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Retroperitoneal and Lateral Pelvic Lymphadenectomy Mapped by Lymphoscintigraphy and Blue Dye for Rectal Adenocarcinoma Staging: Preliminary Results

¹ Colorectal, Pathology and Nuclear Medicine Divisions, Aristides Maltez Cancer Hospital, Av. D. João VI, 332, Brotas, 40285-001, Salvador, Bahia, Brazil
² Pelvic Surgery Department, Hospital do Cancer A.C. Camargo, São Paulo, Brazil
³ Surgical Clinic Post-Graduation Program, School of Medicine, University of São Paulo, São Paulo, Brazil

Correspondence: Address correspondence and reprint requests to: Claudio Almeida Quadros, MD; E-mail: caquadros{at}gmail.com

Background: Total mesorectal excision (TME) is the standard surgical choice for rectal adenocarcinoma. Better prognostic results, achieved with a retroperitoneal and lateral pelvic lymphadenectomy (RLPL), have questioned that TME might not be satisfactory for adequate patient staging, affecting therapeutic definitions. The aims of the ongoing study are to define the accuracy of dye and probe search in the detection of metastatic retroperitoneal and lateral pelvic nodes (RLPN) resected with RLPL, and to evaluate the metastasis frequency in these nodes and its eventual upstaging impact.

Methods: Thirty rectal adenocarcinoma patients were submitted to RLPL, with RLPN mapping using technetium (Tc 99 m) and patent blue, having nodes examined histopathologically and immunohistochemically.

Results: Eight hundred and two nodes were analyzed, mean of 26.7 per patient; RLPL was responsible for 41% (330) of the examined nodes, mean of 11 per patient. Metastatic RLPN have occurred in 20% of the patients; the RLPN were metastatic in only 6.7% of the patients; RLPL upstaged 13.3%. For identification of metastatic RLPN with technetium, sensitivity was 33%, specificity 79%, positive predictor value (PPV) 29%, negative predictor value (NPV) 83% and false negative (FN) rate 67%. For patent blue and technetium metastatic RLPN identification, sensitivity was 17%, specificity 92%, PPV 33%, NPV 82% and FN 83%.

Conclusions: Preliminary results have pointed out technetium and blue dye low accuracy to identify metastatic RLPN; no metastatic RLPN were reported in the patients submitted to preoperative chemoradiation and important upstaging with RLPL. Considering no increase in morbi-mortality rates with RLPL, definitive conclusions will be obtained as the study carries on.

Key Words: Rectal cancer • Retroperitonial and lateral pelvic lymphadenectomy • Lateral node dissection • Lymph node mapping • Rectal adenocarcinoma staging