Fatal myocardial infarction in the Scottish adjuvant tamoxifen trial. The Scottish Breast Cancer Committee

OBJECTIVE

To investigate the incidence of fatal myocardial infarction in women in the two randomised arms of the Scottish adjuvant tamoxifen trial.

DESIGN

Retrospective review of hospital notes to determine with the greatest possible certainty women who had died of an acute myocardial infarction.

SETTING

Scottish Cancer Trials Office, the University of Edinburgh.

PATIENTS

1070 postmenopausal women with operable breast cancer who were randomised to receive either adjuvant tamoxifen for five years or until relapse (539 patients) or tamoxifen for at least six weeks on the confirmation of first recurrence (531 patients).

MAIN OUTCOME MEASURES

Incidence of fatal myocardial infarction in women with no known or suspected systemic cancer.

RESULTS

Of the 200 women who died in the adjuvant tamoxifen arm of the trial, 44 were free of cancer at death and 10 of these died of myocardial infarction. In the observation arm 251 women died, of whom 61 showed no evidence of systemic cancer and 25 had a fatal myocardial infarction. The incidence of fatal myocardial infarction in the two groups was significantly different (chi 2 = 6.88, p = 0.0087).

CONCLUSION

Tamoxifen given for at least five years as adjuvant therapy for breast cancer seems to have a cardioprotective oestrogen-like effect in postmenopausal women.

Adjuvant systemic therapy for operable breast cancer

Adjuvant systemic therapy is now an important and recognized part of the initial management of patients with operable breast cancer. Its value in delaying relapse and prolonging total survival is established for disease of poor prognosis. For premenopausal patients the currently advised treatment is a 6 months course of CMF polychemotherapy and for postmenopausal patients it is daily tamoxifen for 2-5 years. For patients with disease of good prognosis there is a need to evaluate, within randomized trials, the usefulness of newer biological indicators of prognosis to improve selection for and of treatment. Continued monitoring of long-term results for delayed morbidity is also necessary.

Trophoblastic factors and the maternal recognition of pregnancy in sheep and cattle

The establishment of pregnancy in domestic ruminants depends upon the continued secretion of progesterone by the corpora lutea. In non-pregnant cycles the corpora lutea regress between days 12-15 after oestrus in the sheep; this process must be blocked to ensure continued exposure of the uterus to progesterone. This review discusses the evidence that embryonic products are involved in the maintenance of corpus luteum function, the identification of factors which may be responsible for this maintenance and the probable mechanism of action. The discussion centres on the recent identification of a trophoblast interferon which is thought to be the major trophoblastic factor preventing luteolysis in sheep and cattle.

Is apocrine differentiation in breast carcinoma of prognostic significance?

Apocrine differentiation in human breast cancers has been assessed using immunohistochemistry to detect zinc alpha 2 glycoprotein and the findings related to standard prognostic factors, disease free interval (DFI) and survival in 145 women with early breast cancer. Breast tumour samples from women with a minimum follow-up of 5 years were assessed. Routinely fixed and processed tissue was used throughout. Sixty-six (45%) tumours did not stain with the antibody. Fifty-two (36%) exhibited positive apocrine staining while for 27 (19%) only a few cells were reactive. The presence of apocrine differentiation was unrelated to lymph node status, menstrual status, tumour grade or size, oestrogen receptor (E2R) or progesterone receptor status. However, patients whose tumours exhibited apocrine staining had a shorter disease-free interval (DFI) (P = 0.03) and survival (P = 0.03). A Cox's multiple regression analysis of the data found that the presence of staining added significantly (P = 0.047) to the predictive value of node status (P = 0.0001), menstrual status (P = 0.0001), tumour size (P = 0.0026) and E2R status (P = 0.0014) for patient survival. The other seven prognostic factors tested did not reach significance and were rejected from the model. Apocrine differentiation in breast cancer appears to be an independent predictor of poor prognosis tumours.

Structure of an interferon-alpha 2 gene expressed in the bovine conceptus early in gestation

Genomic and cDNA clones for bovine trophoblast interferon (IFN) have been isolated by probing a bovine genomic library and a bovine embryonic (day-18 post coitus) cDNA library respectively with the ovine trophoblast IFN cDNA. The two DNA sequences were identical; sequence analysis demonstrated 80% identity between the amino acid sequence of bovine trophoblast IFN and ovine trophoblast IFN, and 70% identity with a previously identified bovine IFN-alpha 2. Southern blotting of bovine genomic DNA indicated the presence of a minimum of three trophoblast IFN genes. Primer extension analysis identified the transcription start site in the 5' flanking region of the bovine IFN gene. Computer-aided analysis of the 5' flanking sequence demonstrated a similarity with that of bovine IFN-alpha 2 and the existence of a possible viral induction sequence.

