Mammary Tumors In Female Dogs Research Articles

Clinical, morphological and diagnostic characteristics of malignant mammary tumor in bitches

Mammary tumor is the most frequent neoplasia in bitches in Brazil, and most of the mammary tumors in female dogs in the country, are malignant. This study aimed to evaluate clinical, morphological and diagnostic characteristics of malignant mammary tumors in 32 bitches. The average age of the bitches was 10.1 years, demonstrating that older bitches are more predisposed. Most bitches weren't neutered. Tumor size in most animals was greater than 5 cm. and showed rapid growth in most cases. In all bitches, no signs of metastases in the lungs were observed. The results of the cytological exams showed a mixed malignant tumor and adenocarcinoma, and about 81.5% of adenocarcinomas were confirmed by histopathological exam. It was concluded that non-castrated elderly female dogs were the majority. Malignant tumors larger than 5 cm with fast growth and firm consistency were the most frequent.

Lymph node Staging methods in mammary tumors in female dogs: palpation x sentinel node biopsy

Breast cancer is one of the most common cancers in both women and female dogs. The lymphnode condition is one of the most important prognostic factors in both species. The main goals of this search are to determine the role of inguinal and axilary palpation preoperatively, to find the sentinel node detection rate using the blue dye technique and its role in predicting metastasis. Fifty female dogs havings mammary tumors were included in this study. The protocol included data collection, clinical examination, blood sampling and radiologic exams before surgery. Blue dye subcutaneous injection was performed just after anesthesia and ten minutes before skin incision. Mastectomy was performed according to the previously established hospital protocol. Eighty-six percent of dogs presented with malignant tumor. Lymph node palpation offered high accuracy, low sensitivity, high speficicity, low positive predictive value and high negative predictive value for metastasis detection. The inguinal sentinel lymph node was detected in 92.3% of the female dogs and the axillary sentinel lymph, in 78.9%. Twenty-five percent of all detected lymph nodes contained metastatic carcinoma. Sentinel node detection rate was high both inguinal and axilary, although sentinel metastasis were rare in both stations. The procedure did not cause any additional morbidity. Thus, the optimal protocol according to this study, is lymph node palpation and, in positive cases, the sentinel node biopsy using the blue dye technique.

Sonographic and Histopathological Study of Mammary Tumours in Female Dogs

Sonographic and Histopathological Study of Mammary Tumours in Female Dogs

Risk factors associated with mammary tumors in female dogs

ABSTRACT: Mammary tumors in female dogs are the most frequent and corresponds to half of the canine tumors. The objectives of this study were to determine the risk factors associated with the occurrence of mammary tumors in female dogs and to evaluate the macroscopic characteristics of these neoformations, using 386 dogs from the “Outubro Rosa Pets” events done within the cities of Uberlândia and Patos de Minas, Minas Gerais State, Brazil, in 2015 (n=194), 2016 (n=105) and 2017 (n=87). For the determination of risk factors, the binary logistic regression test (P<0.05) was performed. The occurrence of mammary tumors was 23.6% (91/386). The significant risk factors identified were increased age (P<0.001), overweight (P=0.048) and non-castration (P<0.001) with a chance of, respectively, 1.6, 2.3 and 9.3 times for the development of mammary tumors. In dogs with mammary tumors (n=91), 153 lesions were present, of which 39 female dogs had two or more lesions (42.8%). Most of the lesions were at the caudal abdominal (M4) and inguinal (M5) mammary glands (60.13%, 92/153). Relative to the size of the lesions, it was observed that in 78% of the female dogs the lesions were determined asT1 (<3cm), 16.5% were T2 (3-5cm) and 5.5% T3 (>5cm). At least 15.4% (14/91) of the dogs had one of the regional lymph nodes increased. In conclusion, the occurrence of mammary tumors in the evaluated population was 23.6% and that age, overweight and non-realization of ovariohysterectomy are risk factors associated with the development of mammary tumors.

