Comparison of Perioperative Outcomes for Radical Nephrectomy Based on Surgical Approach for Masses Greater Than 10 cm

Introduction

Since being introduced nearly 30 years ago, minimally invasive radical nephrectomy is now more commonly performed than open radical nephrectomy (ORN). ^1,2 Over this period, it has been demonstrated that laparoscopic radical nephrectomy (LRN) has similar oncological outcomes when compared with ORN, while providing improved perioperative morbidity, blood loss, analgesia requirements, and hospital length of stay. ^3,4 Since the introduction of robot-assisted radical nephrectomy (RRN), multiple studies have attempted to define its role in the management of renal masses while recognizing its high hospital costs. ^5,6 Despite its increased costs without proven benefit in perioperative or oncologic outcomes, RRN continues to become increasingly utilized in the United States. ⁵

There are few studies investigating trends and outcomes with minimally invasive techniques for very large renal masses >10 cm. ORN has remained the preferred approach for these very large masses given the surgical complexity and association with locally advanced or venous extension. ⁷ However, given increasing utilization and comfort with laparoscopic and robotic surgery for many urologic procedures, including radical nephrectomy, we sought to determine the role of minimally invasive approaches in these large renal masses. In this study, we use the National Cancer Data Base (NCDB) to compare the perioperative outcomes of ORN, LRN, and RRN for large renal masses greater than 10 cm.

Methods

Study population

We identified 20,790 patients ages 18 to 80 diagnosed with renal cancer from 2010 to 2015 with renal masses >10 cm. We sequentially excluded 8765 patients with stage cT3b-4 disease, 2152 patients who did not undergo radical nephrectomy, and 585 patients without defined surgical approach. The final study population included 9288 patients (Fig. 1).

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FIG. 1.

Consort flow diagram.

Results

Trends in surgical approach

Over the 6-year study period, RRN use increased from 4.1% to 14.8%, LRN from 20.9% to 25.6%, whereas ORN use decreased from 75% to 59.6%. The percentage of nephrectomies performed open was higher at community cancer programs than at academic programs, comprehensive community cancer programs, or integrated network cancer programs (71.2% vs 67.6%, 63.8%, 62.3%, respectively). ORN use increased from 59.9% to 78% with increasing tumor size (10–12.5, 12.5–15, ≥15 cm), whereas RRN decreased from 10.9% to 6.2% and LRN decreased from 29.2% to 15.7% (Fig. 2).

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FIG. 2.

Trends in surgical approach 2010–2015. LRN = laparoscopic radical nephrectomy; ORN = open radical nephrectomy; RRN = robot-assisted radical nephrectomy. Color images are available online.

In the subset of RRN and LRN, compared with 2010, there was an increasing likelihood to utilize RRN with each year with significance being reached from 2012 to 2015 (OR 1.57 vs 2.04 vs 2.30 vs 3.10 [2012–2015]; p < 0.013). Compared with community care programs, patients at integrated network cancer programs were significantly more likely to undergo RRN (OR 1.68; 95% CI 1.08–2.63). Compared with patients with comorbidity score of 0, patients with comorbidity score ≥2 were significantly more likely to receive RRN (OR 1.35; 95% CI 1.01–1.80). There was no difference with respect to age at diagnosis, race/ethnicity, or insurance type (Results not shown).

Discussion

Minimally invasive approaches for radical nephrectomy continue to grow in popularity. ^5,8,9 The cohort examined in this study not only corroborates these data, but also demonstrates a similar trend in radical nephrectomies for very large renal masses.

Few studies have specifically focused on the application of minimally invasive techniques for removal of large masses, and those exclusively investigating masses >10 cm have been limited by small cohorts. ¹⁰ A recent multi-institutional retrospective analysis conducted by the ROSULA collaborative group compared the perioperative outcomes between RRN and LRN for ≥cT2 renal masses. This was the first study to compare LRN to RRN for large masses on a large scale, however, the masses observed ranged in size from 7.4 to 10.2 cm. ¹¹ Despite the increasing utilization of LRN and RRN for renal masses measuring >10 cm, perioperative outcomes have yet to be reported on the scale that they are within this study.

