Factors influencing loco-regional relapse in older breast cancer patients treated with tumour resection and tamoxifen

BACKGROUND

In breast cancer patients (≥70 years), tumour resection plus tamoxifen (T + T) has a higher loco-regional relapse (LR) rate than mastectomy. This study examines factors influencing local recurrence in these cases.

METHODS

Clinical records of 71 patients aged ≥70 years, randomised to the T + T arm of 2 randomised trials were reviewed. Cox Proportional Hazards model was used to determine the most significant variables.

RESULTS

After 15-years follow-up, LR relapse occurred in 29/71, of whom 5 had synchronous metastatic disease. Most tumours recurred in the index quadrant. Subsequently 21/24 patients with loco-regional recurrence only had salvage mastectomy. Three variables significantly predicted LR: lympho-vascular invasion (LVI) (HR [95% CI]: 11.18 [4.47, 27.95], p < 0.01), ER negative status (HR [95% CI]: 0.27 [0.10, 0.72] p = 0.01), and tumour necrosis (HR [95% CI]: 2.65 [1.10, 6.37], p = 0.03). Final margin status was not associated with LR.

CONCLUSIONS

Tumour resection + Tamoxifen in older patients results in long-term local control in the majority with most loco-regional failures being salvageable. Risk factors for LR are lympho-vascular invasion, ER status and tumour necrosis. Negative tumour excision margins did not significantly change local outcome in the absence of radiotherapy. In these older patients LVI significantly reduced survival time.

Prognosis of synchronous bilateral breast cancer

Background

The prognosis of patients with synchronous bilateral breast cancer (SBBC) is usually based on the tumour with the worst pathological features. There is little evidence in the literature for this assumption, potentially impairing reasoned decisions on optimal adjuvant therapy.

Methods

This was a case–control study in which 68 women with SBBC were matched with 128 women with unilateral breast cancer. Both the GuysRisk prognostic model and the Nottingham Prognostic Index were used to determine the bilateral tumour with the poorer prognosis. Controls were matched for age, menopausal status, date of diagnosis, histological type and grade, and oestrogen receptor and axillary node status.

Results

Both prognostic models indicated the same side tumour with the worst prognosis. Kaplan–Meier survival curves for both disease-free and overall survival showed no significant difference in outcome between the two groups.

Conclusion

Prognosis was determined by the tumour with the worst prognosis, with no additional worsening of outcome incurred from the second tumour.

The impact of the Occupation of Guernsey 1940-1945 on breast cancer risk factors and incidence

To examine the impact of the German Occupation of Guernsey (1940-1945) on breast cancer risk factors and incidence. Under study were 1019 women who stayed, or whose mothers had stayed, in Guernsey, and 1358 women evacuated or born to evacuated mothers. Amongst those born 1926-1934 who remained in Guernsey, the secular trend of earlier menarche disappeared: menarche was delayed by 12 months for those born in 1930. By March 2006, 97 breast cancers had been diagnosed, 37 in the occupied group. Unusually, higher age at menarche appeared to be associated with increased risk of breast cancer (>or=14 years vs. <or=13 years: HR = 1.52, 95% CI = 0.80-2.92). Separate analyses by birth cohort revealed a non-significantly higher incidence in the subgroup born from 1926 to 1934 (HR = 1.30, 95% CI = 0.62-2.76). Delay in menarche among women remaining in Guernsey during the Occupation, rather than being protective, was associated with an increased risk of breast cancer.

Hormone dependency of breast tumours developing in the Guernsey Cohort study

The aim of this study was to determine whether endogenous estradiol levels in postmenopausal women helped determine the estrogen receptor status of subsequent breast cancers. Within the Guernsey Cohort study of 6127 women, 140 have been diagnosed with breast cancer of whom 59 had estradiol assays performed and ER status available. Estradiol levels in serum and urine were measured by radioimmunoassay and ER status of tumours by immunohistochemistry. Of the individuals in the highest tertile of serum estradiol 35% had ER+ve tumours compared with 27% in the lowest tertile. In terms of 16hydroxyestrone excretion the proportions ER+ve tumours were 22% in the lowest tertile and 38% in the highest tertile. This suggests that endogenous estrogen levels do impact on the phenotype of subsequent breast cancer.

