Abstract
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.
Highlights
Serum progesterone and testosterone concentrations were measured for all these women, oestradiol concentrations were measured for all but one case, and sex hormone-binding globulin (SHBG) concentrations were available for all but nine cases and ten control subjects
The samples were thawed on the day of the progesterone assay and aliquots removed and refrozen for the oestradiol, testosterone and folliclestimulating hormone (FSH) assays to be done at a later date
Odds ratios for breast cancer in relation to concentrations of oestradiol, progesterone (0-15 days before menstrual cycle), testosterone and SHBG were calculated for matched case-control sets using conditional logistic regression and the significance of linear trends was judged by likelihood ratio tests
Summary
A total of 6127 women aged 34 years and above who lived on the island of Guernsey were recruited between 1977 and 1990. Follow-up for the diagnosis of breast cancer was through pathology reports (all dealt with by one pathology laboratory), general practitioners, Guernsey death certificates and the Wessex Cancer Registry. This registry covers Southampton where some patients from Guernsey are referred for hospital treatment. The serum concentration of folliclestimulating hormone (FSH) was measured for all but three cases and one control subject to evaluate an individual's true premenopausal status. Serum progesterone and testosterone concentrations were measured for all these women, oestradiol concentrations were measured for all but one case, and SHBG concentrations were available for all but nine cases and ten control subjects. Five cases participated in both recruitment phases and donated two blood samples; the blood samples donated at the first interview have been used in these analyses
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