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

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

Immunohistochemical evaluation of hormone receptor status for predicting response to endocrine therapy in metastatic breast cancer

BACKGROUND: The importance of establishing hormone receptor status of tumors for the treatment of women with hormone receptor-positive breast cancer has been emphasized, however, there is no general agreement as to how immunohistochemical assays should be evaluated. It is critical to evaluate hormone receptor status when considering response to endocrine therapy. METHODS: Estrogen receptor (ER) and progesterone receptor (PgR) expression was examined by immunohistochemistry using Allred's score for primary breast tumors from 75 metastatic breast cancer patients who received first-line treatment with endocrine therapy (56 patients received tamoxifen, 11 patients received aromatase inhibitors, and 8 patients received LH-RH agonist or other endocrine reagents) on relapse. Correlation between hormone receptor status and response to endocrine therapy as well as post-relapse survival was analyzed. RESULTS: The most significant correlation between positive ER expression and response to any endocrine therapy (p = 0.011) or tamoxifen only (p = 0.030) occurred when the cutoff score was set at 10%. When the evaluation was based on Allred's score (TS), a cutoff point of TS>or=4 showed a more significant association between positive ER expression and response to all kinds of endocrine therapy (p = 0.020) or tamoxifen only (p = 0.047). When evaluated at a cutoff point of 1% positive cells, there were fifteen patients with both ER- and PgR-negative tumors, and three patients (20.0%) responded to the therapy. Patients with 1% or more ER or PgR positive cells had better survival after relapse (p = 0.0005 and p = 0.0008, respectively). CONCLUSIONS: The proportion score alone might be enough to predict hormone responsiveness and post-relapse survival in metastatic breast cancer. The cutoff might be set low, for example 1%, especially for metastatic disease.     

Results of two or five years of adjuvant tamoxifen correlated to steroid receptor and S-phase levels

A Swedish cooperative trial demonstrated that 5 years of adjuvant tamoxifen was more beneficial than 2 years of tamoxifen in the treatment of postmenopausal women with estrogen receptor (ER) positive, early stage, invasive breast cancer. The main aim of the present study was to investigate the importance of progesterone receptor (PgR) and ER concentration levels for patients participating in the trial and still distant recurrence free two years after the primary operation. Subgroup analyses revealed that only patients with ER positive and PgR positive breast cancer had improved distant recurrence free survival (DRFS) by prolonged tamoxifen therapy (p=0.0016). Patients with ER negative and PgR negative as well as ER positive and PgR negative tumors showed no significant effect of prolonged tamoxifen (p=0.53 and p=0.80, respectively). The percentage of ER negative and PgR positive breast cancers was too small (2.2%) for any meaningful subgroup analysis. There was a significant positive trend that the concentration level of PgR (high positive vs. low positive vs. negative) decreased the recurrence rate for those with prolonged therapy. No corresponding pattern was found for the ER content. S-phase fraction did not correlate to the recurrence rate of PgR positive breast cancers. Patients recurring during tamoxifen therapy had receptor negative tumors to a greater extent than those recurring after tamoxifen treatment.In conclusion, prolonged tamoxifen therapy for 5 years instead of 2 years was found to be beneficial for patients with ER positive and PgR positive breast cancer, whereas three extra years of tamoxifen had little or no effect for patients with ER positive but PgR negative tumors as well as for steroid receptor negative patients.     

