ESMO expert consensus statements (ECS) on the definition, diagnosis, and management of HER2-low breast cancer.

Human epidermal growth factor receptor 2 (HER2)-low breast cancer has recently emerged as a targetable subset of breast tumors, based on the evidence from clinical trials of novel anti-HER2 antibody-drug conjugates. This evolution has raised several biological and clinical questions, warranting the establishment of consensus to optimally treat patients with HER2-low breast tumors. Between 2022 and 2023, the European Society for Medical Oncology (ESMO) held a virtual consensus-building process focused on HER2-low breast cancer. The consensus included a multidisciplinary panel of 32 leading experts in the management of breast cancer from nine different countries. The aim of the consensus was to develop statements on topics that are not covered in detail in the current ESMO Clinical Practice Guideline. The main topics identified for discussion were (i) biology of HER2-low breast cancer; (ii) pathologic diagnosis of HER2-low breast cancer; (iii) clinical management of HER2-low metastatic breast cancer; and (iv) clinical trial design for HER2-low breast cancer. The expert panel was divided into four working groups to address questions relating to one of the four topics outlined above. A review of the relevant scientific literature was conducted in advance. Consensus statements were developed by the working groups and then presented to the entire panel for further discussion and amendment before voting. This article presents the developed statements, including findings from the expert panel discussions, expert opinion, and a summary of evidence supporting each statement.

Long-term outcomes after adjuvant treatment of sequential versus combination docetaxel with doxorubicin and cyclophosphamide in node-positive breast cancer: BCIRG-005 randomized trial.

BACKGROUND: The optimal regimen for adjuvant breast cancer chemotherapy is undefined. We compared sequential to concurrent combination of doxorubicin and cyclophosphamide with docetaxel chemotherapy in women with node-positive non-metastatic breast cancer. We report the final, 10-year analysis of disease-free survival (DFS), overall survival (OS), and long-term safety. PATIENTS AND METHODS: A total of 3298 women with HER2 nonamplified breast cancer were randomized to doxorubicin and cyclophosphamide every 3 weeks for four cycles followed by docetaxel (AC → T) every 3 weeks for four cycles or docetaxel, doxorubicin, and cyclophosphamide (TAC) every 3 weeks for six cycles. The patients received standard radiotherapy and endocrine therapy and were followed up for 10 years with annual clinical evaluation and mammography. RESULTS: The 10-year DFS rates were 66.5% in the AC → T arm and 66.3% in the TAC arm (P = 0.749). OS was 79.9% in the AC → T arm and 78.9% in the TAC arm (P = 0.506). TAC was associated with higher rates of febrile neutropenia, although G-CSF primary prophylaxis greatly reduced this risk. AC → T was associated with a higher rate of myalgia, hand-foot syndrome, fluid retention, and sensory neuropathy. CONCLUSION: This 10-year analysis of the BCIRG-005 trial confirmed that the efficacy of TAC was not superior to AC → T in women with node-positive early breast cancer. The toxicity profiles differ between arms and were consistent with previous reports. The TAC regimen with G-CSF support provides shorter adjuvant treatment duration with less toxicity. TRIAL REGISTRATION: ClinicalTrials.gov Identifier NCT00312208.

Assessment of HER2 gene amplification in adenocarcinomas of the stomach or gastroesophageal junction in the INT-0116/SWOG9008 clinical trial.

