Immunohistochemical analysis of P-glycoprotein expression correlated with chemotherapy resistance in locally advanced breast cancer

We analyzed the expression of P-glycoprotein in samples from 48 patients with locally advanced breast cancer. Tumor samples from 40 patients were obtained at mastectomy, which was performed after three cycles of induction chemotherapy consisting of doxorubicin, cyclophosphamide, vincristine, and prednisone. P-glycoprotein expression distributed focally was observed in 20 tumors by the immunoperoxidase method using the anti-p170-monoclonal antibody C219. The percentage of the tumor cell population expressing P-glycoprotein varied from less than 5% to greater than 30%; expression was observed significantly more often in tumors that showed less than partial response to the preoperative chemotherapy. Furthermore, P-glycoprotein was not expressed in eight tumor specimens obtained at the time of diagnosis, prior to chemotherapy, from patients who subsequently had pathologic complete responses. A comparative study of P-glycoprotein expression before and after chemotherapy and upon recurrence of tumor was done on a limited number of samples. No significant differences in P-glycoprotein expression were found. Therefore, it is possible that an intrinsic, rather than acquired, drug resistance may play a role in the failure of induction chemotherapy for locally advanced breast cancer.     

Histologic observations and P-glycoprotein expression in gastric and esophageal adenocarcinomas treated with preoperative chemotherapy.

To describe histologic changes associated with chemotherapy response, we reviewed biopsy and resection specimens from 52 patients with locally advanced esophageal or gastric adenocarcinoma who were treated with preoperative chemotherapy, followed by resection. P-Glycoprotein expression in the adenocarcinomas was also determined with the use of antibody C219. Significant changes in morphologic appearance of the tumor between prechemotherapy and postchemotherapy samples was noted in 17 tumors (32.7%). The most frequent changes observed in these 17 tumors were a decrease in tumor cellularity and an increase in dense fibrosis in comparison with the prechemotherapy specimen. In signet-ring cell carcinomas, the intracytoplasmic mucin vacuoles were often smaller after chemotherapy, making tumor cells more difficult to identify. Another finding observed in tumors that showed histologic alteration after chemotherapy was the formation of large mucin pools that contained lymphocytes and macrophages. The remaining 35 tumors showed similar histologic features in prechemotherapy and postchemotherapy specimens. P-Glycoprotein was identified in 15 (29.4%) of 51 specimens after chemotherapy. P-Glycoprotein content of the residual tumors did not correlate with stage, degree of differentiation, or clinically determined chemotherapy response. We concluded that chemotherapy-induced changes in morphology were frequent in patients with upper gastrointestinal tract adenocarcinomas treated with preoperative chemotherapy. These changes should be recognized as they may cause difficulties in both gross and histologic evaluation of the extent of tumor in postchemotherapy resection specimens. The response of adenocarcinomas to this chemotherapy protocol does not appear to be linked to P-glycoprotein expression.     

Prognostic value of Ki67 expression in HR-negative breast cancer before and after neoadjuvant chemotherapy

Background: Immunohistochemical (IHC) expression of Ki67 has been identified as a prognostic and predictive marker in hormone receptor (HR)-positive breast cancer, however, there is little evidence of the association of Ki67 with prognosis in HR-negative patients. We aimed to assess the benefit of Ki67 assessment in HR-negative breast cancers after neoadjuvant chemotherapy (NAC). Methods: In the present study, a total of 183 HR-negative breast cancer patients with Stage II to III that treated with anthracycline and/or taxane-based neoadjuvant chemotherapy between 2004 and 2011 were retrospectively analyzed. Endocrine therapy and trastuzumab was not administered to any patients in this study. Clinical and pathological features of the patients with breast cancer were retrieved from the hospital records. Predictive factors for NAC response and survival were analyzed. Results: Of the 183 patients, 122 (66.6%) were HR- HER2+, and 61 (33.3%) were triple-negative. The clinical response rates were similar across breast cancer subtype. Patients whose tumors contained high Ki67 expression effectively responded to NAC. Ki67 labeling index was a predictive marker for pathologic complete response (pCR). Ki67 expression showed a positive correlation with HER2 status, tumor size, lymph node status, lymphovascular invasion and tumor grade. Furthermore, high Ki67 expression in post-treatment tumors was strongly correlated with poor disease-free survival (DFS), but no correlation of Ki-67 expression with overall survival (OS) was observed. Conclusions: Our results suggest that Ki67 expression in HR-negative breast cancer may improve the assessment of pathological response after NAC, and Ki67 score in residual tumor was an independent prognosticator for DFS in the HR-negative breast cancer patients.     

