nephron - sparing surgery ( nss ) offers equivalent oncologic control , as does radical nephrectomy in patients with appropriately selected stage t1 renal tumors [ 1 , 2 ] .
additionally , nss has been associated with decreased risks for renal impairment [ 35 ] and cardiovascular events [ 6 , 7 ] , which may explain the improved overall survival , documented in partial nephrectomy series .
as the benefits of nss become apparent , the indications may continue to expand . in order to establish standards for future comparisons
, we must fully appreciate the efficacy , safety , and limitations of nss for renal masses larger than 7  cm .
therefore , we reviewed our experience and reported the results in 17 patients with renal masses , which had a maximum diameter of more than 7  cm on preoperative imaging studies , treated with either open or robot - assisted laparoscopic nss during 13 years .
between 2001 and 2012 , a single surgeon ( te ) performed 139 nsss ( 97 open , 35 robot - assisted , and 7 laparoscopic nsss ) in one center .
we retrospectively reviewed the charts of the patients , whose renal tumors measured more than 7  cm in diameter on preoperative imaging ( n = 17 , 17.52% ) .
preoperative evaluation consisted of laboratory tests and cross - sectional imaging studies ( computerized tomography and/or magnetic resonance imaging ) .
( radius , exophytic / endophytic , nearness , anterior / posterior , location ) scoring system . based on preoperative radiologic findings ,
open nephron - sparing surgery ( onss ) was performed using the intercostal ( between 11th and 12th ribs ) extraperitoneal flank approach , as previously described elsewhere in detail .
robot - assisted nephron - sparing surgeries ( ransss ) were performed using the da vinci surgical system ( intuitive surgical , inc . ,
sunnyvale , ca , usa ) with a 5-port approach , including two 8  mm ports for robotic instruments , one 12  mm port for the robotic scope , and 2 ports for the bedside assistant .
ransss were carried out through the transperitoneal route with the patient in the flank position .
after demarcating tumor margins with electrocautery , enucleoresection was carried out using cold scissors , leaving a minimal margin of normal parenchyma .
the tumor bed was overseen with 30 polyglactin sutures ( in case of pelvicalyceal violation ) , and parenchyma was adapted with the sliding clip technique .
operative data consisted of total operative time , estimated blood loss ( ebl ) , warm - ischemia time ( wit ) , and adverse events .
all complications within 30 days of surgery were classified according to the clavien - dindo classification system .
estimated glomerular filtration rate ( egfr ) was determined before and after nss using the modified modification of diet in renal disease ( mdrd ) equation .
tumor staging was designated according to the tnm classification based on the 2009 american joint committee on cancer / international union against cancer classification system .
tumor recurrence was defined as a new renal mass in the resection bed of the kidney in the absence of distant metastasis based on imaging .
followup was calculated from the time of surgery until the last known contact with the patient or until the date of death .
student 's t - test and fisher 's exact test were the statistical methods of reference .
a total of 17 patients with clinical t2 renal masses ( > 7  cm ) have undergone nephron - sparing surgery between 2001 and 2012 , at our institution .
thirteen patients ( 76.4% ) were treated through the open route ( figure 1 ) , while 4 patients ( 23.5% ) were managed by ranss ( figure 2 ) .
mean age of the study population was 49.8  11.3 years ( range = 3066 ) .
mean asa score of the operated patients was 1.1  0.39 ( range = 13 ) .
the majority of the tumors were discovered incidentally ( n = 11 , 64.7% ) .
nss was offered based more commonly on elective indications . the indication to perform nss was imperative
( bilateral mass n = 2 , solitary kidney n = 1 ) in 3 patients ( 17.6% ) . mean tumor size was 8.24  2.45 ( range = 615 ) cm according to the final pathology reports .
diameter of the resected tumor was measured less than 7  cm in 5 patients ( 29.4% ) whose preoperative imaging findings were suggestive of a t2 lesion . mean tumor size in these 5 cases was 6.1  0.14 ( range = 66.3 ) .
mean estimated blood loss amount were 125  35.4 minutes ( range = 75220 ) and 267.6  117.1  ml ( range = 100500 ) , respectively .
mean warm - ischemia time was 15.2  4.1 minutes ( range = 1021 ) in the 8 surgeries ( 47% ) during which tumor was enucleoresected after clamping the renal pedicle .
scores of the tumors that were managed under ischemic and nonischemic conditions was statistically insignificant ( 8.6 versus 8.4  p = 0.72 ) .
