Cyclic biological expression in mouse mammary tumors.

Biological characteristics were assessed in GR mouse mammary tumors during 22 serial transplantations. Although unidirectional progression from hormone dependency to independency was observed, other biological markers such as progesterone receptors, polyploid frequency and thymidine kinase activity demonstrated cyclic phenomena every fourth to sixth transplant generation, suggesting the continued presence of regulatory mechanisms among various cells subpopulations.

Stability of HER-2/neu expression over time and at multiple metastatic sites.

BACKGROUND: Amplification and over-expression of the HER-2/neu oncogene (also known as c-erbB-2) occurs in 20%-30% of invasive breast carcinomas. The extent to which HER-2/neu expression changes over time in association with tumor progression or is heterogeneous at different metastatic sites has received only limited study. PURPOSE: Our purpose was to determine whether primary tumors differ from metastases in HER-2/neu protein content or whether metastases are heterogeneous in regard to HER-2/neu expression. METHODS: In a retrospective study, we examined tumor tissue obtained at autopsy from two to five metastatic organ sites in each of 30 patients who died with metastatic breast carcinoma. Using an immunoperoxidase technique, we stained archival formalin-fixed, paraffin-embedded tissue sections with a monoclonal antibody to the 185-kilodalton protein product (p185) of the HER-2/neu gene. RESULTS: The tissue from eight of 30 patients showed strong diffuse reactivity for p185 at all metastatic sites examined. Tissues from six patients showed faint staining and tissues from 15 were negative, again with a congruent staining pattern. A single case showed discordant staining, in that two of four metastases showed faint staining, whereas the other two showed strong immunoreactivity. In 14 cases, we were able to obtain paraffin blocks from the original biopsy or surgical resection of the primary breast lesion. For these 14 patients, the average length of time between initial diagnosis and death was 4 years (range, 2-9). There was good correlation between results from autopsy and original surgical tissues. CONCLUSIONS: Expression of HER-2/neu appears to be relatively stable over time and is generally congruent at different metastatic sites. IMPLICATIONS: The fact that p185 immunoreactivity is rarely heterogeneous is encouraging, both for the potential use of HER-2/neu-related proteins as serum tumor markers and for innovative therapies targeted at p185 expression.

Psychological symptoms and disease-free and overall survival in women with stage II breast cancer. Cancer and Leukemia Group B.

BACKGROUND: The possible link between psychological factors and length of cancer survival has generated a literature of contradictory findings. Associations usually have not been found when general psychological symptoms are assessed. Associations usually have been found for predictors related to expressive versus repressive emotional coping (e.g., depression, "fighting spirit," hostility, and type C personality); however, even these associations have been relatively small, when compared with those for medical factors. Yet few studies have adequately controlled for medical and treatment-related factors. PURPOSE: Within a Cancer and Leukemia Group B (CALGB) national clinical trial of four adjuvant therapy regimens for stage II breast cancer (CALGB 8082), this study prospectively examined the contribution of potential psychological predictors to length of disease-free and overall survival over a 15-year period. METHODS: Subjects were 280 women with stage II breast cancer, out of a total of 899, who were randomly assigned to receive CMFVP (cyclophosphamide-methotrexate-fluorouracil-vincristine-prednisone) for two 6-week cycles or six 4-week cycles, then subsequently randomly assigned to receive or not to receive VATH (vinblastine-doxorubicin-thiotepa-fluoxymesterone). Subjects were recruited during the period between October 1980 and August 1984, inclusive, and followed until January 1996. Prior to chemotherapy, psychological symptoms were assessed using the Symptom Check List-90-Revised (SCL-90-R). SCL-90-R scores were trichotomized into categories representing high, medium, and low distress. Basic base-line sociodemographic data (including age, ethnicity, education, and marital status) and medical data (including lymph node status, estrogen receptor status, menopausal status, and performance status) were collected. Subjects with psychosocial data differed from those without psychosocial data solely in their higher percentage of classification in the mild limitation category of the Zubrod (Eastern Cooperative Oncology Group) performance status rating (subjects with psychosocial data: 14%; subjects without psychosocial data: 8%). RESULTS: In stepwise Cox regression analyses that controlled for sociodemographic and medical variables, there was no significant predictive effect of the level of distress (as measured by the SCL-90-R trichotomized scores) on length of disease-free and overall survival of the study subjects. Risk ratios for low versus high distress were 1.01 (95% confidence interval [CI] = 0.62-1.66) for disease-free survival and 1.03 (95% CI = 0.58-1.82) for overall survival. CONCLUSIONS: This study failed to provide evidence that psychological factors contributed to length of disease-free or overall survival of women who received adjuvant chemotherapy (either CMFVP alone or CMFVP followed by VATH) for treatment of stage II breast cancer. IMPLICATIONS: In the context of far more potent medical factors, the contribution of psychological factors to disease-free and overall survival is likely to be relatively small. Future research should focus on specific theory-driven predictors rather than on general psychological symptoms. Moreover, it should be based on clinical studies using a controlled, prospective design, in which the effects of medical factors may be distinguished and psychological predictors are clear antecedents of survival outcomes.

