Taking Control with SABR to Postpone Hormone Therapy in Oligometastatic Prostate Cancer

Why Delaying Hormone Therapy Can Matter

When prostate cancer returns after previous treatment, hormone therapy, or androgen deprivation therapy (ADT), is one of the most effective ways of controlling the disease. However, treatment lowers testosterone and can produce side effects including hot flushes, fatigue, loss of sexual function, changes in body composition and effects on bone and metabolic health.

For some men, modern PSMA PET imaging identifies recurrence at a stage when there are only one or a few metastatic sites. In this oligometastatic setting, stereotactic ablative body radiotherapy, or SABR, can sometimes be used to treat the visible disease directly rather than moving immediately to long-term systemic treatment.

The goal is not to suggest that hormone therapy should be avoided when it is needed. Instead, for appropriately selected men with limited recurrent disease, treating individual metastases may provide a period of disease control before ADT needs to be started, restarted or intensified.

What Have the Trials Shown?

The randomised STOMP trial was designed specifically around this question. Men with recurrent prostate cancer and up to three metastases were assigned to surveillance or metastasis-directed treatment. The median time before ADT was required was 21 months after metastasis-directed treatment compared with 13 months with surveillance.

The ORIOLE trial provided further evidence that treating visible metastatic disease can alter the short-term course of prostate cancer. At six months, progression had occurred in 19% of men receiving SABR compared with 61% managed with observation. The study also found that men in whom all PSMA PET-visible disease was treated were considerably less likely to develop new metastatic lesions.

There is also growing evidence that SABR can be useful when hormone treatment has already begun. In the randomised EXTEND trial, adding metastasis-directed therapy to intermittent hormone therapy significantly improved progression-free survival and prolonged the period of disease control after testosterone recovered. This suggests that SABR may have a role not only in delaying the first use of hormone therapy, but also in helping selected men spend longer periods away from treatment.

Together, these trials support a broader strategy of using metastasis-directed treatment to extend periods of cancer control while reducing unnecessary exposure to continuous systemic therapy where clinically appropriate.

Who Might Benefit From This Approach?

Not every man with metastatic prostate cancer should delay hormone therapy. The approach is most relevant to carefully selected patients with a small number of recurrent lesions, particularly where the disease has developed gradually and all visible sites can be safely treated.

PSA level and doubling time, the grade of the original cancer, previous treatments, the interval since initial therapy and the location and number of PSMA PET-positive lesions all help indicate how the cancer is behaving.

The pattern over time is particularly important. A man who develops one or two lesions several years after his original treatment may have very different disease biology from someone developing multiple new metastases over a short period, even if both technically meet a numerical definition of oligometastatic disease.

SABR also does not close off future options. If further limited sites appear, additional metastasis-directed treatment may sometimes be possible, while hormone therapy and other systemic treatments remain available when they become necessary.

A Treatment Strategy Focused on Time Off Therapy

At Pinpoint Radiotherapy, the aim of metastasis-directed SABR is not simply to treat every abnormality seen on a scan. The important question is whether controlling those sites is likely to provide a meaningful period of disease control and change when the next treatment is required.

For selected men with recurrent oligometastatic prostate cancer, that may mean postponing the start of ADT. For others who have already received hormone therapy, it may mean extending a treatment break or delaying escalation to another systemic therapy.

Modern PSMA PET imaging has made this strategy increasingly practical by identifying small-volume recurrent disease earlier and more accurately. When the disease pattern is suitable, SABR provides a highly focused way of treating those sites while preserving systemic treatment options for the future.

The objective is therefore not to avoid hormone therapy at all costs, but to use it at the right time and, where possible, preserve meaningful periods without treatment and its associated side effects.