open conversion during robot - assisted surgery was necessary in 2 cases , whose tumors had r.e.n.a.l .
patients were hospitalized for a mean duration of 5    5.4 days ( range  =   326 ) .
three patients suffered from a total of 6 grade 2 and higher complications within 30 days of surgery .
blood transfusion and bladder recatheterization due to gross hematuria were the recorded grade 2 and 3a complications in 2 patients , respectively .
blood transfusions , angioembolization , double - j catheter insertion due to urinary extravasation , and temporary hemodialysis are counted for the grade 2 , 3a , 3b , and 4a complications encountered during the postoperative course of another patient who had a 9  cm enhancing mass in his solitary kidney ( figure 4 ) .
mean preoperative and postoperative egfr was 89.3  20.5  ml / min/1.73  m ( range = 60136.1 ) and 76.9  23.5  ml / min/1.73  m ( range = 8.3111.6 ) , respectively .
the difference between these 2 mean values was statistically insignificant ( p = 0.11 ) .
mean duration of follow - up was 35.2    28.1 months . during the followup period ,
tumor bed recurrence was detected in one patient ( 5.8% ) , who underwent radical nephrectomy as a complementary procedure in another center .
none of the patients in this cohort was lost either due to rcc or due to other comorbidities .
multiple previous studies have shown the oncological equivalency of nss to radical nephrectomy ( rn ) for t1a and even t1b renal masses [ 2 , 2427 ] . considering the facts that some of these localized renal lesions will be benign and/or
low grade , and renal preservation has documented benefits on long - term cardiovascular health [ 68 ] , the guidelines advocate nss as a standard of care for all t1 renal masses .
although , there is a paucity of clinical series evaluating the oncologic results of nss for t2 renal lesions , initial results are encouraging ( table 2 ) .
found that cancer - specific survival and overall survival were similar between nss and rn for t2 tumors or greater .
karellas et al . found that 71% of the patients were alive and free of disease at a median followup of 17 months .
becker et al . reported 5-year overall and cancer - specific survival rates of 88.0% and 97.0% , respectively .
conversely , hafez et al . found a significant increase in recurrence rates as well as decreased survival in their study consisting of partial resections performed for tumors  7  cm in size .
it is also important to note that a recent analysis of almost 19.000 localized rccs in the seer database showed that greater than 75% of localized renal cancers > 7  cm in size and more than 65% of those > 10  cm in size are low - grade lesions , suggesting that nss for large renal masses may be oncologically sound . in our series , after a median followup of 33 months , all 17 patients were alive and free of disease .
local recurrence was detected only in one patient ( 5.8% ) , 10 months after the nephron - sparing procedure .
undoubtedly , nss for tumors larger than 7  cm represents a surgical challenge , especially in relatively unexperienced hands .
the surgical team has to decide upon the route ( open , laparoscopic , or robot assisted nsss ) by which resection is going to be carried out .
the idea and the method of ( clamping the vasculature or manual parenchymal compression ) creating ischemic conditions is another tough decision to be made . maintaining hemostasis and reconstructing the pelvicalyceal system over a large parenchymal defect might be technically demanding especially while performing minimally invasive nss .
surgical expertise , technologic availabilities , and patient preference will definitely have an influence on the surgical choices .
hence , preoperative morphometric data might tailor the surgical approach . in our series , mean r.e.n.a.l .
score of the tumors that were resected under perfused conditions was insignificantly lower than that of the tumors operated under ischemic conditions . although being lower in the robotic group , the difference between robot - assisted group ( n = 4 ) and open surgical group ( n = 13 ) in terms of mean r.e.n.a.l .
furthermore , none of the patients for whom open surgery was employed had a tumor with low r.e.n.a.l .
conversely , one patient ( 25% ) in the robotic group had a tumor in the low r.e.n.a.l . score category .
long et al . evaluated the results of 46 patients with 49 clinical t2 renal tumors and reported a major urological complication in the form of a urinary fistula in six ( 12.2% ) patients . in the other reported series for ct2 nsss , the rate of urinary fistula was in the range of 3.3 to 18.8% [ 1823 ] . in our series , only one patient ( 5.8% ) suffered from urinary extravasation .
furthermore , our transfusion rate was 11.7% ( n = 2 ) , which is concordant with the range reported in the literature ( 030% ) .
