Association of Microvascular and Capillary-Lymphatic Invasion with Outcome in Patients with Renal Cell Carcinoma

PurposeWe evaluated the association of microvascular and capillary-lymphatic invasion with patient outcome after nephrectomy for renal cell carcinoma.Materials and MethodsWe identified 1,433 patients surgically treated for sporadic, unilateral renal cell carcinoma between 2001 and 2008. All specimens were reviewed by a single uropathologist for microvascular and capillary-lymphatic invasion. Associations with time to metastasis and death from renal cell carcinoma were evaluated using Cox proportional hazards models, controlling for established clinicopathological prognostic variables.ResultsMicrovascular invasion and capillary-lymphatic invasion were identified in 119 (11%) and 17 (2%) of the 1,103 patients with clear cell, 5 (2%) and 1 (less than 1%) of the 219 with papillary, and 1 (1%) and 0 of the 86 with chromophobe renal cell carcinoma, respectively. Median followup in survivors was 6.4 years (range 0 to 11). In clear cell renal cell carcinoma cases microvascular invasion was univariately associated with an increased risk of metastasis and cancer specific death (HR 3.5 and 3.0, respectively, each p <0.001). However, on multivariate analysis these associations were no longer statistically significant (HR 1.2, p = 0.4 and HR 1.3, p = 0.1, respectively). Capillary-lymphatic invasion remained significantly associated with an increased risk of metastasis and death on univariate analysis (HR 15.9 and 11.6) and on multivariate analysis (HR 3.2 and HR 3.1, respectively, each p <0.001).ConclusionsMicrovascular invasion is associated with an increased risk of metastasis and cancer death in patients with clear cell renal cell carcinoma, although this did not remain significant after controlling for established prognostic variables. Capillary-lymphatic invasion appears to be independently associated with metastasis and cancer death even after controlling for known prognostic risk factors. However, given its rarity, this feature may prove to be of limited clinical significance.