BACKGROUND: Trastuzumab has been approved for patients with human epidermal growth factor receptor 2 (HER2)-positive metastatic gastric carcinoma; however, relatively little is known about the role of HER2 in the natural history of this disease. PATIENTS AND METHODS: Patients enrolled in the INT-0116/SWOG9008 phase III gastric cancer clinical trial with available tissue specimens were retrospectively evaluated for HER2 gene amplification by FISH and overexpression by immunohistochemistry (IHC). The original trial was designed to evaluate the benefit of postoperative chemoradiation compared with surgery alone. RESULTS: HER2 gene amplification rate by FISH was 10.9% among 258 patients evaluated. HER2 overexpression rate by IHC was 12.2% among 148 patients evaluated, with 90% agreement between FISH and IHC. There was a significant interaction between HER2 amplification and treatment with respect to both disease-free survival (DFS) (P = 0.020) and overall survival (OS) (P = 0.034). Among patients with HER2-non-amplified cancers, treated patients had a median OS of 44 months compared with 24 months in the surgery-only arm (P = 0.003). Among patients with HER2-amplified cancers, there was no significant difference in survival based on treatment arm. HER2 status was not a prognostic marker among patients who received no postoperative chemoradiation. CONCLUSION: Patients lacking HER2 amplification benefited from treatment as indicated by both DFS and OS. CLINICAL TRIAL: INT-0116/SWOG9008 phase III.

HER2 gene amplification and EGFR expression in a large cohort of surgically staged patients with nonendometrioid (type II) endometrial cancer.

Type II endometrial cancers (uterine serous papillary and clear cell histologies) represent rare but highly aggressive variants of endometrial cancer (EC). HER2 and EGFR may be differentially expressed in type II EC. Here, we evaluate the clinical role of HER2 and EGFR in a large cohort of surgically staged patients with type II (nonendometrioid) EC and compare the findings with those seen in a representative cohort of type I (endometrioid) EC. In this study HER2 gene amplification was studied by fluorescence in situ hybridisation (FISH) and EGFR expression by immunohistochemistry. Tissue microarrays were constructed from 279 patients with EC (145 patients with type I and 134 patients with type II EC). All patients were completely surgically staged and long-term clinical follow up was available for 258 patients. The rate of HER2 gene amplification was significantly higher in type II EC compared with type I EC (17 vs 1%, P<0.001). HER2 gene amplification was detected in 17 and 16% of the cases with uterine serous papillary and clear cell type histology, respectively. In contrast, EGFR expression was significantly lower in type II compared with type I EC (34 vs 46%, P=0.041). EGFR expression but not HER2 gene amplification was significantly associated with poor overall survival in patients with type II EC, (EGFR, median survival 20 vs 33 months, P=0.028; HER2, median survival 18 vs 29 months, P=0.113) and EGFR expression retained prognostic independence when adjusting for histology, stage, grade, and age (EGFR, P=0.0197; HER2, P=0.7855). We conclude that assessment of HER2 gene amplification and/or EGFR expression may help to select type II EC patients who could benefit from therapeutic strategies targeting both HER2 and EGFR.

Association of p53 mutations and a codon 72 single nucleotide polymorphism with lower overall survival and responsiveness to adjuvant radiotherapy in endometrioid endometrial carcinomas.

p53 Genetic alterations are associated with advanced stage and aggressive tumors in a variety of human malignancies. The aim of this study was to examine p53 for genetic alterations and to evaluate the association of these alterations with clinical outcome and response to adjuvant radiotherapy in endometrioid endometrial carcinomas. p53 mutations in exons 2-11 were assessed in 59 endometrioid carcinomas by polymerase chain reaction-single-strand conformational polymorphism and sequence analysis. Twelve mutations (20.3%) and nine polymorphisms were identified. Seven of the nine polymorphisms were codon 72 single nucleotide polymorphisms (SNP) with an Arg/Pro allelotype. Women harboring either a mutation or an Arg/Pro allelotype at codon 72 had a lower overall survival rate than women whose tumors lacked alterations in the p53 gene (P= 0.0029). Women were stratified based on p53 genetic alterations (p53 mutation or p53 codon 72 SNP) and whether or not they received adjuvant radiation therapy. Women with p53 genetic alterations who did not receive adjuvant radiotherapy had the lowest survival rate (P= 0.0005). Treated women with p53 genetic alterations and untreated women with no p53 alteration had similar rates of survival. Among women with p53 alterations, adjuvant radiotherapy substantially increased survival (P= 0.035). In multivariate analyses, the group of women with p53 genetic alterations who did not receive adjuvant radiation therapy had a 5.9-fold increased risk of death (95% confidence interval: 1.5-22.7) compared to women whose tumors lacked p53 alterations and did not receive adjuvant radiation therapy.

