The efficacy of sertraline for controlling hot flashes in women with or at high risk of developing breast cancer.

The aim of the study is to evaluate the efficacy of sertraline for controlling hot flashes in women with or at high risk of breast cancer. This was a randomized, double-blind, placebo-controlled study. All participants were asked to complete hot flash diaries. Participants reporting weekly hot flash scores >15 during baseline week underwent a 1-week single-blind placebo run-in. Those reporting hot flash score reductions >50% following placebo run-in were excluded. The remaining women received an assigned treatment for 4 weeks. Both groups' demographic and clinical characteristics were similar with a greater decline, but not statistically significant, in hot flash frequencies and scores in the sertraline-treated group compared with the placebo (P = 0.13 and P = 0.15, respectively). Emotional well-being improved significantly in the sertraline group (P = 0.041). The study failed to demonstrate effectiveness of sertraline in attenuating hot flashes in women with or at high risk of developing breast cancer who were not recommended to take hormone replacement therapy.

Idoxifene versus tamoxifen: a randomized comparison in postmenopausal patients with metastatic breast cancer.

BACKGROUND: More efficacious and safer hormonal agents are needed for breast cancer treatment and prevention. Idoxifene is a novel selective estrogen receptor modulator (SERM) that, in preclinical models, has greater antiestrogenic but lower estrogenic activity than tamoxifen. PATIENTS AND METHODS: Three hundred and twenty-one postmenopausal patients with hormone receptor-positive or -unknown metastatic breast cancer were randomized to receive either tamoxifen or idoxifene as initial endocrine therapy for advanced disease. Data were analyzed based on intention to treat and all the responses were subject to independent review. RESULTS: At the time of a second planned interim analysis, the trial was stopped for economic considerations, not for reasons related to safety or efficacy. Complete data for the 219 patients included in the second interim analysis are fully available and reported here. Median age was 59.1 years for idoxifene patients and 59.9 years for tamoxifen patients. Complete response (CR) plus partial response (PR) rates were as follows: tamoxifen, 9%; idoxifene, 13% (P = 0.39). Clinical benefit rate [CR + PR + stable disease (SD) >or=6 months] was 34.3% for idoxifene and 38.7% for tamoxifen (P = 0.31). Median time to progression and duration of response were 140 days and 151.5 days, respectively, for tamoxifen compared with 166 days and 218 days for idoxifene. None of these endpoints was significantly different for the two drugs, nor was survival. Adverse events (lethal, serious but not lethal and important but not life threatening) were similar in the two arms. CONCLUSIONS: Idoxifene was both active and well tolerated in postmenopausal women with metastatic breast cancer. Idoxifene had similar efficacy and toxicity to tamoxifen in this randomized comparison.

Ductal lavage for detection of cellular atypia in women at high risk for breast cancer.

BACKGROUND: Breast cancer originates in breast epithelium and is associated with progressive molecular and morphologic changes. Women with atypical breast ductal epithelial cells have an increased relative risk of breast cancer. In this study, ductal lavage, a new procedure for collecting ductal cells with a microcatheter, was compared with nipple aspiration with regard to safety, tolerability, and the ability to detect abnormal breast epithelial cells. METHODS: Women at high risk for breast cancer who had nonsuspicious mammograms and clinical breast examinations underwent nipple aspiration followed by lavage of fluid-yielding ducts. All statistical tests were two-sided. RESULTS: The 507 women enrolled included 291 (57%) with a history of breast cancer and 199 (39%) with a 5-year Gail risk for breast cancer of 1.7% or more. Nipple aspirate fluid (NAF) samples were evaluated cytologically for 417 women, and ductal lavage samples were evaluated for 383 women. Adequate samples for diagnosis were collected from 111 (27%) and 299 (78%) women, respectively. A median of 13,500 epithelial cells per duct (range, 43-492,000 cells) was collected by ductal lavage compared with a median of 120 epithelial cells per breast (range, 10-74,300) collected by nipple aspiration. For ductal lavage, 92 (24%) subjects had abnormal cells that were mildly (17%) or markedly (6%) atypical or malignant (<1%). For NAF, corresponding percentages were 6%, 3%, and fewer than 1%. Ductal lavage detected abnormal intraductal breast cells 3.2 times more often than nipple aspiration (79 versus 25 breasts; McNemar's test, P<.001). No serious procedure-related adverse events were reported. CONCLUSIONS: Large numbers of ductal cells can be collected by ductal lavage to detect atypical cellular changes within the breast. Ductal lavage is a safe and well-tolerated procedure and is a more sensitive method of detecting cellular atypia than nipple aspiration.

