Prognostic value of tumour contour irregularity on surgical strategies for T1bN0M0 renal cell carcinoma: A multi-institutional study

To determine the prognostic value of tumour contour irregularity degree (CID) in surgical strategy options for T1bN0M0 renal cell carcinoma (RCC).We performed a retrospective multi-institutional review of 489 patients with T1bN0M0 RCC treated between January 2009 and June 2019. Cox regression and Kaplan-Meier analyses were performed to analyse the impact of CID on disease-free survival (DFS).The median follow-up time was 55 months (interquartile range, 40-81 months) for 55 (11.2 %) patients with metastasis or recurrence. Logistic analysis indicated that CID was associated with World Health Organization/International Society of Urological Pathology (WHO/ISUP) grades III-IV (odds ratio, 1.015; 95 % confidence interval [CI], 1.008-1.023; p < 0.001). After being classified into high CID (≥50 %) and low CID (<50 %) groups, those with a high CID showed a significantly higher ratio of WHO/IUSP grades III-IV (74/277 [26.7 %] vs 25/212 [11.8 %]) and shorter DFS than the low CID group (p < 0.001). Multivariable Cox regression showed that partial nephrectomy (PN; hazard ratio [HR], 1.889; 95 % CI, 1.020-3.499; p = 0.043), high CID (HR, 6.685; 95 % CI, 2.776-16.100; p < 0.001), and WHO/ISUP grade III-IV (HR, 1.950; 95 % CI, 1.100-3.458; p = 0.022) were independent prognostic factors for DFS. The Kaplan-Meier plot showed that PN had a DFS rate comparable to that of radical nephrectomy (RN; p = 0.994). In the low CID group, patients who underwent PN showed comparable DFS to those who underwent RN (p = 0.903). Furthermore, patients with a high CID tended to have worse DFS in the PN versus RN group (p = 0.044). Multivariable Cox regression showed that PN (HR, 2.049; 95 % CI, 1.065-3.942; p = 0.032) and WHO/ISUP grade III-IV (HR, 2.148; 95 % CI, 1.189-3.881; p = 0.011) were independent prognostic factors of DFS in the high CID group.CID is a reliable preoperative parameter which is positively correlated with WHO/ISUP grade and can help with surgical decision-making in patients with T1bN0M0 RCC.