Significance of immunohistochemical assessment of steroid hormone receptor status for breast cancer patients

The assessment of steroid hormone receptors in resected breast cancer tissues is essential to decide whether endocrine therapy is indicated and to select the best treatment for each patient on the basis of receptor status. Both enzyme immunoassay (EIA) and immunohistochemistry (IHC) have been generally used as methods for examination of estrogen receptor (ER) and progesterone receptor (PgR). In some patients, receptor status cannot be examined for various reasons. A questionnaire survey in Japan clarified that ER status is not examined in approximately 40% of patients receiving breast conserving surgery. To eliminate "receptor unknown" cases, IHC examination on paraffin-embedded tissue is useful to assess the in situ receptor status. The concordance rate of ER and PgR status between EIA and IHC is very high and a study of 88 cases revealed a 97.7% concordance for ER and 92.0% for PgR at a cutoff point of 10%. The cutoff point of IHC is controversial and some studies demonstrated that patients showing 1% ER positive cancer cells would benefit from endocrine therapy. On the other hand, immunohistochemical expression of receptors is heterogeneous and some patients with ER negative invasive tumors have ER positive intraductal components. A study of 65 breast cancers demonstrated that ER positive intraductal components were detected in 3.1% cases of ER negative invasive lesions. According to these results and the recommendation of the St. Gallen International Conference, IHC is thought to be more useful than EIA in the assessment of steroid hormone receptor status for breast cancer patients.     

Letrozole is more effective neoadjuvant endocrine therapy than tamoxifen for ErbB-1- and/or ErbB-2-positive, estrogen receptor-positive primary breast cancer: evidence from a phase III randomized trial.

PURPOSE: Expression of ErbB-1 and ErbB-2 (epidermal growth factor receptor and HER2/neu) in breast cancer may cause tamoxifen resistance, but not all studies concur. Additionally, the relationship between ErbB-1 and ErbB-2 expression and response to selective aromatase inhibitors is unknown. A neoadjuvant study for primary breast cancer that randomized treatment between letrozole and tamoxifen provided a context within which these issues could be addressed prospectively. PATIENTS AND METHODS: Postmenopausal patients with estrogen- and/or progesterone receptor-positive (ER+ and/or PgR+) primary breast cancer ineligible for breast-conserving surgery were randomly assigned to 4 months of neoadjuvant letrozole 2.5 mg daily or tamoxifen 20 mg daily in a double-blinded study. Immunohistochemistry (IHC) for ER and PgR was conducted on pretreatment biopsies and assessed by the Allred score. ErbB-1 and ErbB-2 IHC were assessed by intensity and completeness of membranous staining according to published criteria. RESULTS: For study biopsy-confirmed ER+ and/or PgR+ cases that received letrozole, 60% responded and 48% underwent successful breast-conserving surgery. The response to tamoxifen was inferior (41%, P =.004), and fewer patients underwent breast conservation (36%, P =.036). Differences in response rates between letrozole and tamoxifen were most marked for tumors that were positive for ErbB-1 and/or ErbB-2 and ER (88% v 21%, P =.0004). CONCLUSION: ER+, ErbB-1+, and/or ErbB-2+ primary breast cancer responded well to letrozole, but responses to tamoxifen were infrequent. This suggests that ErbB-1 and ErbB-2 signaling through ER is ligand-dependent and that the growth-promoting effects of these receptor tyrosine kinases on ER+ breast cancer can be inhibited by potent estrogen deprivation therapy.     

Comparison of immunohistochemical and biochemical assay of steroid receptors in primary breast cancer--clinical associations and reasons for discrepancies

Estrogen (ER) and progesterone receptor (PgR) status was analysed in paraffin-embedded breast cancer material with immunohistochemical (IHC) technique and compared with corresponding analyses in cytosols (CYT). ER showed the same status (positive/negative) with both methods in 88% of the samples (352/402). The concordance was also high for PgR status (81% [321/394]). Besides values near cut-off, heterogeneity in the distribution of receptor positive and negative nuclei within a tumour sample was the main reason for discordances. Histological type, presence of sclerosis, necrosis and non-invasive cells, and technical artefacts seem to be of only limited importance for explaining discordances All patients have been treated with adjuvant tamoxifen for two years. The two subgroups, which were ER(CYT)+/ ER(IHC) + or ER(CYT)-/ER(IHC) +, both had a significantly better progression-free survival (PFS; median follow-up: almost 6 years) than the ER(CYT)-/ER(IHC)- group (p < 0.001 and p = 0.007, respectively). The remaining group, ER(CYT)+/ER(IHC)-, had an intermediate PFS. For PgR, the associations with PFS were weaker, with significantly better PFS than the PgR(CYT)-/PgR(IHC)- group being found only for the PgR(CYT) +/PgR(IHC)- group (p = 0.03).     

