Risk factors for breast cancer by oestrogen receptor status: a population-based case-control study.

Data from a population-based case-control study conducted in Adelaide, South Australia, and involving 451 case-control pairs, were analysed to determine whether the associations of menstrual, reproductive, dietary and other factors with risk of breast cancer differed by oestrogen receptor (ER) status. Data on ER status were available for 380 cases. The proportion of tumours which were ER+ increased with age, and there was a higher proportion of ER+ tumours in post-menopausal than in premenopausal women. Both oral contraceptive use (P = 0.055) and cigarette smoking (P = 0.047) were associated with increased (unadjusted) risk of ER- cancer, while having little association with risk of ER+ cancer. Most dietary factors had little association with risk of either cancer type, the main exception being the reduction in risk of ER- breast cancer with increasing beta-carotene intake (P for trend = 0.017). In general, however, links with the factors examined were not strong enough to suggest different causal pathways for ER- and ER+ breast cancer.

Relationship between ploidy and steroid hormone receptors in primary invasive breast cancer.

The relationship between ploidy, as measured by flow cytometry, and the presence of oestrogen and progesterone receptors was investigated in 145 primary invasive breast cancers. The tumours were considered as an integral group, and as subgroups of lobular and ductal carcinomas. An association was found between the presence of aneuploid stemlines and an absence of oestrogen receptors (ER), for the total tumour population (P less than 0.02), and for the ductal carcinoma group (P less than 0.05). An association between aneuploidy and an absence of progesterone receptors (PR) was observed for the total tumour group (P less than 0.05). Evaluation of a combined oestrogen and progesterone receptor status indicated that the association between aneuploidy and an absence of both receptors was highly significant. The probability of such an association was P less than 0.001 for the total tumour population, and P less than 0.01 for the ductal tumour group. Assessment of progesterone receptor expression by breast cancers containing oestrogen receptors indicated that aneuploid tumours were as likely to express PR as were diploid tumours. Hence, the biological activity of oestrogen receptors appears unmodified by the presence of aneuploid nuclei.

Specific binding of oestradiol to guinea-pig prostate cytosol and nuclear fractions.

A high affinity (Kd approximately 0.15 nM), saturable oestradiol binding site, which is specific for natural and synthetic oestrogens has been identified in guinea-pig prostate cytosol fractions. The binding site is protein in nature (heat- and protease-sensitive) and has a sedimentation coefficient of approx. 8S on glycerol gradients. A high affinity (Kd approximately 0.16 nM), saturable oestradiol binding site was also identified in salt-extracted (0.5 M KC1) nuclear fractions. The optimum incubation conditions for measuring the cytosolic and nuclear oestradiol binding sites were determined to be 20 h at 4 degrees C. Saturation analysis studies revealed that following oestrogen treatment of intact animals, approx. 80% of the specific oestradiol binding sites in prostatic cytosol fractions were transferred into the nucleus. The presence of a specific oestradiol binding protein with characteristics of an oestrogen receptor in the guinea-pig prostate, is consistent with oestrogen having biological activity in this tissue. In view of the abundance of stroma in the prostate of this species, and the consistent finding that the stroma of male accessory sex tissues is oestrogen sensitive, the guinea-pig may be an appropriate experimental animal for further investigating the role of oestrogen in the growth and development of the prostate.

The search for occult metastases in breast cancer: does it add to established staging methods?

In 1974 a project was initiated in which patients with apparently operable breast carcinoma underwent special investigations in an attempt to identify occult metastasis in bone and liver. One hundred and seventy-two patients have been followed for two years or more and their axillary node histological findings reviewed. From analysis of these patients the following conclusions may be drawn. Careful clinical assessment, especially measurement of the primary tumour and palpation of the axillary nodes, remains a fundamental guide to the likelihood of early recurrence. Histological confirmation of node metastases is as valuable as clinical assessment, but is not superior unless other features of node histology are considered. Micrometastases do not increase the probability of early recurrence except in comparison with a group whose nodes lack both metastases and other unfavourable features. The majority of special investigations do not have additional predictive value, though a bone scan is useful in the small number (less than 10%) in whom it is positive.

