Absolute indications for PN include a tumour in a solitary kidney, compromised renal function and a hereditary disorder that predisposes to recurrent RCC. However, the value of elective PN is being increasingly shown in studies demonstrating oncologic equivalency to RN in stage T1 tumours,7,8
as well as superiority in renal function preservation.9,10
Huang and colleagues reviewed patients with renal tumours <4 cm and normal renal function. They demonstrated that those who underwent a PN had a much reduced risk of developing CKD compared to those undergoing a RN during the follow-up period.9
Similarly, Lau and colleagues matched a cohort of patients for stage, grade, age, sex, tumour size and year of surgery. They demonstrated the superiority of PN over RN in preserving renal function in patients with unilateral RCC and a normal contralateral kidney.10
The importance of renal function preservation resides not only in preventing end-stage renal disease and dialysis, but also in preventing CKD. CKD is defined as a GFR <60 mL/min/1.73 m2
, and has been demonstrated to be an independent risk factor for cardiovascular disease, hospitalization and death.15,16
Consequently, it has been speculated that overuse of RN for tumours that are otherwise amenable for nephron sparing may lead to increased non-cancer specific mortality. In fact, Huang and colleagues examined the SEER registry for patients over 66 years old with RCC <4 cm treated with RN or PN. They concluded that RN treatment places these patients at increased risk for cardiovascular events and overall mortality.17
It is increasingly evident that PN should be the treatment of choice for small renal masses. In fact, the American Urological Association guidelines place PN as standard treatment for all T1a lesions, as well as an alternate standard to RN for T1b lesions in otherwise healthy patients.18
However, it is unclear whether these results are reproducible with the laparoscopic approach. Beyond the minimally-invasive approach, some major differences distinguish LPN from OPN. Firstly, LPN is mostly performed transperitoneally, whereas a retroperitoneal approach is preferred for OPN. Secondly, cooling is often cumbersome and rarely used in LPN, compared to OPN where it is usually applied. Lastly, hemostatic agents are more widely used in LPN, whereas OPN relies more on suturing of individual vessels. The largest series comparing LPN and OPN examined 1800 PNs performed at the Cleveland clinic, Johns Hopkins and the Mayo clinic.19
OPN patients were more likely to present symptomatically, have a decreased performance status and have impaired renal function or a solitary kidney. In addition, tumours in the OPN group were larger, more centrally located and more likely to be malignant. The advantages of LPN were shorter operative time, decreased blood loss and decreased hospital stay. The advantages of OPN were decreased ischemia time, decreased postoperative complications and a decreased number of subsequent procedures. The two approaches were equivalent for three-year cancer-specific survival and renal function at three months.
Increasing tumour size seems to add to the complexity of a PN. Gill and colleagues have shown that 8.8% of LPN tumours were T1b, compared to 31.4% of OPN cases.19
In addition, OPN for tumours >4 cm have been shown to be associated with increased operative time, blood loss, transfusions and urinary fistula.20
Data on the impact of tumour size on outcomes in LPN are lacking. We have shown that increased tumour size is associated with increased WIT in LPN. Whether this increased WIT translates into any long-term impact on renal function remains to be seen. In addition, the mean WIT in this series was 34 minutes. There was, however, a clear trend for a decline in WIT with increasing experience. In a review of the current literature, it would appear that WIT in LPN are consistently longer than OPN.21
It has been speculated that given the increased abdominal pressure in laparoscopy leading to oliguria, there is a preconditioning of the renal unit to tolerate increased WIT in LPN. This, however, remains controversial and very little comparative data exists to distinguish the impact on renal function of OPN and LPN. In this series, we demonstrated a modest impact on renal function after LPN.
Finally, the oncologic control obtained with LPN compares favourably with OPN over the intermediate term. The local recurrence rates and cancer specific survival appeared to be similar with both techniques.21
It is noteworthy, however, that most OPN series are quite mature, whereas only the Cleveland clinic has reported five-year cancer-specific survivals in a limited number of patients.22
In this series, no incidence of local or systemic recurrence has been noted over a 44.3 months follow-up period.