Vitamin B6 status and interferon-γ-mediated immune activation in primary hyperparathyroidism.

OBJECTIVES: Primary hyperparathyroidism (PHPT) has been associated with low-grade inflammation and elevated risk of cardiovascular disease (CVD). In inflammatory conditions, interferon-γ (IFN-γ) activity is enhanced and a decreased circulating concentration of vitamin B6 is often observed. Such changes in IFN-γ activity or vitamin B6 levels have been associated with increased incidence of CVD. The aim of the study was to investigate systemic markers of IFN-γ-mediated immune activation, such as neopterin, the kynurenine-to-tryptophan ratio (KTR) and kynurenine pathway metabolites, as well as B6 vitamers in patients with PHPT. DESIGN/SUBJECTS: A total of 57 patients with PHPT and a control group of 20 healthy blood donors were included in this study. PHPT patients who responded positively to parathyroidectomy were followed for 6 months. Forty-three patients participated in the longitudinal study in which blood samples were taken at inclusion and 1, 3 and 6 months after surgery. RESULTS: Plasma concentrations of the B6 vitamers pyridoxal 5'-phosphate (PLP) (P = 0.007) and pyridoxal (P = 0.013) were significantly lower in the patient group compared to healthy control subjects. An increase in the KTR indicated that the kynurenine pathway of tryptophan metabolism was altered in PHPT patients (P = 0.015). During the initial 6 months after surgery, levels of PLP (P < 0.001) and anthranilic acid (P < 0.001) increased significantly, whereas neopterin decreased (P = 0.018). CONCLUSIONS: The results of this study demonstrate altered levels of vitamin B6 and the KTR in PHPT patients, both of which may reflect cellular immune activation. These abnormalities should be considered in relation to the increased risk of CVD previously observed in patients with PHPT.

RINF (CXXC5) is overexpressed in solid tumors and is an unfavorable prognostic factor in breast cancer.

BACKGROUND: We have previously described the essential role of the retinoid-inducible nuclear factor (RINF) during differentiation of hematopoietic cells and suggested its putative involvement in myeloid leukemia and preleukemia. Here, we have investigated whether this gene could have a deregulated expression in malignant tissues compared with their normal tissues of origin and if this potential deregulation could be associated with important clinicopathological parameters. PATIENTS AND METHODS: RINF messenger RNA expression was examined in biopsies from locally advanced breast tumors, metastatic malignant melanomas, and papillary thyroid carcinomas and compared with their paired or nonpaired normal reference samples. Further, the prognostic role of RINF expression was evaluated in locally advanced breast cancer. RESULTS: RINF expression was significantly higher in all tumor forms (primary breast, and thyroid cancers and metastatic melanomas) as compared with normal control tissues (P < 0.001 for each comparison). Importantly, high levels of RINF expression correlated to a poor overall survival in breast cancer (P = 0.013). This finding was confirmed in three independent public microarray datasets (P = 0.043, n = 234; P = 0.016, n = 69; P = 0.001, n = 196) and was independent of tamoxifen therapy. Notably, high levels of RINF was strongly associated with TP53 wild-type status (P = 0.002) possibly indicating that high levels of RINF could substitute for TP53 mutations as an oncogenic mechanism during the malignant development of some cases of breast cancer. CONCLUSIONS: Our data indicate that (i) RINF overexpression is associated with the malignant phenotype in solid tumors and (ii) RINF overexpression represents an independent molecular marker for poor prognosis in breast tumors.

Specific P53 mutations are associated with de novo resistance to doxorubicin in breast cancer patients.

The mechanisms causing resistance to chemotherapeutic drugs in cancer patients are poorly understood. Recent evidence suggests that different forms of chemotherapy may exert their cytotoxic effects by inducing apoptosis. The tumor suppressor gene P53 has a pivotal role inducing apoptosis in response to cellular damage. In vitro investigations have shown intact p53 to play a critical role executing cell death in response to treatment with cytotoxic drugs like 5-fluorouracil, etoposide and doxorubicin. Recently, mutations in the P53 gene were found to confer resistance to anthracyclines in a mouse sarcoma tumor model, and overexpression of the p53 protein (which, in most cases, is due to a mutated gene) was found to be associated with lack of response to cisplatin-based chemotherapy in non-small cell lung cancer. Previous studies have shown mutations in the P53 gene or overexpression of the p53 protein to predict a poor prognosis, but also a beneficial effect of adjuvant radiotherapy or chemotherapy in breast cancer. In this study we present data linking specific mutations in the P53 gene to primary resistance to doxorubicin therapy and early relapse in breast cancer patients.

