Factors Associated with Receipt of Partial Nephrectomy or Minimally Invasive Surgery for Patients with Clinical T1a and T1b Renal Masses: Implications for Regionalization of Care.

Abstract

OBJECTIVES

To identify factors associated with receipt of partial nephrectomy (PN) and minimally invasive surgery (MIS) in patients with clinical T1 renal cell carcinoma (RCC) using the National Cancer Data Base (NCDB).

METHODS

We queried the NCDB from 2010–2014 identifying patients treated surgically for cT1a-bN0M0 RCC. Logistic regression was used to examine associations between socio-economic, clinical, and treatment factors, and receiving MIS or PN within the T1 patient population.

RESULTS

Our cohort included 69,694 patients (cT1a n= 44,043; cT1b n= 25,651). For cT1a tumors, 70% of patients received PN and 65% underwent MIS. For cT1b tumors, 32% of patients received PN and 62% underwent MIS. cT1a and cT1b patients with household income <$62,000, without private insurance, and those treated outside academic centers were less likely to receive MIS or PN. cT1a patients traveling >31 miles were more likely to undergo MIS. For both cT1a/b, the farther a patient traveled for treatment the more likely a PN was performed.

CONCLUSIONS

Overall, data showed an increase in utilization of MIS and PN from 2010–2014. However, patients in the lowest socio-economic groups, were less likely to travel, and were more likely to receive more invasive treatments. Based on these findings, additional research is needed into how regionalization of RCC surgery will affect treatment disparities.

INTRODUCTION

Renal cell carcinoma (RCC) represents 3% of all malignant tumors in adults and is among the most common cancers in both men and women¹. It is estimated that there will be 73,820 new RCC cases diagnosed in 2019 in the United States alone². Approximately 65% of patients present with localized disease, which makes determining the optimal surgical approach and extent of resection a common occurrence in urologic practice³.

Surgical resection via partial or radical nephrectomy remains the most effective treatment option for clinically localized RCC. Traditionally, radical nephrectomy (RN) was the first-line surgical intervention for all tumor sizes, and the most common treatment for small renal masses (SRM), which are ≤4 cm (T1a)⁴. However, many clinical studies have demonstrated that partial nephrectomy (PN) for SRMs has comparable oncological outcomes to RN, with the advantage of preserving more renal function and minimizing the risk of chronic kidney disease (CKD)^5–8. A meta-analysis of over 50 studies involving more than 31,000 patients found that PN, compared to RN, was associated with a 19% reduction in all-cause mortality, a 29% reduction in cancer-specific mortality, and a 61% reduction in CKD⁹.

In 2009, the American Urological Association (AUA) and European Association for Urology (EAU) began recommending PN for T1a masses in response to retrospective studies showing equivalent oncologic outcomes with better preservation of renal function^4,10. In 2017, updated AUA guidelines for localized renal cancer recommended PN as the standard of care for cT1a renal masses (≤ 4 cm), PN over RN for the management of cT1b masses (>4 and ≤ 7 cm) when technically feasible and oncologic outcomes would not be compromised, as well as the utilization of minimally invasive surgery (MIS) when possible¹¹. While, recent studies demonstrated a general increase in the use of PN for managing cT1a and MIS PN for managing cT1a and T1b renal masses^12,13, these guidelines also acknowledge that adherence to their recommendations may require treatment by an expert surgeon at a high-volume center¹¹.

It is well known that there are significant disparities in cancer care and outcomes across race, ethnicity, and socio-demographic characteristics such as insurance status, income, and education¹⁴. Within the scope of RCC in particular, studies have found that Hispanic ethnicity is an independent predictor of worse disease-specific survival, and that African American (AA) patients undergoing robotic partial nephrectomy have a higher proportion of positive surgical margins when compared to white patients^15,16. Currently, the impact of socio-economic variables in surgical approach (RN, PN) or modality (i.e., open, robotic, laparoscopic) used in treating RCC is unknown. PN is a more technically challenging procedure when attempted on larger tumors, and recent guidelines have expanded the indications for PN to include more complex cases. To date, we are unaware of any reporting on the differences between cT1a and cT1b patient populations or factors predictive of what treatment is received.

