Renal tumors and amongst them, Wilms tumor is the most common tumor in children with excellent outcomes. Multimodal approach towards the tumor is important, however, surgery in addition has critical role in staging and thus further management of these tumors. Lymph nodes sampling is crucial in renal tumors since positive lymph nodes upstages the tumor with the resultant upgradation of intensity of treatment in the form of addition of doxorubicin and abdominal radiation. About 41% of stage III disease is identified on the basis of lymph nodes invasion alone. Intra-operatively, normal looking lymph nodes may harbor tumor deposits in 4-11% and in contrast enlarged lymph nodes may be negative in 40%.

Nodal assessment and sampling is based on surgeon’s discretion with the possibility of not removing sufficient numbers, removal of only enlarged nodes or not removing any lymph nodes. NWTS have reported sampling of minimum seven nodes for better assessment of the lymph node basin. The pattern of lymph nodes metastasis has not been studied in children with renal tumors and the significance or incidence of skip metastasis is not known. Moreover, there are no guidelines recommended for sampling of retroperitoneal lymph nodes. The assumption of sampling only the renal hilar lymph nodes as they are the first echelon lymph nodes is challenged in adults with renal cell carcinoma since non-hilar nodes may be involved without metastasis in the hilar nodes.

Primary objectives

·        Study of pattern of lymph nodal spread in pediatric renal tumors.

Secondary objectives

·        To correlate radiological and pathological feature in stage III (i/v/o positive lymph node) disease.

·        To describe the incidence of lymph node metastasis in patients undergoing upfront surgery and surgery after neoadjuvant chemotherapy.

·        To define the minimum number of lymph nodes required for detecting metastasis

All patients with renal tumors will undergo conventional work-up including CECT of abdomen/pelvis and thorax. Patients enrolled in CMART (ongoing WT project no: 993) study will also be included. Eligible patient will either receive preoperative chemotherapy or operated upfront. Surgery will be performed using abdominal or thoracoabdominal approach and lymph node sampling will be performed from lymph node stations (described below) after resection of the primary tumor.

Lymph node stations (right =R, left =L)- See figure

1)    Right renal tumor

a.    Suprahilar paracaval

b.    Hilar paracaval

c.    Infrahilar paracaval

2)    Left renal tumor

a.    Suprahilar pararotic

b.    Hilar pararotic

c.    Infrahilar pararotic

3)    In all

a.    Interaortocaval suprahilar

b.    Interaortocaval infrahilar

For right sided tumor – to remove A,B,C,D and E

For left sided tumor – to remove D,E,F,G and H.

The tumor specimen and lymph nodes will be appropriately labeled and sent for histopathological examination.

 The chemotherapy and radiotherapy will be as per the CMART study protocol.

Inclusion criteria

•      All renal tumors <18 years of age at diagnosis

•      Willing to give consent for the study

Exclusion criteria

·         Previously treated patients,

·         Recurrent or residual disease; and

·         Patients not willing for consent.

Lymph node sampling in childhood renal tumors is the standard of care, however there are no recommendations for lymph node sampling even in cooperative group studies. A systematic sampling of defined Lymph node stations will help us to the know the pattern of lymphatic spread and will help to identify Lymph node which are more likely to have metastatic deposits.  This may help us to reduce sampling errors and provide opportunities to correctly stage the patients since Lymph node involvement is very imp in staging and the treatment of renal tumors.