Clinical management of women with genomic BRCA1 and BRCA2 mutations.

PURPOSE: There is increasing evidence that BRCA1 and BRCA2 associated tumors may differ from sporadic cancers. The purpose of this report is to review the current state of knowledge of BRCA1 and BRCA2, the biology of associated tumors, and possible risk reduction strategies in women with these deleterious mutations. DESIGN AND METHODS: We conducted an extensive literature search of all published articles (including Medline) on preclinical data on the function of BRCA1 and BRCA2, associated tumor pathology, and the clinical management for both unaffected carriers and affected patients. RESULTS: BRCA1 and BRCA2 are likely to act as tumor suppressor genes, and together with RAD51 operate in a common DNA damage response pathway implicated in double-strand repair. Breast cancers associated with BRCA1 are frequently of a higher grade, steroid hormone receptor negative, and appear to have a higher proportion of atypical or typical medullary subtype. Conversely, BRCA2 associated breast cancers do not differ significantly from sporadic cancers. No special tumor phenotype has been ascribed to BRCA1 or BRCA2 associated ovarian cancers. Guidelines for risk reduction strategies for the high risk unaffected carrier have been recommended by expert panels in the USA and Europe. Lifestyle changes, multi-modality screening, chemoprevention, and prophylactic oophorectomy and mastectomy, with their possible benefits and attendant risks are described. Finally, locoregional and systemic treatment in breast and ovarian cancers associated with these mutations, and differences between these and sporadic cancers are discussed. CONCLUSIONS: Although the incidence of breast or ovarian cancers that can be attributed to BRCAI or BRCA2 mutations account for less than 5% of all cancers, these cancers may differ from sporadic cases in terms of tumor biology and phenotype. These differences may impact directly on clinical management of breast and ovarian cancer patients, and their relatives. Further recommendations of these patients are constantly changing as new information emerges on the clinical behavior of these cancers.

Tumor characteristics and clinical outcome of elderly women with breast cancer.

BACKGROUND: The number of elderly patients with breast cancer is increasing. Limited age-related information available about this disease prompted this study. PATIENTS AND METHODS: The study population was derived from 50828 and 256287 patients with invasive breast cancer in San Antonio breast cancer databases and the Surveillance, Epidemiology, and End Results (SEER) registry, respectively. Tumor biologic and clinical characteristics, local and systemic therapies, and survival according to the patient's age were analyzed. Survival was also compared with that of age-matched women from the general population. RESULTS: In patients 55 years old or older, there was an association between increasing age at diagnosis and the presence of more favorable biologic characteristics of the tumor, including more tumors that express steroid receptors, lower proliferative rates, diploidy, normal p53, and absence of the expression of epidermal growth factor receptor and c-erbB2. In older patients with lymph node-negative disease and/or small tumors, the observed and expected survivals were almost identical. In the SEER registry, the 8-year survival of lymph node-negative patients relative to the expected survival of age-matched women from the general population was 1.01 (95% confidence interval [CI] = 0.98-1. 04) for patients 70-74 years old, 1.06 (95% CI = 1.01-1.11) for patients 75-79 years old, and 1.09 (95% CI = 0.98-1.20) for patients 80-84 years old. CONCLUSION: In women 55 years old or older, advancing age is associated with more favorable tumor biology, and breast cancer survival in older women is similar to survival in the general population irrespective of disease status. This favorable outcome should be considered when making clinical decisions in older patients.

Prognostic value of p53 for local failure in mastectomy-treated breast cancer patients.