Effects of CYP2D6 and SULT1A1 genotypes including SULT1A1 gene copy number on tamoxifen metabolism.

BACKGROUND: Tamoxifen is hydroxylated by cytochrome P450 (CYP) 2D6 to the potent metabolites 4-hydroxytamoxifen (4OHtam) and 4-hydroxy-N-demethyltamoxifen (4OHNDtam), which are both conjugated by sulphotransferase (SULT)1A1. Clinical studies indicate that CYP2D6 and SULT1A1 genotypes are predictors for treatment response to tamoxifen. Therefore, we examined the relationship between CYP2D6 genotype, SULT1A1 genotype, SULT1A1 copy number and the pharmacokinetics of tamoxifen. PATIENTS AND METHODS: The serum levels of tamoxifen and metabolites of 151 breast cancer patients were measured by high-pressure liquid chromatography-tandem mass spectrometry. The CYP2D6 and SULT1A1 polymorphisms and SULT1A1 copy number were determined by long PCR, PCR-based restriction fragment length polymorphism, DNA sequencing and fluorescence-based PCR. RESULTS: The levels of 4OHtam, 4OHNDtam and N-demethyltamoxifen were associated with CYP2D6 predicted enzymatic activity (P < 0.05). The SULT1A1 genotype or copy number did not influence the levels of tamoxifen and its metabolites. However, the ratios of N-demethyltamoxifen/tamoxifen and N-dedimethyltamoxifen/N-demethyltamoxifen were related to SULT1A1 genotype. CONCLUSION: CYP2D6 and SULT1A1 genotypes may partly explain the wide inter-individual variations in the serum levels of tamoxifen and its metabolites. We propose that therapeutic drug monitoring should be included in studies linking CYP2D6 and SULT1A1 genotypes to clinical outcome.

Induction of apoptosis in human cells by RNAi-mediated knockdown of hARD1 and NATH, components of the protein N-alpha-acetyltransferase complex.

Protein N-epsilon-acetylation is recognized as an important modification influencing many biological processes, and protein deacetylase inhibitors leading to N-epsilon-hyperacetylation of histones are being clinically tested for their potential as anticancer drugs. In contrast to N-epsilon-acetyltransferases, the N-alpha-acetyltransferases transferring acetyl groups to the alpha-amino groups of protein N-termini have only been briefly described in mammalians. Human arrest defective 1 (hARD1), the only described human enzyme in this class, complexes with N-acetyltransferase human (NATH) and cotranslationally transfers acetyl groups to the N-termini of nascent polypeptides. Here, we demonstrate that knockdown of NATH and/or hARD1 triggers apoptosis in human cell lines. Knockdown of hARD1 also sensitized cells to daunorubicin-induced apoptosis, potentially pointing at the NATH-hARD1 acetyltransferase complex as a novel target for chemotherapy. Our results argue for an essential role of the NATH-hARD1 complex in cell survival and underscore the importance of protein N-alpha-acetylation in mammalian cells.

Expression of c-erbB-3 and c-erbB-4 proteins in papillary thyroid carcinomas.

c-erbB-3 and c-erbB-4 protein expression was analyzed using immunohistochemistry in 138 fresh-frozen thyroid tissue samples from 106 patients, including 56 cases of papillary thyroid carcinoma. Increased expression of c-erbB-3 and c-erbB-4 proteins was observed in papillary carcinomas compared to nonneoplastic thyroid tissue. No amplifications of the c-erbB-3 and c-erbB-4 genes were detected. Coexisting overexpression of epidermal growth factor receptor, c-erbB-2, c-erbB-3, and c-erbB-4 was demonstrated in 36 (64%) of 56 papillary thyroid carcinomas. These findings suggest a common regulatory mechanism for the type I (epidermal growth factor receptor-related) receptors in papillary thyroid carcinomas and provide numerous possibilities for functional receptor interactions.

Expression and alternative splicing of c-ret RNA in papillary thyroid carcinomas.