Smoking and prognosis in women with breast cancer

The hypothesis was that smokers might have more aggressive types of breast cancer because of either delayed diagnosis or higher grade and hence have a worse prognosis. A cohort of breast cancer patients completed a lifestyle questionnaire at the time of diagnosis, including whether they were current smokers, ex-smokers or lifelong non-smokers. Ex-smokers were asked when they had stopped. The participants were 166 women with stage I/II invasive breast cancer diagnosed between October 1984 and March 1987. Participants were divided into three groups: current smokers, ex-smokers and non-smokers. Survival curves were produced by using Cox proportional hazards analysis, with outcome variables for overall and breast cancer-specific survival together with distant relapse-free survival. Smoking was the third most important predictor of distant relapse-free, breast cancer-specific and overall survival after stage and age at diagnosis. These results suggest that smokers are not only more likely to die of other diseases, but also have a higher mortality from breast cancer, compared with those with the disease who have never smoked. The best prognosis, however, was found in those who had given up smoking.

A prospective study of serum insulin-like growth factor-I (IGF-I), IGF-II, IGF-binding protein-3 and breast cancer risk

The associations between serum concentrations of insulin-like growth factor-I (IGF-I), IGF-II and IGF-binding proteins (IGFBP)-3 and risk of breast cancer were investigated in a nested case–control study involving 117 cases (70 premenopausal and 47 postmenopausal at blood collection) and 350 matched controls within a cohort of women from the island of Guernsey, UK. Women using exogenous hormones at the time of blood collection were excluded. Premenopausal women in the top vs bottom third of serum IGF-I concentration had a nonsignificantly increased risk for breast cancer after adjustment for IGFBP-3 (odds ratio (OR) 1.71; 95% confidence interval (CI): 0.74–3.95; test for linear trend, P=0.21). Serum IGFBP-3 was associated with a reduction in risk in premenopausal women after adjustment for IGF-I (top third vs the bottom third: OR 0.49; 95% CI: 0.21–1.12, P for trend=0.07). Neither IGF-I nor IGFBP-3 was associated with risk in postmenopausal women and serum IGF-II concentration was not associated with risk in pre- or postmenopausal women. These data are compatible with the hypothesis that premenopausal women with a relatively high circulating concentration of IGF-I and low IGFBP-3 are at an increased risk of developing breast cancer.

Body mass index, serum sex hormones, and breast cancer risk in postmenopausal women

BACKGROUND

Obesity is associated with increased breast cancer risk among postmenopausal women. We examined whether this association could be explained by the relationship of body mass index (BMI) with serum sex hormone concentrations.

METHODS

We analyzed individual data from eight prospective studies of postmenopausal women. Data on BMI and prediagnostic estradiol levels were available for 624 case subjects and 1669 control subjects; data on the other sex hormones were available for fewer subjects. The relative risks (RRs) with 95% confidence intervals (CIs) of breast cancer associated with increasing BMI were estimated by conditional logistic regression on case-control sets, matched within each study for age and recruitment date, and adjusted for parity. All statistical tests were two-sided.

RESULTS

Breast cancer risk increased with increasing BMI (P(trend) =.002), and this increase in RR was substantially reduced by adjustment for serum estrogen concentrations. Adjusting for free estradiol reduced the RR for breast cancer associated with a 5 kg/m2 increase in BMI from 1.19 (95% CI = 1.05 to 1.34) to 1.02 (95% CI = 0.89 to 1.17). The increased risk was also substantially reduced after adjusting for other estrogens (total estradiol, non-sex hormone-binding globulin-bound estradiol, estrone, and estrone sulfate), and moderately reduced after adjusting for sex hormone-binding globulin, whereas adjustment for the androgens (androstenedione, dehydroepiandrosterone, dehydroepiandrosterone sulfate, and testosterone) had little effect on the excess risk.