Thus, the aims of this study were: (1) to identify socio-economic, clinical, and treatment factors associated with the use of PN and MIS as part of RCC treatment in patients with cT1a and cT1b disease; and (2) to improve characterization of the cT1 patient population by comparing differences between cT1a and cT1b patient groups.

METHODS

Data Source

The National Cancer Data Base (NCDB) compiles cases from over 1,500 accredited cancer centers and is the largest U.S. hospital-based oncology registry which captures approximately 70% of all newly diagnosed cancer cases annually¹⁷. As the data used in this study are de-identified, this study was institutional review board exempt. All statistical analyses and conclusions were formed solely by the investigators.

Study Population

We performed a retrospective cohort study of patients with RCC from 2010–2014 NCDB. We queried the NCDB to capture clinical stage T1a and T1b RCC patients who received surgical treatment. Patients with metastatic disease (n= 36,870), non-surgical treatments (n= 24,001), clinical stages 2–4 (n=18754) and missing information (n=2,000) were excluded from the analysis. The final sample size for main analyses was n=69,694.

Study Variables

Patient socioeconomic information included age, sex, race, ethnicity, education attainment, household income, distance traveled to treatment facility, and insurance type. Education attainment was defined by NCDB as the proportion of adults in the patient’s zip code who did not graduate from high school. Household income was determined by matching patient’s zip code at diagnosis against the 2012 American Community Survey Data (US Census Bureau). Individual clinical characteristics included year of cancer diagnosis (2010–2014), clinical primary tumor stage (1–4), Charlson-Deyo comorbidity index (categorized as 0, 1, or 2 and above to indicate increasing level of comorbid conditions), and hospital type (classified according to Commission on Cancer criteria, based on caseload and services offered). The treatment variables available for analysis included surgical approach (RN, PN) and surgical modality (i.e., open, robotic, laparoscopic). PN surgeries included partial or subtotal nephrectomies while RN surgeries included complete/total/simple and radical nephrectomies. MIS modality included both robotic and laparoscopic surgeries.

Statistical Analysis

Frequency distributions were calculated for all categorical variables. Chi-square and Krustal-Wallis tests were used to compare proportions and medians. Logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (95%CI) for receiving (1) a PN or (2) MIS. Because clinical stage was the main factor associated with receiving PN or MIS and we wanted to improve characterization of the cT1 population, we stratified the study population based on clinical stage: cT1a and cT1b. We evaluated all available socioeconomic and clinical variables as potential confounders in univariate models for each clinical stage group. Statistical significance was set at p<0.05. All statistical analyses were conducted using SAS Version 9.4 (SAS Institute Inc. Cary, NC, USA).

RESULTS

The total cohort included 69,694 patients, 44,043 patients with cT1a tumors and 25,651 patients with cT1b. Clinical and socioeconomic characteristics of the study population are shown in Table 1. In the cT1a population, 70% of tumors were treated with a PN while 65% underwent MIS (Table 2). In the cT1b population, 32% of tumors were treated with a PN and 68% and 62% received MIS. Over the four-year period, the number of PNs increased on average 8% per year from 6445 cases in 2010 to 9143 cases in 2014, while the annual number of RNs remained stable. In 2010, 53.6% of patients with cT1a tumors and 53.7% of patients with cT1b tumors underwent MIS. Those numbers increased to 73% for cT1a and 70% for cT1b tumors at the end of the investigatory period.

Table 1.

Baseline Characteristics of Patients with Clinical Tumor Stage 1a and 1b Renal Cell Carcinoma