Comparison of gene expression profiles predicting progression in breast cancer patients treated with tamoxifen

Background Molecular signatures that predict outcome in tamoxifen treated breast cancer patients have been identified. For the first time, we compared these response profiles in an independent cohort of (neo)adjuvant systemic treatment naïve breast cancer patients treated with first-line tamoxifen for metastatic disease. Methods From a consecutive series of 246 estrogen receptor (ER) positive primary tumors, gene expression profiling was performed on available frozen tumors using 44K oligoarrays (n = 69). A 78-gene tamoxifen response profile (formerly consisting of 81 cDNA-clones), a 21-gene set (microarray-based Recurrence Score), as well as the HOXB13-IL17BR ratio (Two-Gene-Index, RT-PCR) were analyzed. Performance of signatures in relation to time to progression (TTP) was compared with standard immunohistochemical (IHC) markers: ER, progesterone receptor (PgR) and HER2. Results In univariate analyses, the 78-gene tamoxifen response profile, 21-gene set and HOXB13-IL17BR ratio were all significantly associated with TTP with hazard ratios of 2.2 (95% CI 1.3–3.7, P = 0.005), 2.3 (95% CI 1.3–4.0, P = 0.003) and 4.2 (95% CI 1.4–12.3, P = 0.009), respectively. The concordance among the three classifiers was relatively low, they classified only 45–61% of patients in the same category. In multivariate analyses, the association remained significant for the 78-gene profile and the 21-gene set after adjusting for ER and PgR. Conclusion The 78-gene tamoxifen response profile, the 21-gene set and the HOXB13-IL17BR ratio were all significantly associated with TTP in an independent patient series treated with tamoxifen. The addition of multigene assays to ER (IHC) improves the prediction of outcome in tamoxifen treated patients and deserves incorporation in future clinical studies.     

Immunohistochemistry compared to cytosol assays for determination of estrogen receptor and prediction of the long-term effect of adjuvant tamoxifen

The purpose of this study is to compare immunohistochemistry (IHC) and cytosol-based assays for determination of estrogen receptor (ER) and prediction of response to adjuvant tamoxifen treatment in postmenopausal women with early-stage invasive breast cancer. The Stockholm Breast Cancer Study Group conducted a randomized trial during 1976 through 1990 comparing adjuvant tamoxifen versus control. The patients were stratified according to tumor size and lymph node status in high-risk and low-risk groups. In this study we evaluated 683 patients with “low risk” breast cancer (size ≤30 mm, lymph node-negative) for whom ER status had been determined by both the cytosol assays and IHC at one pathology laboratory. The median follow-up was 17 years. Six hundred eighty-three patients had tumors with ER determined by both methods, 536 (78.5%) were ER-positive by cytosol assays using the cutoff level at ≥0.05 fmol/μg DNA and 539 patients were ER-positive (79%) by IHC using the cutoff level at ≥10% cell stained. Thirty-nine tumors (5.7%) were ER-positive by cytosol but not by IHC, whereas the opposite pattern was found for 42 cases (6.1%). Only seven tumors had stained cells between 0 and 9% by IHC. The concordance between IHC and cytosol assays was high (88%). The kappa statistic was 0.65, 95% CI 0.58–0.72. Among patients classified as ER-negative no therapeutic benefit from tamoxifen was observed. Among patients with ER-expressing tumors, tamoxifen resulted in significantly better recurrence-free survival irrespective of the method (IHC: HR, 0.53, P < 0.001; cytosol: HR, 0.53, P < 0.001). The effect on overall survival was not statistically significant probably due to the limited sample size. Both IHC and cytosol assay accurately predict long-term response to adjuvant tamoxifen.     

