Prostate cancer under the microscope: © heitipaves – stock.adobe.com
A new study led by Ryan Hankins, MD, urologist at MedStar Georgetown University Hospital, suggests that rectal spacers used during prostate cancer radiation therapy may help reduce the long-term prevalence of erectile dysfunction (ED). While rectal spacers are commonly used to protect the rectum from radiation exposure, this research offers the first large-scale real-world evidence that their benefits may extend to preserving sexual function in patients with prostate cancer.1
Rectal spacers have already been shown in clinical trials to reduce rectal toxicity during prostate radiotherapy (RT), improving overall treatment tolerance. However, until now, their impact on erectile function had not been explored using national real-world data. The new study evaluates the association between rectal spacer use and ED diagnoses among prostate cancer patients receiving RT, using a robust dataset spanning thousands of US counties.
The analysis drew on Medicare 5% and 100% standard analytic files, covering adult patients treated with intensity-modulated radiation therapy, brachytherapy, stereotactic body radiation therapy, or proton therapy between 2015 and 2022. Researchers focused on the proportion of patients diagnosed with ED in the years following treatment, comparing it with the proportion of patients in each county who had received rectal spacers during RT 1 to 5 years prior.
The study included 247,250 patients with prostate cancer across 3132 US counties. On average, 1.3% of patients treated with RT were diagnosed with ED annually. Notably, rectal spacer use rose significantly during the study period, from just 2.9% in 2015 to 18.9% by 2022. Researchers used zero-inflated Poisson regression models to assess the association, controlling for various demographic and socioeconomic factors at both the patient and population levels.
After adjusting for these variables, the results showed that counties with higher rectal spacer usage saw significantly lower rates of ED diagnoses 4 to 5 years later. Specifically, a 10-percentage point increase in rectal spacer utilization was associated with a 7.7% reduction in ED diagnosis after four years (P <.001) and an 8.4% reduction after five years (P =.006), suggesting a delayed but meaningful protective effect.
“We do believe that the use of rectal spacers may actually decrease the incidence of being diagnosed with erectile dysfunction after treatment with radiation therapy,” explained Hankins in an interview with Targeted OncologyTM.
A close-up of a microscope lens capturing a vibrant blue cancer cell, symbolizing the groundbreaking findings: © catalin – stock.adobe.com
Future research will aim to better understand the biological mechanisms behind this time lag and explore the impact of rectal spacers in long-term, patient-level clinical trials.
In the interview, Hankins further discussed these findings supporting the long-term benefit of rectal spacing in preserving sexual function in patients with prostate cancer who are undergoing prostate RT.
Targeted OncologyTM: Can you discuss the rationale behind investigating the association between rectal spacer use during prostate radiotherapy and subsequent diagnosis of erectile dysfunction using this large dataset?
Hankins: We use rectal spacers to help prevent [adverse events] from radiation therapy for prostate cancer. The spacers [were] developed to help with rectal toxicity, primarily to prevent rectal toxicity from radiation therapy. We are seeing now that there may be other benefits
There have been some studies to show that there are benefits to bladder symptoms, but now we’re seeing that there may be benefits to erectile dysfunction diagnoses in patients treated for prostate cancer that have received rectal spacers, which is very interesting.
Your study utilized county-level data. What were the key considerations that led you to choose this approach rather than individualized patient-level analysis?
These are large datasets that are readily available. So, this is based on diagnoses that are reported—or really government-reported diagnosis codes. And so, we can dive into large datasets to see if we can find associations with improvement in these side effects. And that’s really why we used this information.
The study really was able to include 247,000 men, nearly a quarter of a million prostate cancer patients, that were treated with radiation therapy across over 3,000 US counties.
Were you surprised by the 4- to 5-year delay in ED reduction? What did you expect going into this?
We were very surprised when we saw this. With prostate cancer treatment using radiation therapy, we know that there can be a delay, sometimes, in treatment [adverse events]. But it was very surprising to see that there may be a delay in even benefit with regard to these treatment-related [adverse events].
How clinically significant is the 7% to 8% reduction in erectile dysfunction prevalence with increased spacer use?
There are various rates of erectile dysfunction after radiation therapy in the published literature, and it ranges somewhere between 20% and 37% or so. So, when you see somewhere around a 7% to 8% reduction in the incidence of the diagnosis of erectile dysfunction after the treatment of prostate cancer, I think that really is somewhat significant, or a very interesting thing that we should continue to look into.
What other findings were significant or important to note?
I think the most interesting issue is that of why there is such a delay that we see in the decreased incidence of the diagnosis of erectile dysfunction. It is important to note that using this diagnosis and county-level data, there is a possible association here. It does not necessarily mean that there’s causation or causative factors. We need to look into this a bit further. And I think personalized further research into this topic is warranted.
Which controlled factors most influenced your findings?
It is hard to know using this type of dataset what factors influenced these findings. But we know that this is a comparative study of patients that received rectal spacers in comparison to patients that don’t receive rectal spacers. We really cannot make a definitive comment on what findings led to this. However, we do believe that the use of rectal spacers may actually decrease the incidence of being diagnosed with erectile dysfunction after treatment with radiation therapy.
What is the main message for oncologists from this study?
I think we have great evidence now, and evolving evidence, that shows multiple benefits for the use of rectal spacers in patients that have prostate cancer and are planning or considering radiation therapy as a definitive treatment. I think it just adds to the body of literature that shows we do recommend patients receive a rectal spacer. It’s a minimally invasive procedure that’s done in the office under local anesthesia, and it can have significant benefits for patients.
We think that it’s an important thing patients should consider having done. I think that radiation oncologists and urologists should be versed in doing it and understanding the benefits.
And we saw that during this, just looking at this data, there was an increase in the utilization of spacers from between 3% 5 years prior, up to 20.9% by 2022. So, there’s an increase in the utilization year over year, and I think that will just continue to occur as physicians become more versed in placing rectal spacers and the benefits that it has.
What are the next steps for research?
Really looking into this, and ideally into long-term, prospective, comparative trials, that’s going to be the most important thing. This is a study looking at diagnosis codes and with available Medicare 5% and 100% standard analytic file datasets. However, more intense research and long-term studies on patients receiving treatment is really going to be warranted and needed to know and really parse out the details here.