Partial Nephrectomy in pT3a Tumors Less Than 7 cm in Diameter Has a Superior Overall Survival Compared to Radical Nephrectomy

Objectives We conducted this study to analyze the survival rates of patients with advanced renal tumors <7 cm in diameter treated surgically by partial nephrectomy (PN) compared to those who received radical nephrectomy (RN). Material and methods We retrospectively analyzed clinical data from 55 consecutive patients from our institutional database with T3a renal cell carcinoma of <7 cm treated surgically either by PN (n = 38) or RN (n = 17) in the Department of Urology of Ludwig Maximilians University from January 2006 to August 2014. The overall survival (OS) rates were calculated according to Kaplan-Meier estimation. Results The median age of the population was 67.9 years (range: 39.4 to 87.9 years). The median blood loss was 164.1 ml (range: 0 to 1200 ml), and the median clamping time was 8.85 minutes (range: 0 to 38 minutes). On average, the surgery lasted for 118 minutes (range: 40 to 210 minutes). The median serum creatinine level measured was 1.2 mg/dl (range: 0.7 to 2.3 mg/dl) preoperatively, and 1.4 mg/dl (range: 0.7 to 4.3 mg/dl) postoperatively. The median creatinine serum level measured during follow up was 1.4 ng/ml in individuals with a PN (range: 0.7 to 3.2 ng/ml), and 1.5 ng/ml in those with an RN (range: 0.9 to 4.3 ng/ml). Patients with an RN had a median OS of 38.6 months (range: 0 to 63.3 months). The median OS for patients with a PN was not reached after a follow-up of 80 months. The difference in OS in patients with PN and RN was statistically significant (P < 0.005). Conclusion Performing a PN in T3a tumors leads to better survival rates compared to an RN. In tumors <7cm, cT3a does not seem to be a contraindication for a PN. Further data should be analyzed to prove this survival benefit in a larger, multi-institutional cohort.


Material and methods
We retrospectively analyzed clinical data from 55 consecutive patients from our institutional database with T3a renal cell carcinoma of <7 cm treated surgically either by PN (n = 38) or RN (n = 17) in the Department of Urology of Ludwig Maximilians University from January 2006 to August 2014. The overall survival (OS) rates were calculated according to Kaplan-Meier estimation.

Results
The median age of the population was 67.9 years (range: 39.4 to 87.9 years). The median blood loss was 164.1 ml (range: 0 to 1200 ml), and the median clamping time was 8.85 minutes (range: 0 to 38 minutes). On average, the surgery lasted for 118 minutes (range: 40 to 210 minutes). The median serum creatinine level measured was 1.2 mg/dl (range: 0.7 to 2.3 mg/dl) preoperatively, and 1.4 mg/dl (range: 0.7 to 4.3 mg/dl) postoperatively. The median creatinine serum level measured during follow up was 1.4 ng/ml in individuals with a PN (range: 0.7 to 3.2 ng/ml), and 1.5 ng/ml in those with an RN (range: 0.9 to 4.3 ng/ml). Patients with an RN had a median OS of 38.6 months (range: 0 to 63.3 months). The median OS for patients with a PN was not reached after a follow-up of 80 months. The difference in OS in patients with PN and RN was statistically significant (P < 0.005).

Conclusion
Performing a PN in T3a tumors leads to better survival rates compared to an RN. In tumors <7cm, cT3a does not seem to be a contraindication for a PN. Further data should be analyzed to prove this survival benefit in a larger, multi-institutional cohort.

Introduction
Surgery is carried out in a curative intention in patients with localized renal cell carcinoma (RCC). According to the European Association of Urology Guidelines, a partial nephrectomy (PN) is indicated in patients with T1a tumors (<4 cm). In T1b tumors (4 to 7 cm), a PN is favored over a radical nephrectomy (RN) whenever feasible. For T2 and advanced RCC, the decision to use PN should be made individually based on localization, kidney function, comorbidities, and surgical experience [1].
Nephron-sparing surgery improves overall survival (OS) in patients with localized RCC <4 cm, mainly due to the reduction in postsurgical kidney impairment [2][3][4]. A reduced glomerular filtration rate is associated with higher cardiovascular mortality, and an RN leads to a higher rate of kidney failure [2][3][4]. Several studies have shown a similar oncological outcome, a higher OS rate, and reduced morbidity after a PN [5][6]. Thus, PN has become the standard treatment for small renal tumors. Sometimes, after PN, the final pathology reports of small renal tumors reveal an advanced histological stage.
This study aimed to compare the oncological and functional results in patients who underwent a PN versus an RN with tumors classified as pT3a (<7 cm in diameter).