Structural alterations and stabilization of rabbit uterine estrogen receptors by natural polyamines.

Estrogenic regulation of gene expression involves interaction of the hormone with its receptors, which undergo structural and conformational changes to interact with specific DNA sequences. Putrescine, spermidine, and spermine, are ubiquitous cellular components. We studied the effects of these polyamines on rabbit uterine estrogen receptors by sucrose gradient centrifugation and ligand dissociation kinetics. The native 7S receptor converted to a 9S-10S form in the presence of 100 microM spermidine or spermine. Higher concentrations caused precipitation of the receptor. This precipitation was reduced by RNase treatment of the receptor. RNase-treated receptors sedimented at 4S and 7S regions of sucrose gradient. The dissociation rate constant (k) of the 4S receptor is 2.8 X 10(-3) min-1 in the presence of 1 mM spermidine, compared to a control value of 7.7 X 10(-3) min-1. Similar effects were observed with putrescine and spermine. The dissociation of the RNase-treated 7S receptor was biphasic, with about 50% of the receptors dissociating at a faster rate (k1 = 40 X 10(-3) min-1) than the other half (k2 = 7.4 X 10(-3) min-1). Spermidine (1 mM) caused a 2-fold reduction in k2, whereas k1 was not affected. This study shows that polyamines affect the structural organization and ligand dissociation kinetics of estrogen-receptor complexes.

Modulation of the binding of progesterone receptor to DNA by polyamines.

Putrescine, spermidine, and spermine are a group of small organic cations, collectively known as polyamines. They are present in all living cells, and their levels are generally increased in tumor cells. Progesterone receptor is a gene-regulatory protein that plays a major role in gestation and in hormonal responsiveness of breast cancer. We studied the effects of putrescine, spermidine, 2 lower homologues of spermidine, N1- and N8-acetyl spermidines, spermine, and N1-acetyl spermine on the sedimentation profile and DNA binding of progesterone receptor from rabbit uterus. Progesterone receptor, prepared in hypotonic buffer, sedimented at the 7S region of sucrose gradients. In the presence of 1 mM putrescine, a part of the receptor was converted to a 5S form. In the presence of 1 mM spermidine or 0.25 mM spermine, the receptor was completely transformed to the 5S form. The DNA binding of the 7S form of progesterone receptor was 7 +/- 3%. After incubating this receptor with 1 mM putrescine, 1 mM spermidine, or 0.25 mM spermine, its DNA binding increased to 16 +/- 4, 37 +/- 3, and 44 +/- 5%, respectively. The structural specificity of polyamines in facilitating the DNA binding of progesterone receptor was examined by using two spermidine homologues. The first homologue with one methylene group less than that of spermidine was as effective as spermidine in transforming progesterone receptor. Removal of two methylene groups, however, had a dramatic effect in reducing the efficacy of the resulting molecule to the level of putrescine. Taken together, our results show that natural polyamines are capable of modulating the binding of progesterone receptor to DNA. Since progesterone receptor is associated with the hormonal responsiveness of human breast cancer, polyamine levels in tumor cells might play an important role in the gene-regulatory function of progesterone receptor.

Direct modulation of tumor suppressor connexin 26 gene by human chorionic gonadotropin in rat mammary glands.