PURPOSE: The loss of p53 function is a recognized adverse prognostic factor in invasive breast cancer. Several studies have shown a relationship between the nuclear accumulation of p53 protein (a surrogate marker of p53 inactivation) and poor disease-free and overall survival. In general, however, these studies did not report the prognostic value of p53 for local failure, which we have therefore assessed retrospectively here. MATERIALS AND METHODS: Accumulation of p53 protein was evaluated by immunohistochemistry in 1,530 mastectomy-treated breast cancer patients (259 radiation therapy [RT]- and 1,271 mastectomy only [No RT]-treated patients). Statistical comparisons were made between p53 protein accumulation, estrogen/progesterone receptors, nodal status, tumor size, and local failure rate (LFR). Local failure was defined as tumor recurrence involving the chest wall and/or the ipsilateral supraclavicular/axillary lymph nodes. The median follow-up period was 62 months. RESULTS: In the No RT group, the LFR was 9.1% and 16. 5% in p53-negative and p53-positive patients, respectively (P<.001). Multivariate analysis revealed that p53 protein accumulation was significantly associated with an increased risk of local relapse (relative risk [RR], 1.7; 95% confidence interval [CI], 1.2 to 2.4). Nodal status and tumor size were also significant factors. In the RT group, the LFR was 9.3% and 21.5% in p53-negative and p53-positive patients, respectively (P = .009). Multivariate analysis revealed that p53 protein accumulation was significantly associated with an increased risk of local relapse (RR, 2.5; 95% CI, 1.1 to 5.7), as was nodal status. CONCLUSION: Nuclear accumulation of p53 protein is independently associated with a significantly increased local failure rate in breast cancer patients treated with mastectomy, with or without radiation.

Estrogen receptor (ER) and progesterone receptor (PgR), by ligand-binding assay compared with ER, PgR and pS2, by immuno-histochemistry in predicting response to tamoxifen in metastatic breast cancer: a Southwest Oncology Group Study.

Results of estrogen receptor (ER) and progesterone receptor (PgR) ligand-binding assays (LBAs) are strongly correlated with ER and PgR by immuno-histochemistry (IHC). To investigate whether ER and PgR by IHC are also strongly correlated with tamoxifen response, time to treatment failure (TTF) and overall survival (OS), the results of the 2 methods were directly compared in 205 patients with ER(+) metastatic breast cancer treated with daily tamoxifen (Southwest Oncology Group protocol 8228) with 9 years median follow-up. pS2, another estrogen-regulated molecule, was also analyzed. Tumors were scored for IHC from 0 to 5, according to the proportion of positively stained cells. These IHC scores for both ER and PgR were significantly associated with LBA levels (p < 0.001). There was a significant direct relationship between higher IHC ER, PgR and pS2 and increasing response to tamoxifen. TTF and OS were also significantly longer for patients with higher ER or PgR, but not pS2, IHC scores. Low, intermediate and high ER or PgR categories showed similar differences in response rates whether defined by LBA or IHC. In logistic regression models which included ER, PgR and pS2 by IHC; ER and PgR by LBA; and menopausal status, only ER (IHC) and pS2 (IHC) retained significance for predicting tamoxifen response (p = 0. 02 and p = 0.005, respectively), along with menopausal status (for PgR by IHC, p = 0.09). Increasing ER and PgR by IHC, as by LBA, are thus significantly associated with a progressively better response and longer survival in ER(+) metastatic breast cancer. pS2 is also predictive in this setting.

Tumor characteristics and clinical outcome of tubular and mucinous breast carcinomas.

PURPOSE: To comprehensively characterize the clinical and biologic features of tubular and mucinous carcinomas in a large cohort of patients and to relate this to clinical outcome and management. PATIENTS AND METHODS: The clinical and biologic features of 444 patients with tubular and 1,221 patients with mucinous carcinomas were compared with those of 43,587 patients with infiltrating ductal carcinoma, not otherwise specified (NOS). Disease-free survival (DFS) and overall survival (OS) for patients with tubular and mucinous carcinomas were compared with those of patients with NOS carcinomas and with age-matched sets from the general population. RESULTS: Tubular and mucinous carcinomas were more likely to occur in older patients, be smaller in size (tubular only), have substantially less nodal involvement, be estrogen receptor- and progesterone receptor-positive, have a lower S-phase fraction, be diploid, and be c-erbB-2- and epidermal growth factor receptor-negative compared with NOS carcinomas. Axillary node involvement was a poor prognostic feature in mucinous but not tubular carcinomas. Mucinous carcinomas < or = 1 cm had a < or = 5% incidence of node involvement. The 5-year DFS and OS were 94% and 88% for tubular, 90% and 80% for mucinous, and 80% and 77% for NOS carcinoma, respectively (P < .001 for differences among all three types for both DFS and OS). The 5-year OS of females from the general population age-matched to the patients with tubular and mucinous carcinomas was 89% and 82%, respectively, which is not different from the OS of patients with tubular or mucinous carcinomas. CONCLUSION: The biologic phenotype of tubular and mucinous carcinomas is quite favorable. Consistent with this observation, the survival of patients with tubular and mucinous carcinomas is similar to that of the general population. Systemic adjuvant therapy and node dissection may be avoided in many patients with these special types of carcinoma.