The effects of hormonal and chemotherapy on tumoral and nonneoplastic breast tissue

One hundred four sequential pretherapy and posttherapy breast tissue specimens from 57 patients with locally advanced and metastatic breast cancer were evaluated in an attempt to define the effects of systemic chemotherapeutic agents on the tumors and residual nonneoplastic breast tissue. The patients were treated uniformly at the National Cancer Institute on an experimental protocol combining systemic chemotherapy with attempted hormonal synchronization. Tumors were sampled prior to and following several cycles of chemotherapy to a maximum objective clinical response (average number of cycles, 7). In 38 cases, the posttreatment biopsy was positive for tumor. The most striking histologic change was extreme vacuolization of tumor cells that often resembled histiocytes. Atrophy of the terminal duct lobular unit (TDLU) and atypia of epithelial cells in TDLU and large ducts were also seen. Severe degrees of epithelial atypia occasionally proved to be difficult to distinguish from residual intraductal carcinoma. Breast biopsies were stained with antibodies to cytokeratin, epithelial membrane antigen (EMA), B72.3, lactalbumin, and SP1 using immunoperoxidase techniques. The number of cases showing immunoreactivity with antibodies to cytokeratin, EMA, and B72.3 remained approximately the same before and after therapy, while SP1 expression decreased and lactalbumin expression increased after therapy. Recognition of chemotherapeutic changes in breast tissue is important since systemic chemotherapy plays an important role in the management of breast cancer.     

Expression of vascular endothelial growth factor and proliferation marker MIB1 are influenced by neoadjuvant chemotherapy in locally advanced breast cancer.

Neoadjuvant chemotherapy (NACT) has become the standard of care for patients with locally advanced breast cancer (LABC). This was a retrospective review of 21 consecutive women who received NACT as initial treatment of LABC, followed by surgical excision. The pre- and post-treatment breast specimens and post-treatment axillary lymph nodes with metastases were immunostained to evaluate for proliferative index (PI) (MIB-1 Immunotech) and vascular endothelial growth factor (VEGF) expression (Santa Cruz, CA, clone A-20). Thirteen of the 21 patients (62%) had more than 50% tumor shrinkage following NACT. The breast's mean PI decreased from 47.86% to 23.95% after treatment (P = 0.005). The mean PI in the post-treatment lymph nodes was 24.47%. A nodal post-NACT PI of less than 10% and progesterone receptor-positive tumor status were associated with better survival, as all such patients are alive. A high PI after NACT was associated with recurrence or death. All of the patients who showed an excellent clinical response had either a decrease in the PI or an absence of a high level of VEGF after NACT. Most patients exhibited persistent expression of VEGF after NACT. Pathologic response in the primary tumor did not correlate with the response in the lymph nodes or with overall survival. NACT reduces the size and PI of the primary breast tumor independent of the patient's node status. The PI may be an early means by which to identify tumors most likely to reduce in size with chemotherapy. A low PI after NACT is associated with better survival. There is persistent expression of VEGF in post-NACT residual breast carcinoma. Thus, anti-VEGF drugs after conventional chemotherapy may benefit patients with residual carcinoma.     

Expression of multidrug resistance-associated proteins in rhabdomyosarcomas before and after chemotherapy: the relationship between lung resistance-related protein (LRP) and differentiation

Rhabdomyosarcomas generally respond well to chemotherapy, and the residual lesions often are better differentiated than their primaries. This phenomenon may be explained by selective multidrug resistance (MDR) of differentiated tumor cell populations. We assess the role of MDR proteins in chemotherapy-induced differentiation in rhabdomyosarcomas in a clinical setting. Paraffin-embedded samples of 13 pairs of primary untreated rhabdomyosarcomas and their residual, recurrent, or metastatic lesions after chemotherapy were assessed for expression of MDR proteins, including P-glycoprotein (Pgp), multidrug resistance-associated protein (MRP-1), and lung resistance-related protein (LRP). Expression was semiquantitatively scored based on the percentage of isolated immunoreactive tumor cells as follows: 0, negative; 0.5, <5%; 1, 5% to 25%; 2, 26% to 50%; 3, 51% to 75%, and 4, >75%. All specimens after chemotherapy, except the late recurrences, were better differentiated than their primary, untreated specimens. Pgp or MRP-1 expression did not change significantly, but LRP expression increased significantly after chemotherapy. In both untreated and treated samples, LRP was expressed primarily in differentiated cells. The findings indicate that the in vivo expression of LRP, but not of Pgp and MRP-1, is induced by chemotherapeutic treatment in rhabdomyosarcomas. The preferential expression of LRP in differentiated cells and the subsequent more extensive expression after chemotherapy suggests that LRP plays a role in therapy-induced differentiation.     