Human chorionic gonadotropin (hCG) has been shown to reduce the incidence of carcinogen-induced rat mammary tumors. Because connexin 26 (Cx26), a tumor suppressor gene candidate, can be up-regulated in mammary epithelial cells during lactation, we examined the in vivo and ex vivo effects of hCG on Cx26 expression in rat mammary tissues and used its effect on the expressions of beta-casein and Cx43 as controls. The Cx26 mRNA and protein expressions were up-regulated by daily administrations of 100 units of hCG, starting on day 5 and reaching a 14-fold maximum increment on days 16 through 21. It remained elevated above the basal level even 20 days after hCG withdrawal. The changes in beta-casein expression ran parallel to that of Cx26, whereas the expression of Cx43 was down-regulated. There was no correlation between steroidal hormone levels and Cx26 expression, except for the first 5 days of hCG treatment. In the ex vivo organ culture system, exposure of mammary glands to 10 units/ml hCG for 5 days up-regulated Cx26 but had no effect on beta-casein expression. These results imply a direct induction of the tumor suppressor Cx26 gene by hCG in mammary epithelial cells, a mechanism unrelated to lactation.

Metabolism of testosterone by GR mouse mammary tumors.

The metabolism of testosterone by GR mouse mammary tumors following serial transplantation was studied. Oophorectomized female recipients were maintained on estrone and progesterone (OEP) or without hormone maintenance (oophorectomized-only group) in order to assess whether the growth of the tumor was hormone dependent (HD) or hormone independent (HI). Tumors in the early generations of the OEP group were HD (generations 1 to 4), which became HI in the latter generations (G5 to G18). All tumors developed in the oophorectomized-only group (generations 1 to 18) were HI. All tumors investigated were capable of metabolizing testosterone to 4-androstenedione, 16 alpha-hydroxytestosterone, 5 alpha-dihydrotestosterone, 5 alpha-androstanedione, and 5 alpha-androstanediol. Total 5 alpha-reduction in OEP group ranged between 50 and 60% of neutral metabolites in HD tumors and dropped to 13 to 28% in HI tumors (generations 5 to 18), similar to the activities (20 to 30%) of the HI tumors in the oophorectomized only group. Different patterns of estrogen synthesis were observed among these tumors. Although tumors showed the presence of appreciable amounts of estriol, estrone was synthesized only in 5 of the 9 HI tumors in the oophorectomized only group. The most striking contrast was that estradiol was synthesized by all HI tumors in the oophorectomized-only group and the OEP group but not in the HD tumors.

Nuclear estrogen receptor and nonhistone chromosomal proteins in hormonal independency of murine breast cancers.

The capability of nuclear binding of cytosol estrogen receptors (ERc) was studied in GR mouse mammary tumors during their alteration of hormonal dependency through serial transplantations. Nuclei from GR mouse mammary tumors were incubated with uterine cytosol receptor complexes labeled with 125I-estradiol, and the amount of receptor binding in the 0.4 M KCl nuclear extracts was determined. The originally ERc-positive-hormone-dependent (type I) tumors were capable of nuclear receptor binding, while this function was markedly reduced in the evolved hormone-independent (type II) tumors, although the ERc content in the latter was still positive. The originally hormone-independent (ERc-negative, type III) tumors, however, retained the nuclear binding capability. It appears that the hormonal independency in type III tumors is due to a lack of ER, while in type II tumors it may be attributed to the loss of nuclear binding capability for receptor complexes. Nonhistone chromosomal proteins (NHCP) were analyzed by the 2-dimensional gel electrophoretic technique. A Mr 31,000 NHCP was present in 11 of 12 type I, and four of four type III tumors. Following serial transplantation of the type I tumors, this NHCP was either markedly diminished or not observed in all 14 type II tumors examined. Although it coincides with the capability of nuclear receptor binding, the biological function of this NHCP is still undefined and warrants further investigation.

Binding characteristics of zearalenone analogs to estrogen receptors.

The estrogenic effect of zearalenone derivatives was investigated for their binding characteristics to cytosol and nuclear receptors in the uterus. Competition with 17beta-estradiol at the cytosol receptor sites was observed in four of the six derivatives tested, namely trans- and cis-zearalenone, zearalenol, and zearalanol. The other two, 8'-hydroxyzearalenone and 6'-aminozearalene, lacked the binding ability to receptors and were biologically inactive. trans-Zearalenone, like 17beta-estradiol, could elicit an immediate translocation of cytosol-receptor complexes into the uterine nuclei. However, it differs from either 17beta-estradiol or antiestrogens (tamoxifen) in three aspects: (a) a second wave of translocation occurred 6 to 12 hr following zearalenone injection; (b) there was a much longer nuclear retention (over 24 hr) than in the case of 17beta-estradiol; and (c) following a depletion of cytosol receptors, trans-zearalenone induced an overreplenishment by 24 hr, whereas tamoxifen is reported to suppress the replenishment.

