Oral mirtazapine decreases the gastrointestinal adverse effects in cats on doxorubicin chemotherapy

Anorexia, depression, and vomiting are the common adverse effects of chemotherapy in humans and animals. Mirtazapine is primarily used as an appetite stimulant and antiemetic in dogs and cats. Therefore, we evaluated the efficacy of mirtazapine in reducing the gastrointestinal adverse effects in cats receiving doxorubicin chemotherapy. This single-masked, placebo-controlled crossover study enrolled 11 cats with malignant mammary gland tumors. The cats were randomly assigned to receive either mirtazapine (1.88 mg/cat) or placebo every 48 h for 2 weeks from the first initiation of doxorubicin chemotherapy. Each cat was then crossed over to the alternate group on the subsequent chemotherapy with a 1-week wash-out period. The owners were asked to record appetite score, activity score, episodes of vomiting and diarrhea for 2 weeks after each doxorubicin administration. Cats treated with mirtazapine showed significantly increased bodyweight compared with those on placebo (P = 0.010). The appetite and activity scores during mirtazapine treatment was significantly higher than those during placebo treatment (P = 0.005 and 0.018, respectively). Furthermore, the prevalence of episodes of vomiting during mirtazapine treatment was significantly lower than that during placebo treatment (P = 0.026). Our results demonstrate that mirtazapine can significantly increase bodyweight, appetite, and activity and reduce vomiting in cats after doxorubicin chemotherapy.

Platelet count and MCHC as independent prognostic markers for feline mammary carcinomas

Mammary neoplasms are common in felines species and represent a significant disease for its unfavorable prognosis. Changes in the blood count and serum biochemical profile of these patients have potential as non-invasive prognostic markers prior to mastectomy, however, they are poorly described in literature. In this study univariate and multivariate analyses were performed using these factors to determine the effect of each parameter on the one-year survival time after the surgical procedure in these animals. The median overall survival (OS) and the disease-free survival (DFS) were 365 and 242 days, respectively. In univariate analysis, values within the reference range of monocyte, platelet and creatinine counts were identified as significant prognostic factors for OS and only creatinine was significant for DFS (P < 0.05). In the multivariate analysis, platelets and mean corpuscular hemoglobin concentration (MCHC) remained independent prognostic factors for OS. The results presented suggest that monocytes, platelets and creatinine may be important non-invasive pre-surgical prognostic markers, and that platelet count and MCHC are independent prognostic markers for feline mammary carcinomas (FMC). The correlation between such alterations is of important relevance for veterinary oncology, and prospective studies are needed to validate their clinical use and that platelet count and MCHC are independent prognostic markers for FMC. The results found in this study can also be studied in human medicine, regarding blood markers in human breast cancer (HBC).

The protein and miRNA profile of plasma extracellular vesicles (EVs) can distinguish feline mammary adenocarcinoma patients from healthy feline controls

Feline mammary adenocarcinomas (FMA) are aggressive tumours with metastatic capability and limited treatment options. This study aims to investigate whether miRNAs associated with FMA tumours are secreted in extracellular vesicles (EVs) and whether they can potentially be used as a cancer biomarker in EVs from feline plasma. Tumours and matched tumour free margins from 10 felines with FMA were selected. Following a detailed literature search, RT-qPCR analyses of 90 miRNAs identified 8 miRNAs of interest for further investigation. Tumour tissue, margins and plasma were subsequently collected from a further 10 felines with FMA. EVs were isolated from the plasma. RT-qPCR expression analyses of the 8 miRNAs of interest were carried out in tumour tissue, margins, FMA EVs and control EVs. Additionally, proteomic analysis of both control and FMA plasma derived EVs was undertaken. RT-qPCR revealed significantly increased miR-20a and miR-15b in tumours compared to margins. A significant decrease in miR-15b and miR-20a was detected in EVs from FMAs compared to healthy feline EVs. The proteomic content of EVs distinguished FMAs from controls, with the protein targets of miR-20a and miR-15b also displaying lower levels in the EVs from patients with FMA. This study has demonstrated that miRNAs are readily detectable in both the tissue and plasma derived EVs from patients with FMA. These miRNAs and their protein targets are a detectable panel of markers in circulating plasma EVs that may inform future diagnostic tests for FMA in a non-invasive manner. Moreover, the clinical relevance of miR-20a and miR-15b warrants further investigation.