CONCLUSION

The results are compatible with the hypothesis that the increase in breast cancer risk with increasing BMI among postmenopausal women is largely the result of the associated increase in estrogens, particularly bioavailable estradiol.

A prospective study of serum bile acid concentrations and colorectal cancer risk in post-menopausal women on the island of Guernsey

Secondary bile acids produced by the action of the colonic microflora may increase risk of colorectal cancer. Serum bile acid concentrations reflect the faecal bile acid profile and may be of value as biomarkers of risk of colorectal cancer. In a pilot investigation we examined: (i) the reproducibility of measurements of serum bile acids in two blood samples collected several years apart; and (ii) the hypothesis that relatively high levels of secondary bile acids, particularly deoxycholic acid, would be positively associated with an increased risk of colorectal cancer in a prospective study of 3680 women in Guernsey. There was poor reproducibility between repeat measurements of absolute serum concentrations of bile acids, but there was moderately good reproducibility for the ratios of serum concentrations of deoxycholic/cholic acid, lithocholic/chenodeoxycholic and secondary/primary bile acid concentrations (duplicate blood samples were available for 30 women). There were no significant differences in ratios of serum secondary to primary bile acids or in absolute concentrations of bile acids between the 46 women who developed colorectal cancer and their matched controls, although there was a suggestion that an increased risk was associated with a high ratio of deoxycholic/cholic acid (relative risk in top third compared to lower third=3.92 (95% CI 0.91-17.0, P for trend=0.096). These findings suggest that the ratios of serum bile acid concentrations are sufficiently reproducible for epidemiological studies, but that a larger study than our own is needed to adequately test the hypothesis of their relation to cancer risk.

Urinary androgens and breast cancer risk: results from a long-term prospective study based in Guernsey

Between 1961 and 1967 a cohort of over 5000 women volunteered for a prospective study to determine the relationship between the urinary androgen metabolites, androsterone (A) and aetiocholanolone (E), and risk of breast cancer. During the first 10 years of the study the concentration of urinary A and E was determined in 1887 of the urine specimens. In 1971 we reported that subnormal amounts of urinary A and E were associated with a significantly increased risk of breast cancer. The cohort has been followed regularly during the 37 years since inception of the study and, by May 1998, 248 women had been diagnosed with breast cancer. Urinary androgen metabolites had been measured in 116 of these cases. Analysis of these data confirmed that women diagnosed in the first decade of the study were more likely to have low levels of urinary androgen metabolites. In the following decades, however, those who developed breast cancer were more likely to have manifested an increased A and E excretion. The reversal in the relationship between androgen metabolite excretion and risk suggests that age, or probably more importantly, menopausal status at diagnosis is an important modifying factor. Dichotomizing at age 50 it was found that in the younger age group (predominantly premenopausal) the rate ratios in the lowest tertile of A or E excretion were two- to threefold greater than for those in the highest tertile (chi2(1) = 3.57; P = 0.06: chi2(1) = 4.70; P = 0.03 for A and E respectively). In contrast, in the older age group comprising predominantly post-menopausal women, the rate ratios associated with the lowest tertile of A or E were half that of those in the highest tertile (chi2(1) = 4.10; P = 0.04; chi2(1) = 8.72; P = 0.003 for A and E respectively). This suggests that there may be different endocrine promotional factors for pre-and post-menopausal breast cancer. Hormonal risk factors may vary during the lifetime of an individual woman and this may have profound consequences for prevention strategies.

