Wilms’ tumor: the Expanding role for partial nephrectomy Brodie Parent, R3 UW General Surgery

Wilms’: The Plan Brief: epidemiology, pathogenesis, staging, survival My Patient, who had partial nephrectomy for Wilms’ Technique: radical vs. partial nephrectomy (PN) PN: rationale and indications PN outcomes Conclusion

Wilms’ Tumor, Briefly Epidemiology: incidence is 8.1/million/year, 500 new cases per year in the US, #4 most common childhood cancer* Associations: hemihypertrophy, Denys-Dash, Beckwith-Wiedemann, aniridia, WT1 Pathogenesis: precursor = nephrogenic rests. ** Staging, 5-year Survival: * Favorable histo: Stage I >97%, Stage IV = 86%. Unfavorable histo: Stage I = 83%, Stage IV = 38%. *Children’s Oncology Group ** Holcomb, Murphy. Ashcraft’s Pediatric Surgery. Lippincot and Williams.

Patient TPT 6y male, left constant abdominal pain, intermittent fevers OSH mid-May: CT showed two masses in the left kidney; CT guided biopsy showed round blue cell tumor PMH: SVD, term birth Intubated briefly perinatally for meconium aspiration. Myringotomies at 9mo. Umbi hernia repair at age 3. I Immunizations UTD. Mother dxed with thyroid cancer last year, but no other malignancy hx. Fam Hx neg for malignancy

Patient TPT

Patient TPT Stage III disease, presumed Wilms’. Neoadjuvant chemo – decreased tumor size by est 40%. Partial nephrectomy early September. Path: 80% necrosed Wilms’, margins negative. Doing well postop, starting chemo

Radical Nephrectomy: Technique* 1. Incision: Subcostal Chevron Flank thoracoabdominal Midline incision = risk of tumor rupture, ligation of SMA *Fischer, Mastery of Surgery, 5th Ed.

Radical Nephrectomy: Technique* 2. Reflect omentum and colon medially White line of Toldt, Lienorenal ligament, Gerota’s fascia Beware: splenic vessels, pancreas 3. Dissection off retroperitoneum: start posterolateral, removing adrenal and kidney 4. Isolate vessels, ureter. Ligate artery prior to vein 5. Ligate artery prior to vein 6. Dissect ureter, ligate close to bladder 7. Obtain pericaval, periaortic, renal hilar lymph node basins *Fischer, Mastery of Surgery, 5th Ed.

Partial Nephrectomy (PN): Technique* Exposure of operative field, then… 1. Know relation of tumor to: a. true renal pelvis, b. major vessels. 2. Isolate vessels, clamping artery, then vein, vessel loop around ureter; consider bowel bag with ice. 3. outline tumor with electrocautery and enucleate 4. hemostasis, oversew collecting system injuries *Fischer, Mastery of Surgery, 5th Ed.

PN: Technique* 5. Close defect with mattress sutures vs pledgets *Fischer, Mastery of Surgery, 5th Ed.

Traditional Indications for PN: PN for Wilms’ when: solitary kidney Bilateral disease Multifocal disease Cost, et al. Oncologic Outcomes of Partial Versus Radical Nephrectomy for Unilateral Wilms Tumor. Pediatr Blood Cancer. 7/2011.

PN: Rationale for expanding applications Survival for low risk Wilms’ >97%. Therefore, focus on improving morbidity rather than mortality. Adult population with radical nephrectomy is 1.9 fold more likely to have ARF and CKD when compared to PN patient population. * 840 adults, small renal masses. RN vs PN followed over 1 year. Pediatric population with RN has average Cr 1.27 vs PN has Cr 0.7. ** 26 children with unilateral renal tumors followed over 72 months. 16 with RN vs 10 with PN. *Sun, et al. Chronic kidney disease after nephrectomy in patients with small renal masses: a retrospective observational analysis. Eur Urol. 2012 Oct, Vol 62. **Cozzi, et al. Renal function adaptation in children with unilateral renal tumors treated with nephron sparing surgery or nephrectomy. J Urol 2005.

PN: Rationale for expanding applications Increased renal dysfunction in RN population associates with worse cardiac morbidity and mortality. 178 adult patients, underwent RN. Those who developed GFR <45 had 3.5 fold increased risk cardiac event.* Increased renal dysfunction in RN population associates with worse erectile dysfunction. 432 adult patients, mean f/u 6 yrs. Those with PN had de novo ED 9% vs those with RN had de novo ED 30%. *Takeshita et al. Impact of renal function on cardiovascular events in patients undergoing radical nephrectomy for renal cancer. Intnl J Urol 2012, vol 19. **Kopp, et al. Does radical nephrectomy increase the risk of erectile dysfunction compared to partial nephrectomy? A cohort analysis. BJU Mar 2013.

New Indications for PN: Planning with CT Study population: 60 pts, <2yo, unilateral, no mets, stage I Wilms (low risk). Criteria for PN selection: <9cm diameter (<550gm), >1cm margin with >1/3 kidney preserved, no vascular involvement, no true renal calyx invovlement Even in small, low risk tumor population, only 5/60 pts were candidates for partial resection. Ferrer, et al. Image based Feasibility of Renal Sparing Surgery for Very Low Risk Unilateral Wilms Tumors: A Report from the Children’s Oncology Group. J Uro. 11/2013

PN:Planning with CT Ferrer, et al. Image based Feasibility of Renal Sparing Surgery for Very Low Risk Unilateral Wilms Tumors: A Report from the Children’s Oncology Group. J Uro. 11/2013

PN Outcomes Lit review: nonsyndromic unilateral Wilms’ treated by PN 82 pts identified with long term outcome data; control group nonsyndromic unilateral Wilms’ treated by RN (at Dallas Childrens’) Overall, no significant difference between PN and RN in recurrence in overall survival. Subgroup analysis: Patients with Stage 2 or less – no difference in recurrence or survival Stage 3 or higher – recurrence significantly higher in PN compared to RN. Therefore, offer PN only to localized, low stage Wilms’ Cost, et al. Oncologic Outcomes of Partial Versus Radical Nephrectomy for Unilateral Wilms Tumor. Pediatr Blood Cancer. 7/2011.

Radical vs PN: Comparison of Subgroups of Wilms’ Patients by Stage Wilms’ PN Outcomes Radical vs Partial Nephrectomy: Comparison of All Stages of Wilms’ Patients Radical vs PN: Comparison of Subgroups of Wilms’ Patients by Stage Cost, et al. Oncologic Outcomes of Partial Versus Radical Nephrectomy for Unilateral Wilms Tumor. Pediatr Blood Cancer. 7/2011.

Wilms’ and PN: Questions Unanswered Trial underway: Does preop chemo effectively shrink tumor to produce more candidates for partial nephrectomy? Trial underway: Is PN an option for patients with tumor predisposition syndromes? (Beckwith- Wiedemann, WAGR). No trial yet: Does the presence of unfavorable histology (anaplasia) prohibit PN?

Two lines to remember: When compared to radical nephrectomy, partial nephrectomy has a substantial reduction in short and long-term morbidity. Partial nephrectomy is becoming a more accepted therapy for low risk, localized Wilms’ tumors, with good oncologic results.