Xtandi (enzalutamide) is not a chemotherapy drug. It belongs to a class of medications called androgen receptor inhibitors, which work by blocking the hormones that fuel prostate cancer growth. This is fundamentally different from chemotherapy, which kills rapidly dividing cells throughout the body. The distinction matters because the two treatments work differently, feel different for patients, and carry different side effect profiles.
How Xtandi Actually Works
Prostate cancer cells rely on male hormones called androgens (primarily testosterone) to grow and survive. Xtandi interferes with this process at multiple points. It blocks testosterone from attaching to receptors on cancer cells, prevents those receptors from entering the cell nucleus, and stops them from activating the genes that tell cancer cells to multiply. By cutting off the hormonal signals at three separate steps, Xtandi essentially starves prostate cancer cells of the fuel they need.
Chemotherapy drugs like docetaxel take a completely different approach. They target all rapidly dividing cells in the body, damaging the internal structures cells use to split into new copies. That broad mechanism is why chemotherapy causes hair loss, nausea, and drops in blood cell counts. It kills cancer cells, but it also damages healthy cells that divide quickly, like those in the gut lining, hair follicles, and bone marrow.
Xtandi’s hormonal approach is far more targeted. It focuses specifically on the androgen receptor pathway, so it largely spares the fast-dividing cells that chemotherapy destroys. Doctors classify it as a hormonal therapy or endocrine therapy, not as cytotoxic (cell-killing) chemotherapy.
What Xtandi Is Approved to Treat
The FDA has approved Xtandi for several stages of prostate cancer. It can be used for castration-resistant prostate cancer (when the disease keeps growing despite standard hormone-lowering treatment), metastatic castration-sensitive prostate cancer (cancer that has spread but still responds to hormone therapy), and, as of November 2023, non-metastatic castration-sensitive prostate cancer with biochemical recurrence at high risk for metastasis. That last approval covers men whose PSA levels are rising after initial treatment even though scans don’t yet show cancer spread.
In most cases, Xtandi is taken alongside standard androgen deprivation therapy (ADT), the baseline hormone treatment for advanced prostate cancer. The combination has shown strong survival benefits. In the ARCHES trial, which followed men with metastatic hormone-sensitive prostate cancer for just over five years, adding Xtandi to ADT reduced the risk of death by 30% compared to ADT alone. For men with high-volume disease, the difference was especially striking: median overall survival was 83 months with Xtandi versus roughly 48 months without it.
What Taking Xtandi Looks Like Day to Day
Unlike chemotherapy, which typically requires IV infusions at a clinic on a set schedule, Xtandi is a pill you take at home once a day. The standard dose is 160 mg, which comes as either two 80 mg tablets or four 40 mg capsules. You can take it with or without food, at whatever time of day works for you, as long as you’re consistent.
Treatment continues for as long as the drug is working and the side effects remain manageable. There’s no predetermined number of cycles the way there is with chemotherapy. Some patients stay on Xtandi for months, others for years. Your oncologist will monitor your PSA levels and scans to track how well the drug is controlling the cancer.
Side Effects Compared to Chemotherapy
Because Xtandi works through a hormonal mechanism rather than by killing dividing cells, its side effect profile is notably different from chemotherapy. You won’t experience the hair loss, severe nausea, or dangerous drops in white blood cell counts that typically come with drugs like docetaxel.
The most common side effects of Xtandi reflect its hormone-blocking action and its effects on the nervous system. Fatigue is the most frequently reported issue. Falls occur in about 12% of patients (compared to 6% on placebo), and fractures affect roughly 13% of patients. These bone-related risks make sense given that blocking androgens weakens bone density over time. Xtandi can also cause hot flashes, joint pain, and muscle weakness.
The most serious rare risk is seizures, which occurred in about 0.6% of patients in clinical trials. Among patients who already had risk factors for seizures, such as a history of brain injury or certain medications, the rate was 2.2%. Ischemic heart disease is also slightly more common on Xtandi (3.5% vs. 2% on placebo), so your doctor may monitor cardiovascular health more closely if you have existing heart risk factors.
Why the Distinction Matters
Knowing Xtandi is not chemotherapy can change how you think about your treatment plan. Some patients delay or refuse treatment because they associate the word “chemotherapy” with debilitating side effects. Xtandi’s hormonal approach carries real side effects, but the experience is substantially different from what most people picture when they hear “chemo.” You take a pill at home, continue your daily routine, and avoid the immune suppression that makes chemotherapy patients vulnerable to infections.
It’s also worth understanding that hormonal therapy and chemotherapy are sometimes used together or in sequence for advanced prostate cancer. Xtandi isn’t a replacement for chemotherapy in every situation. For aggressive or late-stage disease, your oncologist may recommend docetaxel at some point. In the ARCHES trial, Xtandi showed survival benefits both in patients who had received prior chemotherapy and in those who hadn’t, suggesting it works well regardless of where it falls in a treatment sequence.