Epidemiology and risk factors for mammary tumours in female cats

OBJECTIVES

This study aimed to estimate the incidence and risk factors for mammary tumours in female cats attending UK primary-care practices. The study hypothesised that middle-aged, intact and certain breeds are associated with increased mammary tumour risk.

MATERIALS AND METHODS

A case-control study design identified mammary tumour cases by assessment of electronic patient records, nested within a denominator population of 259,869 female cats attending 886 primary-care VetCompass participating veterinary practices in the UK in 2016.

RESULTS

From 2858 potential mammary tumour cases identified within the denominator, 270 cats met the case definition, giving an incidence risk of 104 per 100,000 (0.104%, 95% confidence interval 0.092 to 0.117%) during 2016. In the risk factor analysis increasing age, purebred compared to crossbred and veterinary group were associated with increased odds of mammary tumour. Median survival after the diagnosis of mammary tumour cats was 18.7 months.

CLINICAL SIGNIFICANCE

The current study provides an updated estimate of the incidence of mammary cancer in cats seen in primary care veterinary practice in the UK with increasing risk seen in older cats and with purebred status. This study can aid veterinary surgeons to identify cats at greater risk of mammary tumour and advise on survival after diagnosis.

Prevalence of Reproductive Disorders including Mammary Tumors and Associated Mortality in Female Dogs

Female dogs, especially intact or neutered lately, are at increased risk for reproductive disorders including mammary tumors (MTs). This retrospective study evaluated the prevalence of reproductive pathology and associated mortality in a cohort of female dogs presented at a single veterinary clinic. The medical records of female dogs born in 2000–2003 were reviewed. The study included 599 cases, of which 293 were followed up until death. Causes of death were analyzed according to the spaying status. Among the 599 female dogs, 306 were intact (51%), 50 (8%) had been spayed before 2 years of age (ES, early spaying), and 243 (41%) after 2 years (LS, late spaying). During their lifetime, 79 dogs (13.2%) developed pyometra, and 160 (26.7%) a mammary tumor. Among the 293 dogs with complete follow-up, 103 (35.1%) had at least one MT during their lifetime, of which 53 (51.5%) died of their mammary cancer. Spayed (ES + LS) female dogs had a 4-fold decreased risk of dying from mammary cancer (OR = 0.23, 95% CI 0.11–0.47, p < 0.0001) compared to intact females. In this low-sterilization rate population, MTs developed in 35.1% of female dogs over their lifetime and was the cause of death in half of them.

Sonographic Assessment of the Normal and Abnormal Feline Mammary Glands and Axillary and Inguinal Lymph Nodes

Ultrasound has been used as a diagnostic tool in normal mammary glands and mammary tumors of several species. This study aims to describe the B-mode and Doppler ultrasound features of the mammary glands and draining lymph nodes in 32 adult female cats. Group 1 (G1) consisted of 22 cats without changes in the mammary glands. The average age was 45 ± 25.09 months, where 63.6% (n = 14) were neutered and 31.8% (n = 7) had received progestin at some point for reproductive control. Mammary gland structure was predominantly hypoechoic and homogeneous, with well-defined margins. The average thickness was 1.52 ± 1.59 mm, although it may be affected by estrus, pregnancy, and lactation. In G1, 100% of lymph nodes were homogeneous, 98% were hypoechoic, and 100% were with well-defined margins and hilar vascularization. Group 2 (G2) consisted of 10 cats with mammary nodules. The average age was 88.8 ± 40.5 months, and 70% were intact and all had already received progestin. Ultrasound demonstrated enlarged mammary glands, with nodules of different textures clinically, mainly affecting the abdominal mammary glands (61%). In 33.33%, there were visible mammary ducts. Only 54.17% were homogeneous, 95.83% were hypoechoic, and the margins were regular in 52.08%. Lymph nodes in abnormal mammary chains may present changes in size, shape, echotexture, and echogenicity. Ultrasound examination of the mammary glands and lymph nodes are possible to evaluate the entire mammary chain as well the superficial inguinal and axillary lymph nodes for abnormalities in the feline.