Differences in immunoreactivity of estrogen receptor (ER) in tamoxifen-sensitive and -resistant breast carcinomas: preclinical and first clinical investigations

Inherited or acquired tamoxifen resistance is a major constraint in the endocrinological treatment of breast carcinomas. We developed an enzyme-immunoassay that discriminates between tamoxifen-sensitive and -resistant tumors. The procedure was established and standardized using two xenografted breast carcinomas – 3366 (highly sensitive to tamoxifen) and 3366/TAM (acquired tamoxifen resistance). The latter model was developed by treatment of 3366 tumor-bearing nude mice during serial passaging over 3 years with tamoxifen. Both lines were estrogen receptor (ER) positive (101 or 82 fmol/mg protein), and revealed no differences in the nucleotide sequences of the hormone binding domain of the ER protein. However, while in the sensitive tumors an upregulation of ER levels was registered after estradiol treatment of tumor bearing nude mice, the ER expression in the resistant line remained unchanged. The tamoxifen sensitive and -resistant breast carcinoma 3366 differed, additionally, in their immunoreactivity of ER to mAB H222. While an incubation with estradiol or tamoxifen of immobilized ER prepared from cytosols of the sensitive tumors 3366 led to a significant increase in immunoreactivity, samples of resistant tumors failed in the exposition of additional immunologically reactive epitopes. These results were the basis for the development of an assay for determination of the tamoxifen response in patients. Our retrospective results with 38 breast tumors from a tumor bank indicated that patients with an increase of immunoreactivity of ER more rarely had a recurrence while under going tamoxifen therapy compared with patients expecting no increase. However, the data indicate interesting changes occurring with the ER of tam-resistant tumors that are to be explained by further mutational or protein-chemical analysis.     

Estrogen Receptor Mutations and Changes in Estrogen Receptor and Progesterone Receptor Protein Expression in Metastatic or Recurrent Breast Cancer

To investigate the frequency of estrogen receptor ( ER ) gene mutation in metastatic or recurrent breast cancer, metastatic lymph nodes or recurrent breast cancer tissue from 35 patients with ER-positive primary tumors were screened for mutations in the hormone-binding domain of the ER gene by sequence analysis. Four missense mutations, Val316Ile, Gly344Val, Ala430Val and Gly494Val, were identified in these lesions. Second, to clarify whether there is any disparity in hormone receptor status between primary and metastatic or recurrent tumors, we immunohistochemically studied 117 specimens including the above 35 specimens obtained from metastatic or recurrent breast cancer patients using monoclonal anti-ER and progesterone receptor (PgR) antibodies. Although hormone receptor status, especially ER, was highly maintained through disease progression, negative change in PgR expression at relapse (33%) was identified more frequently than in metastatic lymph nodes (6.7%). Therefore, it was suggested that development of PgR-negative phenotype might correlate with disease progression in some breast cancer patients. These results suggest that ER mutations in metastatic or recurrent breast cancer may be more frequent than in primary lesions, irrespective of high maintenance of ER protein expression through disease progression.     

Estrogen receptor status by immunohistochemistry is superior to the ligand-binding assay for predicting response to adjuvant endocrine therapy in breast cancer.