Incidence of pathologic complete response in women treated with preoperative chemotherapy for locally advanced breast cancer: correlation of histology,hormone receptor status,Her2/Neu,and gross pathologic findings

Neoadjuvant chemotherapy is the standard of care for patients with locally advanced breast cancer and is used increasingly for large operable breast cancer. The aim of this study was to assess the rate of pathologic complete response (pCR) in our patient population with locally advanced breast cancer and identify predictive factors for pCR after neoadjuvant chemotherapy. We studied a cohort of 205 patients and compared histologic features and biomarkers in the pretreatment biopsy with the corresponding pathologic response in the subsequent resection specimen. A pCR was defined as the absence of any microscopic evidence of tumor in the mastectomy specimen and axillary lymph node dissection. The tumor size was reduced in 60% of patients; 16 patients had a pCR. Histologic grade, histologic type, and hormone status did correlate with a pathologic response. None of the 29 invasive pure micropapillary carcinomas had a pCR. Pathologic complete response among Mexican patients with locally advanced breast cancer is low (8%), and the presence of invasive pure micropapillary carcinoma could be an independent predictor for pCR.     

Aldehyde dehydrogenase 1A1 expression in breast cancer is associated with stage, triple negativity, and outcome to neoadjuvant chemotherapy

Studies have shown that ALDH1A1 expression in the breast is associated with worse clinical outcome. ALDH1A1 inactivates cyclophosphamide, which is an integral agent in breast cancer chemotherapy regimens. The purposes of this study were to verify these results, to correlate ALDH1A1 expression with clinical outcome in patients treated with cyclophosphamide as part of the chemotherapy (adjuvant or neoadjuvant), and to evaluate ALDH1A1 as a useful marker to predict the clinical outcome of breast cancer subsets. A total of 513 primary breast cancers were studied. Tissue microarrays of the studied cases were stained with ALDH1A1. Key clinicopathological information was obtained. Disease-free survival and overall survival were calculated. Patients with neoadjuvant therapy who had substantial residual cancer burden (RCB) were included in the study. Fisher's exact test and Kaplan-Meier methods were used for statistical analysis. ALDH1A1 was expressed in 53 (10%) patients, with a higher frequency in triple negative, followed by HER2+, and finally hormonal receptor+/HER2- (P<0.0001). Tumors with advanced stage, node-positive, or larger tumor size were correlated with ALDH1A1 expression (P=0.006, P<0.0001, and P=0.05, respectively). ALDH1A1 expression was also correlated with worse disease-free survival (P<0.006) and overall survival (P<0.01) in patients who were treated with neoadjuvant chemotherapy. In all, 8 of 22 (36%) received neoadjuvant chemotherapy and died of disease-expressed ALDH1A1 (P=0.008). Similarly, 8 of 23 (35%) who received neoadjuvant chemotherapy and had tumor recurrence expressed this marker (P=0.002). The risk of recurrence was fivefold greater than negative ALDH1A1 tumors. The risk of recurrence became 11-fold greater when cyclophosphamide but not trastuzumab was part of the regimen. Our results are consistent with previous studies. Moreover, we found that ALDH1A1 could be a useful marker to predict worse clinical outcome after chemotherapy in the neoadjuvant setting with substantial RCB. However, a larger cohort is required to verify our results.     

