More circulating tumor cells may enter the bloodstream after open radical nephrectomy for renal cell carcinoma (RCC) compared with laparoscopic nephrectomy, according to a small, proof-of-concept study conducted in Japan. Even so, experts question how clinically meaningful this finding will be.

In the study, researchers looked at 60 patients diagnosed with RCC, including 22 who underwent laparoscopic radical nephrectomy, 19 who underwent laparoscopic partial nephrectomy, 8 who underwent open radical nephrectomy, and 11 who underwent open partial nephrectomy. Of the 19 people who underwent laparoscopic partial nephrectomy, 10 had robot-assisted laparoscopic partial nephrectomy.

The investigators collected blood samples drawn from participants’ peripheral arteries right before and after surgery. The researchers also looked at the patients’ clinical histories, blood laboratory results, data of abdominal computed tomography to determine tumor-node-metastasis (TNM) stage, and the R.E.N.A.L. nephrometry score.

The researchers focused on examining the number of pre- and postoperative circulating tumor cells and the perioperative change in circulating tumor cells for each surgery type. They also looked at potential reasons for greater circulating tumor cell counts before and after surgery and changes in these counts.

When the investigators looked at baseline data, they saw that patients in the radical nephrectomy groups tended to have longer tumor diameters and higher R.E.N.A.L. nephrometry scores compared with patients in the partial nephrectomy groups. The partial nephrectomy groups exhibited an earlier clinical TNM stage compared with the radical nephrectomy groups.

Upon examining the different surgical methods, the researchers did not find significant differences among the preoperative CTC counts. However, the investigators did observe significantly higher postoperative CTC counts in the open radical nephrectomy group compared with the other 3 groups in the study. Moreover, the open radical nephrectomy group also exhibited a greater perioperative change in CTC counts compared with the laparoscopic radical nephrectomy group and the open partial nephrectomy group.

These findings suggest that laparoscopic radical nephrectomy might be better than open radical nephrectomy for preventing CTCs from getting into the bloodstream, the authors wrote. But they also noted that all patients who underwent laparoscopic radical nephrectomy were operated on using a retroperitoneal approach, whereas all patients who underwent open radical nephrectomy were operated on using the transperitoneal approach. Thus, it is possible that the difference in postoperative CTCs could have stemmed from the difference between the two approaches rather than the laparoscopic versus non-laparoscopic surgical procedure.

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More research is also needed to establish whether the increased number of postoperative CTCs following open radical nephrectomy will actually translate into occurrence of distant metastasis, the authors noted.

Thomas Bradley, MD, the system head of genitourinary oncology at Northwell Health Cancer Institute in Lake Success, New York, who was not involved in the research, said he does not think the results will have implications for practice in the US. “It is an interesting concept, but it was a small, single-center study, and it is something that might be worth looking at larger-scale if there was some impact upon overall survival, which I don’t think we will ever be able to determine,” he said.

“The findings of this study are provocative but should be interpreted with extreme caution,” said Anas Al-Janadi, MD, vice president of oncology for Spectrum Health Cancer Center in Grand Rapids, Michigan, who was not involved in the study. “The importance of detecting circulating tumor cells in the blood of a patient with kidney cancer in the absence of established metastases is unknown.  A careful follow-up is required, and [an] update on long-term outcome will be most helpful.”

The laparoscopic approach is the preferred type of surgical therapy for the condition in terms of patient recovery, said Robert Greenwell, MD, chief of nephrology at Mercy Medical Center in Baltimore, Maryland, who was not involved in the study. “It is comforting to know that the preferred surgery is at least not increasing the amount of circulating cells that are present,” he said.

Reference

Haga N, Onagi A, Koguchi T, et al. Perioperative detection of circulating tumor cells in radical or partial nephrectomy for renal cell carcinoma [published December 12, 2019]. Ann Surg Oncol. doi: 10.1245/s10434-019-08127-8

This article originally appeared on Cancer Therapy Advisor