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EDITORIAL COMMENT

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cally resected renal cell carcinoma. J Clin Oncol2002; 20: 4559.

13. Karakiewicz PI, Briganti A, Chun FK et al: Multi-institutional validation of a new renal cancer-specific survival nomogram. J Clin Oncol 2007;25: 1316.

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17. Karakiewicz PI, Hutterer GC, Trinh QD et al: Un-classified renal cell carcinoma: an analysis of 85cases. BJU Int 2007; 100: 802.

18. Karakiewicz PI, Trinh QD, Rioux-Leclercq N et al:Collecting duct renal cell carcinoma: a matchedanalysis of 41 cases. Eur Urol 2007; 52: 1140.

19. Kuroda N, Toi M, Hiroi M et al: Review ofsarcomatoid renal cell carcinoma with focus onclinical and pathobiological aspects. Histol His-

predict the natural history of patients with surgi- 52: 155. topathol 2003; 18: 551.

This review using the SEER database reconfirms anobservation made from autopsy data in the last cen-tury, that is that primary RCC size is proportional tothe likelihood of metastasis. Although some recentstudies questioned this finding, these authors recon-firm the original observation in a rather convincingmanner.

There are clearly a number of limitations to thisstudy and the authors address most of them. Thereis no central pathological evaluation, no standardmetastatic assessment, a bias toward surgical cases

helpful in supporting the initial findings. With thatsaid, the take-home message is that size is propor-tional to metastasis and clear cell carcinoma has ahigher SM incidence than papillary carcinoma. Iwould not be willing to make any assessment withreference to chromophobe renal carcinoma without astandardized pathological evaluation.

W. Scott McDougal

Department of UrologyHarvard Medical School

Massachusetts General Hospital

and a lack of long-term followup, which would be Boston, Massachusetts

We agree that the SEER database lacks some im-portant information which would have strengthenedour results. Despite its limitations, our study corrob-orates the findings from a large, tertiary care Euro-pean cohort (5,376 patients), which showed similarresults regarding the rate of synchronous metasta-sis (reference 9 in article). In that study a nomogramwas developed and the presence of a 2.5 cm tumor(T1a) was associated with a predicted 3.0% risk ofsynchronous metastasis. Similarly, in patients withT1b RCC the presence of a 6.5 cm lesion was asso-ciated with a 5.8% risk of synchronous metastasis.

synchronous metastasis rates among surgicallytreated patients in the SEER database with T1a andT1b tumors, respectively. These findings at leastpartially confirm the validity of the nomogram pre-dicting metastatic RCC that was developed and ex-ternally validated in a European cohort (reference 9in article). Moreover, they also confirm that the met-astatic potential of small renal masses is similar onboth sides of the Atlantic. However, it is noteworthythat the synchronous metastasis rates in these 2studies are significantly higher than those recentlyreported by Thompson et al in a single institution,

These observations are similar to the 2.3% and 6.7% tertiary care center study.1

REFERENCE

1. Thompson RH, Hill JR, Babayev Y et al: Metastatic renal cell carcinoma risk according to tumor size. J Urol 2009; 182: 41.