Histopathologic assessment of tumor regression after neoadjuvant chemotherapy in advanced-stage ovarian cancer

To date, no histopathologic criteria have been established to describe treatment response after neoadjuvant chemotherapy in ovarian cancer. The aim of this study was to identify histopathologic features of tumor regression in ovarian cancer specimens obtained after neoadjuvant chemotherapy regarding their ability to indicate treatment response. This study systematically evaluated histopathologic features of tumor regression in advanced-stage ovarian cancer treated with neoadjuvant chemotherapy (n = 49) and in a control group treated with primary surgery (n = 35). In addition, the largest tumor size was measured in the surgical specimens. Overall survival served as the reference standard with a median follow-up of 49 months. There was a significantly higher presence of regressive changes in the postchemotherapy group compared with the untreated control group (P < or = .04). The presence of scattered solitary tumor cells, fibrosis, foamy macrophages, and giant cells of foreign-body type each indicated previous neoadjuvant chemotherapy with high specificity (80.0%-100%) but with low sensitivity (18.4%-63.3%). Inflammatory cell infiltrates, isolated psammoma bodies, and hemosiderin were also associated with previous chemotherapy but with lower specificity. The presence of necrosis was significantly correlated with larger tumor size within the specimens (rho = 0.5, P < .0001) and was more often found in the control group. For both groups, the extent of regressive changes, evaluated as a single parameter or in combination, showed no correlation with overall survival. However, patients with absence of residual tumor, scattered solitary tumor cells, or residual tumor foci of 5 mm or less after neoadjuvant chemotherapy had a significantly longer median overall survival of 45.6 versus 27.3 months in patients with larger tumors (P = .02). Various histopathologic features generally associated with posttreatment changes did not allow differentiation of responding from nonresponding patients and provided no prognostic information. The residual tumor size after neoadjuvant chemotherapy was the only criterion significantly correlated with treatment response and subsequent overall survival.     

Clinicopathological significance of the immunologic signature (PDL1, FOXP3+ Tregs,TILs) in early stage triple-negative breast cancer treated with neoadjuvant chemotherapy

Patients with breast cancer are appropriate candidates for neoadjuvant chemotherapy (NAC) to facilitate conservative surgery. The chemotherapeutic agents may exert their action by inducing the anti-tumor immune response. This study aimed to evaluate the tumor immune microenvironment including PD-L1, Foxp3+ Tregs, and TILs count in early stages TNBC patients (stage T1, T2) before and after neoadjuvant chemotherapy and their correlation with the clinical and pathological response. Fifty patients of TNBC patients were enrolled in this study; all of them received neoadjuvant chemotherapy. TILs count, Foxp3+ Tregs, and PD-L1 immunohistochemical expression were investigated in all cases before NAC and then evaluated in residual masses after surgery. Data on the clinical and pathological response to NAC were collected and then statistically analyzed. PDL1 expression was detected in 24% of all studied cases, all of them were node-positive (P < 0.002); while Foxp3+ Tregs expressed in 50% and high TILs in 28%. Pathological complete response (pCR) was achieved in 40% of patients and was associated with high TILs expression (P < 0.02) and absence of Foxp3+ Tregs and PDL1 (P < 0.001 for each). In conclusion, Pathologic complete response to NAC was associated with the immunological profile of TNBC. High TILs expression with concomitant decreased PD-L1 expression and low FOXP3+ Tregs is associated with favorable tumor prognosis. Combined therapeutic approaches aiming to PD-L1 block and Tregs depletion might improve treatment efficacy in TNBC.     

Longitudinal study of the assessment by MRI and diffusion-weighted imaging of tumor response in patients with locally advanced breast cancer undergoing neoadjuvant chemotherapy

Measurements of tumor apparent diffusion coefficient (ADC), volume and diameter in assessing the response of patients with locally advanced breast cancer (LABC) (n = 56) undergoing neoadjuvant chemotherapy (NACT) at four time periods (before treatment and after three cycles of NACT) were carried out at 1.5 T using diffusion-weighted imaging (DWI) and MRI. Ten benign tumors and 15 controls were also investigated. The MR tumor response was compared with the clinical response. Mean ADC before treatment of malignant breast tissue was significantly lower than that of controls, disease-free contralateral tissue of the patients, and benign lesions, and gradually increased during the course of NACT. Analysis of the percentage change in ADC, volume and diameter after each cycle of NACT between clinical responders and non-responders showed that the change in ADC after the first cycle was statistically significant compared with volume and diameter, indicating its potential in assessing early response. After the third cycle, the sensitivity for differentiating responders from non-responders was 89% for volume and diameter and 68% for ADC, and the respective specificities were 50%, 70% and 100%. A sensitivity of 84% (specificity of 60% with an accuracy of 76%) was achieved when all three variables were taken together to predict the response. A cut-off value of ADC was also calculated using receiver operator characteristics analysis to discriminate between normal, benign and malignant breast tissue. Similarly, a cut-off value for ADC, volume and diameter was obtained after the second and third cycles of NACT to predict tumor response. The results show that ADC is more useful for predicting early tumor response to NACT than morphological variables, suggesting its potential in effective treatment management.     

