Racial Differences in Risk Factors for Kidney Stone Formation

BACKGROUND AND OBJECTIVES

Incidence of kidney stone disease is rising. It is not known whether mechanisms of stone formation differ across racial groups. Our objective was to identify differing lithogenic risk factors across racial groups in idiopathic nephrolithiasis.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We conducted a retrospective cohort study evaluating metabolic risk factors in black and age-matched white idiopathic stone formers at our tertiary referral center. We compared serum and urine metabolic risk factors pre- and post-treatment across racial groups using analysis of covariance. Generalized linear modeling was used to build regression models for risk of stone formation in both groups.

RESULTS

Among 117 black and 172 white stone formers, urine volume was lower in black stone formers (1.4±0.8 versus 2.0±0.8 L/d, P<0.001). Urine calcium was lower in black stone formers (116±70 versus 217±115 mg/d, P<0.001). Supersaturations for calcium oxalate were similar among the groups, whereas calcium phosphate supersaturation was higher in white stone formers, and uric acid supersaturation was higher in black stone formers. Electrolyte free water clearance was significantly lower in black stone formers (207±780 versus 435±759 ml/d, P=0.02). In the subgroup of 77 black patients and 107 white patients with post-treatment evaluations, urine volume rose significantly and similarly in both groups. Urine sodium was unchanged in whites but increased in blacks by 40 mmol/d (95% confidence interval, 32 to 48 mmol/d). Electrolyte free water clearance remained lower in black stone formers (385±891 versus 706±893 ml/d, P=0.02). Post-treatment supersaturations were similar across the groups except for calcium phosphate, which improved with treatment in whites.

CONCLUSIONS

Black stone formers have lower 24-hour urine calcium excretion and urine volume. Increases in urine volume with treatment were associated with increased solute, but not free water, excretion in black stone formers.

The role of inguinal lymph node dissection in men with urethral squamous cell carcinoma

INTRODUCTION

Urethral squamous cell cancer is a rare disease with limited clinical recommendations regarding management of the inguinal lymph nodes. Despite the similarities to penile cancer in terms of squamous cell carcinoma (SCC) histology and lymphatic drainage, there is not enough evidence to recommend for or against a prophylactic inguinal lymph node dissection (ILND) in patients with clinically negative groins and a primary tumor stage of T1b or higher. The objective of the study was to identify the rate of prophylactic inguinal lymph node dissection, node positive rate, and overall survival in patients with clinical T1 to T4 stage. The patients were separated into clinical N stage and the rates of node positivity were compared. We hypothesize that the node positivity rate would be similar to that observed in penile cancer of similar clinical T and N stage and provide evidence for prophylactic inguinal lymph node dissection in urethral squamous cancer. We also sought to determine the value of ILND in clinically node positive (cN+) and clinically node negative (cN-) patients.

METHODS

The National Cancer Database was queried for all cases of primary urethral cancer in men from 2004 to 2014. Patients with other cancer diagnoses, metastasis, nonsquamous histology, female patients, and patients with a history of radiation therapy were excluded. Male patients with urethral squamous cell cancer of the anterior urethra with T1 or higher T stage were included in this study. All-cause mortality was compared using multivariable Cox regression controlling for covariates.

RESULTS

The study included 725 men with urethral SCC with T1 or higher clinical T stage. The median age was 63 years (33-83 interquartile range). Of the 725 men, 536 men did not receive an ILND and 189 (26%) underwent ILND. Patients who received LND had significantly higher clinical T and clinical N stage. There was no difference in age, sex, or histology between those with ILND versus no ILND. In patients with T1 to T4 and clinical N0, the ILND rate was 21.8% (89/396). The lymph node positive rate in patients with N0 and T1 to T4 primary tumor was 9%. In patients with clinically node positive disease (N1/N2), the overall ILND rate was 76%. The lymph node positive rate for patients with clinical nodal disease was 84%. On multivariable analysis cox regression, lymph node positivity was associated with worse overall survival when controlling for T stage, clinical N stage, and age (HR 1.56, 95% 1.3-1.9, P = 0.000). On multivariable analysis after controlling for T stage, sex, and age, having an ILND was associated with improved OS in patients with clinical N1 or N2 disease (HR 0.46, 95% 0.28-0.78 P = 0.002).