Somatic rearrangements of the ret receptor tyrosine kinase have been consistently reported in papillary thyroid carcinomas (PTC). It is unclear whether the expression of wild-type c-ret may also be implicated in thyroid tumorigenesis. We studied ret mRNA expression in PTC from Norwegian patients. Using RT-PCR, wild-type ret mRNA was detected in all of 22 PTC and in a PTC cell line. c-ret mRNA was clearly overexpressed in PTC as compared to non-neoplastic thyroid tissue. Hybridization using ret exon DNA dot blot arrays and complex cDNA probes confirmed expression of ret RNA in thyroid biopsies. In accordance with the RNA data, Western immunoblotting showed evidence of wild-type Ret protein in PTC. Rearrangements generating the ret/PTC oncogenes co-existed with c-ret mRNA in PTC. Multiple alternative ret splicing variants were detected in PTC. Four novel ret splicing events were found in the region encoding the extracellular domain. The open reading frames of these transcripts were all in-frame with the Ret tyrosine kinase domain. In the central ret mRNA region encoding the cysteine-rich, transmembrane, and main tyrosine kinase domains, no evidence of alternative splicing was detected. Two alternative splice events were detected in the ret mRNA encoding the C-terminal part of Ret protein harboring tyrosine residues important for Ret signaling, excluding exon 19, or retaining intron 19, respectively. Ribonuclease protection assays confirmed the presence of ret alternative splicing events in thyroid biopsies. We conclude that in addition to ret/PTC rearrangements, wild-type c-ret mRNA and alternatively spliced ret transcripts are present in PTC. Transcriptional up-regulation and post-transcriptional mechanisms of c-ret RNA processing may contribute to differences in expression of Ret protein observed in PTC compared to non-neoplastic thyroid tissue.

Novel inflammatory biomarkers in primary hyperparathyroidism.

OBJECTIVE: Primary hyperparathyroidism (PHPT) has been associated with low-grade inflammation and increased risk of cardiovascular disease (CVD). The aim of the study was to investigate systemic levels of pro-inflammatory proteins that previously have not been examined in patients with PHPT. The selection of the pro-inflammatory biomarkers included in this study, MMP9, S100A4, S100A8/A9 and the receptors sCD14 and RAGE, was based on a previous microarray screen of mRNAs in adipose tissue from PHPT patients. DESIGN: A prospective study was conducted on a total of 57 patients with PHPT and a control group of 20 healthy blood donors. METHODS: PHPT patients with normalisation of serum calcium levels after parathyroidectomy were followed for 6 months. Forty-two patients participated in the longitudinal study, in which blood samples were taken at inclusion, and 1, 3 and 6 months after surgery. RESULTS: We observed increased serum levels of MMP9 (P=0.029), S100A4 (P<0.001) and sCD14 (P=0.002) in the 57 patients with PHPT compared to the control-group. During 6 months of follow up, S100A4 (P=0.022) and sCD14 (0.002) decreased significantly, while serum levels of MMP9 increased (P=0.025). CONCLUSIONS: The results demonstrate an increased inflammatory response in PHPT patients shown by elevated MMP9, S100A4 and sCD14 at inclusion. During the 6 months of follow-up, MMP9 increased further, possibly due to the tissue repair process after parathyroidectomy. S100A4 and sCD14 decreased after surgery demonstrating a partial reversal of the systemic inflammation.

Plasma total homocysteine levels during short-term iatrogenic hypothyroidism.

Hypothyroidism is associated with increased cardiovascular morbidity, which cannot be fully explained by the atherogenic lipid profile observed in these patients. We have previously found elevated levels of the cardiovascular risk factor, plasma total homocysteine (tHcy), in hypothyroidism. We conducted a longitudinal study on 17 patients who had undergone total thyroidectomy for thyroid cancer. During 6 weeks of discontinued T4 substitution before radioscintigraphy (phase I), they attained a hypothyroid state, which was reversed by resupplementation (phase II). Plasma tHcy, serum creatinine, serum and red blood cell folate, serum cobalamin, and serum cholesterol were determined at 2-week intervals throughout phases I and II. There was a progressive and parallel increase in tHcy (mean, 27%), serum creatinine (37%), and serum cholesterol (100%) during phase I, and these values returned to the original level within 4-6 weeks after reinitiating T4 therapy. Serum and red blood cell folate levels showed only minor, but statistically significant, changes. In a bivariate model, serum creatinine and serum cholesterol were strongly associated with the changes observed in tHcy during short term hypothyroidism. In conclusion, we found a transient increase in both plasma tHcy and serum cholesterol during short term iatrogenic hypothyroidism, and the tHcy response is probably mainly explained by concurrent changes in renal function. The increase in both plasma tHcy and serum cholesterol may confer increased cardiovascular risk in hypothyroid patients.

