Small Renal Masses Often Not A Threat
Active surveillance appropriate in many cases.
In a prospective multicenter study, Kamal Mattar, MD, of the
Dr. Mattar's group actively monitored patients with serial imaging at three-month intervals for the first year and six-month intervals in the second year or until tumor progression (defined as an increase to 4 cm in diameter or volume doubling within one year). After a median follow-up of seven months, 18 patients (22%) dropped out of the study. Two patients (2.2%) experienced metastases.
The average tumor growth rate was 0.14 cm per year, which was not significantly different from zero. Dr. Mattar told listeners that, based on the findings, initial active surveillance with serial imaging is appropriate for most elderly patients with renal masses.
The researchers noted that their study is the first multicenter prospective study looking at the natural history of renal masses as well as the first to involve routine needle biopsy.
The McGill study, which was led by T. Abou Youssif, MD, followed patients for a mean of 44.3 months. Patients had tumors with a median diameter of 2.1 cm at the time of diagnosis. Of the 35 patients, 31 (88.6%) were asymptomatic at the time of diagnosis.
The mean tumor size growth rate was 0.21 cm per year and the mean and median volume growth rate was 2.7 and 1.4 cc per year, respectively. Progression to metastatic disease was observed in two patients (5.7%). Eight patients (22.9%) underwent surgical resection of their tumor and eight (22.9%) died from other causes. Two patients (5.7%) were lost to follow-up.
“Most renal masses will grow if observed and may require treatment,” the authors concluded. “Initial tumor size cannot predict the natural history of renal cancer.”
One of the investigators, Simon Tanguay MD, head of the division of urologic oncology at McGill, said observation should be restricted to patients who have risks associated with surgery, such as advanced age and multiple medical problems.
In a paper published recently in the Journal of Urology (2007;177:1692-1697), researchers at Fox Chase Cancer Center in Philadelphia presented data showing that radiographic tumor size is a significant clinical predictor of the presence of biopsy proven synchronous metastatic renal cell carcinoma (RCC). The conclusion was based on a study comparing 110 cases of biopsy proven synchronous metastatic RCC at presentation and 250 controls with clinically localized RCC.
The researchers, led by Robert G. Uzzo, MD, found that each 1 cm increase in tumor size was associated with a 22% increase in the likelihood of presenting with synchronous, biopsy proven metastatic disease. A 3.5 cm increase in primary tumor size is associated with a doubling in the risk of metastasis.
“These data have important implications for extent of disease evaluations in patients with large tumors and for the active surveillance of small enhancing renal masses,” the investigators wrote.