CONCLUSION

The node positivity rate in patients with T1 to T4 and N0 is 9%, much lower than reported in penile cancer with a high-risk primary tumor but clinically negative groins. This argues against routine prophylactic inguinal ILND in patients with urethral SCC who are clinically N0, perhaps suggesting different biological behavior of urethral SCC compared to penile SCC. Performing a lymph node dissection in patients with clinically N1 or N2 disease is associated with improved OS.

The Association Between Tetrahydrocannabinol and Lower Urinary Tract Symptoms Utilizing the National Health and Nutrition Examination Survey

OBJECTIVE

To further define the relationship between tetrahydrocannabinol (THC) and lower urinary tract symptoms (LUTS), specifically how THC use associates with the frequency of LUTS in young community-dwelling men in the United States.

MATERIALS AND METHODS

The National Health and Nutrition Examination Survey database was queried (2005-2008). Men ages 20-59 who completed the urinary and substance abuse questionnaires were included. The presence of LUTS was defined as having ≥2 of the following: nocturia (≥2), hesitancy, incomplete emptying, or incontinence. THC use was self-reported, and participants were considered regular smokers if they endorsed smoking at least once per month. Multivariable logistic regression was performed to analyze the relationship between THC and LUTS.

RESULTS

Among 3,037 men who met inclusion criteria, 14.4% (n = 477) of subjects reported THC use. In multivariable analyses, adjusting for clinical variables, regular THC users remained significantly less likely to report LUTS (odds ratio of 0.55; confidence interval 95% 0.408-0.751, P <.01) compared to nonusers.

CONCLUSION

Obesity, diabetes, and multiple comorbidities are well-established risk factors for LUTS within the National Health and Nutrition Examination Survey. Regular THC use, however, appears to be protective from LUTS in young community-dwelling men.

Proteinuria is a Predictor of Renal Functional Decline in Patients with Kidney Cancer

PURPOSE

Prior studies have shown that 26% to 34% of patients with suspected renal cancers have a glomerular filtration rate less than 60 ml/minute/1.73 m(2) but limited information exists regarding proteinuria. We investigated the extent of proteinuria in patients with renal tumors to determine the impact on the classification and progression of chronic kidney disease.

MATERIALS AND METHODS

Among 1,622 patients evaluated between 1999 and 2014, 1,016 had preoperative creatinine and proteinuria measurements available. Patients were classified according to the risk of chronic kidney disease progression into low, moderately increased, high and very high risk groups according to 2012 KDIGO guidelines. Predictors of risk group and chronic kidney disease progression were analyzed using univariable and multivariate models.

RESULTS

Before treatment 32% had a glomerular filtration rate less than 60 ml/minute/1.73 m(2). Preoperative proteinuria was present in 22%. Proteinuria was detected in 30% with a reduced glomerular filtration rate and 18% with a normal glomerular filtration rate. Among the 44% at increased risk for chronic kidney disease progression 24%, 12% and 8% were at moderately increased, high and very high risk, respectively. The presence of proteinuria also reclassified 25% with stage III chronic kidney disease as high or very high risk. KDIGO classification predicted renal functional decline, which occurred in 2.2%, 4.4%, 9.4% and 34.6% at 3 years in low, moderately increased, high and very high risk categories, respectively. Predictors of KDIGO group included age and tumor size (each p <0.001), and the main predictors of renal functional decline were KDIGO group, tumor size and radical nephrectomy (each p <0.0001).

CONCLUSIONS

Identification of chronic kidney disease using only glomerular filtration rate left 18% of patients undiagnosed. The assessment of glomerular filtration rate and proteinuria classified patients according to risk of chronic kidney disease progression, identifying 44% to be at increased risk. As proteinuria predicted renal functional decline, we advocate for routine evaluation before treatment.

