Prognostic impact of stromal periostin expression in upper urinary tract urothelial carcinoma

BACKGROUND: Periostin is an extracellular matrix protein that has been known to be implicated in fibrillogenesis and cell migration, including cancer metastasis. Periostin overexpression in cancer cells and/or intervening stroma is usually related to tumor progression and poor patient outcomes in various human cancers; however, its role in urothelial carcinoma, especially upper urinary tract urothelial carcinomas (UTUCs), remains inconclusive. METHODS: Samples from 126 consecutive cases of invasive UTUC (69 renal pelvic cancers and 57 ureteral cancers) were histologically reviewed and analyzed for periostin expression using immunohistochemistry. The intensities of immunoreactivity and the fraction of positive cancer cells and stroma (i.e., epithelial and stromal expression, respectively) were classified into four categories each (intensity, 0-3; fraction, 0-25% = 1; 26-50% = 2; 51-75% = 3; and > 75% = 4). The overall score was determined by multiplying both scores, and overall scores ≥ 6 were considered to indicate high periostin expression. RESULTS: Among 126 UTUCs, 55 (44%; 27 renal pelvic and 28 ureteral cancers) showed high stromal periostin expression. None of the cases were considered to have high epithelial periostin expression. High stromal periostin expression was associated with non-papillary gross findings, higher pathological T category, lymphovascular invasion, concomitant carcinoma in situ, subtype histology, lymph node metastasis, positive surgical margins, high tumor budding, and high tumor-associated immune cell status. Multivariate analysis revealed that high stromal periostin expression was an independent predictor of overall survival (p = 0.00072, hazard ratio = 3.62), and lymphovascular invasion and high stromal periostin expression were independent predictors of cancer-specific survival (p = 0.032 and 0.020, hazard ratio = 2.61 and 3.07, respectively). CONCLUSIONS: Stromal periostin expression was often observed in invasive UTUCs with adverse clinicopathological factors and may be a useful predictor of patient outcomes.