Heat shock proteins hsp27 and hsp70: lack of correlation with response to tamoxifen and clinical course of disease in estrogen receptor-positive metastatic breast cancer (a Southwest Oncology Group Study).

In this study, we tested the hypothesis that heat shock proteins (hsps) 27 and 70 are associated with clinical resistance to tamoxifen. hsp27 is, like progesterone receptor, an estrogen-regulated protein. hsp70 is also of interest because of its interaction with estrogen receptors and because hsp70 is a component of the molecular chaperone machinery functioning in the assembly and trafficking of steroid receptors. In addition, hsps in general help protect cells against noxious stimuli and stress, and their expression has been linked to drug resistance. The study involved 205 tumors from estrogen receptor-positive tamoxifen-treated breast cancer patients with metastatic disease. All patients received daily tamoxifen as initial therapy for metastatic disease. The study began in 1982, and follow-up is now 9 years. hsp27 and hsp70 were detected by immunohistochemistry and scored according to the nuclear and/or cytoplasmic content. Expression of hsp27 or hsp70 was unrelated to estrogen receptor content, progesterone receptor content, menopausal status, age, and presence of visceral disease. Cytoplasmic and nuclear hsp27 positivities were weakly and inversely related to each other (P = 0.05). There was a significant association between cytoplasmic hsp27 and cytoplasmic hsp70 content (P < 0.001), as well as between nuclear hsp70 and nuclear hsp27 content (P = 0.001). Cytoplasmic and nuclear hsp70 were also associated (P = 0.02). However, increased hsp27 and hsp70 expression (nuclear or cytoplasmic) was not significantly associated with response to tamoxifen, time to treatment failure, or survival. Thus, this study clarifies the lack of clinical utility of hsp27 and hsp70 in predicting the response to tamoxifen in an estrogen receptor-positive breast cancer population.

HER-2 expression and response to tamoxifen in estrogen receptor-positive breast cancer: a Southwest Oncology Group Study.

HER-2/neu is a growth factor receptor, the expression of which has been associated with a more aggressive breast tumor biology and resistance to some types of chemotherapy. Preliminary laboratory and clinical data have led to claims that HER-2/neu expression is also associated with resistance to tamoxifen. Therefore, to test the hypothesis that HER-2/neu expression is associated with a poorer response to tamoxifen, a shorter time to treatment failure (TTF), and worse survival in estrogen receptor (ER)-positive metastatic breast cancer, we examined 205 paraffin-embedded blocks of tumors from patients enrolled on Southwest Oncology Group 8228 for HER-2/neu expression. Tumors were ER positive (ER level > 3 fmol/mg cytosolic protein in either primary tumors or metastases), and patients had not received any prior therapy for metastatic disease. All patients were treated with daily tamoxifen. The study began in 1982, and median follow-up of patients who are still alive is now 9 years. Membrane staining for HER-2/neu was evaluated by immunohistochemistry using antibody TAB 250 and was scored according to the proportion of cells staining positive; tumors were deemed positive if > 1% of the cells stained for HER-2/neu. HER-2/neu positivity was associated with lower ER values (P = 0.04) and low bcl-2 (P = 0.01). HER-2/neu positivity was not significantly associated with response rate (negative versus positive, 57 versus 54%; P = 0.67), TTF (median, 8 versus 6 months; P = 0.15), or survival (median, 31 versus 29 months; P = 0.36). There was also no significant evidence of a progressive relationship between an increasing proportion of cells expressing HER-2/neu and a shorter TTF or survival. HER-2/neu expression in ER-positive metastatic breast cancer is not significantly associated with a poorer response to tamoxifen or a more aggressive clinical course. Earlier suggestions to the contrary may have been due to failure to rigorously exclude ER-negative tumors, which are much less likely to respond to tamoxifen and more likely to have high HER-2/neu levels.

Radiation therapy and survival in breast cancer patients with 10 or more positive axillary lymph nodes treated with mastectomy.

