Date of Award

January 2012

Document Type

Open Access Thesis

Degree Name

Medical Doctor (MD)



First Advisor

Dinesh Singh

Subject Area(s)



Introduction: Current standard treatment of small renal masses (SRM) is surgical resection, but it is not plausible in all patients. Since the behaviors of SRM are not completely understood, the management of such lesions remains controversial. We evaluated the rates of linear and volumetric growth and metastasis of solid SRM in patients followed by active surveillance (AS).

Materials and Methods: We performed a retrospective medical records review of 38 patients followed by AS for solid SRM. We reviewed radiographic imaging and hospital records. Extracted variables included size of lesions at diagnosis and surveillance, duration of surveillance, available pathology and progression to metastasis.

Results: Of the original 44 lesions, 36 lesions in 32 patients were included. Mean lesion size at initial presentation was 1.73cm. Mean duration of surveillance was 34.3 months. Benign and malignant lesions demonstrated mean linear growth rates of 0.19cm/yr vs. 0.31cm/yr and volumetric growth rates of 0.95cm3/yr vs. 2.91cm3/yr, respectively. Seven patients crossed over to surgery due to patient preference or significant interval lesion growth. Pathology was obtained in 25% of lesions, of which 44% proved to be malignant renal tumors known as renal cell carcinoma (RCC). There was no correlation between initial lesion size and growth rate. Progression to metastasis was not seen in any of the subjects. Neither of two deaths during surveillance was due to renal cancer.

Conclusions: Most enhancing SRM grow slowly, making active surveillance a safe alternative to surgery in nonsurgical candidates. Changes in lesion volume may be a better predictor of cancer cell growth than linear growth.