Date Published: August 29, 2011
Publisher: Hindawi Publishing Corporation
Author(s): Ehab A. Elzayat, Ali A. Al-Zahrani.
The standard surgical treatment of invasive bladder cancer is the radical cystectomy and pelvic lymph node dissection (PLND). Up to one-third of patients with invasive bladder cancer have lymph node metastasis. Thus, PLND has important therapeutic and prognostic benefits. The number of lymph nodes that should be removed and the extent of the PLND are still a controversial issue. Recently, the trend of PLND increased toward more
extended PLND. Several prognostic factors related to PLND were reported in the literature. In this paper, we will discuss the different PLND templates, number of lymph nodes that should be resected, lymph node density, lymphovascular invasion, tumor burden, extracapsular extension, and the aggregate lymph node metastasis diameter.
According to cancer statistic 2010, bladder cancer is the fourth most common tumor in men in the United States, the number of new cases diagnosed were estimated to be 70,530 (52,760 men and 17,770 women), leading to 14,680 deaths . In Europe, bladder cancer represents 6.6% and 2.1% of the total cancers and 4.1 % and 1.8% of total deaths for cancer in men and women, respectively .
The lymphatic drainage of the bladder consists of the visceral lymphatic plexus inside the submucosa and the muscular layer, the small intercalated lymph nodes located within the perivesical fat, pelvic collecting trunks which is medial to the iliac LNs, regional pelvic LNs, which include the external and internal iliac, and sacral LNs, lymphatic trunks from the regional pelvic LNs to the common iliac LNs . The pelvic LNs are embedded in fat and difficult to be appreciated during the surgery. The primary drainage sites include external and internal iliac and obturator LNs, secondary drainage from the common iliac LNs, and tertiary drainage from the trigone and posterior bladder wall is to the presacral nodes . LNs mapping studies in RC shows that the rate of positive LNs detected decreased gradually from distal to more proximal sites and the most common site of LN metastasis were in the obturator and iliac LNs. Positive LNs were found in the perivesical fat and in the pelvic region in 22.7% of all patients, in the common iliac nodes in 8%, in the presacral region in 5.1% and at or above the aortic bifurcation in 4% . In another study, the distribution of the LN metastasis in the external iliac, obturator, and internal iliac region was 33%, 38%, and 29%, respectively. Metastases in only one region were found in 33% of patients (13% in the external iliac LNs, 10% in the obturator LNs, and 10% in the internal iliac LNs); 50% of all patients had lymph node metastases in the internal iliac region .
In 2004, Herr et al.  reported on 1091 consecutive RC performed by 16 experienced surgeons from 4 institutions between 2000 and 2002. Surgeons performed a standard PLND in 67% of patients, extended PLND in 13% of patients, and for various reasons 20% had a limited (9%) or no node dissection (11%). In analysis of the Surveillance, Epidemiology and End Results (SEER) data of 3603 RC performed between 1992 and 2003, Hollenbeck et al.  divided the hospitals according to the node count during cystectomy, low (no patients with ≥ 10 LNs removed), medium (up to 20% of patients with ≥ 10 LNs removed), and high (greater than 20% of patients with ≥ 10 LNs removed). The authors found that only 0–4 nodes were retrieved in 88.9% and 52.8% of cases in the low and high node count hospitals, respectively. The percentages of patients who had ≥ 10 LNs removed were 0% at low LN count hospitals, 12.7% at medium LN count hospitals, and 35.3% at high LN count hospitals. It seems that the majority of cystectomy patients had ≤4 LNs removed irrespective of the hospital and optimal PLND is not commonly performed.
The accurate assessment of LN specimen depends on the carful work of the pathologist when searching the specimen for LNs and the way of specimen submission for pathological examination. Bochner et al.  found that individual LN specimen yielded more LNs compared to en bloc specimen in standard PLND (8.5 versus 2.4 LNs, P = 0.003) and extended PLND (36.5 versus 22.6 LNs, P = 0.02). This result confirmed by Stein et al.  who suggests 13 separate nodal packets to increase the total number of lymph nodes removed compared with en bloc submission.
Laparoscopic PLND for prostate cancer was initially described by Schuessler et al. . The laparoscopic surgery is minimally invasive with advantages of decreased blood loss, shorter hospital stay, and early recovery. Several reports showed that there is no significant difference in the intraoperative complications and the number of LNs removed by laparoscopic approach when compared with open surgery [60, 61].
Although, RC is major surgery with potential high rates of complications, extended PLND does not increas morbidity or mortality. There is no significant difference between LN-positive and -negative patients in terms of postoperative complications . In a study comparing extended PLND (up to the aortic bifurcation) to a more limited PLND, similar mortality rates were observed in the 2 groups . Similarly, Leissner et al.  observed that the postoperative complications such as lymphocele and lymphoedema were similar in patients with <16 lymph nodes removed and patients with >16 nodes removed (2% versus1%). Although the extended PLND increased the operative duration by 63 minutes, the limited and extended PLND patients did not differ significantly in terms of perioperative mortality and morbidity. Complications requiring surgical interventions occurred in 9% patients in limited PLND and 11% in extended PLND group (P = 0.28) .
PLND is an essential part of the surgical treatment of bladder cancer for its staging, curative, and prognostic role. The benefits of extended PLND were demonstrated in several studies with no significant difference in morbidity and mortality when compared to standard PLND. Despite the growing evidence that support the extended PLND up to the inferior mesenteric artery, the optimum PLND template is still controversial and its boundaries and the number of retrieved LNs have not yet been defined. Well-designed randomized controlled trials comparing standard to extended PLND in RC patients is still needed. The extent of PLND and the number of positive LNs are well-established risk factors; however, the cut off number of positive LNs is still to be defined. Several reports suggested that LVI and LN density should be included in the pathologic staging of bladder cancer. The prognostic value of ECE and ALNMD still need more investigations.