Three markers of adult non-myelin-forming Schwann cells, 217c(Ran-1), A5E3 and GFAP: development and regulation by neuron-Schwann cell interactions

Immunohistochemical methods are used to investigate in detail the development and regulation of three proteins (217c(Ran-1), A5E3 and GFAP) specifically associated with adult non-myelin-forming Schwann cells in the rat sciatic nerve, from embryo day 15 to maturity. 217c(Ran-1), which is probably the NGF-receptor, and A5E3 are expressed by the majority of cells in the nerve at embryo day 15 and by essentially all cells at embryo day 18. GFAP first appears at embryo day 18; this is an intrinsically programmed developmental event which occurs in cultured Schwann cells even in the absence of serum. Postnatally, the expression of 217c(Ran-1), A5E3 and GFAP is suppressed in cells that form myelin but retained in non-myelin-forming Schwann cells. Mature myelin-forming cells nevertheless maintain the potential to express all three proteins but will only do so if removed from contact with myelinated axons. In neuron-free cultures Schwann cells express all three proteins. This work, together with our previous observations on N-CAM, shows that removal of a diverse set of surface proteins and a change in intermediate filament expression is one of the major consequences of axon to Schwann cell signalling during myelination in the rat sciatic nerve. Unlike myelin-forming cells, adult non-myelin-forming Schwann cells remain very similar to embryonic and newborn cells with respect to expression of surface proteins, in contrast to the previously established developmental changes that occur in their surface lipids.

Relation between apocrine differentiation and receptor status, prognosis and hormonal response in breast cancer

The release of a gross cystic disease fluid protein (GCDFP 15) by tumour explants grown in tissue culture was used to measure apocrine differentiation in 117 women with breast carcinoma. GCDFP 15 was detected by radioimmunoassay in the media from 90% of tumours (range 2-2100 ng/ml, mean 41). Tumour secretion of GCDFP 15 was higher in oestrogen receptor rich (over 20 fmol/mg) tumours (P less than 0.05) but did not correlate with any other prognostic factors or with survival. Response to hormonal therapy was assessable by UICC criteria in 33 women (6 partial responses, 8 stable disease, 19 progression). Responders had significantly higher tumour oestrogen receptor levels (P less than 0.005) but a lower GCDFP 15 secretion than non-responders (P less than 0.02). Apocrine differentiation in breast cancer may be a marker for oestrogen receptor positive tumours that do not respond to hormonal therapy.

Expression of the proto-oncogene fos (c-fos) by preimplantation blastocysts of the pig

Blastocyst material was obtained from 25 pigs during the period 10 to 33 days post coitum, and fixed thin sections of tissue were hybridized in situ to sense and antisense fos RNA probes synthesized using the expression vector Bluescribe M13. Indirect immunofluorescence using antisera to a synthetic peptide fragment of c-fos was used to confirm the tissue distribution of oncogene-encoded proteins, which were shown by immunoprecipitation to have Mrs of 55,000 and 40,000, which are the known Mrs of the fos gene product and an associated nucleoprotein, respectively. Northern and slot blots were used to assess the distribution of c-fos mRNA and the size of the fos transcript was found to be 2.3 kbases. C-fos was expressed in trophectoderm from blastocysts early in pregnancy but declined with increasing blastocyst development so that it was virtually absent by day 19 of gestation. High levels of fos proto-oncogene expression were, however, retained in the allantoic membranes up to at least day 19 of pregnancy. The expression of the fos protein could be prolonged in trophectodermal cells in monolayer culture by addition of conditioned medium from blastocysts cultured for 2 h, suggesting the presence of a growth-factor-like substance.