PURPOSE: Immunohistochemistry (IHC) is a newer technique for assessing the estrogen receptor (ER) status of breast cancers, with the potential to overcome many of the shortcomings associated with the traditional ligand-binding assay (LBA). The purpose of this study was to evaluate the ability of ER status determination by IHC, compared with LBA, to predict clinical outcome-especially response to adjuvant endocrine therapy-in a large number of patients with long-term clinical follow-up. PATIENTS AND METHODS: ER status was evaluated in 1,982 primary breast cancers by IHC on formalin-fixed paraffin-embedded tissue sections, using antibody 6F11 and standard methodology. Slides were scored on a scale representing the estimated proportion and intensity of positive-staining tumor cells (range, 0 to 8). Results were compared with ER values obtained by the LBA in the same tumors and to clinical outcome. RESULTS: An IHC score of greater than 2 (corresponding to as few as 1% to 10% weakly positive cells) was used to define ER positivity on the basis of a univariate cut-point analysis of all possible scores and disease-free survival (DFS) in patients receiving any adjuvant endocrine therapy. Using this definition, 71% of all tumors were determined to be ER-positive by IHC, and the level of agreement with the LBA was 86%. In multivariate analyses of patients receiving adjuvant endocrine therapy alone, ER status determined by IHC was better than that determined by the LBA at predicting improved DFS (hazard ratios/P = 0.474/.0008 and 0.707/.3214, respectively) and equivalent at predicting overall survival (0.379/.0001 and 0.381/.0003, respectively). CONCLUSION: IHC is superior to the LBA for assessing ER status in primary breast cancer because it is easier, safer, and less expensive, and has an equivalent or better ability to predict response to adjuvant endocrine therapy.     

Estrogen receptor analysis in primary breast tumors by ligand-binding assay, immunocytochemical assay, and northern blot: a comparison

Estrogen receptor (ER) status is an important parameter in breast cancer management. In this study, ER protein contents established by two conventional techniques were confronted to ER mRNA level, to analyze whether the latter may be introduced in routine assay. Eighty-seven breast tumor samples were examined. ER amounts were determined by ligand-binding assay (LBA) and by computer-assisted immunocytochemical assay (ICA), ER mRNA was analysed and quantified by northern blot. Seventy-seven percent of tumor samples examined were positive for ER mRNA and they all expressed the 6.7-kb receptor signal. No trace of small-sized ER mRNA variants was detected in any sample. Following akaike information criterion (AIC) discriminant analysis, a simple linear correlation was found between ER mRNA levels and ER amounts provided by LBA. This was not observed when either mRNA or LBA values were compared to ICA values. These latter were found to rapidly reach a plateau at increasing mRNA or LBA values. In conclusion, our data points to the linear correlation between ER amounts determined in breast tumors at both protein and mRNA levels by quantitative methods; they also indicate that the semi-quantitative computer-associated ICA may complement rather than replace these quantitative methods.     

Comparison of estrogen and progesterone receptor status to lymphocyte immunity against tumor antigens in breast cancer patients

Summary Estrogen (ER) and progesterone receptor (PgR) content of tumors were determined by both the dextrancoated charcoal (DCC) cytosol and immunocytochemical assays (ICA), and these hormone receptor results were compared to lymphocyte immunity against tumor antigen(s) for 52 breast carcinoma patients. Hormone receptor analysis by both methods demonstrated that 60% of the patients' tumors had ERs, while 44% were positive for PgRs. The ICA procedure was more sensitive than the cytosol technique for determining PgR content of the tumors. This increased sensitivity was not observed for ER by ICA. Patient age, tumor size, and nodal status were not related to the ER and PgR receptor status. A total of 21/52 (40%) of the patients had positive lymphocyte immunity against tumor antigen. This immunity was independent of patient age, tumor size, and nodal status. There was no significant relationship between lymphocytic immunity against tumor antigen and ER or PgR content of tumors, suggesting that patient lymphocyte immunity against tumor is independent of hormone receptor status. This is further evidence that lymphocyte immunity against tumor antigen status is an independent prognostic indicator that may be useful in the selection of a subset of node negative patients for adjuvant chemotherapy.     