Do urinary oestrogen metabolites predict breast cancer? Guernsey III cohort follow-up

This is the first prospective study of urinary measures of the two major competing pathways of oestrogen metabolism, 16alpha-hydroxyoestrone (16alpha-OHE1) and 2-hydroxyoestrone (2-OHE1), in relation to incident breast cancer risk. Experimental and case-control study results suggest that metabolism favouring the more oestrogenic 16alpha-OHE1 pathway may be linked to higher breast cancer risk. Women aged 35 and older from Guernsey (n = 5104) were surveyed in 1977-85 and have been continuously monitored for breast cancer and mortality up to the present (Guernsey III, Imperial Cancer Research Fund). Incident cases of breast cancer were matched to three control subjects for comparison of urinary oestrogen metabolite levels measured by enzyme immunoassay (EIA) in spot urine samples collected at baseline and stored frozen for up to 19 years. Consistent with case-control study results, post-menopausal (but not premenopausal) women at baseline who went on to develop breast cancer showed about a 15% lower 2:16alpha-OHE1 ratio than matched control subjects. Further, subjects with metabolite ratios in the highest tertile of 2:16alpha-OHE1 had about a 30% lower risk than women with ratios in the lowest two-thirds, although results were not statistically significant (OR = 0.71, 95% CI = 0.29-1.75). It is of potential importance that, in contrast to most risk factors for breast cancer, such as late age at first birth, oestrogen metabolism appears to be modifiable via diet and exercise, offering women the possibility of lowering breast cancer risk through non-pharmacological measures, although this remains to be tested.

Pregnancy and menstrual hormone levels in mothers of twins compared to mothers of singletons

This study examined the hormonal differences between premenopausal mothers of twins and other premenopausal parous women during and after pregnancy. Serum concentrations of oestradiol and testosterone between 6 and 20 weeks of gestation were measured for 11 mothers of twins and 115 mothers of singletons selected from the controls in a case-control study of cryptorchidism. Serum concentrations of oestradiol, progesterone, testosterone, follicle stimulating hormone and sex hormone-binding globulin during the menstrual cycle were measured for 25 mothers of twins and 38 mothers of singletons recruited as a part of a prospective study of breast cancer risk. During pregnancy, women carrying twins had a 58% higher geometric mean oestradiol concentration (p = 0.02) and a 50% higher testosterone concentration (p = 0.03) than women carrying singletons. Women who had previously had twins demonstrated a 49% higher mean concentration of follicle stimulating hormone (p = 0.02) and a 42% higher concentration of sex hormone-binding globulin (p = 0.03) than women who had singletons only, but no significant differences in oestradiol, progesterone and testosterone concentrations. The increased concentrations of follicle stimulating hormone during the menstrual cycle of mothers of twins, which has also been reported in two previous studies suggests that follicle stimulating hormone level may be an important determinant of dizygotic twinning.

Breast cancer risk is positively associated with height

Inter- and intra-national epidemiological studies point to an association between socio-economic status and breast cancer risk. Although there is no direct evidence, the most favoured reason for this relationship is nutritional. An enhanced dietary status, especially during childhood, would be reflected in adult body build. It is, therefore, surprising that there is uncertainty in the literature concerning the association between height and breast cancer risk. In reviewing the publications on this topic it became apparent that case-control studies which found no association between height and risk tended to use self-reported height. In contrast reports claiming a significant, and positive, correlation tended to use heights which were measured by the investigators. In a prospective study we found in a cohort of 2731 ostensibly normal women that, although there was a highly significant linear correlation between self-reported and measured height, the shortest women over-estimated their height whilst the tallest volunteers under-estimated theirs. The significance of crude relative risk and height in this cohort was markedly attenuated when self-reported height was used compared to measured height. Such a systematic error could have a profound effect on the conclusions of studies in this field which relied on self-reporting and could explain the conflicting reports in the literature.

A prospective study of endogenous serum hormone concentrations and breast cancer risk in premenopausal women on the island of Guernsey

The associations between serum concentrations of oestradiol, progesterone, testosterone and sex hormone-binding globulin (SHBG) and risk of breast cancer in premenopausal women were investigated in a prospective study of breast cancer on the island of Guernsey. Sixty-two women diagnosed with breast cancer an average of 8 years subsequent to blood collection were matched for day of menstrual cycle, age and year of blood collection with 182 control subjects. Cases had a 12% higher mean oestradiol concentration over the whole menstrual cycle (P = 0.17) with a large difference at mid-cycle (75% higher, P = 0.04). Differences between cases and control subjects in progesterone (luteal phase), testosterone and SHBG were small and not statistically significant: luteal phase progesterone 9% lower in cases, P = 0.64; testosterone 4% higher, P = 0.57; SHBG 8% higher, P = 0.24. The small difference in oestradiol concentration could be aetiologically important, but larger prospective studies are needed.

