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EDITORIAL COMMENT

Among patients with renal cell carcinoma the size of the primary lesion has been reported to correlate with its biological potential and with prognosis, and this contribution providing data on patients whose maximum tumor diameter is 3.0 cm. or less is of interest. In this report renal tumors 3.0 cm. or smaller comprised 8.7% of all renal cell carcinomas treated during the 20-year interval studied, and in 61% of these patients the tumors were detected during the course of an evaluation of symptoms that were either nonspecific or were not directly referable to a renal tumor. Moreover, and consis- tent with other studies, a 2-fold increase in the detection of such

lesions was found aRer the introduction of more sensitive imaging techniques, suggesting in the future that lead time bias may con- found reporta of the detection, treatment and survival of patients with renal cell carcinoma.

While a direct comparison of the cancer-speafic survival rates on a stage for stage basis between patients with lesions larger than 3.0 cm. in diameter compared to those with smaller lesions is not pro- vided, a comparison with historical controls suggests that despite small tumor size such lesions have a clear potential for metastasis and that detection, even when accomplished at the current limits of resolution, confers relative but by no means absolute survival ad- vantage. In addition, and while this report deals primarily with tumor size and provides no information on tumor grade, it is of note that 93% of the lesions were clear cell tumors, suggesting that clear cell tumors smaller than 3.0 cm. in diameter may represent a unique biological subset of renal cell carcinoma, since most reported series of renal cell carcinoma do not contain this preponderance of clear cell cancers.

Multifocal renal cell carcinoma was detected in 15% of patients with tumors smaller than 3.0 cm. in diameter, which correlates well with the incidence of multifocal renal cell carcinoma found in pa- tients undergoing radical nephrectamy in general. This finding would seem to suggest that mul t i fd i ty in such c e s represents the possible existence of a field lesion or of a genetic propensity for malignant transformation, since despite a relatively small size these tumors have undergone more than 70% of the total doubhgs. Par- adoxically, however, the paucity of bilaterality in these c88es re- mains unexplained.

This study, therefore, provides important information concerning the biology of small renal cell carcinoma, a lesion that due to the availability of increasingly sensitive imaging techniques is more likely to become clinically relevant. However, the optimal therapy for such lesions, particularly with respect to nephron sparing surgery and renal parenchymal preservation, remains to be defined.

Gerald Sufnn Department of Urologv SUNY at Buffalo Buffalo, New York