Reproductive factors and subtypes of breast cancer defined by hormone receptor and histology.

Reproductive factors are associated with reduced risk of breast cancer, but less is known about whether there is differential protection against subtypes of breast cancer. Assuming reproductive factors act through hormonal mechanisms they should protect predominantly against cancers expressing oestrogen (ER) and progesterone (PR) receptors. We examined the effect of reproductive factors on subgroups of tumours defined by hormone receptor status as well as histology using data from the NIHCD Women's Contraceptive and Reproductive Experiences (CARE) Study, a multicenter case-control study of breast cancer. We estimated odds ratios (ORs) and 95% confidence intervals (CIs) as measures of relative risk using multivariate unconditional logistic regression methods. Multiparity and early age at first birth were associated with reduced relative risk of ER + PR + tumours (P for trend=0.0001 and 0.01, respectively), but not of ER - PR - tumours (P for trend=0.27 and 0.85), whereas duration of breastfeeding was associated with lower relative risk of both receptor-positive (P for trend=0.0002) and receptor-negative tumours (P=0.0004). Our results were consistent across subgroups of women based on age and ethnicity. We found few significant differences by histologic subtype, although the strongest protective effect of multiparity was seen for mixed ductolobular tumours. Our results indicate that parity and age at first birth are associated with reduced risk of receptor-positive tumours only, while lactation is associated with reduced risk of both receptor-positive and -negative tumours. This suggests that parity and lactation act through different mechanisms. This study also suggests that reproductive factors have similar protective effects on breast tumours of lobular and ductal origin.

Heritable breast cancer in twins.

Known major mutations such as BRCA1/2 and TP53 only cause a small proportion of heritable breast cancers. Co-dominant genes of lower penetrance that regulate hormones have been thought responsible for most others. Incident breast cancer cases in the identical (monozygotic) twins of representative cases reflect the entire range of pertinent alleles, whether acting singly or in combination. Having reported the rate in twins and other relatives of cases to be high and nearly constant over age, we now examine the descriptive and histological characteristics of the concordant and discordant breast cancers occurring in 2310 affected pairs of monozygotic and fraternal (dizygotic) twins in relation to conventional expectations and hypotheses. Like other first-degree relatives, dizygotic co-twins of breast cancer cases are at higher than usual risk (standardised incidence ratio (SIR)=1.7, CI=1.1-2.6), but the additional cases among monozygotic co-twins of cases are much more numerous, both before and after menopause (SIR=4.4, CI=3.6-5.6), than the 100% genetic identity would predict. Monozygotic co-twin diagnoses following early proband cancers also occur more rapidly than expected (within 5 years, SIR=20.0, CI=7.5-53.3). Cases in concordant pairs represent heritable disease and are significantly more likely to be oestrogen receptor-positive than those of comparable age from discordant pairs. The increase in risk to the monozygotic co-twins of cases cannot be attributed to the common environment, to factors that cumulate with age, or to any aggregate of single autosomal dominant mutations. The genotype more plausibly consists of multiple co-existing susceptibility alleles acting through heightened susceptibility to hormones and/or defective tumour suppression. The resultant class of disease accounts for a larger proportion of all breast cancers than previously thought, with a rather high overall penetrance. Some of the biological characteristics differ from those of breast cancer generally.

Germ-line HER-2 variant and breast cancer risk by stage of disease.

HER-2 gene amplification and protein overexpression has been associated with increased risk of advanced-stage breast cancer and poor prognosis. Recently, a single missense point mutation (Ile(655)Val) in the transmembrane domain of the HER-2 gene was associated with a 40% increase in breast cancer risk among women 45 years of age and younger. In this analysis, we measured the association between the Ile(655)Val variant and postmenopausal breast cancer among women participating in the Hawaii and Los Angeles Multiethnic Cohort. Risk of localized breast cancer was significantly elevated among women with the HER-2 variant, but not among women with regional or metastatic disease. Women with at least one copy of the Valine variant were approximately one-half as likely to have high-stage as low-stage breast cancer (P =.02), and this effect was present across racial/ethnic groups.