A prospective study of endogenous serum hormone concentrations and breast cancer risk in post-menopausal women on the island of Guernsey

The associations between serum concentrations of oestradiol, testosterone and sex hormone-binding globulin (SHBG) and risk of breast cancer in post-menopausal women were investigated in a prospective study on the island of Guernsey. Sixty-one women who developed breast cancer an average of 7.8 years after blood collection were matched for age, year of blood collection and number of years post-menopausal with 179 control subjects. Women using exogenous hormones at the time of blood collection were excluded from the study. Women who subsequently developed breast cancer had a 29% higher geometric mean oestradiol concentration than control women (P = 0.004). The odds ratio for breast cancer in the top third compared with the lowest third of the oestradiol concentration distribution was 5.03 (95% confidence interval 2.02-12.49, P for trend < 0.001). Adjusting for testosterone and SHBG concentrations did not substantially alter the odds ratio for oestradiol. Although testosterone and SHBG concentrations were associated with breast cancer risk, the concentrations of these hormones were correlated with those of oestradiol; the associations were not statistically significant after adjusting for oestradiol concentration. These data provide evidence that serum oestradiol concentrations in post-menopausal women may have a substantial effect on breast cancer risk.

Cigarette smoking and urinary oestrogen excretion in premenopausal and post-menopausal women

Cigarette smoking is associated with a reduction in the risk for endometrial cancer in post-menopausal women and it has been suggested that this is because smoking has an anti-oestrogenic effect. To investigate this, concentrations of oestrone, oestradiol and oestriol were measured in 24 h urine samples from 167 premenopausal women (53 smokers, 114 non-smokers) and 200 post-menopausal women (54 smokers, 146 non-smokers). Among premenopausal women there were no significant differences in oestrogen excretion between smokers and non-smokers. Among post-menopausal women, geometric mean excretion rates for oestrone and oestradiol did not differ significantly between groups, but oestriol excretion was 19% lower (95% confidence interval -34% to -1%) in smokers than in non-smokers. This may partly explain the reduced risk for endometrial cancer among post-menopausal smokers.

Breast cancer and hormonal contraceptives: further results. Collaborative Group on Hormonal Factors in Breast Cancer

The Collaborative Group on Hormonal Factors in Breast Cancer has brought together and reanalysed the worldwide epidemiological evidence on breast cancer risk and use of hormonal contraceptives. Original data from 54 studies, representing about 90% of the information available on the topic, were collected, checked and analysed centrally. The 54 studies were performed in 26 countries and include a total of 53,297 women with breast cancer and 100,239 women without breast cancer. The studies were varied in their design, setting and timing. Most information came from case-control studies with controls chosen from the general population; most women resided in Europe or North America and most cancers were diagnosed during the 1980s. Overall 41% of the women with breast cancer and 40% of the women without breast cancer had used oral contraceptives at some time; the median age at first use was 26 years, the median duration of use was 3 years, the median year of first use was 1968, the median time since first use was 16 years, and the median time since last use was 9 years. The main findings, summarised elsewhere, are that there is a small increase in the risk of having breast cancer diagnosed in current users of combined oral contraceptives and in women who had stopped use in the past 10 years but that there is no evidence of an increase in the risk more than 10 years after stopping use. In addition, the cancers diagnosed in women who had used oral contraceptives tended to be less advanced clinically than the cancers diagnosed in women who had not used them. Despite the large number of possibilities investigated, few factors appeared to modify the main findings either in recent or in past users. For recent users who began use before age 20 the relative risks are higher than for recent users who began at older ages. For women whose use of oral contraceptives ceased more than 10 years before there was some suggestion of a reduction in breast cancer risk in certain subgroups, with a deficit of tumors that had spread beyond the breast, especially among women who had used preparations containing the highest doses of oestrogen and progestogen. These findings are unexpected and need to be confirmed. Although these data represent most of the epidemiological evidence on the topic to date, there is still insufficient information to comment reliably about the effects of specific types of oestrogen or of progestogen. What evidence there is suggests, however, no major differences in the effects for specific types of oestrogen or of progestogen and that the pattern of risk associated with use of hormonal contraceptives containing progestogens alone may be similar to that observed for preparations containing both oestrogens and progestogens. On the basis of these results, there is little difference between women who have and have not used combined oral contraceptives in terms of the estimated cumulative number of breast cancers diagnosed during the period from starting use up to 20 years after stopping. The cancers diagnosed in women who have used oral contraceptives are, however, less advanced clinically than the cancers diagnosed in never users. Further research is needed to establish whether the associations described here are due to earlier diagnosis of breast cancer in women who have used oral contraceptives, to the biological effects of the hormonal contraceptives or to a combination of both. Little information is as yet available about the effects on breast cancer risk of oral contraceptive use that ceased more than 20 years before and as such data accumulate it will be necessary to re-examine the worldwide evidence.