Up-regulation of estrogen receptors by nonsteroidal antiestrogens in human breast cancer.

Development of resistance to hormonal therapy in breast cancer is frequently associated with a decline or loss of cellular estrogen receptors. Agents which up-regulate the receptor may reduce the incidence of hormonal resistance. Antiestrogens at concentrations ranging from 0.1 to 1 microM produced a 2- to 4-fold increase of estrogen receptors in MCF-7 and T-47D breast cancer cells. This increase, which occurred as early as 3 h and was sustained throughout the 4 days of continuous exposure to tamoxifen, was primarily due to an enhancement in receptor synthesis.

Regulation of ornithine decarboxylase gene expression in MCF-7 breast cancer cells by antiestrogens.

Ornithine decarboxylase (ODC) is an enzyme intimately related to cell growth regulation. The metabolic products of ODC, the polyamines, are known to play a vital role in the structure and function of biological macromolecules including nucleic acids and proteins. The activity of ODC is stimulated by estrogens in their target cells. In order to gain insight into the molecular mechanism of action of antiestrogens in human breast cancer, we studied the effect of tamoxifen and 4-hydroxytamoxifen on the concentration of ODC mRNA, ODC activity, and the polyamine levels in a hormone-responsive breast cancer cell line, MCF-7. ODC mRNA concentration was reduced to 40% of the controls after 6 h of treatment of the cells with 100 nM 4-hydroxytamoxifen, but tamoxifen had no significant effect on ODC mRNA after treating with even 1 microM concentration for 36 h. ODC activity was, however, reduced to 40 and 75% of the controls after 24 h of treatment with 4-hydroxytamoxifen and tamoxifen, respectively. There was a significant reduction in the concentration of putrescine to 63% of control in tamoxifen-treated cells, but spermidine and spermine levels were not affected. With 4-hydroxytamoxifen, putrescine, spermidine, and spermine levels were reduced to 41, 62, and 79% of the control, respectively. In addition, exogenous putrescine was able to reverse the growth inhibitory effects of 4-hydroxytamoxifen. Overall, these results indicate that ODC and polyamine levels in MCF-7 cells are controlled by antiestrogens, and that suppression of polyamine biosynthesis plays a critical role in the growth inhibitory effects of antiestrogens.

Mapping and characterization of the basal promoter of the human connexin26 gene.

Connexin26 (Cx26) is a major gap junction protein expressed in mammary and endometrial epithelial cells. Previously, we have cloned the genomic upstream sequence of the human connexin26 gene. In this paper, we studied the structure and function of its basal promoter. Various 5'-flanking regions of the human Cx26 gene were inserted upstream of the bacterial chloramphenicol acetyltransferase (CAT) reporter gene and transfected into human immortalized mammary MCF-10A and MCF-12A cell lines and endometrial RL95-2 cancer cell line. Through CAT reporter gene analysis, we identified the basal promoter of human Cx26 gene in the proximal 5'-flanking region from -128 to +2 (relative to the transcription initiation site). Further deletion analyses suggested that the critical regulatory area was located within a 29 bp region (from -97 to -69), where two GC consensus boxes (CCGCCC) resided, one at -93 and the other at -81. Labeled oligonucleotides encompassing these two GC box DNA sequences could bind the nuclear extracts from MCF-12A and RL95-2 cells in the electrophoretic mobility shift assay. These binding complexes could be competitively reduced by non-labeled self or Sp1 consensus oligonucleotide, and supershifted by antibodies against either Sp1 or Sp3. Mutations in the core sequence of these two GC boxes from CCGCCC to CCGAAC caused a loss of competitive ability and also produced a drastic reduction of basal promoter activity when integrated into promoter/reporter constructs. Furthermore, co-transfection of Sp1 and/or Sp3 expressing plasmids could trans-activate the expression of human Cx26 promoter/reporter constructs in Drosophila Schneider line 2 (SL2) cells. Taken together, these data indicated that the two GC boxes in the proximal promoter region play an important role in the control of human Cx26 gene expression.

Breast cancers negative for estrogen receptor but positive for progesterone receptor, a true entity?

