Hormone therapy in the treatment of breast cancer and main outcomes in sexuality

Hormone-dependent breast cancer has growth factors that respond positively to the hormones estrogen and progesterone. Thus, adjuvant endocrine therapy causes decreased or undetectable serum levels of these hormones. However, this treatment can have side effects that compromise the sexual health of patients, such as dyspareunia, vaginal dryness and decreased libido. In this scenario, the objective of this work was to document the main outcomes in sexuality in women after treatment for hormonepositive breast cancer. Thus, this is an integrative literature review, in which the following databases were used: U.S. National Library of Medicine (PubMed), Virtual Health Library (BVS), SCOPUS and Scientific Electronic Library Online (SCIELO), using the descriptors: "sexuality", "antineoplastic agents, hormonal" and "breast neoplasms", joined by the Boolean operator "AND". Full articles published in the last 5 years (2017-2022) were included; written in Portuguese or English. Articles dealing with non-hormone-dependent or metastatic breast cancer, or with patients younger than 18 years, or articles that did not answer the research question were excluded. In total, 26 articles were identified, of which 7 comprised the final sample of this review. A total of 3,850 women participated in the included studies. The main sexual dysfunctions found were: dyspareunia, hot flashes, decreased libido, vaginal dryness, breast tenderness, self-image concerns and hair loss. The symptom vaginal dryness was the most prevalent, mentioned in 71.4% of the articles included. In view of the adverse effects listed in this review, there is a need to carry out more studies on this topic, since the diagnosis of this comorbidity brings clinical, psychological, emotional, sociocultural and economic outcomes for the patient. Thus, a multidisciplinary team must assertively address these complaints to improve the overall quality of life of these women (AU)

Boys in white: um clássico da pesquisa qualitativa completa cinquenta anos / Boys in white: a classic of qualitative research turns 50

O artigo analisa o livro Boys in white: student culture in medical school, de Howard S. Becker, Blanche Geer, Everett C. Hughes e Anselm Strauss, considerado um dos modelos de pesquisa qualitativa em sociologia. A análise aborda as trajetórias dos autores, do livro, da pesquisa qualitativa e dos estudantes de medicina, enfatizando sua importância nas origens da sociologia médica e da sociologia da educação médica. Na trajetória dos autores são apresentados aspectos biobibliográficos; na da pesquisa qualitativa, o modo como essa metodologia de investigação atravessa a construção do trabalho de campo; e na dos estudantes, sua forma de atravessar os primeiros anos da escola médica e construir sua própria “cultura do estudante”.

This article analyzes Boys in white: student culture in medical schoolby Howard S. Becker, Blanche Geer, Everett C. Hughes and Anselm Strauss, considered a model of qualitative research in sociology. The analysis investigates the trajectories of the authors, the book, qualitative analysis, and the medical students, emphasizing their importance in the origins of medical sociology and the sociology of medical education. In the trajectory of the authors, bibliographical information is given. The trajectory of qualitative research focuses on how this methodology influences the construction of the field. The investigation of the students’ trajectory shows how they progress through their first years at medical school to build their own student culture.

[Case report. Aggressive angiomyxoma of vagina. A rare tumor diagnosed]. / Angiomixoma agresivo de vagina: un tumor poco diagnosticado.

The case of a female patient of 35 years of age, with a pedunculated tumor dependent of the vagina, of approximately 25 x 12 x 8 cm, who had a wide resection. The report was consistent with myxoid aggressive angiomyxoma. This is a myxoid mesenchymal neoplasm of slow growth, which mainly appears in deep soft tissues of the pelvic, genital or perineal areas of adult women. It is usually diagnosed after surgical resection by histopathologic examination. Routine evaluation includes: complete physical examination, imaging and pathology report of diagnostic confirmation.

[Synchronous bilateral breast cancer in a male]. / Carcinoma mamario bilateral sincrónico en un varón.