Correlation of p53 mutations with resistance to platinum-based chemotherapy and shortened survival in ovarian cancer.

PURPOSE: The p53 tumor suppressor gene plays a central role in cell cycle regulation and induction of apoptosis. We analyzed p53 alterations and their impact on response to chemotherapy and clinical outcome in ovarian cancer patients. EXPERIMENTAL DESIGN: One hundred seventy-eight ovarian carcinomas, snap frozen and stored at -80 degrees C, were analyzed for mutations of the p53 gene (exons 2-11) by single-strand conformation polymorphism and DNA sequencing and for p53 overexpression by immunohistochemistry (monoclonal antibody DO7). RESULTS: p53 mutations were found in 56% (99 of 178) of the tumors, and 62% of these were located in evolutionary highly conserved domains of the gene. Time to progression and overall survival were significantly shortened in patients with p53 mutations compared with wild-type p53 (P = 0.029 and P = 0.014) and patients with mutations in highly conserved domains as opposed to nonconserved domains or wild-type p53 (P = 0.010 and P = 0.007). p53 protein overexpression (>10% positively stained nuclei) was found in 62% (110 of 178). Time to progression and overall survival were shorter in cases with p53 overexpression (cutpoint, 10%: P = 0.071 and P = 0.056) but only marginally significant. Resistance to adjuvant cisplatin or carboplatin chemotherapy was significantly more frequent in patients with p53 overexpression (P = 0.001) or p53 missense mutations (P = 0.008) than patients with normal p53. CONCLUSIONS: p53 alterations correlate significantly with resistance to platinum-based chemotherapy, early relapse, and shortened overall survival in ovarian cancer patients in univariate analysis. In multivariable analysis though, p53 was not an independent prognostic factor.

Alternative and aberrant messenger RNA splicing of the mdm2 oncogene in invasive breast cancer.

mdm2 is part of a complex mechanism that regulates the expression of p53 as well as the function of Rb, p19ARF, and other genes. In humans, mdm2 dysregulation is associated with gene amplification. This study was undertaken to characterize altered mdm2 expression in a cohort of 38 invasive breast cancers and 9 normal breast specimens. Reverse-transcription PCR with primers spanning the entire open reading frame of the mdm2 gene in breast tissue RNA samples generated PCR products of full-length mdm2 (1526 bp) as well as smaller products (653, 281, 254, and 219 bp). Sequence analysis demonstrated that the 653-bp product was an alternatively spliced product (defined as splicing at the exon/intron boundary consensus sites), whereas the 281, 254, and 219 bp mdm2 products were aberrantly spliced products (splicing at sites not considered to be exon/intron boundary sites). Reverse-transcription-PCR with normal breast tissue RNA samples yielded only the 1526-bp product in five samples and the 1526-bp product and the 653-bp product in four samples. The 653-bp alternatively spliced product was expressed in 21% of breast cancers, and the smaller, aberrantly spliced mRNA products (281 bp, 254 bp, and/or 219 bp) were expressed in 16% of breast cancers. The protein products predicted by the alternatively spliced mRNAs and the aberrantly spliced mRNAs lacked either the entire binding domain for p53 or the majority of the binding domain for p53. Immunohistochemical analysis of HER2/neu (c-erbB2), estrogen receptor, progesterone receptor, epidermal growth factor receptor, and p53 protein was performed. p53 sequence alterations were identified by mismatch detection and confirmed by p53 oligonucleotide microarray technology. An association was demonstrated between the expression of aberrantly and/or alternatively spliced mdm2 mRNAs and a lack of progesterone receptor. An association was also demonstrated between mdm2 aberrantly and/or alternatively expression products and the presence of p53 tumor suppressor gene mutations. mdm2 is transcribed from two different promoters: one, p53-dependent, and the other, p53-independent. The 5' untranslated region of the transcripts was evaluated to determine the promoter usage in each breast cancer specimen. No correlation was observed between mdm2 splice products and promoter usage. The presence of aberrant expression products of mdm2 in breast cancer specimens was correlated with a shortened overall patient survival. These observations suggest that mdm2 expression is altered in invasive breast cancer and is associated with more aggressive disease.