PURPOSE: Adjuvant loco-regional radiation (XRT) frequently is recommended after mastectomy and adjuvant systemic therapy in patients with 10 or more positive axillary lymph nodes (ALN) to reduce the high loco-regional failure rate observed in this subset. In this study, we explored the possibility that adjuvant loco-regional radiation therapy (LR-XRT) also could decrease distant failure and improve overall survival (OS) in this subset of poor-prognosis patients. PATIENTS AND METHODS: Retrospectively, 618 breast patients with 10 or more positive ALN were studied. The median follow-up time was 7.5 years. All patients received systemic adjuvant therapy and 35% also received adjuvant radiation therapy. Loco-regional failure, distant failure, and OS analyses were adjusted for age, tumor size, number of positive ALN, and estrogen receptor (ER) status using Cox regression model. RESULTS: As expected, patients had a very high risk of loco-regional and distant failure. At 5 years, 30% of patients had loco-regional failure as a first event and 54% had distant failure. Radiation dramatically reduced loco-regional failure (hazards rate ratios [RR]=0.29; 95% confidence interval [CI], 0.19 to 0.45). The adjusted 5-year loco-regional failure rate was 13% with radiation and 38% without radiation (P=.0001). Radiation also was associated with improved distant control (RR=0.75; 95% CI, 0.58 to 0.96). The adjusted 5-year distant failure rate was 48% with radiation and 58% without radiation (P=.02). OS also improved with radiation (RR=0.68; 95% CI, 0.53 to 0.85). The adjusted 5-year OS was 56% with radiation and 42% without radiation (P=.001). CONCLUSION: In this cohort of high-risk breast cancer patients, XRT was associated with less loco-regional and distant failure and improved OS. This suggests that improved loco-regional control might decrease secondary systemic spread and improve survival.

bcl-2 and apoptosis in lymph node positive breast carcinoma.

BACKGROUND: Because bcl-2 can block apoptosis in vitro, and because lower levels of apoptosis might lead to malignant cell accumulation and therefore to a more aggressive clinical course, the authors tested the hypothesis that high bcl-2 and low apoptosis would result in a worse prognosis for breast carcinoma patients. METHODS: Primary breast tumor specimens from 979 patients with positive axillary lymph nodes were evaluated for bcl-2 protein expression by immunohistochemistry (IHC). Apoptosis was evaluated by using IHC to detect 3' DNA fragments end-labeled with biotinylated uridine. Results were analyzed with respect to patient characteristics, prognostic factors, and clinical outcome. Median follow-up was 61 months. RESULTS: High bcl-2 expression was significantly associated with a number of favorable prognostic factors, including a lower number of positive lymph nodes, absence of p53 protein accumulation, estrogen receptor (ER) and progesterone receptor (PR) positivity, diploidy, and a lower proliferative rate. However, although bcl-2 is generally considered a negative regulator of apoptosis, in these tumors there was no significant association between bcl-2 and apoptosis. Patients with high bcl-2 expression had significantly improved disease free survival (DFS) (P < 0.0001) and overall survival (OS) (P < 0.0001). In a multivariate analysis, bcl-2 expression was independently associated with better DFS (P = 0.004). Regarding apoptosis, the presence of > or = 1% apoptotic cells was significantly associated with a greater number of positive lymph nodes, p53 protein expression, ER and PR negativity, aneuploidy, and a higher proliferation rate, although there was no significant association with a worse clinical outcome when this dichotomized cutoff was used. CONCLUSIONS: For lymph node positive breast carcinoma patients, high bcl-2 expression is associated with a number of good prognostic factors and is independently associated with better clinical outcome. Apoptosis is associated with a number of poor prognostic factors but not with a significantly worse outcome.

Models for early chemoprevention trials in breast cancer.

Several models are being explored for use in the phase I and phase II evaluation of breast cancer chemoprevention agents. The short-term DCIS/small invasive cancer model is probably best used in late phase I trials in conjunction with agents likely to have activity in the progression phase of neoplastic development in addition to activity in earlier phases. The core biopsy or FNA hyperplasia models may be best used with drugs that are likely to have activity primarily in the promotion phase of neoplastic development and that are suitable for longer duration trials lasting several months to years. Morphology currently is the key surrogate endpoint biomarker for assessing efficacy in phase II trials. Other biomarkers that may undergo modulation will have to be validated, in that modulation will have to be shown to be directly related to decreased cancer risk in subsequent phase III trials. Only then can they be considered as validated surrogate endpoint biomarkers and used as stand-alone efficacy markers in phase II trials. Despite accrual challenges and technologic hurdles, interest in phase I and phase II chemoprevention trials is high.

Prognostic and predictive value of p53 and p21 in breast cancer.

