living with the disease. Our professionals are here to support you and answer your questions, seven days a week. Contact us at 1-855-899-2873 or visit our website procure.ca