Clinical and Ultrasonographic Aspects of Benign and Malignant Mammary Tumors in Female Dogs

Background: Mammary neoplasms in dogs are commonly observed in veterinary clinical routine, most of which being malignant. Hormonal stimulation, endogenous or exogenous, may possibly influence its development. In addition to clinical evaluation, ultrasound analysis can provide information about the characteristics of breast lumps. The association between clinical-epidemiological and pathological data is important for diagnosis. Therefore, given the importance of this pathology for the health of affected dogs, we aimed to evaluate the clinical and ultrasound alterations, along with the factors associated with the development of benign and malignant mammary neoplasms in female dogs. Materials, Methods & Results: We examined 47 samples from the mammary tumors of 35 female dogs at the Small Animal Clinic of the Veterinary Hospital (HV) of the Santa Cruz State University (UESC). The dogs underwent a complete clinical examination, with clinical staging, via TNM classification, followed by hematological, biochemical, radiological and ultrasound, abdominal, and breast exams. Breast ultrasound examination was used to evaluate the shape parameters such as, limits, margins or contour, ecotexture, echogenicity, hyperechoic halo, posterior acoustic shading, surrounding changes, and nodule components. These criteria were associated with the histopathological classification of neoplasms. Epidemiological data was studied through an adapted questionnaire containing information on risk factors associated with breast cancer. The same questionnaire was applied to tutors of 19, age-matched, female dogs with no history of breast cancer. The results revealed that most female dogs with neoplasia were over eight years of age, with no specific breed and were not castrated, and 31.4% of them had already been administered with contraceptives during the reproductive period. Ovariohysterectomy acted as a protective factor (OR 0.06) to the development of breast tumors, while contraceptive use was considered as a risk factor (OR 6.99). The average time reported between tumor perception and clinical care was 13.2 months. The caudal and inguinal abdominal breasts were the most affected. Among the samples evaluated, 76.6% were malignant, with mixed tumor carcinoma being the most frequent type and 69.4% graded in grade I. Nodules classified as malignant showed the largest diameter (P < 0.05). Breast ultrasound results revealed that tumors with heterogeneous echotextures and mixed components were associated with malignancy (P < 0.05). Discussion: The fact that the average age of female dogs with breast cancer was over eight years of age corroborates the literature. Considering that a greater age would mean a longer exposure to the carcinogenic initiators responsible for mutations, and to promoters, such as hormonal changes. Contraceptives increase the risk of breast lumps, while reduce that of ovariohysterectomy, in female dogs, even when performed after the second heat. The size of the nodules and ultrasound criteria related to echotexture and the type of component of the neoplasia may be used as prognostic parameters of female breast nodules. Additionally, most nodules evaluated in this study were malignant (mixed tumor carcinoma was the most common subtype), possibly due to the owners' delay in seeking veterinary care after tumor observation. Although malignant, most nodules presented with a low histopathological grading.Background: Mammary neoplasms in dogs are commonly observed in veterinary clinicalroutine, most of which being malignant. Hormonal stimulation, endogenous or exogenous,may possibly influence its development. In addition to clinical evaluation, ultrasound analysiscan provide information about the characteristics of breast lumps. The association betweenclinical-epidemiological and pathological data is important for diagnosis. Therefore, given theimportance of this pathology for the health of affected dogs, we aimed to evaluate the clinicaland ultrasound alterations, along with the factors associated with the development of benignand malignant mammary neoplasms in female dogs.Materials, Methods & Results: We examined 47

Expression of Periostin in Cancer-associated Fibroblasts in Mammary Cancer in Female Dogs.

Mammary neoplasms, like breast neoplasms in women, are one of the most common tumours in female dogs. Cancer-associated fibroblasts (CAFs) found in the tumour stroma play a role in angiogenesis and increase cell migration, contributing to tumour growth and progression, as well as metastasis. The aim of our work was to determine the level of periostin (POSTN) expression in CAFs in mammary tumours of female dogs. The research material consisted of 77 carcinomas and 24 adenomas of the mammary ridge in female dogs. Immunohistochemistry tests were performed using antibodies directed against the antigens POSTN, Ki-67, ERB-B2 receptor tyrosine kinase 2 (HER2), vimentin, and alpha smooth muscle actin (αSMA). Expression of POSTN at the mRNA level was determined using real-time polymerase chain reaction methods in 20 cases of mammary neoplasms. Expression of POSTN in CAFs was observed in 92% of mammary cancer samples and in 25% of mammary adenoma samples in female dogs. A statistically significant increase in POSNT expression in CAFs was found in the carcinomas compared with mammary adenomas in female dogs. Expression of POSTN in CAFs in mammary carcinomas in female dogs positively correlated with the histological malignancy grade of tumours and the expression of Ki-67 proliferative antigen. Our results suggest a role of POSTN on the pathogenesis of mammary tumours in female dogs. Moreover, POSTN may prove to be a useful marker in the evaluation of cancerous stroma of mammary tumours in female dogs, and may have prognostic significance.