Patient Characteristics	cT1a Population N(%)†	cT1b Population N(%)†	p-value‡
Age (years)
≤50	13194(30)	6438(25)	<0.01
>50–60	11710(27)	6557(26)
>60–70	10637(24)	6142(24)
>70	8502(19)	6514(25)
Sex
Female	17780(40)	9527(37)	<0.01
Male	26263(60)	16124(63)
Race
White	36291(82.5)	21613(84)	<0.01
African American	5826(13)	2996(12)
American Indian	213(0.5)	134(0.5)
Asian	863(2)	468(2)
Other	432(1)	204(1)
Hispanic Ethnicity
No	39679(93)	23121(93)	0.77
Yes	2747(7)	1616(7)
Charlson Comorbidity Index
0	30077(68)	16998(66)	<0.01
1	10432(24)	6364(25)
2	3534(8)	2289(9)
Distance to Facility (miles)
≤5.5	10941(25)	6383(25)	<0.01
>5.5–12.6	11141(25)	6219(25)
>12.6–31.1	10866(25)	6358(25)
>31.1	11095(25)	6691(25)
Income 2008–12 ($)
≥62,000	14146(32)	7818(30)	<0.01
≥47,999–62,999	11825(27)	6951(27)
≥38,000–47,999	10214(23)	6134(24)
<38,000	7729(18)	4669(18)
Education Attainment*
<7%	10203(23)	5598(22)	<0.01
7–12.9%	14486(32)	8535(33)
13–20.9%	11780(27)	6862(27)
>21%	7462(17)	4593(18)
Insurance
Private Insurance	21407(49)	11587(45)	<0.01
Not Insured	1240(3)	888(3)
Medicaid	2713(6)	1431(6)
Medicare	17537(40)	11074(43)
Other Government	610(1)	355(2)
Hospital Type
Academic/Research Cancer Program	18611(45)	9880(40)	<0.01
Community Cancer Program	2337(6)	1714(7)
Comprehensive Community Cancer Program	15586(38)	10081(41)
Integrated Network Cancer Program	4661(11)	2795(11)
Type of Surgery
Partial	30310(70)	7940(32)	<0.01
Radical	13160(30)	17266(58)
Surgical Modality
Robotic	18430(42)	6268(24)	<0.01
Laparoscopic	10125(23)	9689(38)
Open	15488(35)	9694(38)
Year of Diagnosis
2010	8051(18)	4643(18)	<0.01
2011	8321(19)	4869(19)
2012	8898(20)	5165(20)
2013	9155(21)	5365(21)
2014	9618(22)	5609(22)

^*Number of adults in the patient’s zip code who did not graduate from high school

^†Column Percentages

^‡Chi-Square Test

Table 2:

Proportions of partial nephrectomy, radical nephrectomy, open surgery, and MIS for cT1a and cT1b patients

	cT1a	cT1b
PN	70%	32%
RN	30%	68%
Open	35%	38%
MIS	65%	62%

Overall, the cT1a and cT1b patient populations were very similar in factors associated with receipt of PN (Table 3). Education attainment was the only socio-economic variable that was not associated with receipt of PN in either cohort. Patients with a median annual income <$62,000 were less likely to have a PN (cT1a patients OR range = 0.75–0.83, cT1b patients OR range = 0.70–0.84). The effect of race differed significantly between the cT1a and cT1b patients. Compared to White patients, African American patients in the cT1a cohort were less likely to receive a PN (OR: 0.77, 95% CI: 0.72–0.83), while those in the cT1b group were more likely to receive a PN (OR: 1.20, 95% CI: 1.09–1.32). Compared to patients with private insurance, those without insurance [cT1a (OR: 0.78, 95% CI: 0.77–0.89), cT1b (OR: 0.67, 95% CI: 0.56–0.81)] or with Medicare [cT1a (0R: 0.64, 95% CI: 0.6–0.68), cT1b (OR: 0.85, 95%CI: 0.78–0.93)] were less likely to receive PN. Patients treated outside an academic research center had a decreased likelihood of undergoing a PN (cT1a OR range = 0.43–0.75; cT1b OR range = 0.29–0.60). Any patient traveling more than 12.6 miles to receive treatment were more likely to undergo PN compared to those traveling <5 miles.

Table 3:

Multivariable Logistic Regression Model for the Association between Socio-economic and Clinical Factors and Partial Nephrectomy in Patients with Clinical Tumor Stage 1a and 1b Renal Cell Carcinoma

	cT1a Population	cT1b Population
Patient Characteristics	PN OR (95% CI)	PN OR (95% CI)
Age (years)
≤50	Reference	Reference
>50–60	0.89(0.71–0.85)	1.01(0.71–0.85)
>60–70	0.97(0.89–1.05)	0.92(0.83–1.02)
>70	0.77(0.71–0.85)	0.79(0.70–0.89)
Sex
Female	Reference	Reference
Male	1.00(0.96–1.05)	1.22(1.14–1.30)
Race
White	Reference	Reference
African American	0.77(0.72–0.83)	1.20(1.09–1.32)
American Indian	0.63(0.46–0.88)	1.09(0.71–1.66)
Asian	0.97(0.82–1.16)	0.88(0.70–1.11)
Other	1.14(0.88–1.48)	1.44(1.03–2.02)
Ethnicity
Non-Hispanic	Reference	Reference
Hispanic	0.98(0.86–1.12)	0.99(0.88–1.10)
Charlson Comorbidity Index
0	Reference	Reference
1	0.92(0.87–0.98)	1.11(1.03–1.19)
2	0.67(0.62–0.73)	1.07(0.96–1.20)
Distance to Facility (miles)
≤5.5	Reference	Reference
>5.5–12.6	1.05(0.98–1.12)	1.04(0.95–1.14)
>12.6–31.1	1.14(1.06–1.22)	1.20(1.10–1.32)
>31.1	1.30(1.20–1.39)	1.41(1.29–1.54)
Income 2008–12 ($)
≥62,000	Reference	Reference
≥47,999–62,999	0.83(0.77–0.89)	0.84(0.77–0.93)
≥38,000–47,999	0.80(0.74–0.87)	0.76(0.69–0.84)
<38,000	0.75(0.68–0.83)	0.70(0.61–0.79)
Education Attainment*
<7%	Reference	Reference
7–12.9%	1.00(0.93–1.08)	0.91(0.83–1.00)
13–20.9%	0.93(0.86–1.01)	0.94(0.84–1.04)
>21%	0.92(0.84–1.02)	0.98(0.86–1.12)
Insurance
Private Insurance	Reference	Reference
Not Insured	0.78(0.68–0.90)	0.67(0.56–0.81)
Medicaid	0.91(0.81–1.01)	0.90(0.78–1.03)
Medicare	0.64(0.60–0.68)	0.85(0.78–0.93)
Other Government	0.81(0.65–1.00)	0.94(0.72–1.22)
Hospital Type
Academic/Research Cancer Program	Reference	Reference
Community Cancer Program	0.43(0.39–0.48)	0.29(0.25–0.34)
Comprehensive Community Cancer Program	0.54(0.51–0.57)	0.43(0.40–0.46)
Integrated Network Cancer Program	0.75(0.69–0.81)	0.60(0.55–0.67)
Surgical Modality
Open	Reference	Reference
Robotic	2.62(2.47–2.78)	1.59(1.48–1.70)
Laparoscopic	0.28(0.27–0.30)	0.17(0.16–0.19)
Year of Diagnosis
2010	Reference	Reference
2011	1.16(1.08–1.25)	1.28(1.16–1.42)
2012	1.23(1.14–1.33)	1.39(1.26–1.54)
2013	1.23(1.14–1.32)	1.36(1.23–1.51)
2014	1.25(1.16–1.35)	1.34(1.21–1.48)

PN: partial nephrectomy, MIS: minimally invasive surgery, OR: odds ratio, CI: confidence interval

^*Education Attainment: proportion of adults in the patient’s zip code who did not graduate from high school

Patients with cT1a tumors and an annual income of <$62,000 were associated with a decreased receipt of undergoing MIS (OR range 0.79–0.90) (Table 4). However, income was not a statistically significant factor for patients with cT1b tumors. Education was also not predictive of receiving MIS. African Americans in both populations were less likely to undergo MIS (cT1a OR: 0.92, 95%: CI: 0.86–0.98; cT1b OR: 0.88, 95% CI: 0.81–0.96). American Indians with cT1a tumors (OR: 0.64, 95% CI: 0.48– 0.87) also had a decreased likelihood of undergoing MIS. cT1a patients without private insurance were less likely to receive MIS (uninsured OR:0.58, 95%CI: 0.51–0.67; Medicaid OR: 0.83, 95% CI: 0.76–0.92; Medicare OR: 0.92, 95% CI: 0.89–0.97) compared to private insurance patients. In the cT1b cohort, uninsured patients were less likely to undergo MIS (OR: 0.74; 95%, CI: 0.64–0.86) compared to private insurance payor. Only patients treated at a community hospital were less likely to receive MIS (cT1a OR: 0.48, 95%CI: 0.44–0.53 and cT1b OR: 0.63, 95%CI: 0.56–0.7) compared to those treated at academic centers. Those patients with cT1a tumors who traveled >31 miles (OR: 1.10, 95% CI: 1.03–1.17) to a treatment facility were more likely to undergo MIS, while patients with cT1b tumors who traveled more than 12.6 miles were more likely to under MIS.

