2020 PELVIC LYMPH NODE DISSECTION FOR BLADDER CANCER

more of an operation adds no additional harm-it is less impozant moibi&ty of the procedure. -

EDITORIAL COMMENT

The authors argue persuasively that extended pelvic lymph node dissection with cystectomy improves the survival of some patients with invasive bladder cancer. Presumably, extended dissection pro- vides a more complete resection of occult nodal or soft tissue tumor than limited dissection. Therefore, a wider dissection would seem to favor more advanced than less advanced disease but this is not the case. The authors report no difference in recurrence-free survival among the 194 patients, whether they had extended or limited pelvic lymph node dissection. Instead, they identified a survival advantage in favor of extended dissection only in patients who had pathological tumor confined to the bladder (pT3a or less) and negative lymph nodes (NO). Other reasons must be sought for the apparent benefit of extended pelvic lymph node dissection in this subset of patients.

Extended dissection provides a wider dissection of the bladder and surrounding perivesical tissue, and probably does not remove more microscopic nodal and soft tissue tumor foci than limited dissection (whether or not the pathologist identifies such occult tumor). Indeed, more patients had positive nodes or tumor invasion outside the bladder in the extended dissection compared to the limited dissection group. However, survival curves for all patients with stage pT3a or less (fig. 2) and those with stage less than pTBa, NO (fig. 4, A) appear as if they could be superimposed, suggesting that extended pelvic lymph node dissection had little overall impact on survival in those with nodal metastasis. This finding does not discount the possibility that wide dissection during extended pelvic lymph node dissection may facilitate more complete resection of soft tissue pelvic bladder cancer, and this principle may be equally or more important than extent of lymph node dissection. In fact, our data show a 5-year survival rate of 71% after radical cystectomy (when the plane of dissection is the musculoskeletal boundaries of the pelvis) and lim- ited pelvic lymph node dissection (as defined by the authors) among patients with tumor confined to the bladder and limited (Nl) nodal involvement.

The most likely explanation for the improved survival with ex- tended pelvic lymph node dissection in patients with organ confined disease is stage migration. More patients will have microscopic nodal and soft tissue disease after extended dissection in adjacent and remote nodes, and pelvic soft tissues, which raises the pathological stage in some while it identifies others who have tumor truly con- fined to the bladder. The net effect of stage migration is that overall survival in the subsets of patients (bladder confined and extravesi- cal) is improved regardless of the extent of lymphadenectomy, espe- cially in retrospective analysis of a nonrandomized series.

Academic concerns aside, it is difficult to fault the surgeon who extends the limits of cystectomy in an effort to help some patients who might not otherwise be saved by a lesser operation. As long as

whether the proposed benefits can be absolutely proved. Since CUT- rent surgical methods alone may help only a few patients, it is unlikely that even a randomized trial could h l y establish signifi- cant benefit of extended over limited pelvic lymph node dissection.

Harry W. Herr Department of Surgery Urology Service Memorial Slwn-Kettering Cancer Center New York, New York

REPLY BY AUTHORS

Radical cystectomy, including an extended lymph node dissection, not only improves the survival of the subpopulation of patients with tumors confined to the bladder without nodal metastasis (stage pTSa, pNO or less) but also provides a similar survival advantage to the entire population of patients with tumors confined to the bladder. This finding disputes the supposition that stage migration contrib- utes to the results. It is true that the extended node dissection probably increases the sensitivity in detecting nodal metastasis SO that segregation according to lymph node status might introduce a selection bias when comparing the outcome of the subpopulations without nodal metastasis. We believe that we have discounted this source of error by comparing the survival of the entire population of patients with tumors conked to the bladder since a priori the true incidence of nodal metastasis should be similar in these 2 groups.

The 5-year probability of recurrence-free survival following radical cystectomy, including extended node dissection, was 85% for the entire population with tumors confined to the bladder wall (stage pT3a or less) compared to 90% for the subpopulation without nodal metastasis (stage pTBa, pNO or less). This similarity is to be expected since only 12.5% of patients had nodal metastasis. Consequently, the overall survival mainly reflects that of the overwhelming majority of patients without nodal disease. Nevertheless, the population with tumors confined to the bladder and limited nodal involvement have consistently been reported to have a surprisingly high 5-year prob- ability of survival of about 50%.

We do not believe that extending the limits of pelvic lymphadenec- tomy from the bifurcation of the common iliacs to the bifurcation of the aorta influences histopathological pT staging of the bladder tumor (bladder confined versus extravesical) significantly. Even with limited dissection the plane of dissection is far from the bladder wall, and so it is unlikely that stage migration can account for the consid- erable survival advantage of the population with tumors confined to the bladder wall following extended dissection. We concur that an extended lymphadenectomy should be included in the radical cystec- tomy procedure as it may save some lives without addine to the