BACKGROUND: male breast cancer is a disease with low incidence, which is further reduced when it comes to bilateral synchronous presentation. There are few published cases in recent years. The aim is to establish guidelines for the management of this disorder that is so rare. CLINICAL CASE: a 75-year-old with tumors in both breasts, which were completely resected with removal of palpable nodes. The histopathological study reported ductal carcinoma. The indicated treatment was adjuvant tamoxifen and radiotherapy. The patient is currently in a disease-free period. CONCLUSIONS: this is a rare disease, whose main treatment is surgery, hence the importance of early diagnosis. Most cases require adjuvant chemotherapy and radiotherapy because they are usually diagnosed at an advanced stage.

antecedentes: el cáncer de mama en el hombre es una enfermedad con baja incidencia, que se reduce aún más cuando es bilateral sincrónica. Existen pocas publicaciones en los últimos años. Objetivo: establecer pautas para el tratamiento de este cáncer, aunque sea infrecuente. Caso clínico: paciente masculino de 75 años de edad, con tumores en ambas mamas, que se le resecaron completamente con exéresis de ganglios palpables. El estudio histopatológico informó que se trataba de un carcinoma ductal infiltrante no especificado. Se indicó tratamiento adyuvante con tamoxifeno y radioterapia; en la actualidad está libre de enfermedad. Conclusiones: el carcinoma mamario bilateral sincrónico en el varón es una enfermedad poco frecuente. Su tratamiento principal es la cirugía, de ahí la importancia del diagnóstico temprano. En la mayoría de los casos se requiere quimioterapia y radioterapia adyuvante porque suelen diagnosticarse en un estadio avanzado.

The sequential use of endocrine treatment for advanced breast cancer: where are we?

BACKGROUND: Hormone receptor-positive advanced breast cancer is an increasing health burden. Although endocrine therapies are recognised as the most beneficial treatments for patients with hormone receptor-positive advanced breast cancer, the optimal sequence of these agents is currently undetermined. METHODS: We reviewed the available data on randomised controlled trials (RCTs) of endocrine therapies in this treatment setting with particular focus on RCTs reported over the last 15 years that were designed based on power calculations on primary end points. RESULTS: In this paper, data are reviewed in postmenopausal patients for the use of tamoxifen, aromatase inhibitors and fulvestrant. We also consider the available data on endocrine crossover studies and endocrine therapy in combination with chemotherapy or growth factor therapies. Treatment options for premenopausal patients and those with estrogen receptor-/human epidermal growth factor receptor 2-positive tumours are also evaluated. CONCLUSION: We present the level of evidence available for each endocrine agent based on its efficacy in advanced breast cancer and a diagram of possible treatment pathways.

Cáncer de próstata y apoptosis / Prostate Cancer and Apoptosis

El cáncer de próstata presenta una progresión andrógeno-dependiente mediada por el receptor de andrógeno (AR), por lo que el bloqueo androgénico es la terapia estándar para su tratamiento en estado avanzado. Sin embargo, a pesar de una sensibilidad inicial, estos cánceres usualmente evolucionan hacia un estado hormono-resistente. Esta resistencia puede ser debida a una amplificación del gen AR, a sus mutaciones y al aumento en la expresión de proteínas co-activadoras. Igualmente, el receptor AR puede permanecer activo, independientemente de la fijación del ligando por fosforilación de factores de crecimiento y de citosinas. Adicionalmente, hay otras posibles vías independientes del receptor AR, como lo ejemplifica la adquisición del fenotipo neuroendocrino. En esta revisión se examinan tanto los mecanismos moleculares involucrados en la progresión del cáncer de próstata así como la forma en que sus células evaden la apoptosis.

Prostate cancer presents an androgen-dependent growth mediated by the androgen receptor (AR). Androgen pathway blockage is the standard therapy for the treatment of prostate cancer at an advanced stage. In spite of an initial sensitivity, prostate cancer usually becomes refractory to hormone treatment. This resistance can be due to the amplification of the AR gene, AR mutations and the increase in co-activator protein expression. Likewise, growth factors and cytokines can induce AR phosphorylation, independently of ligand fixation. Moreover, there are other AR-independent pathways, such as the acquisition of the neuroendocrine phenotype. In this review, we examine the molecular mechanisms that are involved in the progression of prostate cancer, as well as the ways its cells evade apoptosis.

[Letrozole vs. tamoxifen as neoadjuvant therapy for postmenopausal patients with hormone-dependent locally-advanced breast cancer]. / Letrozol vs tamoxifeno como terapia neoadyuvante para pacientes posmenopáusicas con cáncer de mama hormono-dependiente localmente avanzado.