Table 4:

Multivariable Logistic Regression for the Association between Socio-Economic and Clinical Factors and Minimally Invasive Surgery in Nephrectomies in Patients with Clinical Tumor Stage 1a and 1b Renal Cell Carcinoma

Patient Characteristic	CT1a Population	CT1b Population
	MIS OR(95% CI)	MIS OR (95% CI)
Race
White	Reference	Reference
African American	0.92(0.86–0.98)	0.88(0.81–0.96)
American Indian	0.64(0.48–0.87)	0.74(0.51–1.06)
Asian	1.00(0.85–1.17)	0.93(0.76–1.14)
Other	1.07(0.85–1.36)	0.81(0.58–1.12)
Ethnicity
Non-Hispanic	Reference	Reference
Hispanic	0.90(0.82–0.99)	0.98(0.87–1.11)
Charlson Comorbidity Index
0	1.00	1.00
1	0.99(0.94–1.04)	0.94(0.89–1.01)
2	0.92(0.86–1.00)	0.88(0.80–0.97)
Distance to Facility (miles)
≤5.5	Reference	Reference
>5.5–12.6	1.02(0.96–1.09)	1.10(1.03–1.20)
>12.6–31.1	1.00(0.95–1.07)	1.06(0.98–1.14)
>31.1	1.10(1.03–1.17)	1.01(0.93–1.09)
Income 2008–12 ($)
≥62,000	Reference	Reference
≥47,999–62,999	0.90(0.85–0.96)	1.01(0.93–1.09)
≥38,000–47,999	0.79(0.74–0.85)	0.92(0.84–1.00)
<38,000	0.79(0.72–0.86)	0.92(0.82–1.03)
Education Attainment*
<7%	Reference	Reference
7–12.9%	0.99(0.92–1.05)	1.00(0.92–1.09)
13–20.9%	1.01(0.94–1.09)	0.92(0.83–1.01)
>21%	0.98(0.89–1.07)	0.91(0.81–1.03)
Insurance
Private Insurance	Reference	Reference
Not Insured	0.58(0.51–0.67)	0.74(0.64–0.86)
Medicaid	0.83(0.76–0.92)	0.91(0.80–1.03)
Medicare	0.93(0.89–0.97)	1.01(0.95–1.07)
Other Government	1.22(1.01–1.47)	1.19(0.94–1.50)
Hospital Type
Academic/Research Cancer Program	Reference	Reference
Community Cancer Program	0.48(0.44–0.53)	0.63(0.56–0.70)
Comprehensive Community	1.04(0.99–1.09)	1.12(1.05–1.19)
Cancer Program
Integrated Network Cancer Program	1.01(0.94–1.08)	1.05(0.96–1.15)
Year of Diagnosis
2010	Reference	Reference
2011	1.32(1.24–1.41)	1.17(1.08–1.28)
2012	1.61(1.51–1.72)	1.37(1.26–1.50)
2013	2.06(1.93–2.21)	1.76(1.61–1.92)
2014	2.36(2.20–2.52)	1.95(1.79–2.13)

PN: partial nephrectomy, MIS: minimally invasive surgery, OR: odds ratio, CI: confidence interval

^*Education Attainment: proportion of adults in the patient’s zip code who did not graduate from high school

DISCUSSION

Using a population-based cohort, our study was able to identify socioeconomic factors that influence the use of partial nephrectomy as well as MIS to treat cT1a and cT1b renal masses. Our study sheds light on the shift in general practice patterns required to be fully compliant with the most recent AUA guideline regarding the treatment of localized renal masses. There are opportunities for improvement with respect to the use of MIS for both cT1a and cT1b patients, as well as furthering the application of nephron sparing surgery in patients with larger tumors. Over the study period, there were yearly increases in the number of patients undergoing surgery in both cT1a and cT1b populations, which was reflected in the increased utilization of both PN and MIS and has been previously described^10,12.

