Prognostic Value of Ki67 and Other Clinical and Histopathological Factors in Canine Apocrine Gland Anal Sac Adenocarcinoma

Simple Summary

Apocrine gland anal sac adenocarcinoma (AGASACA) is a locally aggressive tumor with a high metastatic rate to the regional ileo-sacral lymph nodes and later to distant sites. Clinical signs depend on the tumor and regional lymph nodes size or on the paraneoplastic hypercalcemia. Therefore, dogs are often referred for perineal swelling, tenesmus, constipation and/or polyuria, polydipsia. Surgical excision of both the neoplastic anal sac and the metastatic regional lymph nodes represents the standard of care. Adjuvant chemotherapy and/or radiotherapy are also indicated. Prognostic factors include tumor size, hypercalcemia, regional lymph nodes metastasis and tumor histologic features. The aim of the study was to retrospectively evaluate the prognostic significance of tumor Ki67 expression. The authors’ hypothesis was that higher Ki67 index correlated with decreased disease-free interval and overall survival time. Clinical data such as tumor size, regional lymph nodes metastasis and hypercalcemia at presentation and histological features such as tumor pattern, mitotic count, necrosis, inflammatory infiltration, vascular invasion, anisokaryosis, and anisocytosis were also investigated and correlated to the oncologic outcome in the dogs included in the study.

Abstract

Apocrine gland anal sac adenocarcinoma (AGASACA) is locally aggressive and highly metastatic to regional lymph nodes. The aim of this study was to evaluate the prognostic significance of Ki67 in surgically excised AGASACA. Prognostic impact of size, regional lymph nodes metastasis, hypercalcemia, histologic pattern, mitotic count, necrosis, inflammatory and lympho-vascular invasion, anisokaryosis and anisocytosis was also evaluated. Thirty-five dogs were included, twenty-four of which also had metastatic lymph nodes. When the entire population was evaluated, only metastatic disease spread to regional lymph nodes, and necrosis and inflammatory infiltration were correlated to prognosis. When only dogs with metastatic disease were evaluated, size, solid histologic pattern, presence of lymphatic and vascular invasion showed influence on prognosis. Ki67 index was not associated with survival time and disease free interval in any case. The results of this study showed that lymph nodes metastasis at diagnosis reduced disease free interval. Moreover, tumor size greater than 5.25 cm, presence of lymphatic and vascular invasion and a solid histologic pattern were associated with a shorter survival time in dogs with metastasis to regional lymph nodes. Ki67 expression was not significantly associated with prognosis, therefore it could not be considered as a prognostic factor in this tumor type, while the role of hypercalcemia remained unclear.

Retrospective assessment of radiation toxicity from a definitive-intent, moderately hypofractionated image-guided intensity-modulated protocol for anal sac adenocarcinoma in dogs

A recent calculation study predicted acceptable toxicity in pelvic organs at risk for a new definitive-intent, moderately hypofractionated radiation therapy (RT) protocol (12 x 3.8 Gy), when used with image-guided intensity-modulated radiation therapy (IG-IMRT). We hypothesized this protocol to result in clinically acceptable radiation toxicities. Dogs diagnosed with and irradiated for anal sac adenocarcinoma (ASAC) were retrospectively assessed. Eleven dogs were included, six had prior surgery. Before any therapy, staging according to Polton et al. resulted in the following distribution: stage 1 (n = 1), stage 2 (n = 1), stage 3a (n = 6), stage 3b (n = 3). We scored radiation toxicities at the end of therapy, at weeks 1, 3 and every 3 months after RT according to Veterinary Radiation Therapy Oncology Group radiation toxicity criteria. Clinical follow-up was maintained on regular intervals combined with computed tomography (n = 3). Median follow-up time for dogs still alive was 594 days (range: 224-972 days). Within 1 week post treatment, eight dogs (73%) developed grade 2 and four dogs (36%) grade 1 acute toxicity in the perianal region. All acute toxicities resolved or improved to grade 1 within 3 weeks after treatment. Late toxicity, for example, chronic colitis/diarrhoea, ulcerations, strictures or myelopathies was not observed in any patient. Five dogs were euthanized 105, 196, 401, 508 and 908 days after RT and six dogs were still alive, one in spite of progressive disease. The median progression-free survival was 908 days (95%CI: 215; 1602). The previous theoretically described definitive-intent, moderately hypofractionated protocol using IG-IMRT for the treatment of advanced ASAC showed clinically acceptable acute and late toxicities.

Evaluation of toceranib for treatment of apocrine gland anal sac adenocarcinoma in dogs

BACKGROUND

There is no widely accepted standard medical treatment for apocrine gland anal sac adenocarcinoma (AGASACA) in dogs. Targeted agents such as toceranib may be effective in treatment of AGASACA, but the number of clinical reports investigating its efficacy is limited.

HYPOTHESIS/AIM

To evaluate the efficacy of toceranib treatment of AGASACA in dogs, and to assess prognostic factors in the study population. Our hypothesis was that toceranib would provide a clinical benefit in the treatment of dogs with AGASACA.

ANIMALS

Thirty-six client-owned dogs with either a cytologic or histologic diagnosis of AGASACA that were treated with toceranib alone or in combination with surgery, nonconcurrent chemotherapy or both.

METHODS

Retrospective study.

RESULT

The median progression-free survival (PFS) and overall survival time (OST) for the study population was 313 days and 827 days, respectively. A clinical benefit from toceranib treatment was observed in 69% of dogs, with 20.7% of dogs experiencing partial response and 48.3% of dogs experiencing stable disease. Dogs that responded to toceranib treatment had significantly prolonged PFS and OST. Hypercalcemia was a negative prognostic factor for clinical outcomes.

CONCLUSIONS

Toceranib is effective in the treatment of AGASACA in dogs. Prospective, controlled clinical trials are needed to determine the efficacy of toceranib in comparison to other treatment protocols for dogs with AGASACA.

Apocrine gland anal sac adenocarcinoma with perineural metastasis in a cat

Case summary

A 15-year-old female spayed domestic shorthair cat was presented for hyporexia and acute development of L4-Cd myelopathy (urinary incontinence, pelvic limb paresis with hyporeflexia and absent tail tone). Humane euthanasia was elected owing to the rapid neurological deterioration and necropsy was performed. Post-mortem examination identified a right-sided anal sac mass and medial iliac lymphadenopathy. No gross lesions were evident in the cauda equina or peripheral nerves. Histopathology and immunohistochemistry utilizing wide-spectrum cytokeratin confirmed apocrine gland carcinoma of the anal sac with lymph node, peripheral nerve and cauda equina metastasis.

Relevance and novel information

This is the first report of feline anal sac adenocarcinoma metastasizing to perineural tissue. In addition, it provides a novel differential diagnosis for L4-Cd myelopathy and urinary incontinence in a cat.