BACKGROUND: Previous studies demonstrated that Letrozole (aromatase inhibitor) and tamoxifen (selective modulator of estrogen receptors) are effective in the treatment of postmenopausal women with locally advanced tumors, stage III and hormone dependent. OBJECTIVE: To present display the complete clinical answer incidence and the complete pathological answer with the use of induction hormonotherapy. METHODS: Put-analysis in 40 patients with breast cancer, to chanalicular infiltrated, eligible were treated in a prospective study, to double blind person, using per os: letrozol, 2.5 mg; tamoxifen, 20 mg, known widely like selective modulator of estrogen receivers; oral route, during 36 consecutive months. Reports at the beginning were taken, subsequent to 3, 6 and 12 months to evaluate the frequency of complete respond. The patients, who did not show answer neoadjuvant therapy, were put under treatment with radiotherapy. The patients who showed good partial pathological respond, or clinical partial respond, went candidates to radical mastectomy. According to the protocol of the study, the patients subsequent to surgery who showed partial pathological respond or complete pathological respond, continued adjuvant handling adyuvant therapy by 2 years consecutive or until the presence of progression of the disease. It was used like statistical method Chi2, with p of Table cloth to evaluate the differences. RESULTS: During a period of 3 years, january of the 2003 to january of the 2005, 2 groups of patients, 40 studied altogether; the age average was of 65,5 years, with a rank of 55 to 75 years with breast cancer, stages: IIA to IIIB. Without complete respond 25% of the group with tamoxifen; 20% with letrozol Those patients happened to radiotherapy. The collateral effects of the use of hormonotherapy with letrozol appeared in a 55% and with the use of tamoxifen in a 60% of the patients with breast cancer (p = 0.5). They did not respond to neoadyuvant therapy (hormonal receptors < to 30%): with letrozol 19% of them and 25% with tamoxifen; reason why they received treatment with radiotherapy. All patients candidates to surgery, were benefitted with the mastectomy handling. CONCLUSIONS: Results although preliminary, suggest that neoadyuvant treatment with hormone-therapy in postmenopausal patients with breast cancer, have good prognosis. Induction therapy, were better tolerated, with greater effectiveness and improved the clinical and objective respond in women with breast cancer in the postmenopausal. Work serves as tool to determine the indication to us of induction hormonotherapy; and identify to those patients with breast cancer, locally advanced in post menopause with better prognosis to be rescued with radical mastectomy. Study needs more background and show the impact of letrozol, as hormonotherapy used in neoadjuvancy, to confirm if relieves period without disease or survives, before mastectomy. In a near future, it shall important to investigate if is useful the radical mastectomy in those postmenopausal patients with complete objective respond, after the use of an aromatase inhibitor.

[Prostate cancer and apoptosis]. / Cáncer de próstata y apoptosis.

Prostate cancer presents an androgen-dependent growth mediated by the androgen receptor (AR). Androgen pathway blockage is the standard therapy for the treatment of prostate cancer at an advanced stage. In spite of an initial sensitivity, prostate cancer usually becomes refractory to hormone treatment. This resistance can be due to the amplification of the AR gene, AR mutations and the increase in co-activator protein expression. Likewise, growth factors and cytokines can induce AR phosphorylation, independently of ligand fixation. Moreover, there are other AR-independent pathways, such as the acquisition of the neuroendocrine phenotype. In this review, we examine the molecular mechanisms that are involved in the progression of prostate cancer, as well as the ways its cells evade apoptosis.

Endocrine therapy of metastatic breast cancer.

Breast cancer growth and dissemination is regulated by estrogen and different growth factor receptor signalling pathways. The increasing knowledge of the biology of breast cancer regarding the interaction of these signalling pathways provides a tool to understand endocrine therapies response and resistance mechanisms. In patients with slowly progressive disease, no visceral involvement, and minimal symptoms, endocrine therapy could be the strategy of choice, even if the tumor has low estrogen receptor expression. Ovarian suppression and tamoxifen are recommended for premenopausal patients whether aromatase inhibitors are the option for postmenopausal ones. Chemotherapy still remains as the right alternative for hormone unresponsive or resistant patients. This is a review focused on the different strategies and combinations of endocrine therapies for metastatic breast cancer patients considering the potential strategies clinically tested to overcome resistance and the different treatments of choice available for each scenario of disseminated disease.

TNF alpha acting on TNFR1 promotes breast cancer growth via p42/P44 MAPK, JNK, Akt and NF-kappa B-dependent pathways.