Shah et al. reported that rapid adoption and expanding utilization of robotic surgery has resulted in an overtreatment of cT1a tumors¹⁸. In our study, overall utilization of MIS was similar between cT1a and cT1b tumors, 65% and 62% respectively, but the 65% of the MIS procedures for cT1a were done robotically compared to only 39% for cT1b tumors. Although, this finding was similar to Shah et al., they did not have data on surgical modality to further examine MIS approaches. Our study showed that while the yearly percent of procedures cT1a tumors done robotically plateaued, the percentage of robotic procedures for cT1b tumors continued to rise every year. A possible explanation for this finding is the increase of surgeons and hospital with the capacity to perform robotic nephron sparing surgery. Recent work from Xia et al. examining national trends in MIS utilization for partial and radical nephrectomies for T1 renal masses demonstrated that MIS use has increased significantly from 2010–2015 ¹³. There is a mastery of the basics that is necessary before applying any new techniques to more complex scenarios, we are now seeing the results of that mastery as every year a larger percentage of patients with cT1b are receiving PNs ¹⁹.

The 2017 AUA guidelines specifically state that RN should be performed only if PN is “not feasible in the hands of an expert”, suggesting that the best outcomes for these patients result from receiving treatment at specialized centers. Of all the factors examined the biggest predictor of receiving a PN or MIS in both cohorts was having surgery at an academic hospital or research cancer center. Long term beneficial outcomes have yet to be definitively proven in RCC^20,21, but receiving treatment at high-volume centers has been associated with improved outcomes and decreased mortality in esophageal, pancreatic, rectal, and testicular cancers ^22–25. We found that patients who traveled >12.6 miles were more likely to receive PN for cT1a and cT1b renal masses, whereas patients traveling more than >31.1 miles were more likely to undergo MIS for cT1a renal masses. For cT1b, the only distance traveled that was a significantly associated to MIS was 5.5–12.6 miles (Table 4). With the current data we are unable to determine what type of hospital these patients were traveling to or if there were closer locations to receive treatment, but the overall data demonstrates that traveling impacts the surgical treatment received. It remains to be understood if these differences impact overall survival or cancer-specific survival in RCC. Multiple retrospective studies on muscle-invasive bladder cancer have shown patients traveling farther for treatment did not experience inferior survival outcomes ^26,27. However, neither of these studies considered what non-medical factors may have influenced a patient’s decision not to travel for their oncologic treatment.

While the full effect of regionalization on oncologic outcomes in the United States is an area of active research, there have been numerous studies showing evidence supporting regionalization²⁸. Bristow et al. showed patients with ovarian cancer who were treated at high volume centers were more likely to receive standard of care treatment and have improved overall survival compared to those at low volume centers ²⁹. Ryan et al. concluded traveling to academic centers was associated with reduced mortality in patients with T2 bladder cancer ²⁷. Lautner et al. reported that patients treated at academic cancer centers had a greater likelihood of undergoing breast conserving surgery compared to those treated at community cancer centers³⁰. Finally, Khandwala et al., which looked at the impact of surgical volume on the outcomes of robotic-assisted partial nephrectomies, reported that high volume and very high volume surgeons have superior peri-operative outcomes compared to low volume surgeons³¹. Regionalization is an excellent way to deliver high-quality, cost-efficient health care by sharing information and standardizing practices, eliminating redundancies, improving resource allocation and capitalization on economies of scale. However, when considering regionalization efforts, health care access to vulnerable populations should be thoroughly examined and effect of the regionalization of RCC surgical treatment should continue to be an active avenue of investigation.