Expression of Podoplanin in Mammary Cancers in Female Dogs.

Mammary neoplasms are very common tumours in female dogs. Cancer-associated fibroblasts (CAFs) play an important role in the oncogenesis process. One of the useful proteins used in the diagnostics of CAFs cells is podoplanin (PDPN). The aim of our study was to assess the expression of PDPN in mammary cancer in female dogs. Our study cohort included 61 cancers and 21 adenomas of the mammary tumour in bitches. Expression of podoplanin, Ki-67 and HER2 was determined using the Immunohistochemical (IHC) method. PDPN expression at the mRNA level was determined using real-time PCR. Expression of PDPN in CAFs was observed in 22.9% of cases of mammary cancers in bitches, with no PDPN expression in adenomas. A positive correlation was found between the expression of PDPN in CAFs and the grade of histological malignancy and expression of Ki-67. PDPN plays a significant role during the process of carcinogenesis of mammary tumours in female dogs.

Uso da termografia infravermelha como auxílio diagnóstico de neoplasia mamária canina

<p>This paper aimed to evaluate the use of thermography as an aid method for the early diagnosis of breast cancer in female dogs assisted at the Veterinary Hospital of IFPB Campus Sousa. Five female dogs diagnosed clinically with mammary neoplasia were selected for this study. The protocol was listed in the chronological order of medical care: anamnesis, physical examination of the tumours, thermography, surgery and collection of material for histopathological examination. Patients underwent thermographic examination with the Flir® Thermovisor equipment, model T420. The examination took place in an acclimatized room and upon permission of the animal’s tutor. 60% were pure breed female dogs. Tumours were observed in three non-castrated female dogs and two castrated ones. The masses exhibited three macroscopic presentation patterns. The majority of them were nodular, followed by pendular and flat. Masses in animal 1 showed no increase in volume and there was no difference in temperature between the breast affected by neoplasia and healthy one, whereas for animals 2, 3, 4 and 5 there was an increase in temperature of 0.6ºC, 1.0°C, 1.2°C and 2.3°C, respectively. Three different types of carcinoma were found according to histopathological examination: complex carcinoma, tubular and tubulo-papillary carcinoma. In 100% of the animals the lesions were malignant, reporting high frequency of malignant epithelial tumours in the canine species. Based on these results, it was concluded that no direct relationship was found between the thermographic imaging pattern among the types of malignant mammary tumours in female dogs. Therefore, the conception of new studies on the matter is necessary due to the small number of animals on this research, where it was not possible to affirm the capacity of the thermography in the early differentiation of the malignancy of the masses. Future researches in oncology will promote a better understanding of the pathological aspects related to mammary tumours.</p>

MicroRNA and cancer: a focus on mammary tumors in female dogs

ABSTRACT: Mammary tumors are the most frequent tumors reported in female dogs and have great relevance in veterinary oncology; however, little is known about the molecular mechanisms involved in the development of metastasis. An increasing number of human studies have suggested that epigenetic alterations, such as DNA methylation, miRNA, and histone modifications, are the predominant events leading to the metastatic phenotype in tumor cells and participate in regulating oncogenic signals associated with tumor spread. Among these epigenetic alterations, miRNAs have stood out in recent years, presenting a fundamental role in tumorigenesis. There are still few studies evaluating the role of miRNAs in canine mammary tissues. Thus, this paper aims to review the role of miRNAs in cancer with a special focus on canine mammary tumors.

BI-RADS classification and gray level histogram of malignant mammary tumors in bitches

ABSTRACT: Mammary tumor is the most frequent among the tumors that affect canine females, with relevant importance in veterinary medicine. The objective of this study was to determine the image characteristics of mammary tumors in female dogs, and compare different ultrasonographic techniques for neoplastic evaluation. During the experiment, 30 bitches with presence of nodular lesion in the mammary gland were used. Initially females were submitted to clinical and laboratory evaluations, and subsequent to the ultrasound examination of the tumor mass, as well as abdominal ultrasound and thoracic x-ray for the metastasis investigation. Quantitative analysis by histogram of the gray levels and categorization of the tumor masses by the BI-RADS system were performed. Later, the bitches were submitted to surgical resection of the tumors, where samples of the neoplastic tissue were collected for histopathological analysis. Carcinoma in mixed tumor showed a higher rate (33.3%), and the malignancy degree of epidermal tumors were classified in grade 1 (n=9), grade 2 (n=12) and grade 3 (n=3). Malignancy degree showed positive correlation with BI-RADS (r=0.55; P<0.05) and with the parameter echotexture - histogram base width (r=0.42, P<0.05). BI-RADS graduation also showed a positive correlation with the echotexture parameters (standard deviation of average echogenicity r=0.66, P<0.05 and base width r=0.55, P<0.05). It was concluded that the BI-RADS method in combination with the echotexture of tumors, can be used to evaluate mammary tumors in dogs and establish the planning of treatment.