By the conventional steroid-binding assay method for receptor, 3% of 1,095 primary breast cancers (or 10.6% of 263 premenopausal tumors) were classified as negative for estrogen receptor (ER), but positive for progesterone receptor (PR). The true ER status in this rare group of tumors was further investigated by the enzyme-immunoassay (EIA) or immunocytochemical (ICA) staining method using monoclonal antibodies H222 and D547. Immunoreactive ER was present in nine ER-/PR+ tumors studied, whereas it was not detectable in nine age-matched ER-/PR- tumors. Immunoreactive ER was also present in 24 ER+ breast cancers studied, and was particularly higher in tumors that were PR+. Measurement of immunoreactive ER by monoclonal antibody method provides certain advantages over the conventional dextran-coated charcoal (DCC) method, especially in ER-/PR+ tumors.

Differential up-regulation of gap junction connexin 26 gene in mammary and uterine tissues: the role of Sp transcription factors.

The mRNA and protein expressions of connexin 26 (Cx26) in rat mammary gland and uterus can be up-regulated during pregnancy as well as by the administration of human CG (hCG). In the present study, we found that the time course and magnitude of Cx26 induction by hCG was different in these two tissues. The molecular mechanism underscoring this difference was therefore investigated. We had previously demonstrated that both Sp1 and Sp3 transcription factors play a functional role in Cx26 expression. By the electrophoretic mobility shift assay, nuclear extracts from both virgin mammary gland and uterus were capable of binding to a labeled oligonucleotide probe that contained the proximal GC box and formed three protein-DNA complexes (C1, C2, and C3). In the mammary gland, pregnancy enhanced the intensity of all three complexes, whereas in the uterine tissue there was a decrease in the C2 and C3 complexes and an emergence of a new major component, C4 complex. In the supershift study, the C1 complex could be supershifted only by an antibody against Sp1, whereas C2, C3, and C4 could all be supershifted by an antibody against Sp3, suggesting a potential presence of Sp3 isoforms of various sizes. We therefore conclude that the basal Sp profiles in virgin mammary gland and uterine tissue are similar. However, in response to pregnancy, the changes in Sp profile are tissue specific and may account for the temporal and quantitative differences between these two tissues in Cx26 induction.

Mechanism of the hypocalcemic effect of mithramycin.

Mithramycin is effective in the treatment of hypercalcemia. The mechanism of its hypocalcemic effect was studied in six patients with hypercalcemia by serum 85Sr or 45Ca kinetic techniques. Mithramycin was given at two dosage levels (25 or 50 microgram/kg iv). Mithramycin at the low dosage had little effect on the rate of bone accretion. However, at both dosage levels, mithramycin caused an upward shift of the slope of the specific activity curve, indicating an inhibitory effect on bone resorption. This effect started 6-12 h after a 25-microgram/kg dose of mithramycin and lasted from 4-6 days. It appears that mithramycin has a preferential effect on bone resorption.

Upstream genomic sequence of the human connexin26 gene.

Human connexin 26 (Cx26) has been considered to be a candidate suppressor gene in mammary epithelial cells. To gain insight into the transcriptional regulation of this gene, we have cloned and sequenced the 5' portion of the gene, which extends 4.8 kb upstream from the ATG translation start site. The 3' end of the non-coding exon 1 (160 bp) is located at 3149 bp upstream from the 5' end of exon 2. Comparison between the human Cx26 gene and the mouse gene reveals a highly conserved promoter region with 81% homology. In addition to six GC boxes and two GT boxes, a TTAAAA box is located at -24 to -19 bp upstream of the transcription start point. Analogous to the mouse beta-casein gene, the promoter region of the human Cx26 gene also contains a YY1-like binding site and a consensus mammary gland factor binding site.

Gap junction Cx26 gene modulation by phorbol esters in benign and malignant human mammary cells.

Connexin (Cx) 26, a major gap junction protein expressed in mammary epithelial cells, has been considered to be a tumor suppressor gene candidate. This study investigated the molecular mechanism of transcriptional up-regulation of Cx26 by phorbol ester (TPA) in human immortalized MCF-10 mammary epithelial cells and MDA-MB-231 mammary cancer cells. Such up-regulation was mediated through the protein kinase C pathway and could be blocked by the PKC inhibitor, calphostin C. Based on the results of the nuclear run-on assay, there was a TPA-induced increase in the rate of transcriptional initiation. We identified a TPA-induced DNase I hypersensitivity (DH) region approximately 1 kb 5' upstream of the ATG translation starting site. Sequence analysis revealed that this DH region was located in intron 1 and contained two TRE-like TGAT/ATCA elements, two 5'TTCA3' motifs and a 5'AGGAAG3' PEA3 motif. Both TRE-like elements were capable of binding AP1. TPA inducibility of this DH region was seen by the CAT reporter assay and appeared to be direction-dependent suggesting a functional cooperation between PEA3/TTCA and TRE.

