Elevated levels of prolactin in nulliparous women

Age-related changes in the female hormonal environment during reproductive life

Previous studies have indicated that serum levels of follicle-stimulating hormone rise with age during the female reproductive life, but the effect on other hormones is not clear. We studied the effects of age, independent of pregnancy, by comparing serum hormone levels in two groups of nulliparous, premenopausal women aged 18 to 23 and 29 to 40 years. We found that increased age during reproductive life is accompanied by a significant rise in both basal and stimulated serum follicle-stimulating hormone levels. This was accompanied by an increase in the serum level of estradiol-17 beta and the urine levels of estradiol-17 beta and 17 beta-estradiol-17-glucosiduronate. The serum level of estrone sulfate decreased with age. Serum and urine levels of other estrogens were unchanged. The basal and stimulated levels of luteinizing hormone were also unchanged. There was a significant decrease in basal and stimulated serum prolactin levels. Serum levels of dehydroepiandrosterone and dehydroepiandrosterone sulfate decreased with age, but serum testosterone was unchanged. It is concluded that significant age-related changes in the female hormonal environment occur during the reproductive years.

Long-term effect of a first pregnancy on the secretion of prolactin

An early first pregnancy is known to protect against subsequent breast cancer. We speculated that this effect may be mediated by a long-term depression of prolactin secretion after pregnancy. We therefore measured basal and post-stimulation serum levels of prolactin, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) in two groups--15 women 18 to 23 years of age and 9 women 29 to 40--before and after a first full-term pregnancy, and in 40 appropriate nulliparous controls. We observed no significant change in basal levels of serum LH or FSH or in the levels stimulated by gonadotropin-releasing hormone in any group. A significant decrease was seen, however, in basal and perphenazine-stimulated levels of prolactin after pregnancy in both the younger and older first-pregnancy groups but not in the controls. In a separate cross-sectional study, we compared basal serum prolactin levels in 29 parous and 19 nulliparous women of similar age. The serum prolactin levels were significantly lower in the parous group but were not related to the number of pregnancies (one to three) or the time elapsed (12 to 150 months) since the last delivery. We conclude that a first pregnancy leads to a long-term decrease in serum prolactin secretion, lasting at least 12 to 13 years.

Plasma hormones in parous, nulliparous and postmenopausal Japanese women

Mechanisms associated with protection against breast cancer in parous women with an early pregnancy are unknown. Elevated or deficient steroid hormone levels or dysfunctional release of prolactin have been postulated. Since these effects have not been reported in low-risk Japanese women, we have compared the hormone levels in age-weight-risk factor matched premenopausal nulliparous and parous Japanese women with established menstrual regularity. Higher luteal phase plasma levels of estradiol and estrone occurred in parous versus nulliparous women, while plasma prolactin and androgen levels were unaltered. It is suggested that the higher estrogen and lower LH levels, as in short versus long menstrual cycles, results from failure of the opioid GnRH. LH axis to return to pre-pregnancy levels.

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

Serum prolactin (HPr) has been measured in 459 patients 1 day before (HPr-1) and in 433 patients 10 days after (HPr-2) treatment. These came from an unselected sequence of 739 patients with operable breast cancer who had been referred to Guy's Hospital over a period of 5 yr. In addition HPr was measured in 100, or more, women at 3, 6 or 12 months after mastectomy. The median levels of either HPr-1 or HPr-2 were higher in pre-menopausal compared with postmenopausal patients (P = 0.03 and 0.06, respectively). Mastectomy was associated with increased serum HPr in both pre- and post-menopausal patients (P less than 0.001 in both cases). Average levels at 3 months, or after, were similar to those found before treatment. Nulliparous women had a higher median amount of HPr-1 than parous which was significant in premenopausal patients (P less than 0.008) whilst HPr-2 levels were not related to parity. Thus the rise in HPr associated with surgery was greater in parous than nulliparous women. Prolactin levels were not related to nodal status or tumour size. However, the amounts of HPR-2 were significantly greater in women with histological grade 3 tumours than those with grade 1 or 2. Standardising for either nodal status, tumour size or histological grade seven situations were found in which HPr-1 or HPr-2 levels were of prognostic significance. Although some of these significant associations could be fortuitous all shared a common feature that the least favourable prognosis was associated with the highest HPr levels.

Diurnal variations in prolactin and growth hormone levels in normal premenopausal vegetarian and omnivorous women

Diurnal levels of plasma prolactin and growth hormone were measured in 47 normal premenopausal women, 26 of whom were established vegetarians and 21 of whom were omnivorous controls. There were no differences between the median prolactin levels of the two groups during a 24-hour period of investigation. When the groups were further subdivided into ovolactovegetarians and vegans, still no differences were found in prolactin secretion. In contrast, the vegetarian women exhibited elevation of growth hormone levels during the period of study, which was particularly marked at midnight and 10 A.M.

Proposal to decrease the risk and improve the prognosis of breast cancer

Of 256 patients with breast cancer diagnosed between 1972 and 1981, 102 have died (mortality, 39.8%). More hormone users had negative axillary nodes (57.1%) than did nonusers (41.8%). The mortality of the hormone users (22.2%) was significantly lower (p less than or equal to 0.01) than that of the nonusers (45.5%). In 162 patients whose diagnosis of breast cancer was made prior to 1979, the 5-year survival rate in hormone users was 76.2% compared to 48.1% in nonusers. During the prospective phase of the study from 1975 to 1981, the lowest incidence of breast carcinoma (67.3:100,000) was observed in the estrogen-progestogen users and was significantly lower than that of the untreated group (342.3:100,000) and lower than that expected from both the Third National Cancer Survey and the National Cancer Institute System for Electronic Evaluation and Retrieval (SEER) data (p less than or equal to 0.01). Estrogen therapy does not increase the risk of mammary malignancy, but added progestogen significantly decreases the risk.

'Hormonal' risk factors, 'breast tissue age' and the age-incidence of breast cancer

For most cancer sites there is a linear log-log relationship between incidence and age. This relationship does not hold for breast cancer, and certain 'key' breast cancer risk factors suggest that breast tissue does not 'age' in step with calendar time. A quantitative description of 'breast tissue age' is suggested which brings the age-incidence curve of breast cancer into line with the common log-log cancers and explains quantitatively the known key risk factors. The model also explains the 'anomalous' finding that although early first birth is protective, late first birth carries a higher risk than nulliparity. US breast cancer rates are some four to six times the rates in Japan--the model suggests that the key risk factors, when considered jointly with weight, can explain about 85% of the difference.