Tumor necrosis factor alpha (TNF alpha) enhances proliferation of chemically-induced mammary tumors and of T47D human cell line through not fully understood pathways. Here, we explored the intracellular signaling pathways triggered by TNF alpha, the participation of TNF alpha receptor (TNFR) 1 and TNFR2 and the molecular mechanism leading to breast cancer growth. We demonstrate that TNFalpha induced proliferation of C4HD murine mammary tumor cells and of T47D cells through the activation of p42/p44 MAPK, JNK, PI3-K/Akt pathways and nuclear factor-kappa B (NF-kappa B) transcriptional activation. A TNF alpha-specific mutein selectively binding to TNFR1 induced p42/p44 MAPK, JNK, Akt activation, NF-kappa B transcriptional activation and cell proliferation, just like wild-type TNF alpha, while a mutein selective for TNFR2 induced only p42/p44 MAPK activation. Interestingly, blockage of TNFR1 or TNFR2 with specific antibodies was enough to impair TNF alpha signaling and biological effect. Moreover, in vivo TNF alpha administration supported C4HD tumor growth. We also demonstrated, for the first time, that injection of a selective inhibitor of NF-kappa B activity, Bay 11-7082, resulted in regression of TNF alpha-promoted tumor. Bay 11-7082 blocked TNF alpha capacity to induce cell proliferation and up-regulation of cyclin D1 and of Bcl-xLin vivo and in vitro. Our results reveal evidence for TNF alpha as a breast tumor promoter, and provide novel data for a future therapeutic approach using TNF alpha antagonists and NF-kappa B pharmacological inhibitors in established breast cancer treatment.

The oestrogen-dependent biology of breast cancer. Sensitivity and resistance to aromatase inhibitors revisited: a molecular perspective.

Endocrine treatment of breast cancer was the first molecular targeted anti-cancer therapy to reach clinical practice. Among the several options that share the common denomination of hormonal treatment, aromatase inhibitors (AIs) in the postmenopausal setting show the highest efficacy rates. These drugs have become the standard of care both in the advanced and adjuvant scenarios. Nevertheless resistance to AIs either upfront or after initial clinical response is almost a universal feature whenever tumour excision is not possible. Multiple reports have established the role of alternative pro-growth signalling pathways in the acquisition of resistance to the oestradiol deprivation that AIs produce. However the first clinical trials addressing the double blockade of both the oestrogen and other growing factor pathways raise some concerns on the efficacy of this approach. This review presents the evidence on the molecular events underpinning the response and resistance to AIs and suggests some key issues to consider when designing clinical research projects in this context.

A possible anti-proliferative and anti-metastatic effect of irradiated riboflavin in solid tumours.

Riboflavin is a potent photosensitizer as well as part of the vitamin B complex. Recently we demonstrated that the products generated by irradiation of riboflavin have potential as anti-leukaemic therapy. The possible action, however, of the riboflavin photoproducts in solid cancers has not been addressed. Hence, we investigated the effects of irradiated riboflavin on androgen-independent human prostate cancer cells (PC3), a known model for solid tumour cells with an exceptional resistance to therapy. Our results show that riboflavin photoproducts are cytotoxic to these cells in a FasL-Fas-dependent manner. Furthermore, irradiated riboflavin inhibited matrix-degrading proteases, caused downregulation of VEGF and upregulation of TIMP1 suggesting anti-metastatic potential. Together, these results show that the anti-neoplastic action of riboflavin photoproducts is not limited to haematological malignancies, warranting clinical studies in solid tumours.

Aromatase inhibitors and male breast cancer.

The majority of breast cancers in male patients are hormone receptor positive. Tamoxifen has proven to be successful in both adjuvant and metastatic settings and remains the standard of care. Given the improved outcomes in female patients with aromatase inhibitors (AI), these drugs have become a potential therapeutic tool for male patients. Preliminary data show effective suppression of oestradiol levels in males treated with AI and some reports have demonstrated objective responses. Here we report a case of a male patient with metastatic breast cancer treated with letrozole who achieved clinical response associated with a decrease in blood oestradiol levels.

Circulating tumoral cells lack circadian-rhythm in hospitalized metastasic breast cancer patients.

BACKGROUND: The relationship between breast cancer and circadian rhythm variation has been extensively studied. Increased breast tumorigenesis has been reported in melatonin-suppressed experimental models and in observational studies. OBJECTIVES: Circulating Tumor Cells (CTC) circadian- rhythm may optimize the timing of therapies. This is a prospective experimental study to ascertain the day-time and night-time CTC levels in hospitalized metastasic breast cancer (MBC) patients. MATERIAL AND METHODS: CTC are isolated and enumerated from a 08:00 AM and 08:00 PM blood collections. 23 MBC and 23 healthy volunteers entered the study. 69 samples were collected (23 samples at 08:00 AM and 23 samples at 08:00 PM from MBC; 23 samples from healthy volunteers). Results from two patients were rejected due to sample processing errors. No CTC were isolated from healthy-volunteers. RESULTS AND DISCUSSION: No-differences between daytime and night-time CTC were observed. Therefore, we could not ascertain CTC circadian-rhythm in hospitalized metastasic breast cancer patients.

