Socioeconomic Disparities Drive Alarming Racial Gaps in Kidney Cancer Patient Survival Rates - Nirmish Singla

December 11, 2023

Nirmish Singla presents research on socioeconomic determinants and racial disparities in renal cell carcinoma. Dr. Singla's study, published in Urologic Oncology, explores the complex interplay of biological, socioeconomic, and cultural factors influencing race-specific outcomes in healthcare. Focusing on African American and Caucasian patients with renal cell carcinoma, the study analyzes data from nearly 400,000 patients in the National Cancer Database. Key findings reveal that African American patients are diagnosed at a younger age and earlier stage but have more comorbidities and face greater socioeconomic challenges. Despite earlier diagnoses, African Americans show poorer overall survival across all stages and histologic subtypes, including clear cell and papillary RCC. The study highlights the need for public health awareness and improved access to care to mitigate these disparities. Dr. Singla emphasizes the importance of understanding both biological differences and socioeconomic factors to improve renal cell carcinoma outcomes for underrepresented minorities.


Nirmish Singla, MD, MSc, Brady Urological Institute at Johns Hopkins University, Baltimore, MD

Ruchika Talwar, MD, Urologic Oncology Fellow, Department of Urology, Vanderbilt University Medical Center, Nashville, TN

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Ruchika Talwar: Hi, everyone, and welcome back to UroToday's Health Policy Center of Excellence. As always, my name is Ruchika Talwar. And today, I'm really excited to be joined by Dr. Nirmish Singla from the Brady Institute at Johns Hopkins. We'll be discussing a body of work that he's recently published on socioeconomic determinants of health and racial disparities as they relate to renal cell carcinoma. Thanks, Dr. Singla, for being here with us.

Nirmish Singla:
Absolutely, Dr. Talwar. Thanks very much for highlighting our work, and it's really my honor and privilege to be able to chat a little bit about what we're interested in and what we have found so far in this arena.

All right. So I'm looking forward to sharing a little bit about our work. And just for reference, this is the paper that we had recently published earlier this year in Urologic Oncology. I have no relevant disclosures.

So just to give a little bit of background, as we know it in healthcare in general, studying race-specific outcomes can be very challenging to investigate. And the reason for this is because there is a considerable degree of multifactorial complexity when it comes to understanding race and ethnicity and outcomes more generally speaking.

Not only can there be perhaps inherent biological differences that are dictated by genetic ancestry, but there can also be a number of other factors. These include socioeconomic disparities, access to care and resources, particularly pertaining to oncology, access to multidisciplinary care teams, and also cultural differences, public awareness, and differences in trust in the healthcare system.

Specifically, in renal cell carcinoma, studies that have tried to evaluate the impact of race have been somewhat inconsistent on the clinical level. Some have commented on disparate outcomes among African Americans relative to their Caucasian counterparts, whereas others have shown no such differences.

Based on this background, we sought to try and more comprehensively analyze multiple socioeconomic determinants of racial disparities in overall survival among patients with renal cell carcinoma by leveraging a national population-based cancer registry from the National Cancer Database. Specifically, we focused on comparing outcomes in African Americans versus Caucasian patients. We looked at those patients who were diagnosed with renal cell carcinoma between 2004 and 2017 with robust survival data for at least five years thereafter among nearly 400,000 patients.

We sought to evaluate all-comers across all stages and histologic subtypes and also elected to perform additional matched subgroup analysis given differences in determining factors for outcomes. These included patients on one end of the spectrum with small renal masses, and then on the other end of the spectrum, those who presented with metastatic disease. We also looked at histologic-based matched sub-cohorts. These include patients who had clear cell renal cell carcinoma, which we know as the most common subtype of kidney cancer. And then we also looked at those who were diagnosed with papillary RCCs. And the reason for this is because papillary RCC, interestingly enough, is proportionately overrepresented among African American patients, and the biology behind this still remains not fully well-known.

And then finally, we also elected to do both stage and histology-based matched analysis.

Overall, within our cohort, we found a few interesting observations. First, we noted that African American patients were diagnosed at a relatively earlier age, at a median of three years younger compared to their Caucasian counterparts, and furthermore were also diagnosed at a relatively earlier stage. However, they did tend to harbor more comorbidities. And importantly, we noted that consistently socioeconomic disparities, and these include uninsured status, lower income quartile, and lower education quartiles, were disproportionately represented in African American patients as well.

We sought to look at overall survival outcomes as the main outcome of interest captured by the NCDB registry, and we found that, across all stages, African Americans did demonstrate poorer outcomes in terms of survival compared to Caucasians. This held true across small renal masses, as well as across metastatic patients at diagnosis. Although not shown here, this was also significantly different across different histologic subgroups as well, including both clear cell and papillary RCC patients.

We also noted that among the patients with metastatic disease, there seemed to be a lower likelihood of administering systemic therapy. Perhaps this may reflect differences in access to care or multidisciplinary care teams, whereby systemic therapy is considered the mainstay of treatment for metastatic disease in the majority of cases.