Reversal of myelofibrosis in advanced breast cancer.

Reversal of myelofibrosis and splenomegaly is described in a 41 year old woman with metastatic breast cancer. After intensive chemotherapy and hormonal therapy, the tumor regressed, the splenomegaly receded, the hemogram showed no abnormalities, and the dense collagen and reticulin fibers in the marrow disappeared. The severe thrombocytopenia and leukoerythroblastosis noted before therapy were not obstacles to clinical management. In our report we document that myelofibrosis associated with breast cancer is not an ominous sign. Patients may benefit from an intensive, but well titrated, therapeutic program.

Detection of c-erbB-2 activation in paraffin-embedded tissue by immunohistochemistry.

Commercially available monoclonal antibodies were tested for their ability to detect increased levels of c-erbB-2 protein in formalin-fixed, paraffin-embedded breast carcinomas. Of five antibodies studied, four (TAB-250, CB11, 3B5, and N3/D10) showed strong cytoplasmic membrane reactivity in 23% (11 of 47) of routinely processed tumors, although interpretation of the immunoreactivity with 3B5 and N3/D10 occasionally was difficult due to cytoplasmic granular staining. Since the c-erbB-2 oncogene is activated by DNA amplification and overexpression of mRNA and protein, the same tumors were analyzed for c-erbB-2 activation by other techniques. c-erbB-2 activation in these 11 tumors was confirmed by immunohistochemistry of frozen tissue (nine of nine tumors), in situ hybridization (nine of 11 tumors), and Southern blot analysis (five of eight tumors). In some of these tumors the failure to demonstrate c-erbB-2 DNA amplification may be due to the small percentage of malignant cells. One additional tumor showed probable c-erbB-2 protein overproduction based on strong immunoreactivity with two antibodies (TAB-250 and CB11), although no definite activation could be demonstrated by additional techniques. Three other tumors (6%) showed equivocal c-erbB-2 protein overproduction based on weak immunoreactivity only with TAB-250, although unequivocal activation could not be demonstrated by additional techniques. The 32 carcinomas (68%) that showed no significant immunoreactivity with any antibodies in routinely processed tissue also showed no detectable c-erbB-2 activation by additional techniques. We conclude that TAB-250 and CB11 are reliable antibodies for detecting c-erbB-2 protein overproduction in routinely processed tissue. TAB-250 also weakly stains a few tumors showing no definite c-erbB-2 activation by other techniques. Two additional antibodies (3B5 and N3/D10) detect c-erbB-2 protein overproduction in paraffin-embedded tissue, but are more difficult to interpret. A fifth antibody, TA-1, is an excellent reagent for use on frozen tissue, but prolonged formalin fixation may impair recognition of its antigenic epitope.

Gross cystic disease fluid protein-15 as a marker for breast cancer: immunohistochemical analysis of 690 human neoplasms and comparison with alpha-lactalbumin.

The identification of metastatic carcinoma of the breast may be difficult in the absence of a previous history of breast cancer. Various immunophenotypic markers have been introduced to aid in this process. A monoclonal antibody directed at a 15-kilodalton (kd) gross cystic disease fluid protein (GCDFP-15) was applied immunohistochemically to paraffin sections of 105 breast cancers and 585 nonmammary malignancies in order to assess its value in this context. In addition, GCDFP-15 was compared with another putative mammary epithelial marker, alpha-lactalbumin (ALA), with respect to sensitivity and specificity for a diagnosis of breast carcinoma. Overall, the rates of specificity and sensitivity and the predictive value of a positive result for GCDFP-15 were 95%, 74%, and 74%, respectively. Corresponding statistical parameters for ALA were 50%, 50%, and 23%. A consistent congruency between the reactivity patterns of primary and metastatic breast cancers was noted for GCDFP-15 but not for ALA. Besides mammary carcinomas, the major tumor types that expressed GCDFP-15 were carcinomas of the salivary glands, sweat glands, and prostate. Since the latter three types of lesions are unlikely to be diagnosed as metastatic breast cancer, statistical indices were recalculated after exclusion of these three tumor types. Following this exclusion, the adjusted rate of specificity of GCDFP-15 and the predictive value of a positive result for a diagnosis of metastatic carcinoma of the breast were each 99%. In contrast, predictive parameters for ALA were not altered. These results show that GCDFP-15 is a specific marker for breast cancer and is superior to ALA in this respect.