Positive margins have limited impact on RCC outcome

By Laura Cowen, medwireNews Reporter

Positive vascular wall margins are not associated with systemic recurrence or cancer-specific survival in patients with nonmetastatic renal cell carcinoma (RCC) with tumour thrombus, US research shows.

However, “[c]omplete surgical excision should always be attempted because positive vascular wall margins increase local recurrence rates”, say E Jason Abel (University of Wisconsin School of Medicine and Public Health) and colleagues in BJU International.

The researchers reviewed the medical records of 256 patients treated surgically for RCC with venous thrombus and no evidence of metastasis at presentation between 1993 and 2009. Microscopic tumour was present at the vascular resection margin in 47 (18.4%) patients.

During a median follow-up period of 36.7 months, 112 (43.8%) patients had either distant or local recurrence of RCC. Overall recurrence rates were significantly higher in patients with positive vascular margins than in those with negative margins, at 57.6% versus 40.4%.

Fifteen (5.9%) patients experienced local recurrence, and the local recurrence rate was higher in patients with positive versus negative margins (12.8 vs 4.3%). The vast majority of these patients also had distant recurrence; there were only two (0.8%) who had local recurrence without concomitant distant recurrence.

This suggests that “more extensive surgical resection of the vascular structures may be of little benefit”, the researchers remark.

“The presence of microscopic tumour at the vascular wall margin should be considered a poor prognostic factor which may identify those patients at higher risk of postsurgical recurrence, who may benefit from greater surveillance or participation in adjuvant therapy clinical trials”, they add.

Indeed, multivariate analyses showed that a positive vascular margin was independently associated with a threefold increased risk of local recurrence compared with a negative margin.

No such association was observed for overall recurrence or for cancer-specific survival even though the median disease-free period and cancer-specific survival were significantly shorter for patients with positive versus negative margins, at 22.1 versus 70.2 months and 37.7 versus 93.0 months, respectively.

Abel et al also found that patients with positive vascular margins were more likely to have perinephric fat invasion, a higher level of thrombus and a higher Fuhrman grade than those with negative margins.

This may “reflect a worse phenotype of RCC in patients with extensive invasion of the vein wall”, they write.

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