Prostate cancer disparities observed in American Indian/Alaskan Native patients

"One thing that I think is increasingly clear is that for prostate cancer, access to early baseline PSA testing is a great equalizer," says Matthew R. Cooperberg, MD, MPH.

In this interview, Carissa E. Chu, MD, and Matthew R. Cooperberg, MD, MPH, discuss their study, “Prostate cancer disparities among American Indians/Alaskan Natives in the United States”.¹ Chu is a urologic oncology fellow at Memorial Sloan Kettering Cancer Center in New York, NY, and Cooperberg is a professor of urology at the University of California, San Francisco.

Could you describe the background for this study?

Cooperberg: There's been increasing focus in recent years on disparities in many areas of healthcare, including prostate cancer. A lot of this focus has been on the well-described increased incidence of prostate cancer and high-grade prostate cancer among African American men. But there has been less attention on other groups who are typically underrepresented in both epidemiologic research and interventional studies, one of whom are Native American patients who are classed in the US Census as American Indian or Alaskan Native.

We have seen some reports looking at multiple cancers, suggesting higher rates of cancer and worse outcomes in this group who have typically been very much understudied, in prostate cancer and elsewhere. So we conducted a study in [Surveillance, Epidemiology, and End Results] (SEER) focused on the incidence management and outcomes of prostate cancer among Native Americans.

Chu: This was a large population-based study, using SEER data to compare incidence, primary treatment, and cancer-specific mortality across different racial groups, different racial classifications in the SEER database. Over the past decade or so, it's been increasingly clear that American Indian and Alaska Native men in the United States have faced significant disparities in cancer care in respect to all cancers, with lower rates of screening, delayed diagnosis, decreased treatment access, and poor overall health outcomes.

Our purpose for this study was to look more closely at this group and look at what stage and grade of disease these patients are being diagnosed at and what their primary treatment modality is at the time of diagnosis for patients who are eligible for definitive treatment. We felt that linking some of these disparities with first treatment selection was an important unanswered question in the current literature.

What were some of your notable findings? Were any of these surprising to you and your coauthors?

Chu: In this study, we identified nearly half a million patients, including over 1500 American Indian/Alaskan Native men, 23,000 Asian Pacific Islanders, over 70,000 Black men, and 390,000 White men. Our median follow-up time was 6 years. We found that American Indian/Alaskan Native men were diagnosed at a similar median age as White men, slightly later than Black men, and much more likely to reside in rural areas in counties with the lower percentage of high school level or higher education, areas of higher density of poverty [and] unemployment rates, and also lower density per capita physicians, urologists, and radiation oncologists with fewer hospital beds available per county.

Consistent with existing literature, we found that American Indian and Alaskan Native patients were diagnosed at higher PSA levels; greater proportion of Gleason score 8 or higher disease; greater incidence of non-organ confined disease, so T3 or higher; and an overall higher risk of prostate cancer with a greater incidence of metastasis at diagnosis than any other group. After adjusting for age, PSA, Gleason score, and clinical stage, American Indian and Alaskan Native patients with localized prostate cancer were more likely to undergo external beam radiation than surgery and have the highest rates of no documented treatment.

Overall, the prostate cancer specific mortality was highest among American Indian and Alaska Native men, 3% compared with 1.6% for Asian and Pacific Islander men, 2.5% among Black men and 2% among White men. This was statistically significant on univariable analysis.

One of the interesting findings from this study was that we linked the SEER data with the area health resource files, which is publicly available data put out by HERSA, or the Health Resources and Services Administration, which provides some measure of health care density and health care access by county. When we adjust for some of these county level characteristics [such as] provider density, hospital size, hospital bed availability, we found that there were no differences after multivariable adjustment between American Indian/Alaskan Native men and White men in terms of prostate cancer specific mortality.

So, [although] American Indian/Alaskan Native patients do present with more advanced prostate cancer, show lower rates of definitive treatment, and higher mortality, once we adjust for some of these disparities in access, we found that there were no significant differences in mortality. This latter finding was novel and a little bit surprising to us. [It] suggests that focused health policy interventions can be beneficial to address some of these disparities in this particular group.

Cooperberg: Are these results surprising? Unfortunately, probably not. The Indian Health Service has been long recognized to be underresourced. We know Native Americans have not been studied, particularly in terms of prostate cancer or other cancer conditions, but the per capita spending in the Indian Health Service has historically been far below what we see in other sectors of the healthcare system. The fact that prostate cancer screening and diagnostic efforts would lag the private system and the VA and other health care settings within the US, unfortunately, it's really not surprising. I think perhaps the extent of the disparity was even more striking than we might have anticipated.

What implications might these findings have for patients and urologists?

Chu: That's a great question. I recently listened to a talk from Dr. Knudsen at ASCO GU, I think it was last year, highlighting the importance of disparities in cancer care across the United States. This study highlights one of the biggest underlying disparities, which is care for our American Indians and Alaskan Natives. When we talk about disparities, a lot of times these studies do not even include this group in studies on disparities, so they are underrepresented in that literature as well.

If you compare outcomes of American Indians and Alaskan natives to other groups in the United States, you see what the effect of differences in access to care and differences to screening may be. One of the most important things we can do going forward is to continue to represent American Indian and Alaskan Native men in current studies on disparities and do more than what we've been able to do in this study, which has really scratched the surface with a 30,000-foot view of some of these disparities and what may be underlying them. So, exploring some of these individual system-level factors in more depth.

Cooperberg: There are many different perspectives and opinions on what we need to do to remedy healthcare disparities for men with prostate cancer across the US and around the world. There's lots of discussion and unanswered questions in terms of how much of these disparities might reflect genetic differences versus environmental exposures versus structural problems with the health care system, including timely access to care.