Changes in Radiation Sensitivity and Steroid Receptor Content Induced by Hormonal Agents and Ionizing Radiation in Breast Cancer Cells in Vitro

Possible influences of tamoxifen and estradiol on in vitro radiation sensitivity and cellular receptor content after irradiation and/or tamoxifen treatment were studied in breast cancer cell lines; estrogen receptor (ER) and progesterone receptor (PgR) positive cell lines MCF-7 and MCF-7/TAM^R-1 and the ER and PgR negative cell line MDA-MB-231. The tamoxifen resistant MCF-7/TAM^R-1 cells were more resistant to ionizing radiation than the MCF-7 and MDA-MB-231 cells. Exposure to tamoxifen made the MCF-7 cells more radiation resistant, while estradiol made the MDA-MB-231 cells more radiation sensitive. A radiation dose of 6 Gy reduced the ER content in cytosol in both MCF-7 and MCF-7/TAM^R-1 cells, but brought no alterations to the PgR content. In MCF-7/TAM^R-1 cells tamoxifen exposure significantly increased the ER and reduced the PgR content, an effect not observed in the MCF-7 cells. To conclude, the present study indicates that irradiation and tamoxifen may modify the ER and PgR content in cytosol in breast cancer cells. Hormonal treatment may alter the radiation sensitivity, even in ER negative cells, suggesting that hormonal agents may act both via receptor and non-receptor binding mechanisms.     

Estrogen and progesterone receptor profile patterns in primary breast cancer

Summary Estrogen (ER) and progesterone receptor (PgR) analyses have been performed in 884 primary, malignant human breast tumor biopsies. Receptor contents were evaluated with respect to age and menopausal status. The frequency of ER + tumors was found to be significantly higher in postmenopausal than in pre/perimenopausal women. Age rather than menopausal status was found to be associated with this difference. The significant association with age was found in the post- but not the pre/perimenopausal women.The frequency of PgR + tumors was found to be significantly lower in the postmenopausal than in the pre/perimenopausal women. Neither age nor menopausal status alone could account for this difference, which appears to be due to a compound effect of the two factors.The distribution of receptor profile patterns is described according to menopausal status. The patterns differ significantly in pre- and postmenopausal women. PgR dominates in the premenopausal tumor while ER dominates in the postmenopausal tumor. This difference is apparent within the subgroup of ER + PgR + patients as well.The current tenets for prediction of recurrent disease utilizing steroid hormone receptor determinations are discussed for the group of ER + PgR + patients.sponsored by The Danish Cancer Society     

Molecular aspects of estrogen receptor variants in breast cancer

Summary Measurements of the estrogen receptor (ER) and the estrogen-induced progesterone receptor (PgR) are used by most clinicians as indicators of both overall prognosis and likelihood of response to endocrine therapy. Patients with ER+/PgR+ tumors have the highest likelihood of response; conversely, patients with ER-/PgR- tumors have the lowest likelihood of response. Unfortunately, most patients treated successfully with endocrine therapy eventually develop endocrine-resistant disease recurrence. In an effort to study potential mechanisms of endocrine resistance, we have studied discordant ER-/PgR+ tumors, in which the normally estrogen-regulated PgR gene is induced in the apparent absence of ER. Our laboratory has previously cloned, from ER-/PgR+ tumors, a variant ER mRNA precisely missing the sequence corresponding to ER exon 5, and has demonstrated that the truncated protein product translated from this variant RNA is capable of constitutively inducing the expression of an estrogen-responsive reporter gene in a yeast expression vector system (Fuqua et al, Cancer Res 51:105-109, 1991). In the present report we describe further experiments to characterize the activity and biological consequences of expression of this variant ER in human breast cancer cells. We have stably transfected MCF-7 human breast cancer cells with a mammalian expression vector for the exon 5 deletion variant ER. These transfected cells produce a truncated ER protein of the expected 40 kDa size. Cells expressing the exon 5 ER deletion variant constitutively express PgR, and manifest increased anchorage-independent colony formation in the absence of estrogen. Furthermore, the anchorage-dependent growth of these cells was not inhibited by the triphenylethylene antiestrogens tamoxifen or 4-hydroxytamoxifen, unlike MCF-7 cells transfected with a control plasmid, which were growth inhibited by both of these compounds. Interestingly, the pure antiestrogen ICI 164,384 did inhibit the growth of exon 5 ER deletion variant-expressing transfectants. The implications of these results with regard to the treatment of tamoxifen-resistant disease are discussed.     