Expression of P-glycoprotein in hepatocellular carcinoma. A determinant of chemotherapy response

To characterize the P-glycoprotein (Pgp) expression in human hepatocellular carcinoma (HCC), we studied 101 cases of HCC treated with surgical resection without prior treatment. Pgp expression was detected immunohistochemically using 2 monoclonal antibodies (C494, C219) and correlated with pathologic features, survival, and p53 expression. Chemotherapy response was analyzed in a separate group of patients with inoperable HCC treated with systemic chemotherapy. Positive immunostaining was seen in 92% and 80% of the tumors with C494 and C219, respectively; bile canalicular type staining was seen in all positive tumors. Pgp expression was less extensive in the tumors than in the corresponding nontumorous liver tissue. Tumor Pgp expression with either antibody had no association with cellular differentiation, aggressive pathologic features, survival, or p53 overexpression. In patients with inoperable HCC, the chemotherapy response was significantly inversely related to Pgp expression with C494 and C219. Pgp was expressed in human HCC but was patchy and less extensive than in the nontumorous tissue. Response to systemic chemotherapy was inversely related to the level of Pgp expression in patients with inoperable tumors. Pgp expression in tumors not treated with chemotherapy was not associated with a more aggressive tumor phenotype or p53 overexpression and did not influence survival.     

Establishing a platform for immunotherapy: clinical outcome and study of immune reconstitution after high-dose chemotherapy with progenitor cell support in breast cancer patients.

Tumor vaccine after high-dose chemotherapy (HDC) and autologous stem cell transplantation (ASCT) aims at directing immune recovery toward tumor responses after optimizing minimal residual disease. We have characterized T-cell recovery and tumor response after a regimen devised as a platform for such immunotherapy. One hundred patients with high-risk or metastatic breast cancer received 3 to 7 cycles of paclitaxel and cyclophosphamide (overall response rate, 78%) and then HDC with melphalan and etoposide. Seventy-one patients received HDC and ASCT (no mortality at 100 days). At 24 months after transplantation, progression-free and overall survival probabilities for patients with stage IIIA, IIIB, and IV disease were 82%, 81%, and 42% and 100%, 94%, and 68%, respectively. The median progression-free and overall survivals from entry on study for stage IV patients were 15.3 and 38.1 months, respectively. CD3 + , CD8 + , and CD4 + cells were severely depleted after ASCT. Although total CD8 + T-cell numbers approached the normal range by 3 months, most of these cells were CD28 - . Naive CD45RA + CD4 + T cells approached the normal range only 18 months after ASCT and only in younger patients. The described observations provide the basis for devising a strategy for cancer vaccine administration after ASCT. Incorporating immune reconstitution enhancement after ASCT may be advantageous.     

CIAPIN1 gene silencing enhances chemosensitivity in a drug-resistant animal model in vivo

Overexpression of cytokine-induced apoptosis inhibitor 1 (CIAPIN1) contributes to multidrug resistance (MDR) in breast cancer. This study aimed to evaluate the potential of CIAPIN1 gene silencing by RNA interference (RNAi) as a treatment for drug-resistant breast cancer and to investigate the effect of CIAPIN1 on the drug resistance of breast cancer in vivo. We used lentivirus-vector-based RNAi to knock down CIAPIN1 in nude mice bearing MDR breast cancer tumors and found that lentivirus-vector-mediated silencing of CIAPIN1 could efficiently and significantly inhibit tumor growth when combined with chemotherapy in vivo. Furthermore, Western blot analysis showed that both CIAPIN1 and P-glycoprotein expression were efficiently downregulated, and P53 was upregulated, after RNAi. Therefore, we concluded that lentivirus-vector-mediated RNAi targeting of CIAPIN1 is a potential approach to reverse MDR of breast cancer. In addition, CIAPIN1 may participate in MDR of breast cancer by regulating P-glycoprotein and P53 expression.     