A prospective study of urinary oestrogen excretion and breast cancer risk

To test the hypothesis that high levels of endogenous oestrogens increase the risk for developing breast cancer, concentrations of oestrone, oestradiol and oestriol were measured in 24 h urine samples from 1000 women participants in a prospective study of breast cancer on the island of Guernsey. Sixty-nine subjects were diagnosed with breast cancer subsequent to urine collection. Among women who were premenopausal at the time of urine collection, cases excreted less oestrogen than controls; the odds ratios (95% CI) for breast cancer in the middle and upper thirds of the distribution of oestrogen excretion, in comparison with the lower third (reference group, assigned odds ratio = 1.0), were 0.5(0.2-1.2) and 0.4(0.2-1.1) respectively for oestrone, 0.8(0.4-1.8 and 0.4(0.2-1.1) for oestradiol, 0.7(0.3-1.6) and 0.7(0.3-1.6) for oestriol and 0.9(0.4-2.0) and 0.5(0.2-1.3) for total oestrogens. Among women who were post-menopausal at the time of urine collection, the trend was in the opposite direction, with an increase in risk associated with increased oestrogen excretion; the odds ratios were 0.9(0.3-2.2) and 1.1(0.5-2.8) for oestrone, 0.8(0.3-2.3) and 1.9(0.8-4.6) for oestradiol, 1.5(0.6-3.9) and 1.8(0.7-4.6) for oestriol and 0.9(0.4-2.6) and 1.9(0.7-4.7) for total oestrogens. The trends of increasing risk with increasing oestrogen excretion among post-menopausal women were statistically significant for oestradiol (P = 0.022) and for total oestrogens (P = 0.016). We conclude that high levels of endogenous oestrogens in post-menopausal women are associated with increased breast cancer risk, but that the relationship of oestrogens in premenopausal women with risk is unclear.

Serum prolactin levels and their relationship to survival in women with operable breast cancer

The prognostic value of serum prolactin levels was assessed in a sequential series of 739 patients who were initially treated at Guy's Hospital, London, between 1975 and 1980. Prolactin was measured in 472 patients 1 day before (Hpr1) and in 457 patients 10 days after (Hpr2) mastectomy. Follow-up of the patients was up to August 1992 giving 6139 women-years with a median follow-up time of 11.5 years (13.7 for patients still living and 5.1 for those dead). The association between the three prolactin variables and reproductive and clinical factors was examined before assessing the prognostic value of prolactin levels in terms of overall, disease-specific and disease-free survival. Multivariate survival models were used in order to adjust for the effect of other prognostic variables. These were found to be: tumour size, degree of nodal involvement, tumour grade and age at diagnosis. The results showed that high Hpr2 or high postoperative increase in prolactin (i.e. Hpr2-Hpr1) were significantly related to shorter disease-specific survival (p = 0.04 and 0.01, respectively) in postmenopausal women. In addition there was some indication, which did not attain formal significance, for this association to occur for disease-free survival. Thus the rise in blood prolactin levels after surgery may be a weak indicator of poor prognosis of breast cancer in postmenopausal women.