Immunohistochemical markers of mammary tumors in female dogs from Northeastern Algeria

Immunohistochemical markers of mammary tumors in female dogs from Northeastern Algeria

Corrigendum: Prevalence and Histopathologic Analyses of Mammary Tumors in Female Dogs in the Northeast of Algeria

Correction to: OnLine Journal of Biological Sciences http://doi.org/10.3844/ojbsci.2017.166.177, published online 26 September 2017; updated 10 April 2018 The original version on this Article did not include Dr. Amir Agabou as a Co-Author. In addition, the Author's Contribution section has been updated to the following. Zahra Gabli: This work was carried out in collaboration between all authors. The first author assisted all the steps of this work: He designed the study, assisted sample collection, data analysis and manuscript preparation. Leila Beddar: Supervised the study, coordinated the data-analysis and contributed to the writing of the manuscript. Amir Agabou: Participated actively in data analyses and interpretation, writing the paper and critically revising it. Zouhir Djerrou: Contributed in drafting the manuscript and reviewing it critically. Edouard Reyes-Gomez: Performed histopathological findings, analyzed and interpreted the results, coordinated the data-analysis and contributed to the writing of the manuscript. These errors have now been corrected in the HTML and PDF versions of the Article. http://doi.org/10.3844/ojbsci.2018.115

Prevalence and Histopathologic Analyses of Mammary Tumors in Female Dogs in the Northeast of Algeria

Cancers development and complications are a major cause of death in dogs all over the world. The current study attempts to describe the prevalence and anatomo-pathologic traits of mammary gland tumors (MGTs) in bitches in northeast Algeria. From November 2013 to April 2016, a total of 215 bitches originating from four provinces (Constantine, Oum El Bouaghi, Annaba and Skikda) were enrolled. The overall prevalence of MGTs was 19.53%. It was higher in littoral provinces (27.22%) than in inland ones (15.33%). A high rate was documented in Caniche (43.75%) as compared to Cross-breed (16.17%) and German shepherd (14.78%) bitches. The mean age of positively diagnosed animals was 9±0.3 years and the mean size of tumors was 5.4±04 cm. Histopathological classification revealed that 40.47% tumors were benign (mainly benign mixed tumors and benign complex tumors), 30.95% were malignant (especially epidermoid carcinoma, mammary sarcoma and malignant complex tumors) and 28.57% were identified as dysplasia (Mostly Osteo-mammary, benign hyperplasia and fibrocystic mastopathy). Finally, more epidemiological investigations are needed to determine the risk factors that may be implicated in the initiation and evolution of these health problems.

Epidemiological Study of Mammary Tumors in Female Dogs Diagnosed during the Period 2002-2012: A Growing Animal Health Problem.

Epidemiological studies enable us to analyze disease behavior, define risk factors and establish fundamental prognostic criteria, with the purpose of studying different types of diseases. The aim of this study was to determine the epidemiological characteristics of canine mammary tumors diagnosed during the period 2002-2012. The study was based on a retrospective study consisting of 1,917 biopsies of intact dogs that presented mammary gland lesions. Biopsies were sent to the Department of Pathology FMVZ-UNAM diagnostic service. The annual incidence of mammary tumors was 16.8%: 47.7% (benign) and 47.5% (malignant). The highest number of cases was epithelial, followed by mixed tumors. The most commonly diagnosed tumors were tubular adenoma, papillary adenoma, tubular carcinoma, papillary carcinoma, solid carcinoma, complex carcinoma and carcinosarcoma. Pure breeds accounted for 80% of submissions, and the Poodle, Cocker Spaniel and German Shepherd were consistently affected. Adult female dogs (9 to 12 years old) were most frequently involved, followed by 5- to 8-year-old females. Some association between breeds with histological types of malignant tumors was observed, but no association was found between breeds and BN. Mammary tumors in intact dogs had a high incidence. Benign and malignant tumors had similar frequencies, with an increase in malignant tumors in the past four years of the study. Epithelial tumors were more common, and the most affected were old adult females, purebreds and small-sized dogs. Mammary tumors in dogs are an important animal health problem that needs to be solved by improving veterinary oncology services in Mexico.

