Excising peri-renal fat essential in pT2, pT3a tumors

January 1, 2006

Amsterdam, Netherlands--Preoperative computed tomography scans may be inconclusive in distinguishing between stage pT2 and pT3a renal tumors. When performing laparoscopic partial nephrectomy, surgeons from the Cleveland Clinic recommend removing all peri-nephritic fat during the excision of locally advanced tumors, a step that they say is essential in duplicating open surgical oncologic principles.

Amsterdam, Netherlands-Preoperative computed tomography scans may be inconclusive in distinguishing between stage pT2 and pT3a renal tumors. When performing laparoscopic partial nephrectomy, surgeons from the Cleveland Clinic recommend removing all peri-nephritic fat during the excision of locally advanced tumors, a step that they say is essential in duplicating open surgical oncologic principles.

Of the 19 cases (average age, 61 years), one case of pT2 (.3%), 17 cases of pT3a (4.3%), and one case of pT3b (.3%) were identified. The mean pathologic tumor sizes were 7.4 cm, 2.9 cm, and 5.5 cm, respectively. Overall, the investigators found grade 2 tumors in 11 cases, grade 3 tumors in five cases, and grade 4 tumors in three cases.

In the follow-up (median, 15 months), only one patient who had T3a disease with grade 4 renal cell carcinoma and a focal sarcomatoid component developed distant metastasis.

Duplicating open principles

"Pathology-confirmed locally advanced renal cell carcinoma was found in 5% of our 400 patients undergoing laparoscopic partial nephrectomy. Since the preoperative prediction of involved peri-renal fat is difficult, excision of the tumor along with peri-renal fat is essential in a manner duplicating open surgical oncologic principles," noted first author Osama Ukimura, MD, PhD, a research scholar in the minimally invasive surgery center at the Cleveland Clinic's Glickman Urological Institute, working with Inderbir S. Gill, MD, and colleagues.

Session co-moderator Mahesh Desai, MD, MS, of Muljibhai Patel Urological Hospital, Nadiad, Gujarat, India, noted that if CT scans seemed unreliable in certain cases, this would warrant a change in the imaging technique used to diagnose kidney tumors.

Caution in staging advised

Co-moderator Chandru Sundaram, MD, of the Indiana University School of Medicine, Indianapolis, concurred that clinicians must pay particular attention to tumor staging. The message of the research, he pointed out, is that all clinically organ-confined tumors should be treated like pT3a tumors when performing partial nephrectomy.

"Just treat them all like you are removing a pT3a tumor to be safe," he advised.

From this non-blinded review, Dr. Ukimura maintains that, when using CT, it is not possible to know whether a tumor's stage is microscopic pT3a. Until such time as there is clarity through better diagnostic techniques, all peri-nephritic fat needs to be removed.

"Prediction of the microscopic involvement of peri-renal fat is difficult," Dr. Ukimura observed. "That is why excision of the tumor with perirenal fat is essential."