Neutrophil-to-lymphocyte ratio is an independent prognostic marker for feline mammary carcinomas

Blood leukocyte counts and respective derived ratios have been described as potential prognostic markers in several tumours in veterinary oncology. This study aimed to evaluate peripheral blood leukocyte subpopulations and neutrophil-to-lymphocyte ratio (NLR) as prognostic factors for feline mammary carcinomas (FMC). Medical records from cats diagnosed with FMC between 2017 to 2019 were reviewed. Cats were included if fully staged, classified as WHO stage I to III, and submitted to mastectomy. Cats were excluded if they had evidence of other diseases. Forty-nine cats were included. The study endpoints were disease-free interval (DFI) and tumour-specific survival (TSS). The median DFI and TSS were 389 days and 528 days respectively. In the univariate analysis, higher values of total white blood cell count (WBC), neutrophil count (NEU) and NLR were identified as significant prognostic factors for both endpoints (P < .05). On the multivariate analysis, NLR remained an independent prognostic factor for TSS (P = .024). In the receiver operating characteristic curve analysis, the estimated cut-off for WBC was 8.49 × 10⁹ /L (DFI and TSS); for NEU was 4.62 × 10⁹ /L (DFI) and 6.65 × 10⁹ /L (TSS) and for NLR was 2.46. These cut-offs were significant prognostic factors for DFI and TSS (P < .05). NLR cut-off remained an independent prognostic factor for both DFI (P = .032) and TSS (P = .043) in the multivariable analysis. Our results suggest that NLR, NEU, and WBC can be important non-invasive presurgical prognostic markers, and that NLR is an independent prognostic marker for FMC. Prospective studies are warranted to validate its clinical use.

Adjuvant doxorubicin vs metronomic cyclophosphamide and meloxicam vs surgery alone for cats with mammary carcinomas: A retrospective study of 137 cases

This study aims to evaluate the efficacy and side effects of low dose cyclophosphamide chemotherapy plus meloxicam as an adjuvant treatment, compared with high dose doxorubicin or surgery alone in cats with mammary carcinoma. Medical records of 228 female cats treated for mammary carcinoma between 2008 and 2018, were reviewed in eight veterinary institutions. Only cats with complete tumour staging and radical mastectomy were included in the study. One hundred and thirty-seven cats were divided into three treatment groups: group 1 (n = 80) cats treated with surgery, group 2 (n = 34) cats that had surgery and adjuvant treatment with doxorubicin, and group 3 (n = 23) cats with surgery and adjuvant treatment with low dose metronomic cyclophosphamide and meloxicam. The study endpoints were disease free interval (DFI) and overall survival (OS). Toxicity was evaluated according to the VCOG-CTCAE criteria. The median DFI was 270, 226 and 372 days in groups 1, 2 and 3, respectively. The median OS was 338 (group 1), 421 (group 2) and 430 (group 3) days. The differences between groups were not significant (DFI P = .280 and OS P = .186). Toxicity was observed in 52.9% (n = 18) of cats in group 2 and 39.1% (n = 9) of cats in group 3, with mild to moderate intensity. Differences were not significant (P = .306). In conclusion, adjuvant chemotherapy treatment did not improve survival and the overall benefit remains unproven. Randomized prospective trials are necessary to clarify the effectiveness of adjuvant chemotherapy treatment for feline mammary carcinomas.