Tumor-proliferative activity, progesterone receptor status, estrogen receptor level, and clinical outcome of estrogen receptor-positive advanced breast cancer

The relations among pretreatment tumor-proliferative activity, progesterone receptor (PgR) status, estrogen receptor (ER) level, and clinical outcome were analyzed in a series of 45 ER-positive advanced breast cancer postmenopausal women treated with tamoxifen (20 mg/day) until disease progression. Tritiated thymidine ([3H]dThd) Labeling Index (LI) by autoradiographic assay was utilized for proliferative activity analysis, whereas the dextran-coated charcoal method was used for ER and PgR evaluation (cutoff value, 10 fmol/mg of protein cytosol). The median [3H]dThd LI value was 1.8%; 73% of cases were PgR positive, and 53% were highly ER positive (greater than 100 fmol/mg of protein cytosol). Clinical responses were more frequently observed in slowly than in quickly proliferating tumors (86% versus 60%; P less than 0.05) but were similar for PgR-positive and -negative cases, as well as for those with high and low ER positivity. Only [3H]dThd LI was found to individualize patients with different survival rates (at 40 mo of follow-up, 78% versus 40% in slowly and quickly proliferating tumors, respectively). The [3H]dThd LI, monitored in ten patients by a second tumor biopsy after 14 days of tamoxifen therapy, was found to have a significantly lower median value (P = 0.03). These data indicate that pretreatment [3H]dThd LI provides information, which is not available in a study of PgR and ER status, on the clinical outcome of ER-positive advanced breast cancer patients treated by hormone therapy.     

Premorbid body weight and its relations to primary tumour diameter in breast cancer patients; its dependence on estrogen and progesteron receptor status

Hormonal mechanisms have been offered as an explanation for the higher frequency of large tumours, lymph node metastases and poorer prognosis in obese breast cancer patients than in lean ones. If hormonal mechanisms are important for these relations, they should probably act more strongly in patients with hormonal receptor positive tumours than in those with negative ones. We have examined if the relations between premorbid body weight or Quetelet's index (weight/height²) and tumour diameter are modified by estrogen receptor alpha (ER) and progesteron receptor (PgR) status. The analyses were based on 1,241 women with unilateral disease treated with modified radical mastectomy living in the geografic area of Haukeland Hospital. Their body weight and height have been measured as a mean 12.5years before presentation of the disease. Body weight and Quetelet's index have been adjusted for age. The relations were studied using linear regression analyses adjusting the effect of body weight with height and mean nuclear area of the tumour cells and adjusting the effect of Quetelet's index for mean nuclear area. The main findings showed that patients with high body weight or Quetelet's index presented more often with PgR positive tumours than lean ones. Quetelet's index was also positively related to ER. These relations were present in patients older than 50 years of age (older). Patients with large tumours (>2.0cm) had significantly higher body weight and Quetelet's index than those with small ones. These differences were significantly present in older patients and in patients with PgR negative and ER negative – PgR negative tumours. Linear regression analyses confirmed that tumour diameter increases with body weight and Quetelet's index. These relations were present in both lymph node groups and in older patients. Stratification according to hormonal receptor status showed these relations to be significant in patients with ER negative, with PgR negative and those with ER negative – PgR negative tumours only. Taking age and hormonal receptor status into consideration simultaneously, both body weight and Quetelet's index were significantly related to tumour diameter in older patients with hormone receptor negative tumours. In conclusion body size was positively related to hormone receptor status and to diameter of the primary tumour. The relation to tumour diameter was present in older patients with hormone receptor negative tumours. Although hormonal mechanisms able to act on the tumour can not be excluded, mechanisms acting independent of hormonal receptors must be considered. Different mechanisms related to body fat cytokines are discussed.