Who is this for?
This is for men with metastatic hormone-sensitive prostate cancer (mHSPC) — prostate cancer that has spread beyond the prostate but still responds to treatments that lower testosterone.
That includes two situations:
- Cancer that has already spread at diagnosis (“de novo” or synchronous metastatic disease) — usually to the bones, sometimes to lymph nodes or organs.
- Cancer that comes back and spreads later, after earlier treatment of the prostate (“recurrent” metastatic disease).
What kind of evidence is this?
This is a review that pulls together nine large phase III trials (more than 10,000 men) to answer a practical question: once prostate cancer has spread, is hormone therapy alone enough — or should other drugs be added from the start?
Background: why researchers asked this question
For decades, the first treatment for metastatic prostate cancer was hormone therapy alone — shut off testosterone and the cancer shrinks, often dramatically. But it doesn’t last: on hormone therapy by itself, the cancer usually finds a way to keep growing within about a year, and average survival is only around 3 to 4.5 years.
The insight that changed treatment was simple: hit the cancer in more than one way, from the start. Each add-on works differently — a stronger anti-hormone pill (ARPI) blocks testosterone’s effect more completely, while chemotherapy (docetaxel) kills rapidly dividing cells. Combining treatments with different mechanisms controls the cancer longer.
Over about a decade, nine phase III trials tested these combinations. This review asked: taken together, what do they tell us — and are men actually getting the benefit?
The evidence: what was tested and how
Nine international phase III trials, enrolling over 10,000 men with metastatic hormone-sensitive prostate cancer, compared hormone therapy alone against hormone therapy plus extra treatment. Two questions run through them:
- Does adding one drug beat hormone therapy alone? Trials added either an ARPI pill (abiraterone, apalutamide, enzalutamide) or chemotherapy (docetaxel) — a “doublet.”
- Does adding two drugs beat one? More recent trials tested hormone therapy + an ARPI + chemotherapy — a “triplet” — against hormone therapy + chemotherapy.
The main measure across the trials was overall survival — how long men lived.
A note before the results
When I first started training, the options for treatment of metastatic prostate cancer were limited: surgery or radiation, or both, for the prostate gland, and then hormone medications when the cancer came back. Chemotherapy was a last resort, later on in the disease.
When all these new pills were discovered, they quickly moved up the line of treatment, and now we see these men much earlier in their disease course. We know that being more aggressive with prostate cancer upfront leads to longer response and longer survival!
Results: what they found
The direction was remarkably consistent across trials and drugs: the more you intensify, the longer men live — and the added treatments were generally well tolerated. The numbers below come from representative trials; several others using different drugs pointed the same way.
Building up treatment — overall survival
Median overall survival — how long men lived — jumped from under 4 years to over 6, a 40% lower risk of dying (HR 0.60). Similar gains were seen whether the added second drug was an ARPI pill or chemotherapy.
In men already receiving hormone therapy plus chemotherapy, adding the ARPI darolutamide lifted 4-year overall survival from 50% to 63% — a 32% lower risk of dying (HR 0.68). Adding abiraterone instead (PEACE-1) showed a similar benefit.
One important subtlety: the triplet trials added the ARPI to men who were already receiving hormone therapy plus chemotherapy. So we know that adding an ARPI helps — but we don’t yet have a head-to-head trial showing how much the chemotherapy itself adds on top of hormone therapy plus an ARPI. That harder question is still open. In practice, chemotherapy is reserved for men with the most aggressive disease (a large amount of cancer, higher-risk features, or cancer that was already metastatic at diagnosis) who are fit enough for it, while a two-drug pill combination — hormone therapy plus an ARPI — is a strong option for nearly all.
What’s the difference between the added pill (ARPI) and chemotherapy?
An ARPI (abiraterone, apalutamide, darolutamide, or enzalutamide) is a daily pill that blocks the cancer’s ability to use testosterone even more completely than standard hormone therapy. Docetaxel is a chemotherapy given by IV, usually every three weeks for about six doses, that kills rapidly dividing cells. Because they work in different ways, they can be combined. ARPIs are generally easier to tolerate long-term; chemotherapy is more intensive and time-limited, and needs reasonable fitness.
Who benefits most from adding chemotherapy (the triplet)?
The clearest benefit from the full triplet was in men whose cancer was high-volume (a lot of disease, especially in organs or many bones), high-risk, or already spread at the time of diagnosis (“de novo”). For men with less extensive disease, or who aren’t fit for chemotherapy, hormone therapy plus an ARPI pill (a doublet) is a strong option that still clearly beats hormones alone. The right combination is an individual decision made with your oncologist.
Hormone therapy + an ARPI pill (doublet)
Hormone therapy + chemotherapy (doublet)
- CHAARTED — docetaxel
- GETUG-AFU 15 — docetaxel
The bottom line
For prostate cancer that has spread but still responds to hormones, hormone therapy alone is no longer the right first treatment. Across nine large trials, adding a second drug — a stronger anti-hormone pill or chemotherapy — helped men live substantially longer (for example, 79 vs 46 months in one trial), and for men fit enough, adding chemotherapy as a third drug extended survival further still (4-year survival 63% vs 50%). Today the question is rarely whether to add a second drug, but which one — a conversation worth having with your oncology team as early as possible.
What this could mean for you
- Hormone therapy is the foundation, not the whole plan. If you’ve been started on hormone therapy alone for metastatic prostate cancer, it’s worth asking whether a second drug should be added.
- There’s more than one right answer. Adding an ARPI pill (a doublet) suits nearly everyone; adding chemotherapy too (a triplet) offers the most, especially for aggressive or newly-diagnosed metastatic disease — if you’re fit for chemo.
- Fitness and preference matter. Chemotherapy is more demanding; a pill-based doublet may be the better fit for some men. This is a shared decision.
An oncologist’s perspective
It is easy to offer a pill such as abiraterone, enzalutamide, or darolutamide to men with prostate cancer. The side effects are tolerable and the benefits are clear.
However, at the same time that these new pills were discovered, we also had new trials showing that upfront chemotherapy was helpful in prostate cancer too. We are still trying to answer the question: how much benefit is there to giving chemotherapy on top of the pills and hormone therapy?
In the meantime, I reserve chemotherapy for my fittest patients with the most aggressive disease upfront. Six cycles of docetaxel is tough, and in the future I hope the evidence shows that, in most men, chemotherapy can be avoided.
Questions & comments
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