Breast cancer susceptibility gene 1 (BRCAI) is a coactivator of the androgen receptor.

In the present study, the role of BRCA1 in ligand-dependent androgen receptor (AR) signaling was assessed. In transfected prostate and breast cancer cell lines, BRCA1 enhanced AR-dependent transactivation of a probasin-derived reporter gene. The effects of BRCA1 were mediated through the NH2-terminal activation function (AF-1) of the receptor. Cotransfection of p160 coactivators markedly potentiated BRCA1-mediated enhancement of AR signaling. In addition, BRCA1 was shown to interact physically with both the AR and the p160 coactivator, glucocorticoid receptor interacting protein 1. These findings suggest that BRCA1 may directly modulate AR signaling and, therefore, may have implications regarding the proliferation of normal and malignant androgen-regulated tissues.

Comparison of TP53 mutations identified by oligonucleotide microarray and conventional DNA sequence analysis.

As the rate of gene discovery accelerates, more efficient methods are needed to analyze genes in human tissues. To assess the efficiency, sensitivity, and specificity of different methods, alterations of TP53 were independently evaluated in 108 ovarian tumors by conventional DNA sequence analysis and oligonucleotide microarray (p53 GeneChip). All mutations identified by oligonucleotide microarray and all disagreements with conventional gel-based DNA sequence analysis were confirmed by re-analysis with manual and automated dideoxy DNA sequencing. A total of 77 ovarian cancers were identified as having TP53 mutations by one of the two approaches, 71 by microarray and 63 by gel-based DNA sequence analysis. The same mutation was identified in 57 ovarian cancers, and the same wild type TP53 sequence was observed in 31 ovarian cancers by both methods, for a concordance rate of 81%. Among the mutation analyses discordant by these methods for TP53 sequence were 14 cases identified as mutated by microarray but not by conventional DNA sequence analysis and 6 cases identified as mutated by conventional DNA sequence analysis but not by microarray. Overall, the oligonucleotide microarray demonstrated a 94% accuracy rate, a 92% sensitivity, and an 100% specificity. Conventional DNA sequence analysis demonstrated an 87% accuracy rate, 82% sensitivity, and a 100% specificity. Patients with TP53 mutations had significantly shorter overall survival than those with no mutation (P = 0.02). Women with mutations in loop2, loop3, or the loop-sheet-helix domain had shorter survival than women with other mutations or women with no mutations (P = 0.01). Although further refinement would be helpful to improve the detection of certain types of TPS3 alterations, oligonucleotide microarrays were shown to be a powerful and effective tool for TP53 mutation detection.

p21 (WAF1/CIP1) protein expression is associated with prolonged survival but not with p53 expression in epithelial ovarian carcinoma.

OBJECTIVE: The objective of this study was to clarify the influence of p21 protein expression in ovarian cancer. p21 (WAF1 [wild-type p53 activated fragment 1]/CIP1) is a universal cyclin-dependent kinase inhibitor and can be induced as a downstream effector of the p53 tumor suppressor gene. METHODS: The expression of p21 was evaluated by immunohistochemical analysis with the monoclonal antibody WAF1 (Oncogene Science) on 106 formalin-fixed, paraffin-embedded tissue samples of epithelial ovarian cancer. RESULTS: p21 was expressed in 65 (61%) of all cases. p21 expression was associated with early stage in FIGO classification (FIGO I and II, P = 0.003) and no tumor residues after primary tumor resection (P = 0.018). Immunohistochemical staining results were judged as negative if no tumor nuclei were stained, as weak positive if 1-49% were stained, and as strong positive if over 50% of nuclei were stained. Clinical follow-up showed a better overall survival for cases with strong p21 expression (79 months) versus 40 months for weak expression and 30 months for no expression (P = 0.033). Previously determined p53 expression of this cohort was compared with p21 status. p53 overexpression was observed in 49 cases (48%) and showed no association with p21 expression. CONCLUSION: No correlation was found between p21 and p53 expression. p21 expression is a significant prognostic marker for improved survival in ovarian cancer and is associated with early FIGO stage and zero tumor residues after primary tumor resection.