Influence of Surgical Technique on Overall Survival, Disease Free Interval and New Lesion Development Interval in Dogs with Mammary Tumors

The best surgical technique for the treatment of mammary tumors in female dogs has been exhaustively debated among the scientific community. Despite biological knowledge of these tumors, some authors have suggested aggressive procedures, without any clinical advantage. The aim of this study was to evaluate the influence of surgical procedure on the overall survival, disease-free interval and new lesion development interval in dogs with mammary tumors treated according to established prognostic factors. This prospective study included 143 intact female dogs that underwent surgery for mammary neoplasms and were followed up for about 738.5 days. Each animal represented a repetition. Each surgical technique represented a group: lumpectomy (P1), mammectomy (P2), regional mastectomy without cranial abdominal gland involvement (P3), regional mastectomy with cranial abdominal gland involvement (P4), and radical mastectomy (P5). Considering only the first surgical event, 84.6% of animals had more than one mammary tumor, and tumors were identified in two mammary chains in 52.5%. There was no difference in ipsilateral and contralateral tumor development when surgical techniques were compared. Only 33 dogs developed new lesions in remaining mammary tissue, without correlation with primary lesion. Surgical technique had no effect on the overall survival, disease-free interval and new lesion development interval in patients on this study, which respected oncological surgery principles and established prognostic factors for mammary gland tumors in dogs.

Effects of the Missense Mutations in Canine BRCA2 on BRC Repeat 3 Functions and Comparative Analyses between Canine and Human BRC Repeat 3

Mammary tumors are the most common tumor type in both human and canine females. Mutations in the breast cancer susceptibility gene, BRCA2, have been found in most cases of inherited human breast cancer. Similarly, the canine BRCA2 gene locus has been associated with mammary tumors in female dogs. However, deleterious mutations in canine BRCA2 have not been reported, thus far. The BRCA2 protein is involved in homologous recombination repair via its interaction with RAD51 recombinase, an interaction mediated by 8 BRC repeats. These repeats are 26-amino acid, conserved motifs in mammalian BRCA2. Previous structural analyses of cancer-associated mutations affecting the BRC repeats have shown that the weakening of RAD51's affinity for even 1 repeat is sufficient to increase breast cancer susceptibility. In this study, we focused on 2 previously reported canine BRCA2 mutations (T1425P and K1435R) in BRC repeat 3 (BRC3), derived from mammary tumor samples. These mutations affected the interaction of canine BRC3 with RAD51, and were considered deleterious. Two BRC3 mutations (K1440R and K1440E), reported in human breast cancer patients, occur at amino acids corresponding to those of the K1435R mutation in dogs. These mutations affected the interaction of canine BRC3 with RAD51, and may also be considered deleterious. The two BRC3 mutations and a substitution (T1430P), corresponding to T1425P in canine BRCA2, were examined for their effects on human BRC3 function and the results were compared between species. The corresponding mutations and the substitution showed similar results in both human and canine BRC3. Therefore, canine BRCA2 may be a good model for studying human breast cancer caused by BRCA2 mutations.

Serum neopterin levels in female dogs with malignant mammary tumours

In this study, we have determined serum neopterin levels in female dogs with primary malignant mammary tumours. The study involved 50 female dogs which had a malignant mammary tumours removed surgically (32 animals with carcinoma, 12 animals with sarcoma and 6 animals with carcinosarcoma) and 10 clinically healthy female dogs. Serum neopterin levels were determined using a commercial ELISA kit. The mean neopterin levels were lower in the malignant tumour groups than in healthy animals but differences were statistically significant only in carcinoma and sarcoma groups. The decrease of neopterin levels in animals with malignant mammary tumours may suggest their decreased cellular immunity. Moreover, it might indicate that decreased activity of cellular mechanisms of the anti-neoplastic response is one of the factors associated with the development and course of malignant mammary tumours in female dogs; however, further studies are necessary.