Prognostic utility of preoperative neutrophil-lymphocyte ratio in cats with malignant mammary tumors

Although studies have determined the neutrophil-lymphocyte ratio (NLR) to be a useful prognostic predictor in various human cancers, little is known regarding its preoperative prognostic significance in feline mammary tumors (FMTs). Thus, the present study aimed to determine the prognostic utility of preoperative peripheral blood NLR in malignant FMTs. Accordingly, medical records of 34 cats that had undergone mastectomy were searched, after which those histopathologically confirmed to have malignant FMTs were included. Univariate analysis was used to determine the effect of each variable on one-year survival time. Factors determined to be significant during univariate analysis were subsequently included for multivariate analysis. Receiver operating characteristic analysis was used to assess the accuracy of the tests for predicting one-year survival. Univariate analysis showed that a high NLR and large tumor size were significantly associated with shorter survival times (P < 0.01, for both). No significant differences in other factors were observed. Multivariate analysis showed that a high NLR (hazard ratio, 25.03; 95% confidence interval, 2.98-210.40; P < 0.01), but not tumor size and age, was an independent prognostic factor for poor outcomes. The sensitivity and specificity of the NLR (cut-off, 5.67) for predicting one-year survival were 93.8% and 88.9%, respectively. This study suggests that the NLR could potentially be used as a preoperative prognostic factor in FMTs. Preoperative NLR may help to establish therapeutic modalities by allowing prognostic evaluation among cats with mammary tumors.

Exosomes as Biomarkers of Human and Feline Mammary Tumours; A Comparative Medicine Approach to Unravelling the Aggressiveness of TNBC

Comparative oncology is defined as the discipline that integrates naturally occurring cancers seen in veterinary medicine, into more general studies of cancer biology and therapy in humans, including the study of cancer-pathogenesis and new cancer treatments. While experimental studies in mice and rodents offer several advantages, including a wealth of genetic information, reduced variation and short generation intervals, their relevance in cancer biology is somewhat limited. Toward this end, as the biomedical research community works to make the promise of precision medicine a reality, more efficient animal cohort studies are critical. Like humans, companion animals such as cats and dogs living in family homes, are exposed to environmental factors that may influence the development of disease. Furthermore, it has been shown that the basic biochemical and physiological processes of companion animals more closely resemble humans compared to rodents. Research has demonstrated that female domestic cats (Felis catus) may represent a comparative model for investigation of mammary carcinogenesis, and in particular, Triple Negative Breast Cancer (TNBC). TNBC is a subtype of breast cancer that typically lacks the expression of the oestrogen receptor (ER), progesterone receptor (PR), and does not overexpress the human epidermal growth factor receptor 2 (HER2). An exciting and rapidly expanding area in cancer biology is the study of exosomes. Exosomes are nanoparticles released from cells and have been found in biological fluids of humans, domestic cats and dogs. In addition to their role as biomarkers, exosomes are implicated in the pathogenesis of certain diseases, including cancer. This review explores the current understanding of exosome biology in human TNBC, and of the potential benefits of comparative research in naturally-occurring mammary tumours in companion animals.

Effect of perioperative desmopressin in cats with mammary carcinoma treated with bilateral mastectomy

Perioperative administration of desmopressin has shown to significantly decrease rates of local recurrence and metastasis, and increase survival times in dogs with grade II and III mammary carcinomas. The objective of this study was to compare the oncologic outcome of cats with mammary carcinoma treated with bilateral mastectomy with or without perioperative administration of desmopressin. Medical records from nine veterinary institutions were searched to identify cats diagnosed with mammary carcinoma treated with bilateral mastectomy. Sixty cats treated with single-session or staged bilateral mastectomy were included. There were no significant differences in oncologic outcomes found between cats treated and not treated with desmopressin. No adverse effects were seen in any of the cats treated with perioperative desmopressin. Postoperative complications occurred in 18 cats (38.3%) treated with single-session bilateral mastectomy and in three cats (23.1%) treated with staged bilateral mastectomy (P = .48). Histologic grade and a modification of a proposed five-stage histologic staging system were both prognostic for disease-free interval. Incomplete histologic excision was associated with significantly increased rates of metastasis and tumour progression, and a shorter median survival time (MST). Cats that developed local recurrence also had a significantly shorter MST. The results of this study do not support the use of perioperative desmopressin to improve outcome when performing bilateral mastectomy for the treatment of mammary carcinoma in cats.