Bone density of normal women in relation to endogenous and exogenous oestrogens

To evaluate the relationship between duration of hormone replacement therapy (HRT) and forearm bone density, a population-based study has been conducted of 4638 women comparing bone density of 1079 women who had taken HRT for varying times with those who had never taken it. Forearm bone mineral content (BMC) was measured by single photon absorptiometry. Additionally, free oestradiol and sex hormone binding globulin levels were measured in women with high and low bone mineral content. There were no detectable differences in BMC in those who took HRT for up to 24 months compared with those who did not. Thereafter there were significant positive regression coefficients for duration periods of 2 to 5 yr (beta = 0.77, P = 0.04 and beta = 1.76, P = 0.03) and more than 5 yr (beta = 1.66, P < 0.0005 and beta = 1.87, P = 0.009) in post-menopausal and oophorectomized women. The major determinants of BMC were height, and in post-menopausal or oophorectomized women, age. Weight and parity also had additional explanatory power for pre- and post-menopausal women. Those who were in the highest quintile of BMC but had never taken HRT showed significantly elevated percentage free oestradiol compared with those in the lowest quintile. Thus HRT is osteoprotective if taken after the menopause for more than 24 months.

The association of height, weight, menstrual and reproductive events with breast cancer: results from two prospective studies on the island of Guernsey (United Kingdom)

The association with breast cancer of menstrual and reproductive events, family history of breast cancer, and body size have been studied on two cohorts of 6,706 volunteers on the island of Guernsey (United Kingdom), 168 of whom had breast cancer detected during follow-up. The median follow-up time of the non-cases was 21 years in the first study and 10 years in the second. A time-dependent Cox regression model was fitted to the data with age as the time-dependent variable in order to represent the effect of changing menopausal status. Other variables examined in the model were age at menarche, parity, age at first birth, family history of breast cancer, height, weight (both directly measured), relative weight (weight [kg]/height[m]), and Quetelet's body mass index (weight[kg]/height[m]2). Interactions between age and all other covariates also were examined. Family history was found to be the most important risk factor for women aged less than 51 years (relative risk [RR] = 3.5, 95 percent confidence interval [CI] = 2.0-6.0), and intervals between menarche and first birth longer than 14 years were found to increase significantly the risk of breast cancer in women older than 61 years (RR = 2.4, CI = 1.3-4.4). Height was the only indicator of body size which was associated significantly with risk of breast cancer, the estimated regression coefficient indicating an increase in risk of about 70 percent for women on the 90th centile of height relative to those on the 10th centile. A survey of the literature showed that the association between risk of breast cancer and height was found in those studies which used direct measurements of height but not in others which used self-reported values.

Copper in human mammary carcinogenesis: a case-cohort study

In 1968-1975, a cohort of 5,100 ostensibly healthy women was established on the island of Guernsey, England, for investigation of the influence of hormonal factors on breast cancer. At the women's entry into the study, blood samples were drawn from each participant, and each woman completed a questionnaire that provided information on established risk indicators in human mammary carcinogenesis. Plasma copper levels were measured in 46 breast cancer cases diagnosed an average of 11 years (standard deviation (SD), 4) after entry into the study cohort and in an age-stratified random sample of 138 women drawn from the total initial cohort at risk. Plasma copper levels were 1.31 mg/liter (SD, 0.37) in the cases and 1.26 mg/liter (SD, 0.36) in the controls; the 95% confidence interval for the overall difference was -0.07 to 0.17. A U-shaped relation between premorbid plasma copper levels and the risk of developing breast cancer was seen. Adjusted odds ratios for breast cancer were 1.8, 1.0, 1.6, and 3.2, respectively, in the four quartiles of the copper distribution. No major changes in the risk estimates were observed when statistical evaluation was restricted to cases diagnosed more than 10 years after collection of blood samples.