Prognostic importance of various clinicopathological features in papillary thyroid carcinoma.

The influence of various pathological features on tumour recurrences and cancer deaths has been studied in 173 consecutive cases of surgically treated papillary thyroid carcinoma recorded in 1971-1985. During the follow-up (median 7.3 years), 18.6% of the 161 radically treated patients had recurrent disease, and 8.7% died of thyroid cancer. In the univariate life-table analysis, recurrence-free survival was significantly related to age, pTNM category, tumour size, presence of certain growth patterns, tumour necrosis, tumour infiltration in surrounding thyroid tissue and thyroid gland capsule, lymph node metastases, presence of extra-nodal tumour growth and number of positive lymph nodes, whereas only tumour diameter, thyroid gland capsular infiltration and presence of extra-nodal tumour growth remained as significant prognostic factors in the multivariate analysis. Regarding thyroid cancer deaths, sex, age, pTNM category, radicality of surgical treatment, tumour diameter, macroscopic appearance, cellular atypia, tumour necrosis, thyroid gland capsular infiltration, vascular invasion, extra-thyroidal extension and lymph node metastases were all significant variables in the univariate analysis. However, only sex, age, radicality of surgical treatment and vascular invasion were found to be significant predictors of thyroid cancer deaths in the final multivariate Cox model, whereas cellular atypia and necrosis showed a borderline significance. Our study thus documents the independent importance of certain histological features for morbidity and mortality in surgically treated cases of papillary thyroid cancer.

Evidence against involvement of APC mutation in papillary thyroid carcinoma.

Papillary thyroid carcinoma (PTC) is one of several tumours associated with familial adenomatous polyposis (FAP), an inherited tumour syndrome which appears to result from germ-line mutation of the APC tumour suppressor gene. Here we investigate the possibility that somatic mutation of APC might play a role in sporadic PTC. 16 cases of PTC together with matched normal tissue were examined by single-strand conformation polymorphism (SSCP) analysis, concentrating on the mutation cluster region (MCR) of the APC gene (codons 1286-1513). No evidence of mutation was observed in any sample. We conclude that APC mutation, at least in the MCR, is not a significant causal mechanism in sporadic PTC.

Absence of abnormalities of the c-erbB-1 and c-erbB-2 proto-oncogenes in human thyroid neoplasia.

The c-erbB-1 and c-erbB-2 proto-oncogenes are frequently activated by gene amplification and overexpression in a variety of human cancers. In an analysis of a large series of benign and malignant thyroid tumours, no abnormalities of structure or expression of either of c-erbB-1 or c-erbB-2 were found. Activation of these oncogenes is not a necessary event in neoplasia of this epithelial system.

Predictive value of tumour cell proliferation in locally advanced breast cancer treated with neoadjuvant chemotherapy.

We previously reported that defects in apoptotic pathways (mutations in the TP53 gene) predicted resistance to doxorubicin monotherapy. The aim of this study was to evaluate whether cell proliferation, as assessed by mitotic frequency and Ki-67 levels, may provide additional predictive information in the same tumours and to assess any potential correlations between these markers and mutations in the TP53 gene and erbB-2 overexpression. Surgical specimens were obtained from ninety locally advanced breast cancers before commencing primary chemotherapy consisting of weekly doxorubicin (14 mg/m2) for 16 weeks. 38% of the patients had a partial response (PR) to therapy, 52% had stable disease (SD) while 10% had progressive disease (PD). Univariate analysis showed a significant association between a high cell proliferation rate (expressed as a high mitotic frequency) and resistance to doxorubicin (P = 0.001). Further analyses revealed this association to be limited to the subgroup of tumour expressing wild-type TP53 (P = 0.016), and TP53 mutation status was the only factor predicting drug resistance in the multivariate analyses. The finding that a high mitotic frequency, as well as a high Ki-67 staining, correlated to TP53 mutations (P = 0.001 for both), suggests TP53 mutations are the key predictor of drug resistance, although cell proliferation may play an additional role in tumours harbouring wild-type TP53. Regarding overall (OS) and relapse-free survival (RFS), multivariate analyses (Cox' proportional hazards regression) revealed a high histological grade and negative oestrogen receptor (ER) status to be the variables that were most strongly related to breast cancer death (P = 0.001 and P = 0.001, respectively). A key reason for this difference with respect to the factors predicting chemotherapy resistance could be due to the adjuvant use of tamoxifen in all patients harbouring ER-positive tumours.