Reduction of BRCA1 expression in sporadic ovarian cancer.

OBJECTIVE: The purpose of this study was to examine BRCA1 expression and its relationship to cell proliferation in sporadic ovarian epithelial tumors (OETs). METHODS: We investigated BRCA1 expression and cell proliferative activity in 72 unselected OETs. They comprised 16 benign cystadenomas, 18 borderline (low malignant potential) tumors, and 38 carcinomas (OECs). These patients had no known family history of breast and/or ovarian cancer. BRCA1 and the cell proliferation marker, MIB-1, expressions in fixed tissue were investigated in all 72 cases by immunohistochemistry (IHC). BRCA1 mRNA in fresh frozen tissue samples from 20 of these cases was measured by a semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) method. RESULTS: The average percentage of BRCA1-positive cells was 5.6% in cystadenomas, 29.7% in borderline tumors, and 6.6% in OECs. The average decreased steadily with increasing grade of OECs: grade 1 (21.4%), grade 2 (1.1%), and grade 3 (0%). The average percentage of MIB-1-positive cells increased steadily from cystadenomas (7.5%) to borderline tumors (22.6%) to carcinomas (41.2%). BRCA1 expression was highly correlated with MIB-1 expression in cystadenomas and borderline tumors. Six of seven OECs negative for BRCA1 by IHC showed low levels of BRCA1 mRNA by RT-PCR. CONCLUSIONS: BRCA1 expression paralleled cell proliferation in benign and borderline OETs, but not in OECs. Sporadic OECs showed significantly reduced levels, rather than complete loss, of BRCA1 expression. The reduction was closely related to tumor grade. Reduction of BRCA1 expression may be of etiologic significance in the occurrence and progression of sporadic ovarian cancer.

p53 mutations and expression in breast carcinoma in situ.

The p53 tumor suppressor gene is altered in approximately half of human cancers. Although p53 mutations are common in invasive breast carcinoma, few have been identified in breast carcinoma in situ (intraductal breast carcinomas). Most studies of p53 in breast carcinoma in situ are immunohistochemical studies of p53 staining in paraffin-embedded tissue sections. Few studies have isolated the tumor cells and subjected them to DNA sequence analysis. The current study was undertaken to characterize p53 in a cohort of breast carcinoma in situ cases, both with and without invasive disease. Fifty-eight frozen breast biopsy samples were used for these investigations. Twenty-seven cases had only ductal carcinoma in situ (CIS) and 31 cases had evidence of both invasive and in situ carcinoma. DNA sequence alterations in exons 2 through 11 of p53 were screened by the single-strand conformational polymorphism technique. Exons with altered mobility were sequenced. Among breast CIS cases without invasive disease, 22% had p53 mutations and 7% had DNA sequence alterations of unknown significance. Analysis of breast CIS with concurrent invasive disease demonstrated p53 mutations in 19% of cases and one (3%) DNA alteration of unknown significance. Each carcinoma having a p53 mutation in the breast CIS component had the identical mutation in the invasive component of the same tumor indicating a clonal relationship between the two tumor components. p53 protein overexpression was identified in 22% of pure intraductal breast carcinomas and in 35% of breast CIS with invasive disease. Comparison of immunostaining and DNA sequence alterations showed a significant association between overexpression and mutations (P = 0. 0037) in cases of CIS without invasion, and similarly between overexpression and mutations in cases of CIS with invasion (P = 0. 007). p53 mutations and p53 overexpression were relatively common in intraductal breast carcinomas but were not observed in adjacent normal breast lobules or ducts in 9 cases available for DNA analysis. The frequency of p53 alterations when comparing breast CIS with and without an invasive component indicated that p53 mutations usually occur before invasion during the progression of breast cancer, as is observed for a number of other adult solid tumors.