One thing that I think is increasingly clear is that for prostate cancer, access to early baseline [prostate-specific antigen] PSA testing is a great equalizer. We know that the interpretation of PSA and downstream decision-making based on PSA, when it is done relatively young, does have the potential to eliminate or at least to substantially ameliorate these disparities because it will lead to us finding the high-grade cancers earlier when they are still curable.

Unfortunately, the screening conversation is typically out of the hands of urologists. This is a conversation that happens at the primary care level or doesn't happen at the primary care level. We don't have the data on anything prior to diagnosis in SEER, but I would not be at all surprised with subsequent studies in other datasets if we find that rates of screening and early detection are much less in Native American populations than among other groups in the US. This is an area where we're making some progress in terms of hopefully addressing the disparity for Black men in that screening rates for Black men are actually going up a little bit, at least in some areas of the country where this has been studied.

The message for urologists here is to make sure that we, as urologists, are engaging closely with primary care doctors, especially those who are taking care of vulnerable populations. We are the group that understands the data the best—at least we should be—in terms of screening. [Although] screening has been controversial over the past 15+ years, the data are increasingly clear that there is a survival of cancer-specific mortality benefit to early baseline testing with PSA. The challenge being we need to do everything we can to avoid overdiagnosis and overtreatment of low-risk disease. Having good lines of communication between your urologists and primary care doctors and keeping up our end of the bargain in terms of doing everything we can to avoid overdiagnosis, and especially overtreatment of low-risk disease is what's essential to forge productive relationships with primary care that will allow us to find cancers across all populations when they are curable.

Is any further research on this topic planned? If so, what might that focus on?

Cooperberg: This was really just a first foray. There are described 3 levels of disparity research. One is identifying that there is a disparity. The second is figuring out why. And the third is actually trying to set up interventional studies to ameliorate or address the disparities. In the case of Black men with prostate cancer, we at least had that first step solved for many years. A lot of the research is now in the second and hopefully will be getting toward the third.

For Native American men, this is really one of the first studies looking at this population at all. SEER is a uniquely good source of data for this particular group, because there are 3 sites within the SEER consortium of registries, which are specific to the Indian Health Service. It's actually a better source of data for Native American men than most other existing data sources.

This is a good first step. It does not really get us beyond that step 1 of disparity research, though. From the vantage point that adjusting for disease characteristics at presentation, outcomes appear to be similar, we might assume that in this case, it really is a problem of access, more so than, say, genetics or other environmental factors, but certainly, it remains to be proven. In terms of addressing the disparity, I would hope this study will be a bit of a wake-up call that we really do need implementation research with engagement at both the IHS sites and in other parts of the country where there are substantial populations of Native American men to make sure that we are getting messaging out there about early detection and that we are getting men in for diagnosis and appropriate treatment of potentially lethal cancers early.

Chu: We have to move beyond describing disparities a little bit, which is exactly what this study has done, and look at targeted interventions and the outcomes and effects of these targeted interventions. The next step in doing this work is to look at how better screening can be implemented [and] how better access to care can be implemented. These are important initiatives, not just facing American Indian [and] Alaskan Natives in this study, but across the United States as well. Looking at access to care across the country, and how it can vary from region to region.

One last thought is that prostate cancer is the most common cancer among men and the second leading cause of death among men. How one does with prostate cancer is very much a product of where you live, who you have access to for care, and a lot of other social and environmental factors that determine the trajectory of that disease more so than the biology in many ways. There are differences in biology that we have to appreciate, but I think on a population level, it's these health care access factors that make a big difference. This study really highlights that in a very specific group of underserved men.

The takeaway from that is that this continues to show how disparities in prostate cancer care are a reflection of health care access. Taking that to the next step, from an academic perspective, is to do something much more focused and intervention based. That requires collaboration with public health and groups that are on the ground delivering care. That's the gap that we should be trying to bridge in the coming decade.

What is the overall take-home message for practicing urologists?

Chu: From this specific study, the takeaway message is that American Indian and Alaskan Native men present with more advanced prostate cancer, demonstrate lower rates of definitive treatment, demonstrate higher prostate cancer-specific mortality, and hand-in-hand with that, reside in areas of less specialty care. We were able to show that disparities in some of these health care access indices does account for the excess risks of prostate cancer-specific mortality.

For this particular population, thinking more deeply about focused health policy interventions in more rural areas is very important as a public health initiative to address some of these disparities. That's translatable across a lot of different racial groups and a lot of differences in socioeconomic status. The point of this study is to focus specifically on American Native men and highlight the disparities that they're facing and show that they are currently underrepresented in existing literature on disparities as well.

Cooperberg: We still need to work out the specific interventions to address these disparities. It does seem increasingly clear that we can get a lot of yield for relatively low cost by focusing interventions on early detection, diagnosis, and risk-adapted appropriate management of higher risk prostate cancers when they are found. We need to meet men where they are and primary care providers where they are.

One aspect, of course, of the Native American disparity is an urban rural disparity that has also been well described in prostate cancer literature. Hopefully through outreach and better use of telehealth, especially in the in this sort of semi post-COVID world we are living in, we will be able to make strides in relatively near term to address some of these problems and improve the disparities facing them with prostate cancer in the country.

Is there anything else you would like to add?

Cooperberg: I would just emphasize again for any urologists that happen to be [reading] this, that it really is incumbent on us to be the ambassadors for prostate cancer early detection efforts with our primary care colleagues, because it really does seem like this is an area where we can have the nearest term impact in addressing prostate cancer disparities.

Reference

1. Chu CE, Leapman MS, Zhao S, Cowan JE, Washington SL, Cooperberg MR. Prostate cancer disparities among American Indians/Alaskan Natives in the United States. J Natl Cancer Inst. 2023;djad002. doi: 10.1093/jnci/djad002.