Purpose: Ultrasound, computerized tomography and magnetic resonance imaging
are widely available, Incidentally discovered small renal masses are repor
ted more frequently. Most of these masses are low stage renal cell carcinom
as. To understand better the natural history of these lesions and offer app
ropriate management, we followed prospectively a series of patients with th
is type of lesion.
Materials and Methods: A total of 13 patients with radiologically detected
solitary small renal masses who were unfit for or refused surgery were foll
owed with abdominal imaging for a median of 42 months. Median patient age w
as 69 years and mean lesion volume at diagnosis was 13.6 cm.(3) or 2.95 cm.
in diameter. Growth rate was calculated based on tumor volume rather than
bi-dimensional diameter. Individual slopes of tumor size in time were calcu
lated.
Results: Of the 13 patients 5 underwent surgery following a period of surve
illance because of apparent tumor enlargement or new onset of symptoms. Pat
hological evaluation revealed renal cell carcinoma in all 5. No patient had
metastases. Only 2 tumors were fast growing and these were the only 2 case
s in which symptoms developed. When these patients were excluded from analy
sis average growth rate was 1.32 cm.(3) per year (p = 0.5, 95% confidence i
nterval -3.00 to 5.76 cm.(3) per year), which was not statistically signifi
cantly different from 0 slope or no growth.
Conclusions: These results demonstrate that the growth rate of small renal
tumors is variable, tumors that are destined to grow and possibly metastasi
ze do so early and most small tumors grow at a low rate or not at all.