Thyroid carcinoma with mixed tall-cell and columnar-cell features.

Tall-cell and columnar-cell carcinomas have been regarded as aggressive variants of papillary thyroid carcinoma. In the present case report the authors describe a composite tumor where these forms of differentiation coexisted, with transitional changes occurring within single follicular structures. This finding indicates that the two variants are closely related. In local recurrences, one or the other feature appeared in separate lesions. Lung metastases developed, and the patient died 5 1/2 years after diagnosis and primary treatment.

The value of ultrasonography in predicting autoimmune thyroid disease.

Ultrasonography (US) may demonstrate a diffuse reduction in thyroid echogenicity (low-amplitude echoes) in autoimmune thyroid disease (AITD), which includes chronic lymphocytic thyroiditis and Graves' disease, as well as in subacute thyroiditis. The reported occurrence of this finding in AITD varies from 19% to 95%. To assess the validity of diffuse reduction in thyroid echogenicity as a predictor of AITD, 3,077 patients referred for US of the thyroid were examined prospectively with regard to reduced versus normal thyroid echogenicity. The most frequent reasons for referral were goiter, thyroid dysfunction, neck discomfort, and/or difficulty in swallowing. Ultrasonography demonstrated diffuse reduction in thyroid echogenicity in 485 patients. Of these, 452 patients had available records of fine-needle aspiration biopsy (FNAB), and were included in the study. From the remaining patients, with normal thyroid echogenicity, 100 consecutive patients were selected as controls. In 411 of the 452 study patients (90.9%) there was at least one laboratory finding consistent with possible AITD: cytology indicating lymphocytic thyroiditis, 287 of 363 patients (79.1%) with diagnostic specimens; elevated levels of peroxidase antibodies (TPOAb), 225 of 337 (66.8%); elevated thyrotropin (TSH) levels, 290 of 450 (64.4%); or low TSH levels, 79 of 450 (17.6%). The final diagnosis was: chronic autoimmune (Hashimoto's) thyroiditis in 352 patients; Graves' disease in 47 patients; subacute (granulomatous) thyroiditis in 7 patients; toxic nodular goiter in 3 patients; and toxic adenoma in 2 patients. In the remaining 41 patients, those without laboratory results consistent with AITD, the final diagnosis was colloid goiter in 37 and thyroid cancer in 4 patients. In the 100 controls, laboratory results were consistent with possible AITD in 14 patients: elevated TPOAb levels in 5 of 49 patients with retrieved antibody results; lymphocytic thyroiditis in 2 patients; elevated TSH levels in 2 patients; and low TSH levels in 2 patients. In these controls, the final diagnosis was: chronic autoimmune thyroiditis in 7; toxic nodular goiter in 6 patients, and toxic adenoma in 1 patient. The corresponding positive and negative predictive values of reduced thyroid echogenicity as an indicator of AITD were 399 of 452 (88.3% [95% CI, 85% to 91%]), and 93 of 100 (93.0% [95% CI, 88% to 98%]), respectively. Thus, diffuse reduction in thyroid echogenicity was a valid predictor of AITD.

Androgen receptors in operable breast cancer: relation to other steroid hormone receptors, correlations to prognostic factors and predictive value for effect of adjuvant tamoxifen treatment.