Sheep antiluteolytic interferon: cDNA sequence and analysis of mRNA levels

A cloned cDNA has been isolated by probing a sheep blastocyst cDNA library using a synthetic oligonucleotide representing the N-terminal amino acid sequence of the antiluteolytic protein, ovine trophoblast protein-1. Sequence analysis of the cDNA confirms the 70% homology between the antiluteolysin and the interferon-alpha family of proteins; however, the sequence reported here differs at several points from previously reported amino acid and cDNA sequences for the antiluteolysin. In-vitro translation of day-16 poly(A)+ RNA indicated that antiluteolysin mRNA is a major constituent of total mRNA at this stage of blastocyst development, and Northern blotting confirmed that antiluteolysin mRNA production occurred between days 13 and 22 after oestrus. This is consistent with the stage at which embryonic extracts are antiluteolytic on administration in vivo. These and other data confirm that the ovine trophoblast antiluteolysin is an interferon, and suggest that at least five isoforms of this protein may exist.

Breast cancer--which patients?

The question of which breast cancer patients to treat has been addressed by reviewing posters presented at the International Symposium on Endocrine Therapy. To date, tamoxifen therapy is the dominant type of adjuvant treatment in postmenopausal patients. The most promising results have been obtained in node-positive disease where the effect may be influenced by the receptor status, although this may depend on the cut-off level used.

The efficacy of delayed radiotherapy for locoregionally recurrent postmastectomy breast cancer

Using the results from a randomized controlled trial of patients with operable breast cancer (aimed at assessing the need for immediate postmastectomy radiotherapy in patients with no histological evidence of nodal involvement on subpectoral node biopsy), it has been possible to study the effectiveness of salvage radiotherapy for recurrences in the group of patients who had not received postoperative radiotherapy. While only 1 of 43 patients (2.3%) showed progressive disease, there was a further in-field relapse in 16 of the remaining 42 patients (38%). Four of these patients were salvaged by systemic therapy. Ultimately, therefore, there was failure of delayed radiotherapy for locoregional control in 30% of patients. (However, the overall locoregional control in both arms of the trial was identical).

Interferon sequence homology and receptor binding activity of ovine trophoblast antiluteolytic protein

Sequencing of the 40 N-terminal amino acids of the blastocyst protein responsible for blocking corpus luteum regression in early pregnancy in sheep revealed a 37% homology with human alpha-interferon; 28% of the remaining amino acid changes were conservative. 125I-Labelled human alpha-interferon bound to membrane receptors from sheep uteri with an approximate Kd of 4 x 10(-11) M; binding was inhibited by unlabelled alpha-interferon or purified blastocyst antiluteolytic protein. The blastocyst antiluteolytic protein therefore closely resembles the interferon-alpha family of antiviral proteins.

Prognostic significance of oestrogen and progestogen receptor activities in breast cancer

The prognostic significance of the tumour activities of 2 steroid receptors, those for oestrogen (ER) and for progestogen (PgR), has been studied in 372 patients with breast cancer, in whom follow-up was available for 2-6 years (median 41 months). Of 252 patients with operable disease, 75.8 per cent had ER-positive tumours and 46.4 per cent had PgR-positive tumours, though a small additional fraction (6.3 per cent) had an equivocal PgR assay result. For the 236 patients with unequivocal receptor status, the relationships between disease-free interval or overall survival and receptor activity and other factors were evaluated by univariate and multivariate analyses. The latter revealed that only tumour size, node status, menstrual status and ER status related significantly to both disease-free interval and survival, though adjuvant therapy also related to disease-free interval, and tumour grade related to survival. It is concluded that measurements of PgR activity do not add to the prognostic significance of ER status.

ACTH initiation of mammary secretion in pregnant goats is influenced by the stage of gestation and pre partum milking

Pregnant goats were treated with ACTH by intramuscular injection (1 mg/d for 2 d) at various stages of pregnancy to investigate its effect on initiation of mammary secretion. ACTH stimulated lactose secretion and increased udder volume at or after 84 d of gestation, when compared with untreated controls. Treatment with ACTH between d 109 and 127 of gestation increased circulating plasma glucose concentration, mammary blood flow and mammary uptake of glucose which returned to pre injection levels 6 d after treatment. Arterial concentrations of progesterone were not affected by ACTH but mammary progesterone uptake increased 2-fold. Pre partum milking alone stimulated mammary secretion in eight of 13 goats. Subsequent treatment with ACTH resulted in no further change in the composition of the secretion but increase in yield was maintained. ACTH stimulated mammary secretion in those goats which did not respond to pre partum milking. It was concluded that ACTH initiated mammary secretion in pregnant goats by mechanisms which interact with the stimulation of milking but which are independent of circulating progesterone levels.