Pharmacoeconomic analysis of adjuvant therapy with exemestane, anastrozole, letrozole or tamoxifen in postmenopausal women with operable and estrogen receptor-positive breast cancer.

OBJECTIVE: To compare the efficiency of adjuvant therapy with aromatase inhibitors or with tamoxifen in postmenopausal women with operable breast cancer and positive estrogen receptors. MATERIAL AND METHODS: A cost-utility analysis was performed based on a Markov model, from the Spanish National Health Care System perspective, comparing the treatment with exemestane (EXE: 25 mg/day) or tamoxifen (TAM: 20 mg/day) after 2-3 years of monotherapy with TAM; anastrozole (ANA, 1 mg/day) or TAM (20 mg/day) without previous TAM therapy; and letrozole (LET: 2.5 mg/day) or placebo after 5 years of monotherapy with TAM. The follow-up of a hypothetical cohort of women starting treatment at 63 years of age was simulated during 10 and 20 years. The probabilities of transition between health states and quality adjusted life years (QALYs) were obtained from the literature, and the unit costs (euro corresponding to 2004) from a Spanish database. RESULTS: After 10 and 20 years of follow-up, more QALYs per patient would be gained with the EXE scheme (0.230-0.286 and 0.566-0.708, respectively) than with ANA (0.114 and 0.285) and LET (0.176 and 0.474). The cost of gaining one QALY was lower with the EXE scheme (50,801-62,522 euro and 28,849- 35,371 euro, respectively) than with ANA (104,272 euro and 62,477 euro) and LET (91,210 euro and 49,460 euro). The result was stable for the cost per life-year gained (LYG) and in the sensitivity analysis. CONCLUSIONS: The EXE scheme after TAM is more cost-effective than the ANA and LET schemes.

Primary hormone treatment in postmenopausal women with breast cancer.

Clinical benefits of hormone therapy in patients with hormone-sensitive tumors have been clearly established. Postmenopausal women with positive hormone receptors represent the largest group of patients in whom early stage breast cancer is diagnosed. Third-generation aromatase inhibitors (letrozole, anastrozole, and exemestane) are active and well tolerated in postmenopausal women with hormone-sensitive metastasic or locally advanced breast cancer as first or second line treatment. These are also valuable agents in the neoadjuvant setting in postmenopausal women, and even as single treatment in localized breast tumors in women not amenable to surgery.

Molecular biology of breast cancer.

Although Breast Cancer (BC) has been considered for many years as a single entity with a common management and treatment, it is actually a extremely heterogeneous disease which includes at least 4 or 5 very different subtypes. The first step in the recognition of the heterogeneity of BC was the demonstration of the presence of functional hormonal receptors (HR) in nearly two thirds of breast cancer specimens. This finding, which established a first classification of BC in two clear subtypes (HR-positive and HR-negative) was followed by the demonstration of many other differential features. The her2/neu gene alteration, present in nearly 20% of BC tumors, is probably the most relevant of them, but certainly not the only one. The development of new technologies and, in particular, the use of complementary DNA (cDNA) microarrays will allow us now the simultaneous analysis of thousands of genes and the establishment of new, more refined BC subtypes based on gene expression profiles/genetic fingerprints. This review discusses the practical applications of molecular analysis of BC, which can be classified in four categories: 1. Establishment of a new molecular taxonomy of breast cancer. 2. Definition of prognostic factors/prognostic indexes based on molecular/genetic peculiarities. 3. Prediction of response to diverse antitumoral treatments. 4. Identification of molecular targets that allows the development of new tailored antitumor treatments.

Polyphenols purified from the Brazilian aroeira plant (Schinus terebinthifolius, Raddi) induce apoptotic and autophagic cell death of DU145 cells.

