The gained expertise in surgical techniques of partial nephrectomy (PN) has expanded its indication to carefully selected clinical T1b-2 renal masses; however, a possibility of unexpected adverse pathology remains a major concern, which may potentially demand radical nephrectomy (RN) rather than PN. This study investigates a significance of tumour shape irregularity (TSI) for predicting oncologic risks in clinically localised renal cell carcinoma (RCC).
177 patients who underwent PN/RN for clinically localised RCC >4 cm with no apparent venous or perirenal/sinus fat invasion on imaging were analysed. Preoperative CT/MRI were reviewed to assess TSI, which was categorized into four groups with focus on tumour shape and contour: TSI 0 (entirely elliptical shape and smooth contour), 1 (focally [<50%] irregular contour), 2 (extensively [≥50%] irregular contour), and 3 (entirely non-elliptical shape).
Median tumour size was 5.5 cm and 74 patients (42%) presented with R.E.N.A.L.≧10. TSI was determined as 0/1/2/3 in 24 (14%)/82 (46%)/45 (25%)/26 (15%) patients, respectively. Tumour interface with normal renal parenchyma was focally ill-defined in 7 of 26 patients in TSI 3 group. Overall, surgical specimen revealed ≧pT3a in 34 patients (19%). The incidence of ≧pT3a was significantly higher in higher TSI groups (8%/11%/20%/54% for TSI 0/1/2/3, p<0.001). On multivariate analysis, higher age and higher TSI independently associated with ≧pT3a (p=0.01 and <0.001, respectively). Higher TSI was significantly correlated with higher Fuhrman grade (FG) (p=0.001), although TSI 1 and TSI 2 cancers showed similar profiles for this aspect (FG 1-2/3/4: 84%/16%/0% in TSI 0, 55%/38%/7% in TSI 1, 51%/46%/3% in TSI 2, and 20%/56%/24% in TSI 3 group). PN (n=38) was applied mostly for TSI 0-1 patients, while one of seven PNs attempted for TSI 2 cancer was converted to RN due to macroscopically positive resection margin. During median follow-up of 59 months, 34 patients (19%) experienced cancer recurrence. Recurrence rate was significantly higher in patients with higher TSI (8%/15%/24%/36% at 5-year for TSI 0/1/2/3, p=0.005).
Our classification model of TSI stratified the risks of adverse pathology and cancer recurrence after surgery in clinically localised RCCs. This would help surgeons’ decisions regarding surgical approaches.