Between 2010 and 2015, use of LRN gradually decreased, RRN increased, and ORN remained relatively stable for renal masses of all sizes. ⁵ In contrast, for masses >10 cm over the same period, LRN was still increasingly utilized. Over the study period, the proportion of large mass radical nephrectomies completed with LRN increased by 4.7%. The proportion of radical nephrectomies using RRN more than tripled during the same period, increasing by 10.7%. This may demonstrate a growing preference for RRN over LRN despite higher cost. ⁵

A well-documented barrier to wide implementation of minimally invasive radical nephrectomy for larger tumors is its perceived technical difficulty, particularly by surgeons who have not received extensive training in minimally invasive techniques. ^12,13 However, robotic surgery is known to have a less significant learning curve, provide better visualization, offer superior mechanical stabilization and allow for improved ergonomics when compared with laparoscopic techniques. ^14,15

Features unique to the robotic platform, including the use of the fourth arm and the articulation of endowrist instruments may also help with more challenging nephrectomies. These advantages may be a primary factor leading surgeons to increasingly prefer RRN over LRN when choosing a minimally invasive technique, particularly for large masses, which are often more technically complex to remove. ¹⁶ Additional possible contributing factors include growing emphasis on robotic surgery in urology residency/fellowship curriculum and patient demand. ^{17 –20}

Within this cohort, it is evident that ORN remains the preferred method for very large, operatively complicated masses. ORN was used with increased frequency as renal mass size increased, with 78% of masses >15 cm being removed with an open approach. While the advantages of robotic surgery may ultimately have some benefit for large, surgically complex masses, RRN for very large renal masses has only recently become more common. ²¹ Possible explanations for this trend include continued advancement in robotic technology and the comfort level of robotic surgeons to perform more complex procedures. ²² This may explain why academic and integrated network cancer programs were more likely to use RRN than community cancer programs.

On meta-analysis, LRN has demonstrated superiority to ORN in both overall mortality and postoperative complications, but only for masses <7 cm. ²³ Similarly, in more limited studies, RRN has been shown to have equivalent perioperative outcomes and postoperative complication rates to LRN. ^6,24 In our study of large masses, LRN and RRN were statistically equivalent to ORN for all observed perioperative outcomes with the exception of length of hospital stay, which was significantly shorter for both LRN and RRN. Length of stay for LRN and RRN was comparable. These results suggest that both LRN and RRN can be successfully employed for selected renal masses >10 cm, while allotting the patient shorter recovery times.

The cost of procedures is often discussed as a shortcoming of RRN when compared with LRN, given otherwise similar perioperative results. However, conversion to ORN from a minimally invasive radical nephrectomy has rarely been analyzed on a significant scale. ^5,25 Helmers and colleagues found that in a single institution cohort of 319 patients, with masses of a median diameter of 5.5 cm, in years 2010 to 2014, conversion to another approach was significantly higher for RRN than LRN (11.1% vs 1.0%, p < 0.001), although the authors noted that the majority of RRN conversions occurred early in the surgeon's robotic surgery experience. ⁶

A recent meta-analysis of perioperative outcomes for radical nephrectomy from Li and colleagues (mass median diameter 5.6–8.7 cm) demonstrated similar rates of conversion when comparing RRN and LRN (3.88% vs 1.60%, p = 0.16). ²⁶ In this study, a contradictory observation was made that conversion to open was more likely for LRN than RRN (11.4% vs 7.7%; p = 0.0025). The cohort of surgeons reported in this study may have been adequately robust and diverse to account for a small number of RRN conversions attributable to novice robotic surgeons overcoming the learning curve of robotic surgery. It is also possible that surgeons choosing LRN may be more prone to elect to convert to ORN than those with a robotic setup. However, with advancing robotic technology, RRN may offer particular benefit for large masses, leading to the trend observed in this study and explaining the difference in results from studies of masses of smaller median diameter. In other surgical fields, laparoscopic surgery has also been shown to have a greater risk of conversion than robotic surgery and conversion has been shown to substantially increase the cost of surgery. ^27,28 Increased cost associated with conversion is partially due to the associated increased length of hospital stay. ²⁹ On average, conversion to open resulted in an additional 1.3-day hospital stay, which was similar to the average length of stay for ORN. There is evidence to suggest that the cost discrepancy between RRN and LRN may not be as significant as previously thought. ^6,26 Future cost analysis could further justify these findings by determining if the discrepancy in conversion rate between LRN and RRN in large renal masses specifically is considerable enough to offset the higher base cost of RRN.

Conclusion

Minimally invasive approaches are increasingly utilized for very large renal masses. In selected patients, LRN and RRN can be performed as safely as ORN for renal masses >10 cm. After adjusting for covariates, RRN has lower rates of conversion to open but produces comparable perioperative outcomes to LRN. LRN and RRN both resulted in significantly shorter length of inpatient hospital stay but are otherwise equivalent to ORN for all other perioperative outcomes. RRN may offer technical advantages that allow it to be more easily implemented for very large, technically complex, renal masses than LRN, while still offering the benefits of minimally invasive surgery.