Extramedullary hematopoiesis in breast after neoadjuvant chemotherapy for breast carcinoma

We report incidental extramedullary hematopoiesis (EMH) in breasts of 2 patients following neoadjuvant chemotherapy for locally advanced breast cancer. Neither of the patients had a history of hematologic disorders. After chemotherapy, one of the patients had a complete pathologic response and the other had residual carcinoma. In both cases, EMH was mostly seen as myelopoiesis in a background of chemotherapy-induced changes. In the patient with residual carcinoma, EMH was observed in the contralateral prophylactic mastectomy specimen. EMH should be considered a diagnostic pitfall in the differential diagnosis of unusual cellular infiltrates in breast after neoadjuvant chemotherapy. To our knowledge, the association of EMH and neoadjuvant chemotherapy has not been previously reported.     

Clinical Significance of Persistent Tumor in Bone Marrow during Treatment of High-risk Neuroblastoma

The records of 63 high-risk neuroblastoma patients with bone marrow (BM) tumors at diagnosis were retrospectively reviewed. All patients received nine cycles of induction chemotherapy followed by tandem high-dose chemotherapy and autologous stem cell transplantation (HDCT/auto-SCT). Follow-up BM examination was performed every three cycles during induction chemotherapy and every three months for one year after the second HDCT/auto-SCT. BM tumor cells persisted in 48.4%, 37.7%, 23.3%, and 20.4% of patients after three, six, and nine cycles of induction chemotherapy and three months after the second HDCT/auto-SCT, respectively. There was no difference in progression-free survival (PFS) rate between patients with persistent BM tumor and those without during the induction treatment. However, after tandem HDCT/auto-SCT, the PFS rate was worse in patients with persistent BM tumor than in those without (probability of 5-yr PFS 14.7% ± 13.4% vs. 64.2% ± 8.3%, P = 0.009). Persistent BM tumor during induction treatment is not associated with a worse prognosis when intensive tandem HDCT/auto-SCT is given as consolidation treatment. However, persistent BM tumor after tandem HDCT/auto-SCT is associated with a worse prognosis. Therefore, further treatment might be needed in patients with persistent BM tumor after tandem HDCT/auto-SCT.

Graphical Abstract

相似文献   

Complete remission of unresectable colon cancer after preoperative chemotherapy selected by adenosine triphosphate-based chemotherapy response assay

The adenosine triphosphate-based chemotherapy response assay (ATP-CRA) is a chemosensitivity test that offers the potential of selecting cancer treatments based on the responsiveness of individual tumors. We report a case of 47-yr-old male, presented with sigmoid colon cancer with multiple liver and peritoneal metastases, in which there was a complete response for the primary colon cancer after administration of preoperative chemotherapy selected by ATP-CRA. Oxaliplatin was the most sensitive drug based on the ATP-CRA where the specimen obtained by ultrasound- guided percutaneous liver biopsy was used. After twelve cycles of oxaliplatincapecitabine chemotherapy, abdominopelvic computed tomography revealed marked shrinkage of the liver metastases and positron emission tomography showed no uptake of 18F-fluoro-deoxy-glucose (FDG) either in the liver or peritoneum except localized uptake in the sigmoid colon. The patient underwent an anterior resection and radiofrequency ablation of the liver metastases, which resulted in a macroscopic curative resection of the cancer cells. Histological examination revealed no residual cancer cells in the resected specimen of the sigmoid colon. This result suggested that preoperative chemotherapy chosen by ATP-CRA may be useful for treating advanced colon cancer with unresectable liver and peritoneal metastases.     

Vimentin is preferentially expressed in human breast carcinomas with low estrogen receptor and high Ki-67 growth fraction.

Vimentin expression, growth fractions (GF), and estrogen receptor (ER) levels were determined for 90 untreated primary breast carcinomas. Coexpression of keratin and vimentin was found in approximately 20% of the tumors regardless of menopausal status. Vimentin was expressed preferentially in tumor cells of high-grade ductal breast carcinomas (15 of 28 histologic grade 3 vs. 0 of 40 grades 1 and 2). Vimentin expression was found preferentially in tumors with high GF (greater than 15% Ki-67 positive by immunoperoxidase staining) and low ER levels (less than 60 fmols/mg protein by a monoclonal enzyme immunoassay). Sixty-eight percent of tumors in this group were vimentin positive and 88% of all vimentin-positive tumors fell into this category. More than 50% of the tumor cells coexpressed vimentin and keratin. Thus, vimentin expression may be helpful in identifying a substantial subset of ER-independent breast carcinomas with poor prognostic indicators.