Defining Tumour Shape Irregularity for Preoperative Risk Stratification of Clinically Localised Renal Cell Carcinoma

Abstract

BackgroundUnexpected adverse pathology is a major concern in surgical management of clinically localised renal cell carcinoma (RCC). Further studies are needed to improve preoperative risk stratification. ObjectiveTo define and classify tumour shape irregularity (TSI) based on preoperative imaging, and to investigate its effect on pathological and oncological outcomes in clinically localised RCC. Design, setting, and participantsWe retrospectively analysed 474 patients with cT1-2N0M0 RCC managed by partial or radical nephrectomy. Preoperative dynamic computed tomography was used to define and classify TSI, graded as 1 (completely elliptical shape), 2 (elliptical shape with minor and focal protrusions), or 3 (nonelliptical shape presenting with major and/or extensive protrusions). InterventionPartial or radical nephrectomy. Outcome measurements and statistical analysisA logistic regression analysis evaluated the risk factors for pT3a upstaging and Fuhrman grade 3–4. A Cox proportional hazard analysis assessed preoperative variables for recurrence-free survival (RFS). Results and limitationsThe median tumour size was 3.5 cm, and 94 patients (20%) had (R)adius (tumour size as maximal diameter), (E)xophytic/endophytic properties of tumour, (N)earness of tumour deepest portion to collecting system or sinus, (A)nterior (a)/posterior (p) descriptor, and (L)ocation relative to polar lines (RENAL) score ≥10. TSI was graded as 1, 2, and 3 in 214 (45%), 151 (32%), and 109 (23%) patients, respectively. Higher TSI was significantly associated with a larger tumour size and a higher RENAL score. Overall, pT3a upstaging and Fuhrman grade 3–4 were observed in 45 (9.5%) and 116 patients (31% in 380 clear cell RCC cases), respectively. The incidence of pT3a upstaging and Fuhrman grade 3–4 was significantly higher in patients with higher TSI (0.5%, 8.6%, and 28% for pT3a upstaging and 12%, 33%, and 60% for Fuhrman grade 3–4 in TSI 1, 2, and 3 groups, respectively). In multivariable analyses, higher TSI was independently associated with adverse pathological outcomes. During the median follow-up of 6.0 yr, 49 patients (10%) developed recurrence. Multivariable analyses demonstrated that older age and higher TSI were independent risk factors for worse RFS. The limitations include the retrospective design. ConclusionsTSI may be a useful adjunct in preoperative risk stratification for adverse pathology and recurrence after surgery in clinically localised RCC. Patient summaryTumour shape irregularity is significantly associated with unfavourable pathological outcomes, that is, locally advanced stage or high-grade cancer, and with a higher recurrence rate after surgery in patients with clinically localised renal cell carcinoma. Preoperative evaluation of the tumour shape may help in patient counselling and treatment decisions.