Type II papillary histology predicts poor outcome in patients with renal cell carcinoma and vena cava thrombus.

UNLABELLED: What's known on the subject? and What does the study add? In patients with pRCC, the presence of venous tumour thrombus is known to be a predictor of poorer outcomes. However, a paucity of data is available regarding the prognostic significance of histology in patients with RCC and IVC thrombus. In our series, we found that patients with type II pRCC had significantly poorer outcomes when compared to those with cRCC. Although the lack of effective treatment for patients with metastatic pRCC may have contributed to these adverse outcomes, type II papillary histology was independent predictor not only of CSS but also of RFS.

OBJECTIVE: • To analyze the prognostic impact of papillary histology on oncological outcomes in patients with renal cell carcinoma (RCC) and inferior vena cava (IVC) thrombus.

PATIENTS AND METHODS: • We reviewed the medical records of 74 patients who underwent radical nephrectomy and IVC thrombectomy between 1990 and 2010 for clear cell or papillary RCC. • We compared the clinicopathological features and clinical outcomes of 62 patients with clear cell RCC (cRCC) and 12 with papillary RCC (pRCC). • All cases of pRCC were subdivided into type I or type II. • The prognostic role of papillary histology on recurrence-free survival (RFS) and cancer-specific survival (CSS) was estimated using Cox's regression models.

RESULTS: • Upon reclassification of the pRCC subtype, all 12 patients with pRCC had type II tumours. • Patients with type II pRCC were significantly younger (P=0.028) and were more probably women (P=0.025) than those with cRCC • The 2- and 5-year CSS rates were 81.1% and 53.6% in cRCC patients, and 28.1% and 0% in type II pRCC patients, respectively. All eight patients with non-metastatic type II pRCC developed disease recurrence at a median interval of 6 months after surgery, whereas 25 of 44 (56.8%) patients with non-metastatic cRCC experienced such recurrence at a median interval of 10 months after surgery. • Patients with type II pRCC showed significantly lower CSS (P<0.001) and RFS (P=0.002) than those with cRCC. • On multivariate analysis, type II papillary histology was an independent predictor of CSS (hazard ratio, 3.73; P=0.003) and RFS (hazard ratio, 3.15; P=0.015).

CONCLUSIONS: • Type II papillary histology appears to be predominant in cases of pRCC with IVC thrombus. •  Patients with type II pRCC who presented with IVC thrombus had significantly worse outcomes than those with cRCC, and histology is an important prognostic factor in patients with RCC and IVC thrombus.