Page 675 - Withrow and MacEwen's Small Animal Clinical Oncology, 6th Edition

CHAPTER 30 Tumors of the Urinary System 653

respectively. 106 The MST appears shorter for clear cell (87 days) of the BRAF V600E mutation that drives 8% of all human can-
versus chromophobe, papillary, and multilocular cystic RCCs. 106 cer. Although BRAF mutations are rare in human iUC, other
molecular variants are present that turn on the MAPK pathway
Fuhrman nuclear grade, a human RCC histologic grading scheme
VetBooks.ir based on morphologic features of nuclei and nucleoli, was prog- in approximately 30% of human iUC cases. 133 Mutations in
several other genes implicated in the development and progres-
nostic in one study of 70 dogs with RCC with MSTs not reached,
1065 days, 379 days, and 87 days in dogs with grade 1, 2, 3, sion of iUC and other cancers in humans have been identified
and 4 RCCs, respectively. 106 Radiographic evidence of metastasis in canine iUC including EGFR, CDKN2B, PIK 3CA, BRCA2,
is present in 16% to 34% of dogs with primary renal tumors. 94,97 NFκB, ARHGEF4, XPA, NCOA4, MDC1, UBR5, RB1CC1,
Metastasis at death was reported in 88% of dogs with sarcomas, RPS6, CIITA, MITF, and WT1. 17,128,133 Another intriguing
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75% with nephroblastomas, and 69% with carcinomas. finding in canine iUC is the presence of molecular subtypes
defined by gene signatures including luminal and basal sub-
Feline Renal Tumors types initially observed in human breast cancer and then found
in human iUC. 127,134 This is important because cancer behav-
Primary renal tumors are rare in the cat. Excluding lymphoma, ior, treatment response, and prognosis differ between subtypes
reported feline primary renal tumors include tubular RCC, tubu- in humans. 134
lopapillary RCC, sarcomatoid RCC, adenocarcinoma, adenoma,
iUC, squamous cell carcinoma, leiomyosarcoma, nephroblas- Renal Cancer
toma, and hemangiosarcoma. 108–115 The tubular and tubulopapil-
lary RCC were most common in a series of 19 cats. 108 The most Major types of renal cancer in humans include RCC, urothe-
common presenting complaint was weight loss. Metastasis was lial carcinoma of the renal pelvis, and Wilms’ tumor (nephro-
frequently detected at the time of diagnosis. 108 blastoma), which is most commonly diagnosed in children. 135
Polycythemia has been reported in cats with primary renal Renal cancer is newly diagnosed in 64,000 people and results in
tumors. 108,115 In two cats with renal adenocarcinoma, polycy- 15,000 deaths each year in the United States. RCC accounts for
themia resolved after nephrectomy. 115 Hypertrophic osteopathy 90% of adult renal carcinomas. 135 Risk factors for RCC include
has been reported in a cat with renal adenoma. 110 In contrast to cigarette smoking, obesity, and hypertension. 136 Multiple sub-
canine and human RCC, immunohistochemistry did not corre- types of RCC exist including clear cell, papillary types I and II,
late with RCC subtype in a small series of cats. 114 Nephrectomy and chromophobe types. The clear cell type can be sporadic or
could be considered in unilateral cancer. The role of chemotherapy associated with von Hippel–Lindau disease in which mutations
is undefined. Limited information on survival is present, but most occur in the VHL gene. With recent progress in targeted and
reports are associated with short survival times. immunotherapies, the outlook for human RCC has improved
substantially in recent years.
Comparative Aspects
References
Invasive Urothelial Carcinoma

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