The risk of angiosarcoma following primary breast cancer.

Lymphangiosarcoma of the upper extremity is a rare and aggressive tumour reported to occur following post-mastectomy lymphoedema (Stewart-Treves syndrome). Haemangiosarcoma, a related rare tumour, has occasionally been reported to occur in the breast following irradiation. We conducted a case-control study using the University of Southern California-Cancer Surveillance Program, the population-based cancer registry for Los Angeles County, to evaluate the relationship between invasive female breast cancer and subsequent upper extremity or chest lymphangiosarcoma and haemangiosarcoma together referred to as angiosarcoma. Cases were females diagnosed between 1972 and 1995 with angiosarcoma of the upper extremity (n = 20) or chest (n = 48) who were 25 years of age or older and residing in Los Angeles County when diagnosed. Other sarcomas at the same anatomic sites were also studied. Controls were females diagnosed with cancers other than sarcoma during the same time period (n = 266,444). Cases and controls were then compared with respect to history of a prior invasive epithelial breast cancer. A history of breast cancer increased the risk of upper extremity angiosarcoma by more than 59-fold (odds ratio [OR] = 59.3, 95% confidence interval [95% CI] = 21.9-152.8). A strong increase in risk after breast cancer was also observed for angiosarcoma of the chest and breast (OR = 11.6, 95% CI = 4.3-26.1) and for other sarcomas of the chest and breast (OR = 3.3, 95% CI = 1.1-1.7).

The role of immunohistochemistry and fluorescence in situ hybridization for HER2/neu in assessing the prognosis of breast cancer.

Immunohistochemistry has been used in the past to identify overexpression of HER-2/neu protein on the cell membrane of breast cancer cells in fixed tissues. Most studies that have attempted to find an association between HER-2/neu expression and a poor prognosis have relied on this technique, which has intrinsic variability due to the antibody used and the degradation of surface proteins by fixation. Recent studies with fluorescence in situ hybridization have tended to confirm the purported association, showing that HER-2/neu overexpression causes a more aggressive, less responsive breast cancer. In many studies, the amplification of the HER-2/neu gene was the most important variable determining outcome, independent of other variables, such as tumor size and estrogen receptor status.

MDR1 gene expression in primary and advanced breast cancer.

P-glycoprotein (Pgp)-associated multidrug resistance (MDR) is related to intrinsic and acquired cross resistance to anthracyclines, vinca alkaloids, and other antineoplastic antibiotics. Expression of MDR1 is widely considered to play an important role in conferring resistance to adjuvant chemotherapy in women with breast tumor cells in women with disseminated disease, although data supporting this view is, at best, conflicting. The expression of MDR1 gene and its gene product, P-glycoprotein, was investigated in primary and advanced breast cancers (both previously untreated and previously treated on specific treatment protocols) to assess the role of P-glycoprotein in determining responsiveness to adjuvant chemotherapy. Expression was assessed by immunohistochemistry, reverse transcription-PCR (RT-PCR), Northern Blot and Western Blot. MDR1 mRNA was detected in 40% of the breast cancers tested by RT-PCR with 40 cycles of PCR amplification. When reducing the PCR amplification cycles to 28, the MDR1 gene expression signal disappeared from breast cancers of the highest expressers; however, known MDR1 positive control normal tissues, such as adrenal, kidney, and liver continued to show an expression product. Western and Northern blots failed to demonstrate the MDR1 gene product, P-glycoprotein, in these breast cancers. In contrast, physiologic levels of P-glycoprotein was clearly detected in normal adrenal, kidney, and liver by these techniques. Immunohistochemistry confirmed that breast carcinoma cells lacked P-glycoprotein expression; however, interstitial mononuclear cells, morphologically consistent with lymphocytes or macrophages did show immunostaining in some of these breast tumors. MDR1 gene expression identified by RT-PCR was not correlated either with response to paclitaxel therapy (29 patients able to be evaluated, p = 0.34, Fisher Exact Test) or overall survival (32 breast cancer patients with clinical follow-up information, p = 0.336, log rank). In conclusion, P-glycoprotein was not expressed in breast carcinoma cells at significant levels, although it was expressed in stomal lymphocytes or macrophages. These results suggest that P-glycoprotein does not play a significant role in multidrug resistance of breast cancer.

