Natural history of small renal cell carcinoma: evaluation of growth rate, histological grade, cell proliferation and apoptosis.
OBJECTIVE
We investigated the natural history of incidentally discovered small renal cell carcinomas (RCCs), and we evaluated growth rate, apoptosis, cell proliferation and histological grade.


METHODS
A total of 18 patients with RCCs extirpated after at least 12 months of observation were reviewed retrospectively. The period of observation ranged from 12 to 63 months (median 22.5). Median patient age was 56.5 years, ranging from 37 to 71. Annual tumor growth rate was calculated from diameter obtained from computerized tomography or ultrasound. Cell proliferation and apoptosis were assessed by immunostaining using Ki-67 and TUNEL.


RESULTS
Average tumor growth rate was 0.42 cm per year (standard error 0.09, 95% confidence interval 0.24 to 0.61). Of the 18 tumors 7 were grade 1, 8 were grade 2 and 3 were grade 3. Tumor growth rate and Ki-67 positive ratio were not correlated. In contrast, growth rate and positive ratio of TUNEL were significantly correlated. A significant difference in growth rate was observed between grade 2 and 3 tumors but not between grade 1 and 2 tumors.


CONCLUSIONS
The growth rate of RCCs correlates with apoptosis and grade. Most incidentally found RCCs are slow growing. However, those with certain histopathological features can grow rapidly and have a poor prognosis. More attention should be given to the observation of small renal masses.
Department of Urology, Tohoku University School of Medicine, 1-1 Seiryo-machi, Aoba-ward, Sendai 980-8574, Japan. masanori@ec.mbn.or.jp
Masanori
M
Kato
Takashi
T
Suzuki
Yasuyoshi
Y
Suzuki
Yoshio
Y
Terasawa
Hironobu
H
Sasano
Yoichi
Y
Arai
D000328:Adult; D000368:Aged; D017209:Apoptosis; D002292:Carcinoma, Renal Cell / Q000473:pathology* / Q000503:physiopathology; D002455:Cell Division; D005260:Female; D006801:Humans; D020287:In Situ Nick-End Labeling; D019394:Ki-67 Antigen / Q000032:analysis; D007680:Kidney Neoplasms / Q000473:pathology* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged
D019394:Ki-67 Antigen