Preoperative assessment and staging of breast cancer: preliminary communication.

A prospective study has been carried out in 172 women to determine the sensitivity of methods to detect occult metastatic disease in the skeleton and liver. With the exception of bone scintiscans, the results of these tests bore little relationship to recurrence rates. On the other hand, knowledge of the histopathology of the lower axillary (pectoral) lymph nodes is of value in this respect.A follow-up study is also reported which confirms the importance of accurate measurements of the primary tumour clinical node status and oestrogen receptor contact of the tumour in defining prognostic groups. Elastosis (estimated in 165 tumours) did not prove to be a useful prognostic index.

Inter-site variation of oestrogen receptors in human breast cancers.

When large human breast cancers were assayed for oestrogen receptors at multiple sites, 5-fold differences were found in the numbers of oestrogen receptors, between the site within a tumour. This may result from variations in the cell:stroma ratio from site to site. Such differences could be significant when receptor levels in the tumour are low (less than 50 fmol oestradiol bound mg cytosol protein) since the classification distinction between hormone-sensitive and hormone-insensitive breast cancers is based upon numbers of oestrogen receptors detected by the assay. This problem might be remedied by assessment of the cell:stroma ratio in all assayed tumours, and by the combination of the cytoplasmic oestrogen-receptor assay with other hormone-receptor assays.

PIP: Both human mammary gland tumors and human myometrium were used to examine the inherent variability of the estrogen-receptor assay of cytosol fractions derived from the tumors and to report results of assays on multiple sites within large breast cancers. Cytosol and tissue assays of human myometrium showed only small variability in binding site numbers between assays of the same fractions. However, estrogen-receptor assays performed on multiple sites in large receptor-positive mammary gland tumors showed marked intersite variation within each tumor, with up to a 4-fold difference (e.g., a range of 175-523 sites in 1 tumor). This difference may result from variation in the cell:stroma ratio from site to site. In the majority of tumors (5), this variability did not affect classification of receptor status, but in 2 tumors, this variation was significant where receptor levels in the tumors were low ( 50 fmol estradiol bound). Resolution of this assay problem may be achieved by combining: 1) assessment of cell:stroma ratio of the assayed site; 2) estimation of nuclear receptors for estrogen; and 3) estimation of progesterone receptors.

Effect of snap freezing, dithiothreitol and storage on estimations of estrogen receptor sites.

Estrogen receptor assays were performed on human myometrium in order to determine optimal conditions for certain steps of the assay. The findings indicate that: (1) tissue should be snap-frozen in liquid nitrogen prior to assay, (2) dithiothreitol does not increase measurable binding site numbers, (3) estrogen receptors in the cytosol fraction are unstable and should be stored in excess of 1 day; (4) if storage prior to receptor assay is unavoidable, tissue should be stored at -20 degrees C or -70 degrees C for no longer than 1 week.

Adjuvant systemic therapy in "early" breast cancer.

"Early" breast cancer is a systemic disease in the majority of cases. Progress has been and is being made toward the determination of those women at risk of recurrence. Attractive as it seems, the value of systemic adjuvant therapy, given at the time of minimal tumour load i.e., after mastectomy, is not proven. Therefore, for the average case it is better to treat the cancer locally and to observe and leave further evaluation of systemic therapy to those centres which are able to conduct controlled, randomized trails.

Lymph-node biopsy during simple mastectomy.

The distribution of pectoral (external mammary) nodes identified during the operation and removed with the axillary tail of the breast was studied in 45 patients treated by simple (total) mastectomy. Up to 13 nodes may lie within the axillary tail, and these are continuous with the pectoral nodes. Lymph-nodes were identified in 90 percent of patients treated by simple (total) mastectomy without dissection of the axilla.