Clinical outcomes of papillary renal cell carcinoma: Does the subtyping have a prognostic utility?

Introduction: The prognostic value of the histological subtypes of papillary renal cell carcinoma (pRCC) is debatable as different studies have shown different outcomes. This study describes the clinical characteristics and the survival indices of types 1 and 2 pRCC in a cohort of patients from Sri Lanka.
Methods: This was a cohort study involving a consecutive sample of patients who were diagnosed to have pRCC over a period of eight years (2012-2019) in a tertiary care urology unit in Sri Lanka. Death or the longest period of disease-free survival was considered as the primary end points. Non-parametric tests were employed for the analysis since the sample size was small.
Results: A total of 43 patients with histologically confirmed pRCC were followed up. The mean age of the sample was 56.2 years (range 19-74) and the male to female ratio was 2.7:1. Fifteen patients (36.4%) had type 1 pRCC and 28 (63.6%) had type 2 pRCC. Type 2 tumors were larger in size, advanced in stage and had a higher nuclear grade at the time of diagnosis compared to type 1. The five-year survival of patients with type 1 pRCC was significantly lower (61%) compared to the published data, although that of type 2 tumors was comparable (57.3%). Five-year overall survival was not different between patients with type 1 and type 2 tumors.
Conclusion: Although type 2 pRCC presents with larger, advanced stage and higher-grade tumors, the five-year survival between the two groups was not different. The findings of this study show that the use of histopathological subtype as an independent prognostic factor is questionable.