Statistical analysis
The qualitative and quantitative variables were compared using the Chi-squared and Student's t-test. OS rates were calculated with Kaplan-Meier analysis. Log-rank tests were used to compare differences between curves. P-values <0.05 were considered significant. All statistical analyses were processed with Statistical Package for the Social Sciences (SPSS) software version 17.0 (SPSS, Inc, Chicago, IL).

Patients, tumor characteristics, and surgical data
A total of 55 patients from the Department of Urology of LMU were included. There were 40 men (72.7%) and 15 women (27.3%). The median age at diagnosis was 67.9 years (range: 39.4 to 87.9), and the median tumor size measured 4.0 cm (range: 0.8 to 6.9 cm

Comparison of OS according to the type of surgery
After a median follow-up of 80 months, the median OS after PN had not been reached and differed significantly from that after an RN, with a median OS after an RN of 38.6 months (range: 0 to 63.3 months; P < 0.005; Figure 1).

FIGURE 1: OS in patients after PN was higher than in patients after RN with statistical significance (p <0.005)
OS, overall survival; RN, total nephrectomy; PN, partial nephrectomy; pts., patients

Discussion
As the indications for a PN have been pushed towards larger tumors over the last decades, PN is conducted in even advanced renal tumors [6]. As a PN is more challenging than an RN, experienced surgical skills are necessary for these procedures. As a PN is conducted in patients with larger tumors, the number of incidental pT3a tumors rises and clinical to pathological T3a upstaging occurs more frequently [7].
Being confronted with such a pathology report, the urologist might wonder if an RN in pT3a RCC would have resulted in better cancer control. So far, there is no clear evidence on the oncological outcome in limited-size pT3a RCC treated by a PN. To our knowledge, we are the first to demonstrate that a PN in pT3a RCC <7 cm in diameter leads to a survival benefit compared to an RN.
Some studies investigated the outcome after PN in pT3a RCC. Jong Jin Oh et al. compared recurrence-free survival after PN (n = 45 patients) and RN (n = 298 patients) with clinical T1a, pathological T3a RCC and revealed a higher recurrence rate after RN during a 43-month followup (P< .001). In the PN cohort, there was no tumor size above 7 cm. The RN cohort included more large-sized tumors. Performing an RN in large pT3a tumors resulted in a higher risk of recurrence than for a PN in small pT3a tumors (P < 0.001); this could mean that large tumors might have additional aggressive features. This seems to indicate it may be best to not push the indication for a PN above the 7-cm cutoff in advanced renal tumors. In small renal masses (<4 cm), there was no significant difference in oncological outcome [8][9][10][11]. Thus, performing a PN in advanced small RCC seems to be possible. However, this study defined a cut-off of 4 cm.
Lee et al. evaluated recurrence-free, cancer-specific, and OS after PN in patients with cT3a pT3a RCC (n = 43) in comparison with those with pT1a lesions ( n = 1342) and found similar oncological outcomes over a follow-up of 54 months (P = 0.521) [12]. There was no correlation to the outcome after an RN.
Another study evaluated recurrence-free survival after PN in patients with cT1 RCC upstaged to pathological T3a (134 patients of 1448) with a follow-up of 23 months. The recurrence-free survival was significantly lower in upstaged patients (76%) than in those not upstaged (93%; P< 0.001) [13]. The limitation of this study is the lack of a limit on tumor size for a PN to be indicated.

Conclusions
A PN in patients with pT3a tumors leads to prolonged survival rates compared to performing an RN in patients with tumors <7 cm. The cT3a status does not seem to be a contraindication for a PN. Further data should be analyzed to prove this survival benefit.

Additional Information Disclosures
Human subjects: All authors have confirmed that this study did not involve human participants or tissue. Animal subjects: All authors have confirmed that this study did not involve animal subjects or tissue. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work.