Avaliação da superexpressão da proteína p53 e das mutações no éxon 8 do gene TP53 em carcinomas mamários caninos e glândulas normais

Este estudo foi realizado com o objetivo de avaliar a expressão da proteína p53, pela técnica de imuno-histoquímica, em neoplasmas mamários malignos em cadelas, além de investigar mutações no éxon 8 do gene supressor Tp53 por meio do padrão de bandas obtidas por PCR-RFLP. Dezenove mamas de cadelas saudáveis foram usadas como controle (Grupo 1). Amostras de 18 casos de tumores malignos (Grupo 2) e suas glândulas mamárias contralaterais (Grupo 3) foram obtidas na rotina do Hospital Veterinário da UFRPE. Os tumores foram identificados histologicamente e classificados em graus de malignidade. O método da estreptoavidina-biotina peroxidase foi utilizado para a análise da expressão de p53 por imuno-histoquímica, de acordo com a localização e intensidade da coloração. A expressão da proteína p53 não foi observada nas amostras do Grupo 1, mas foi encontrada em todas as amostras de tumores malignos (Grupo 2) seja só no núcleo, ou também no citoplasma. No Grupo 3, a expressão foi observada em quatro amostras normais e em duas que apresentavam tumor. Para a análise molecular, o DNA genômico foi extraído e submetido à PCR-RFLP com as seguintes endonucleases: AluI, BsoBI, DdeI e SmaI. O padrão de bandas foi polimórfico entre os grupos, mas não entre as variantes tumorais. Esse polimorfismo detectou mutações no fragmento estudado - éxon 8 do gene Tp53 - que podem resultar em alterações nos nucleotídeos, localizados nos sítios de restrição das enzimas. Esses achados levam a conclusão de que a imunoexpressão da p53 não tem relação com o subtipo histológico ou grau de malignidade do tumor, mas sim com a presença dos tumores no tecido mamário de cadelas. A PCR-RFLP pode ser usada como importante ferramenta para o estudo da carcinogênese mamária na cadela, possibilitando gerar diagnósticos precoces através do polimorfismo obtido com endonucleases de restrição pré-selecionadas.

Immunohistochemical evaluation of e-cadherin, Ki-67 and PCNA in canine mammary neoplasias: correlation of prognostic factors and clinical outcome

E-cadherin is a cell-cell adhesion molecule and low e-cadherin expression is related to invasiveness and may indicate a bad prognosis in mammary neoplasms. The expression of cell proliferation markers PCNA and especially Ki-67, has also proved to have a strong prognostic value in this tumor class. The expression of these markers was related to the clinical-pathological characteristics of 73 surgically removed mammary tumors in female dogs by immunohistochemistry. There was no statistical correlation between these markers and death by neoplasm, survival time and disease-free interval. However, the loss of e-cadherin expression and marked Ki-67 expression (p=0.016) were considered statistically significant for the diagnosis (p=0.032). When evaluated as independent factors, there was evidence of the relationship between the loss of e-cadherin expression and high PCNA expression with changes in the body status (divided into obese, normal and cachectic) of female dogs (p=0.030); there was also evidence of the relationship between pseudopregnancy and e-cadherin alone (p=0.021) and for ulceration and PCNA alone (p=0.035). The significant correlation between the markers expression and these well known prognostic factors used individually or in combination suggests their prognostic value in canine mammary tumors.

Relation between habitual diet and canine mammary tumors in a case-control study.

In the present case-control study several dietary and nutritional factors were investigated to determine if a relationship exists between diet and development of mammary tumors in female dogs. Control female dogs (n = 86) were compared with a case group of dogs (n = 102) with dysplasias or tumors of the mammary gland. A questionnaire providing information on the dog's body conformation and dietary and reproductive histories was answered by the owners. Serum selenium and retinol concentrations and the fatty acid profile in subcutaneous adipose tissue were analyzed as indicators of nutritional status. Obesity at 1 year of age and 1 year before the diagnosis of mammary nodules was found to be significantly related to a higher prevalence of mammary tumors and dysplasias. The intake of homemade meals (compared to that of commercial foods) was also significantly related to a higher incidence of tumors and dysplasias. Other significant risk factors were a high intake of red meat, especially beef and pork, and a low intake of chicken. The subcutaneous fatty acid profile and the serum selenium concentration were not significantly different in the cases and the controls, with the exception of C18:1 fatty acid (oleic acid) content, which was significantly higher in the cases than in healthy controls. Serum retinol concentration was significantly lower in the cases than in the controls. In the multivariate analysis, older age, obesity at 1 year of age, and a high red meat intake were independently and significantly associated with the risk of developing mammary tumor and dysplasias.