Laparoendoscopic single site, laparoscopic or open surgery for adrenal tumors: Selecting the optimal approach

Numerous surgical modalities are available to treat adrenal lesions. Minimally-invasive approaches for adrenalectomy are indicated in most circumstances, and new evidence continues to be accumulated. In this context, current indications for open surgical adrenalectomy (OS-A), minimally-invasive adrenalectomy (MI-A), and laparoendoscopic single-site adrenalectomy (LESS-A) remain unclear. A comprehensive English-language literature review was performed using MEDLINE/PubMED to identify articles and guidelines pertinent to the surgical management of adrenal tumors. A comprehensive chart review was performed for three illustrative cases. Clinical recommendations were generated based on relevant literature and the expertise of the investigator group. MI-A offers advantages over OS-A in properly selected patients, who experience fewer complications, lower blood loss, and shorter hospital stays. Robot-assisted laparoscopic and retroperitoneoscopic adrenalectomy may offer advantages over transperitoneal surgery, and LESS-A may be an even less-invasive option that will require further evaluation. MI-A remains the surgical treatment of choice for most adrenal lesions. Tumor size and stage are the primary indications for selecting alternative treatment modalities. OS-A remains the gold standard for large tumors (> 10 cm) and suspected or known advanced stage malignancy. LESS-A appears to be an appropriate initial approach for small tumors (< 4-5 cm), including pheochromocytoma and isolated adrenal metastases.

Do we know (or just believe) that partial nephrectomy leads to better survival than radical nephrectomy for renal cancer?

PURPOSE

Partial nephrectomy (PN) has become the gold standard for treating small renal masses amenable to such an approach. Surprisingly, the single randomized controlled trial of PN versus radical nephrectomy (RN) indicated an overall survival benefit for RN over PN. Recent studies have shed light on this discordance, and this review will attempt to discern what is known at present.

RESULTS

Multiple retrospective observational studies have demonstrated superior outcomes with PN compared with RN. Whether the observed survival benefit with PN is the result of renal functional advantages or the result of selection bias and other unmeasured variables is up for discussion. A meta-analysis of 21 studies including the EORTC 30904 found a 19 % reduction in all-cause mortality (p = 0.0001) and 29 % reduction in cancer-specific mortality (p = 0.0002) with PN versus RN. Recent analysis of SEER-Medicare data revealed that patients undergoing RN had similar survival when compared with non-cancer controls, further supporting concerns about selection biases in prior observational series.

DISCUSSION

Although PN is clearly of benefit for those likely to experience end-stage renal disease with RN, a survival benefit with PN in the elective setting is not proven at present. While experts may still believe PN to improve survival for these patients, the only level I evidence in the field would suggest otherwise, and selection bias is undoubtedly responsible for a significant part of the improved survival observed in retrospective studies. Given recent evidence, any further push to limit the role of RN should be tempered until we know PN is indeed superior.

Variation in prostate cancer detection rates in a statewide quality improvement collaborative

PURPOSE

There remains significant controversy surrounding the optimal criteria for recommending prostate biopsy. To examine this issue further urologists in MUSIC assessed statewide prostate biopsy practice patterns and variation in prostate cancer detection.

MATERIALS AND METHODS

MUSIC is a statewide, physician led collaborative designed to improve prostate cancer care. From March 2012 through June 2013 at 17 MUSIC practices standardized clinical and pathological data were collected on a total of 3,015 men undergoing first-time prostate biopsy. We examined pathological biopsy outcomes according to patient characteristics and across MUSIC practices.

RESULTS

The average cancer detection rate was 52% with significant variability across MUSIC practices (range 43% to 70%, p<0.0001). Of all patients biopsied 27% were older than 69 years, ranging from 19% to 36% at individual practices. Men with prostate specific antigen less than 4 ng/ml comprised an average of 26% of the study population (range 10% to 37%). The detection rate in patients older than 69 years ranged from 42% to 86% at individual practices (p=0.0008). In the 793 patients with prostate specific antigen less than 4 ng/ml the cancer detection rate ranged from 22% to 58% across individual practices (p=0.0065). The predicted probability of cancer detection varied significantly across MUSIC practices even after adjusting for patient age, prostate specific antigen, prostate size, family history and digital rectal examination findings (p<0.0001).

CONCLUSIONS

While overall detection rates are higher than previously reported, the cancer yield of prostate biopsy varies widely across urology practices in Michigan. These data serve as a foundation for our efforts to understand and improve patient selection for prostate biopsy.