Steroid hormone receptors have been evaluated as independent prognostic factors as well as predictive factors for endocrine manipulation in the clinical management of breast cancer. The contribution of each receptor or combinations of different receptors remains controversial. In cytosols from 224 patients with operable breast cancer (stages I & II), estrogen receptor (ER), progesterone receptor (PgR) and androgen receptor (AR) content have been measured. An improved AR-assay has been used in order to circumvent some of the problems inherent in other methods. In this study, 91.1% of the patients were classified as AR 'positive' (i.e. greater than or equal to 10 pmol/g). The steroid hormone receptors were significantly correlated (P less than 0.001). Taking the median value of AR as cut-off (50.5 pmol/g), a significantly higher incidence (P = 0.004) of node negative patients was found in the group with a lower AR content. In a multivariate analysis the AR category (median value used as cut-off) was shown to be an independent predictor of the likelihood of axillary metastases (P = 0.001). AR category, however, did not reveal any significant prognostic information concerning relapse free survival. A subpopulation of node positive patients with ER positive tumors, have been included in a randomized trial on the role of tamoxifen as an adjuvant treatment compared with no endocrine treatment. In a multivariate analysis, PgR status was shown to be a single independent prognostic factor (P = 0.016) for relapse free survival in patients with a lower AR content (less than median value). The improved AR assay used in the present study may provide a basis for more correct estimation of the AR content in an individual tumor. The present study suggests that AR analysis and the use of a well-chosen cut-off level may add information about tumor biology to increase our understanding of breast cancer biology and treatment.

Adjuvant endocrine treatment (goserelin vs tamoxifen) in pre-menopausal patients with operable node positive stage II breast cancer. A prospective randomized national multicenter study.

AIMS: To evaluate possible differences in effect on time to recurrence and overall survival in node positive pre-menopausal breast cancer patients (age < or = 50 years) receiving LHRH analogue or tamoxifen as adjuvant endocrine treatment. METHODS: Between January 1989 and July 1994, 320 patients with node positive (pN(+)) and hormone receptor positive or receptor status unknown tumors were included and randomized in a national multicenter study to receive either tamoxifen or goserelin as adjuvant treatment for two years. Primary surgical treatment was employed according to current standards. Final follow-up was completed as of December 2000. Time to events were estimated by the Kaplan-Meier method, and compared by the log rank test. Relative risks were estimated by the Cox's proportional hazards model. RESULTS: No differences in time to first recurrence or overall survival were observed between treatment groups. Proportions of patients in each group having a second breast cancer were also similar. CONCLUSIONS: Standard adjuvant treatment with tamoxifen as compared to adjuvant LHRH analogue therapy employed in this group of breast cancer patients gave similar outcomes, but the number of patients was too small to formally exclude a potentially clinically relevant difference in survival.

The influence of progestins on receptor levels in breast cancer metastasis.

The influence of oral high-dose (HD) medroxyprogesterone acetate (MPA) and megestrol acetate (MA) treatment on steroid hormone receptor levels in metastatic breast tumor tissue was investigated. In ten postmenopausal women with advanced breast cancer, receptor biopsies were obtained from the same tumor before the start, and one and eight weeks after the start of oral HD progestin treatment. Endocrine treatment had been stopped in all patients at least five weeks before the start of progestin treatment. Estradiol receptor (ER) levels were reduced by 26.9% and 20.0% respectively after one and eight weeks of treatment. Progesterone receptors (PgR) were significantly reduced to undetectable levels, possibly due to MPA and MA binding to PgR. A stepwise decrease in androgen receptors (AR) was observed, indicating that the two progestins (MPA and MA) may also act through AR, and/or interfere with the replenishment of AR.

Progesterone-binding cyst protein (PBCP) in operable breast cancer: correlations with prognostic factors and predictive value for effect of adjuvant tamoxifen treatment.

Progesterone-binding cyst protein (PBCP) is a secretory protein which has been found in varying concentrations and incidence in cytosols from benign breast tumors, primary breast cancer and metastasis. In order to evaluate its correlation to other prognostic factors, PBCP was analysed in tumor cytosols from 386 women with stage I and stage II breast cancer. The incidence of PBCP negative (i.e. PBCP = 0) tumors was significantly decreased in node negative patients as compared to node positive (p = 0.012). An inverse correlation between estrogen receptor content and PBCP was found (p = 0.001). In a multivariate analysis PBCP category was found to be an independent predictor of the likelihood of axillary nodal involvement (p = 0.015). In spite of this association, PBCP did not reach statistical significance as an independent prognostic factor with regard to relapse-free survival. To evaluate PBCP category as a possible predictive factor for response to adjuvant endocrine treatment, a subpopulation of node positive patients with ER positive tumors was analysed; in patients with PBCP negative tumors, adjuvant treatment with tamoxifen proved to increase the relapse-free survival significantly (p = 0.011). We suggest that PBCP may have a place among other biochemical parameters in breast cancer, to provide an extended basis for understanding of tumor biology and a better selection of patients for endocrine treatment.