In the U.S., between 2010-2019, nearly 7% of patients diagnosed with prostate cancer had metastatic disease at diagnosis. In 2022, this could translate into more than 18,000 people. Multiple treatment options exist, including combinations of standard androgen deprivation therapy (ADT), novel hormonal therapies, and docetaxel. Since 2019, radiation therapy (RT) to the prostate has been recommended as an option in addition to medication for patients with relatively fewer metastases.
This recommendation was based on initial results from the STAMPEDE clinical trial showing that among patients whose prostate cancer had spread less (“low-burden” disease), those who received RT to the prostate lived longer than those who did not receive RT. Burden of metastatic disease was defined by the number and location of metastases (see Sidebar).
Now, a new publication of long-term results of STAMPEDE confirms the benefit of RT on survival and reports additional outcomes.
STAMPEDE is a very large multi-arm, multi-stage trial conducted in Europe that is comparing the efficacy of several different treatment regimens in men with newly-diagnosed metastatic prostate cancer who are starting long-term ADT. Within the overall trial, one “arm” looked specifically at the benefit of adding RT to ADT. There were two treatment groups (ADT, and ADT + RT), each with more than 1000 patients. 40% of patients had low-burden disease.
Patients were followed for a median of 5 years. In the low-burden disease group, patients treated with RT+ADT were 34% less likely to die than patients receiving ADT alone, and lived, on average, nearly 2 years longer (85.5 months vs 63.6 months). Consistent with the initial trial results, addition of RT to ADT was not linked to longer survival in patients with a high burden of disease.
Advanced prostate cancer can cause complications such as urinary or bowel obstruction. In the low-burden group, addition of RT was linked to lower rates of these complications and need for intervention (such as insertion of a urinary catheter).
There was no difference over the long term in quality of life between the two treatment groups.
It’s also important to know about any side effects from adding RT. Differences were minor, and manageable: for example, at 4 years, 13% of patients in the RT+ ADT had reported a moderate-to-severe adverse event vs 9% in the ADT alone group. The authors noted that “the risk of toxicity from prostate RT, although low, could be further reduced by the use of more contemporary intensity modulated techniques.”
These results add to the evidence showing that more intensive treatment for metastatic prostate cancer at diagnosis can help patients live longer, without increasing side effects. If you have been diagnosed with metastatic prostate cancer, talk to your doctor about what combination treatment options might be right for you.