as shown by previous studies , almost 1/3 of the clinical t2 tumors were either benign or represented a very low - grade malignancy ( chromophobe rcc ) , emphasizing the importance of renal preservation when technically feasible , regardless of tumor size [ 17 , 18 ] . in our cohort ,
23.5% of the tumors were reported to have benign histology , while 46% of the rccs were of either papillary or chromophobe subtype ( table 1 ) .
it has been reported that , up to 26% of the patients with renal masses have preexisting stage 3 and higher chronic kidney disease ( ckd ) , defined as a glomerular filtration rate ( gfr ) of < 60  ml / min/1.73  m .
additionally , radical nephrectomy has been regarded as a significant risk factor for developing ckd .
this mild renal impairment in our study population with a mean age of 50 years and mean asa score of 1.18 should be interpreted cautiously .
our cohort may be subjected to selection biases and therefore may not reflect the actual renal functional status of the patients awaiting nephron - sparing surgery .
in other clinical series dealing with nss for t2 masses , median preoperative egfr varied between 65 and 92  ml / min/1.73  m. in an era , where the incidence of metabolic syndrome and associated clinical consequences are on the rise , these facts should be considered before planning surgery for any renal mass , not only for t1 lesions or imperative indications .
furthermore , renal functional status should be evaluated by egfr calculations , since serum creatinine value is not a sensitive tool that can detect early phases of renal impairment .
the importance of egfr was emphasized by a study showing that as many as 12.5% of all patients and 23% of patients aged 70 years presenting with an enhancing renal mass and normal serum creatinine ( < 1.4  mg / dl ) had unrecognized ckd stage 3 or higher . in the clinical series evaluating the results of nss for tumors
> 7  cm in size ( table 2 ) , renal functional maintenance , which may be considered as the primary advantage of nss , has been highlighted .
long et al . reported advancement in ckd stage in only 11% of their study population .
breau et al . detected a median increase in serum creatinine value by 9.5% compared to 33% for rn . in the studies conducted by becker et al .   and karellas et al .
demonstrated a small increase in mean serum creatinine values at followup in their small cohort of patients . in our study , median egfr value decreased from 89.37 to 79.15  ml / min/1.73  m postoperatively and ckd stage progressed in 5 patients ( 29.4% ) .
temporary renal replacement therapy , in the form of hemodialysis , had to be initiated for one patient who had a large ( 9  cm ) upper pole mass in his solitary kidney .
although the surgery was carried under nonischemic conditions , the extent of the resection may be the factor underlying the need for renal replacement .
our study has several limitations such as the retrospective nature with its inherent biases , small sample size , heterogeneous study population , limited follow - up duration , and pathological understaging in 5 patients .
nonetheless , our findings are in concordance with the previous studies , encouraging the utility of nss for renal masses larger than 7  cm .
nephron - sparing surgery is a feasible option for renal masses , measuring larger than 7  cm on preoperative imaging studies . despite a limited duration of followup in our series
renal functional status did not change significantly after nss for large ( > 7  cm ) renal masses .
less than 1/5 of the study population suffered grade 2 and higher complications during the postoperative period .
regardless of tumor stage , nephron - sparing surgery may be considered for carefully selected patients , including those with a normally functioning contralateral kidney .
 
 objectives . to document the feasibility of nephron - sparing surgery ( nss ) for the surgical treatment of renal masses measuring larger than 7  cm ( ct2 ) on preoperative imaging . methods . 
 a total of 139 patients have undergone nss between 2001 and 2012 by a single surgeon in our clinic . of these 
 , we identified 17 patients whose tumors were measuring greater than 7  cm on preoperative imaging studies and were limited to the kidney . 
 their charts were retrospectively reviewed . 
 results . 
 mean age of the study population was 49.8  11.3 years . 
 thirteen patients were managed by open nss , while 4 patients have undergone robot - assisted nss . 
 mean diameter and mean r.e.n.a.l . 
 score of the tumors that were enucleoresected were 8.2  cm and 8.5 , respectively . 
 a total of 5 clavien grade 2 and higher complications were recorded within 30 days of surgery . 
 histopathologic examination revealed benign histology in almost 1/4 of the cases . after a median followup of 33 months , all of our patients were alive . 
 only one patient ( 5.8% ) experienced local recurrence . 
 conclusions . 
 nss is a feasible and safe option for large ( > 7  cm ) renal masses . 
 it may be considered not only for imperative conditions but also for highly selected cases with a normal contralateral kidney . 
1. Introduction
2. Methods
3. Results
4. Discussion
5. Conclusions