Our work demonstrates that while rates of cT1a and cT1b among African Americans are similar, they are more likely to receive a PN for T1b compared to T1a renal masses (Table 3). Several studies have shed light on the racial disparities among patients with RCC. A comparison of White and Black patients diagnosed with RCC demonstrated that White patients had a survival advantage over Black patients despite adjusting for factors such as age, sex, tumor stage or size, or surgical treatment ³². Furthermore, previous work has demonstrated that Black and Hispanic patients are less likely to receive PN. Moreover, Black patients treated at comprehensive community cancer and academic centers were less likely to received PN for T1a renal mass compared to White patients ³³. Recent work by Alameddine et al. demonstrated that Black and Hispanic patients were less likely to undergo robotic PN and more likely to undergo open PN for T1 renal masses ³⁴. However, our data do not show any significant finding for the Hispanic population after adjustment. While factors that contribute to these disparities are not immediately clear, access to healthcare may be one possible reason for the discrepancy of Black and Hispanics receiving PN for T1 renal masses. An additional factor that may contribute to the racial disparity is the inherent differences in the biology of RCC among different races. In a multi-institutional and prospective study, Sankin et al. showed that African Americans patients had higher rates of papillary RCC and lower rates of clear cell RCC ³⁵. In fact, overexpression of a tumor suppressor gene, BAP1, has been shown to be significantly higher in Black patients and was associated with lower pathologic stage, which may explain why more Black patients present with localized disease ³⁶. Taken together, factors that contribute to racial disparities in patients need further elucidation as they pose a significant challenge for public health efforts, but may also provide promise for possibly developing tailored strategies based on inherent difference in disease biology.

Our analysis found several socioeconomic variables, such as race, insurance status and type, and income to be associated with receipt of PN or MIS. The differences in patients receiving MIS or PN at community, comprehensive community cancer program, and integrated cancer centers compared to academic centers may suggest patients are not receiving the same standard of care at different types of accredited cancer centers and warrant patients traveling farther to receive treatment at large academic centers. Previous research has shown that socioeconomically disadvantaged groups were less likely to be offered MIS PN¹³. Furthermore, they showed that upper middle and high socioeconomic status, a variable that combined quartile ranking of education status and income status, predicted the use of PN for T1 renal masses. Although, both median annual income and education attainment were aggregated variables in our data, our study provides granularity in this matter, showing that household income, but not education level, was associated with type surgery received. Our study raises an important area of inquiry which has yet to be investigated– does the willingness and ability to travel for surgery explain the racial and economic disparities observed. A future avenue of investigation would be comparing socio-economic resources of patients that receive oncologic care at the cancer center closest to their home address to those who don’t.

There are several limitations to our study ^37,38. This study is a retrospective review of medical records and subject to all limitations inherent in such a design including coding and measurement error in data collection and losses to follow up. NCDB only contains data from patients treated at facilities participating in the committee on cancer accreditation, while this captures most cancer patients in the U.S. it is not truly representative of the total population.

CONCLUSION

Prior to the most recent AUA kidney cancer guideline, practice patterns were moving towards an increased utilization of PN and MIS as the use of robotic surgery became more commonplace and was applied to larger tumors. However, patients with fewer economic resources, including the ability to travel, were more likely to receive treatments that were not in line with those trends. We found significant variation in the treatment of patients with cT1a and cT1b RCC based on treatment location as well as a correlation between several socioeconomic variables and the type/extent of surgery received. Based on these findings, additional research is needed into access to specialty care, urologic oncology referral patterns, and the impact of regionalization of RCC surgery on PN and MIS utilization.

We aimed to identify factors associated with receipt of partial nephrectomy and minimally invasive surgery in patients with clinical T1 renal cell carcinoma using the National Cancer Data Base. Overall, data showed an increase in utilization of MIS and PN from 2010–2014. Patients in the lowest socio-economic groups, were less likely to travel, and were more likely to receive more invasive treatments. Based on these findings, additional research is needed on the effects of regionalization of RCC surgery.

In recent years there has been an increase in the utilization of minimally invasive and nephron sparing surgery for the treatment of renal cell carcinoma. Recent studies have also shown that high volume surgery centers and high volume surgeons have better peri-operative outcomes, but to date there has been little investigation into whether these changes have increased healthcare disparities. We attempted to use the national cancer database to see if any disparities based on socio-economic variables could be identified. Overall, data showed an increase in utilization of MIS and PN from 2010–2014. However, patients in the lowest socio-economic groups, were less likely to travel, and were more likely to receive more invasive treatments. Based on these findings, additional research is needed into how regionalization of RCC surgery will affect treatment disparities.