Polyphenols extracted from many plants have shown antiproliferative and antitumor activities in a wide range of carcinogenesis models. The antiproliferative effects of polyphenols purified from the Brazilian aroeira plant (Schinus terebinthifolius, Raddi) were investigated on the androgen-insensitive DU145 human prostatic carcinoma cell line. A F3 fraction purified from leaf extract inhibited the DU145 cell proliferation more than 30-fold compared to the crude extract. By flow cytometric analysis, the polyphenol fraction was demonstrated to induce G0/G1 cell growth arrest and cell apoptosis. This apoptosis was evidenced by caspase 3 stimulation in F3-treated cells as compared to crude extract treated cells. The acid phosphatase activity of lysosomes was strongly activated in the lysosomal fraction of the F3-treated DU145 cells. This lysosomal activation, together with the appearance of autophagic vacuoles, suggests that "type 2 physiological cell death" was also involved in this antiproliferative effect. HPLC analysis of this F3 fraction showed 18 different subfractions. Among these subfractions, F3-3, F3-7 and F3-13 strongly inhibited DU145 cell proliferation in a dose-dependent manner. However, the nature of these polyphenols remains unknown since only one (Isoquercitrin) of the tested pure polyphenols co-migrated with F3-13. Since lysosomotropic drugs are considered as possible regulators of lysosome activity, aroeira polyphenols could target lysosomes of prostatic cancer cells to induce autophagic cell death.

Psychosocial effect of mastectomy versus conservative surgery in patients with early breast cancer.

PURPOSE: To compare the quality-of-life (QoL) and psychosocial changes in a group of patients with early breast cancer who underwent conservative surgery (BCS) or modified radical mastectomy(MRM). METHODS: Self-administered questionnaire assessing body image perception, social habits, sexual attraction and self-consciousness with relatives/friends, was randomly assigned to 125 patients (61 BCS, 64 MRM; aged 53 +/- 8 and 50 + 9 years, respectively, p = NS). RESULTS: MRM patients reported a significantly higher frequency of changes in body image perception and other related social behaviour such as avoiding going to the beach or using low-cut clothes, and reticence with friends. Conversely, no differences were found regarding sexuality, denial of the disease by the husband/partner, or concealing the disease from family members. Also, no significant differences were found between patients above and below the age of 50 years, for all variables studied after adjustment for surgical procedure. CONCLUSIONS: Modified radical mastectomy has a negative effect on body image perception and in social behaviour patterns of patients and with a concomitant decrease in QoL. The sexuality of the patient is not significantly affected.

The effect of tamoxifen on PCNA expression in fibroadenomas.

For almost three decades, tamoxifen has been used in the adjuvant treatment of breast cancer. It has also proven effective in the chemoprophylaxis of this disease and in the treatment of cyclic mastalgia. Since a fibroadenoma is a benign hormone-dependent neoplasm which contains estrogen receptor (ER) levels higher than in the mammary lobule, an evaluation of the effect of this drug on the proliferative activity of both the epithelium and the stroma of fibroadenomas in premenopausal women following the administration of 10 or 20 mg/day over 22 days was proposed. Forty women with fibroadenoma were selected for a randomized double-blind trial. They had regular menstrual cycles and had received neither hormones nor become pregnant 12 months prior to this study. Patients were divided into three groups: A (n = 14; placebo), B (n = 13; tamoxifen 10 mg/day), and C (n = 13; tamoxifen 20 mg/day). The treatment was initiated on the first day of their menstrual cycle and the surgeries were performed on the 22nd day. Estradiol, progesterone, and steroid hormone binding globulin (SHBG) were measured twice. The first measurement was performed on the 22nd day of the previous menstrual cycle and the second one was performed on the day of surgery. The fibroadenoma was fixed in 10% formaldehyde solution and stained with hematoxylin and eosin and then processed through immunohistochemical reaction (PC-10, DAKO code number M879, Denmark A/S). The immunoexpression of the proliferative cell nuclear antigen (PCNA) of at least 500 epithelial and 500 stromal cells was evaluated. Such cells were interactively counted using the Kontron Imaging System KS-300 computerized analysis system, with x 400 magnification. As to PCNA expression in the fibroadenomas' epithelium, the average percentage of stained nuclei in groups A, B, and C was 25.2, 19.3, and 18.0, respectively. However, no significant difference was found in the variance analysis of these data (p = 0.168). As to the study of the fibroadenomas' stroma, the average percentage of stained nuclei found in groups A, B, and C was 32.4, 23.2, and 18.4, respectively. The variance analysis (p = 0.031) and Fisher's multiple comparison test (1.39; 26.67 confidence interval [CI]) confirmed that the number of PCNA-expressing nuclei in the stroma was significantly lower in group C (20 mg/day) compared to group A (control). However, there was no significant difference between group B (10 mg/day) and group C (20 mg/day). It was found that tamoxifen reduced the expression of PCNA in the epithelium and the stroma of the fibroadenoma. However, the effect was only statistically significant in the stroma when a 20 mg/day dose was administered.