On multivariable Cox regression analysis, we found that race and each of the individual socioeconomic factors were independently associated with worse overall survival as well.

To conclude, some of our remarks from reviewing this data have included that socioeconomic disparities do appear to disproportionately affect African American patients diagnosed with renal cell carcinoma. Independently, these factors seem to play an important role in impacting their access to care and their survival. We believe that targeting these social factors and improving public health awareness and access among underrepresented minorities may help close the racial gap in renal cell carcinoma outcomes.

Ruchika Talwar:
Thank you for that comprehensive overview. It's an important question, and answering this question is very much limited by the characteristics of the large databases that we use and the lack of granularity available. So I think that you all did a really elegant analysis with the information that is available for these sorts of studies.

One thing that really caught my eye was what you pointed out regarding African American patients being diagnosed earlier in age and also earlier in stage. Can you tell me a bit about your thoughts on that?

Nirmish Singla:
Yeah. I think it's somewhat interesting. Although not part of this manuscript, we also tried to look at our institutional experience to see if we were able to validate some of the findings that were seen using this national registry, given that we do have a bit more granular data, because this likewise seems a bit counterintuitive. If patients are being diagnosed earlier, if they're being diagnosed at a younger stage, why is it that we're still seeing disparate outcomes in terms of survival?

In our cohort in the local Baltimore area, we have a catchment that is perhaps more proportionately representative of a higher frequency of African American patients with RCC. And so looking at our own database, we actually found relatively similar outcomes. And it is a little bit unclear. With respect to the NCDB, we're limited in only overall survival. So we don't necessarily have information on cancer-specific survival, which I think would be paramount to explore this question further.

Looking at small renal masses, we know that, oncologically, these usually tend to follow a more indolent course. And so even in the setting of active surveillance, we shouldn't expect there to be a substantially high cancer-specific mortality rate among those patients. So I suspect that much of the disparate survival outcomes that were statistically significant among that group may have been attributable more towards other medically related issues that are not necessarily cancer-related.

It's very possible that some of those confounders also have played a role in the cohort at large. I think that the metastatic patients who had worse outcomes certainly could be due to some of the aspects related to the use of systemic therapies, which we know can be life-prolonging in this disease. But certainly, something that I think warrants further investigation for sure.

Ruchika Talwar:
Yeah, exactly. It seems like a good target and an actionable quality improvement target as well that urology as a whole can look to address. And along those lines, when we do these sorts of studies, which are very important, we often should be asking ourselves, "Okay, we've identified a disparity, but what would be the next step in correcting this disparity? And how can we improve the overall quality of care, especially for populations that are already at risk for having other socioeconomic barriers to care?" So just share with us what do you think the next step should be and what are the major takeaways for all urologists?

Nirmish Singla:
Absolutely. I think I will just mention some of the inspiration to look at this question has come from what I think is a more evolved field, which is in prostate cancer disparities. And certainly, there's been a lot of work looking at prostate cancer on a biological level, looking at prostate cancer on a socioeconomic level, etc., on a cultural level. And I think we can learn a lot from ongoing efforts in prostate cancer.

And I think that RCC tends to be overshadowed in many ways. I think the amount of research that has been done looking at healthcare disparities in RCC, there's a lot of work certainly to be done there. And as far as next steps are concerned, I can certainly say that there are several. One is that I think in general, public health awareness, just for general health screening purposes, I think is something that we can target. For RCC, unlike PSA screening that we have for prostate cancer, RCC lacks a routine screening protocol. However, if we can encourage more patients in the community to seek routine medical care or look out perhaps for symptoms that may not even be related to kidney cancer, but amount to a greater rate of diagnosis, this may be one way to enhance our ability to detect these cancers.

There's a greater systemic issue, of course, with respect to access. I think that may certainly play a role in terms of getting good quality care, good quality access to urologists and as needed multidisciplinary care teams. So I think that certainly would be a work in progress.

But then the flip side of the coin is that, in an attempt to disentangle some of these socioeconomic factors from factors that may be more inherently biological, this is another area that actually is an active area of work that we and others have done some work in as well, and we're excited also to try and publish some upcoming findings related to that. But there is both a component of understanding differences in biology by ancestry that I think we need to learn more about, and then trying to see if there are ways that we can target improving access to healthcare in the communities. And if in some ways we can bolster trust in our healthcare system, that may help encourage following guideline-based approaches to care for patients who are diagnosed with kidney masses and kidney tumors in general.

Ruchika Talwar:
Yeah, I couldn't agree more, especially with your latter points. I think we are still learning and often checking ourselves as clinicians and as researchers when we try to separate the differences between race as a social construct and then your ethnicity biologically.

So I think this is just the start of hopefully a robust area of work in RCC, which, as you mentioned, has historically been a bit overshadowed by prostate cancer. So I really applaud you and your authors for taking this on, and thank you for spending a little time with us to share your insights.

Nirmish Singla:
Absolutely. And thank you again for highlighting this area of interest, and we're definitely very excited to continue work in this area.

Ruchika Talwar:
Great. And to our audience, thanks for joining us. We hope to see you next time.