The prognostic and predictive value of p53 has been extensively studied in breast cancer. p53 serves a multifunctional role as a transcriptional regulator, genomic stabilizer, inhibitor of cell cycle progression, facilitator of apoptosis, and also perhaps an inhibitor of angiogenesis. Abrogation of its function should therefore lead to a more aggressive breast cancer phenotype and a worse clinical outcome, and indeed the preponderance of studies confirm this, with the risk of recurrence and death increasing by 50% or more if p53 is abnormal. Lack of unanimity of results may be due to differences in technique, study design, or population, as well as the subjectivity inherent in some approaches; however, the complexity and random nature of genomic change present in cancer cells may well also contribute to the lack of unanimity. Because many anticancer agents may exert a therapeutic effect through genomic damage and subsequent triggering of apoptosis, and because p53 can respond to genomic damage and facilitate apoptosis, it can be hypothesized that an intact p53 would predict sensitivity to therapy. Present data in breast cancer, however, does not clearly indicate that this is the case. There are several potential explanations. Study designs to accurately test the predictive value of a molecular marker are more exacting and difficult to achieve than prognostic studies. There may also be multiple alternative pathways, not involving p53, that play a part in determining the therapeutic effect of a treatment. The prognostic value of a downstream effector of p53 has also been assessed, though less extensively. p21 is transcriptionally upregulated by p53 and is an inhibitor of cyclin-dependent kinases and thus of cell cycle progression. Higher levels of p21 might indicate a more indolent type of breast cancer. However, data from a number of clinical studies is very conflicting, and at present p21 is not a promising prognostic factor in breast cancer.

bcl-2, p53, and response to tamoxifen in estrogen receptor-positive metastatic breast cancer: a Southwest Oncology Group study.

PURPOSE: To test the hypothesis that high bcl-2 expression and accumulation of p53 protein, both of which should inhibit apoptosis, are associated with a poorer tamoxifen response and a more aggressive clinical course in estrogen receptor (ER)-positive metastatic breast cancer. METHODS: A total of 205 paraffin-embedded tumor blocks were evaluated for nuclear p53 (a marker of p53 inactivation) and cytoplasmic bcl-2 by immunohistochemistry (IHC). All patients received tamoxifen as initial therapy for metastatic disease. The study began in 1982 and follow-up duration of the 24 patients last known alive is 8 years. RESULTS: Response to tamoxifen and time to treatment failure (TTF) were not significantly associated with p53 status, although patients with higher p53 had a worse survival (P = .008; median, 36 v 20 months). Higher bcl-2 expression was associated with higher levels of ER (P = .02), better response to tamoxifen (62% v 49%; P = .07), longer TTF (median, 9 v 5 months; P = .002), and better survival (median, 40 months v 25 months; P = .009). In multivariate analyses, including ER, progesterone receptor (PgR), and p53, high bcl-2 remained significantly associated with a longer TTF (P = .007) and survival (P = .07). p53 status was a significant factor for shorter survival (P = .05), but not for TTF (P = .61). CONCLUSION: p53 status, as determined by IHC is not significantly associated with response to tamoxifen, although tumors with altered p53 protein are inherently more aggressive. Contrary to expectation, high bcl-2 identifies a relatively indolent phenotype of ER-positive metastatic breast cancer, in which patients experience a better clinical response to tamoxifen and a longer survival.

WAF1/CIP1 protein expression in human breast tumors.

UNLABELLED: WAF1/CIP1 is a cyclin-dependent kinase inhibitor which is directly induced by p53 and negatively controls cell proliferation. To test the hypothesis that increased levels of WAF1 would be associated with a lower S-phase fraction and better prognosis, WAF1 protein was assessed by immunohistochemistry (IHC) in 115 node-negative human breast tumors, and results were correlated with established prognostic factors and clinical outcome. Nuclear staining was observed in malignant cells in 43% of tumors. In most (90%) of the positive tumors, the proportion of cells staining for WAF1 was low (< 10%). WAF1 was not detected in the cytoplasm, or in non-malignant epithelium. Contrary to expectations, the accumulation of p53 protein, a surrogate marker of p53 inactivation, was weakly but positively associated with WAF1 expression (p = 0.05). Surprisingly, there was no significant correlation with S-phase fraction, ER or PgR status, tumor size, age, ploidy, nuclear grade, or survival. CONCLUSION: WAF1 expression is found in the nuclei of a small fraction of cells in human breast tumors. WAF1 status is not significantly associated with cell proliferation, other established prognostic factors, or clinical outcome.