Localization of human BRCA1 and its loss in high-grade, non-inherited breast carcinomas.

Although the link between the BRCA1 tumour-suppressor gene and hereditary breast and ovarian cancer is established, the role, if any, of BRCA1 in non-familial cancers is unclear. BRCA1 mutations are rare in sporadic cancers, but loss of BRCA1 resulting from reduced expression or incorrect subcellular localization is postulated to be important in non-familial breast and ovarian cancers. Epigenetic loss, however, has not received general acceptance due to controversy regarding the subcellular localization of BRCA1 proteins, reports of which have ranged from exclusively nuclear, to conditionally nuclear, to the ER/golgi, to cytoplasmic invaginations into the nucleus. In an attempt to resolve this issue, we have comprehensively characterized 19 anti-BRCA1 antibodies. These reagents detect a 220-kD protein localized in discrete nuclear foci in all epithelial cell lines, including those derived from breast malignancies. Immunohistochemical staining of human breast specimens also revealed BRCA1 nuclear foci in benign breast, invasive lobular cancers and low-grade ductal carcinomas. Conversely, BRCA1 expression was reduced or undetectable in the majority of high-grade, ductal carcinomas, suggesting that absence of BRCA1 may contribute to the pathogenesis of a significant percentage of sporadic breast cancers.

p53 mutations and expression in ovarian cancers: correlation with overall survival.

The p53 gene is altered in approximately 50% of all human malignancies. p53 overexpression, identified by immunohistochemistry, and p53 mutations, identified by single-strand conformational polymorphism (SSCP) and DNA sequencing, have been described in ovarian cancers. p53 overexpression has been correlated with poor outcome for women with ovarian cancer in some studies. With only limited data, the assumption has been made that p53 overexpression corresponds to p53 mutations. The purpose of this investigation was to assess p53 alterations in ovarian cancer to determine if p53 overexpression corresponds with mutations in the p53 gene, and to assess whether either predicts clinical outcome in ovarian carcinoma. Frozen ovarian carcinoma tumor specimens from 105 patients were analyzed by immunohistochemical staining for p53 expression. SSCP was used to screen for mutations and DNA sequencing was used to confirm the specific mutation in exons 2 to 11, encompassing the entire p53 open reading frame. Those ovarian carcinomas identified as wild-type p53 by SSCP were subjected to automated DNA sequence analysis of the entire open reading frame. Relative to DNA sequence analysis, the sensitivity of SSCP was 85% and the specificity was 98%. Immunohistochemical staining demonstrated that 72 of the 105 (69%) cases had positive immunostaining. SSCP and DNA sequencing identified and confirmed mutations in 60 of the 105 carcinomas (57%). Although there was a statistically significant association between p53 immunostaining and p53 mutations (p = 0.0002), false-negative and -positive results were identified. Tumor grade (p = 0.03), stage (p = 0.08), and overall survival (p = 0.15) were moderately associated with positive p53 immunostaining. Patients with p53 mutations and overexpression had shorter overall patient survival (p = 0.02). The findings demonstrated that, individually, p53 mutations and p53 overexpression were each related to shorter patient survival, but the strongest predictor of outcome was a combination of both mutations and overexpression. Comparisons of overall survival for women with mutations in loop 2, loop 3, and the loop-sheet-helix domains together showed a statistically significant difference in survival compared to survival of women whose ovarian cancers had other mutations (p = 0.046).