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Prescribing Patterns in Metastatic Castrate-Sensitive Prostate Cancer

March 23, 2021


Nataliya Mar, MD, UC Irvine Medical Center, Orange, CA, discusses results from a study exploring prescribing among patients with metastatic castrate-sensitive prostate cancer (CSPC).

These results were presented at the virtual 2021 ASCO Genitourinary Cancers Symposium.


My name is Nataliya Mar. I am an assistant professor at University of California, Irvine. I specialize in genitourinary malignancies.

I wanted to talk to you today about a study, that I was an author on, that was presented at ASCO GU 2021. The title of the study is "Prescribing Patterns in Patients with Metastatic Castrate‑Sensitive Prostate Cancer."

A little bit of background, in the recent years, multiple large studies showed that adding either a novel hormonal therapy, such as abiraterone, apalutamide, or enzalutamide, as well as docetaxel chemotherapy to androgen deprivation therapy in patients with metastatic castrate‑sensitive prostate cancer leads to better outcomes including overall survival.

The point of the study was to look at how are these new agents and these new data utilized in real life and in practices across the United States, in the State of California, and in Southern California.

First‑generation anti‑androgens, such as bicalutamide, have also been historically used in this setting. However, there is a lack of consensus in terms of exact indication for use now that the second generation therapies and docetaxel chemotherapy are available in the setting.

Commonly, these agents are used for tumor flare prevention, when first initiating androgen deprivation therapy, but other than that, there's no uniform standard indication for use. We also wanted to look at how are these agents utilized now in clinical practice, again, in the setting of all of these other agents being approved.

What we did was a retrospective analysis of pharmacy and medical claims data from a database called IQVIA. We look at basically almost five‑years' worth of data from January 1, 2015 to June 30, 2020. The patient population was patients aged 18 and older. They had an ICD‑9 or 10 diagnosis of metastatic prostate cancer with one or more treatment claim.

Patients who received therapy for another primary cancer were excluded. Also, patients with less than 9 months of data post first prostate cancer‑related event were excluded as well.

Now, I am going to briefly go through the results. We look at three tiers of data. The first one was on the national level. The second one was on the level of the State of California. The third one was in Southern California.

It appeared that the trend from 2015 to 2020 was that more second‑generation hormone therapies were being prescribed.

However, if you look at data from 2020—so, the most recent data we have—only 17 percent of these patients with metastatic castrate sensitive prostate cancer were prescribed a second‑generation anti‑androgen, which is interesting because, again, studies supporting their use have category 1 phase 3 randomized trials supporting their use. It appears that although the number of prescriptions seem to be increasing over the years, they're still very underutilized.

In terms of docetaxel chemotherapy, it appears that—again, through this 5‑years' slice of data—the amount of chemotherapy being prescribed is slightly decreasing. In 2020, only 2% of patients nationally were still receiving docetaxel chemotherapy in this setting.

In terms of first‑generation anti‑androgens, like bicalutamide, the percentage of patients receiving that beyond the initial flare indication has been dropping.

In 2020, still 26% of patients were on long‑term bicalutamide in the metastatic castrate‑sensitive setting, which is, to me, appears to be a fairly large figure in the absence of concrete data showing superiority of first‑generation anti‑androgens over second‑generation drugs and/or chemotherapy.

Interestingly, 55% of patients in 2020 were still receiving androgen deprivation therapy alone, with nothing else added.

Similar trends in prescribing patterns were seen in the State of California as well during these 5 years. We then looked at prescribing patterns based on insurance reimbursements—Medicare versus private care—and we did not find any differences. We did not find differences in coverage.

We also looked at the type of prescriber practices. For example, we looked at academic centers versus community‑based practices, and we saw that in Southern California academic centers tended to prescribe more second‑generation hormonal therapies than the community‑based practices.

We also looked at oncology practice vs urology practice in terms of prescribing patterns, and it appeared that oncology practices were prescribing more second‑generation hormonal therapies.

What conclusions can we draw from this data? First, it appears that despite second‑generation hormonal agents' utilization increasing from 2015 through 2020, these agents are still very much underutilized in men with metastatic castrate‑sensitive prostate cancer. Most of these men still received either androgens deprivation monotherapy or ADT plus first‑generation hormonal agents like bicalutamide.

Type of insurance carrier does not appear to affect prescribing patterns. Also, it seems that fairly dramatic variations across treatment settings, for example, academic versus community‑based practice as well as different specialties, oncology vs urology exists.

Academic centers seemed to be prescribing more second‑generation hormonal therapies than community‑based practices. Oncology practices seemed to be prescribing more second‑generation hormonal therapies than neurology practices. In 2020, it appears to be a significant health disparity in this patient population.

One educational point about all of this data is that we definitely want to standardize care delivery for this patient group across all settings and all types of practices in all states to be consistent with the national guidelines. One way to do so would be provider education.

Mar N, Forsyth M. Prescribing patterns in patients with metastatic castrate-sensitive prostate cancer (mCSPC). Presented at: the virtual 2021 ASCO Genitourinary Cancers Symposium; February 11-13, 2021. Abstract 21.

Dr Mar reports no relevant financial relationships.

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