A 12-month moderate-intensity exercise intervention does not alter serum prolactin concentrations

Muscle function, exercise capacity, physical activity level and cardiovascular disease risk factor knowledge in patients with prolactinoma

OBJECTIVE

Prolactinoma can increase the risk of cardiovascular diseases (CVDs), such as arterial stiffness, atherosclerosis, dysrhythmia and heart failure. This study aimed to evaluate and compare muscle function, exercise capacity, physical activity (PA) level, CVD risk factor knowledge level, sleep quality, fatigue and quality of life between prolactinoma patients and healthy controls.

METHODS

Nineteen female patients with prolactinomas and 19 healthy women were included in this study. Quadriceps muscle strength (QMS) was measured using a hand dynamometer, and muscular endurance was evaluated via the squat test. The 6-minute walking test (6MWT) distance was also measured. CVD risk factor knowledge levels were evaluated with the Cardiovascular Diseases Risk Factors Knowledge Level Scale (CARRF-KL), PA levels were assessed with the International Physical Activity Questionnaire-short form (IPAQ), sleep quality was assessed with the Pittsburgh Sleep Quality Index (PSQI), fatigue was assessed with the Multidimensional Fatigue Rating Scale (MAF), and quality of life was assessed with the Short Form-36 questionnaire (SF-36).

RESULTS

Patients with prolactinomas had significantly lower 6MWT distances; CARRF-KL total scores; SF-36 general health and physical limitation scores; and higher IPAQ-sitting scores than did healthy controls (p < 0.05). Moreover, there were no significant differences between the groups in terms of QMS score; number of squats; severity of IPAQ score; severity, moderate, or total walking score; total PSQI score; or total MAF score (p > 0.05).

CONCLUSIONS

Exercise capacity and quality of life are adversely affected, and sedentary behavior is observed in prolactinomas. Patients with prolactinomas have less knowledge about CVD risk factors than healthy individuals. CVD incidence and knowledge and functional capacity should be improved in patients with prolactinomas by the use of a multidisciplinary team for cardiac rehabilitation.

CLINICAL TRIAL REGISTRATION

This study is part of a larger clinical trial registered on ClinicalTrials.gov prior to participant enrollment (NCT05236829).

Determinants of prolactin in postmenopausal Chinese women in Singapore

PURPOSE

Mechanistic and observational data together support a role for prolactin in breast cancer development. Determinants of prolactin in Asian populations have not been meaningfully explored, despite the lower risk of breast cancer in Asian populations.

METHODS

Determinants of plasma prolactin were evaluated in 442 postmenopausal women enrolled in the Singapore Chinese Health Study, a population-based prospective cohort study. At baseline all cohort members completed an in-person interview that elicited information on diet, menstrual and reproductive history, and lifestyle factors. One year after cohort initiation we began collecting blood samples. Quantified were plasma concentrations of prolactin, estrone, estradiol, testosterone, androstenedione, and sex hormone-binding globulin (SHBG). Analysis of covariance method was used for statistical analyses with age at blood draw, time since last meal, and time at blood draw as covariates.

RESULTS

Mean prolactin levels were 25.1% lower with older age at menarche (p value = 0.001), and 27.6% higher with greater years between menarche and menopause (p value = 0.009). Prolactin levels were also positively associated with increased sleep duration (p value = 0.005). The independent determinants of prolactin were years from menarche to menopause, hours of sleep, and the plasma hormones estrone and SHBG (all p values < 0.01).

CONCLUSION

The role of prolactin in breast cancer development may involve reproductive and lifestyle factors, such as a longer duration of menstrual cycling and sleep patterns.

Physical activity does not alter prolactin levels in post-menopausal women: results from a dose-response randomized controlled trial

Background

Increased circulating levels of prolactin have been associated with increased risk of both in situ and invasive breast cancer. We investigated whether or not physical activity had a dose–response effect in lowering plasma levels of prolactin in postmenopausal women.

Methods

Four hundred previously inactive but healthy postmenopausal women aged 50–74 years of age were randomized to 150 or 300 min per week of aerobic physical activity in a year-long intervention. Prolactin was measured from fasting samples with a custom-plex multiplex assay.

Results

A high compared to moderate volume of physical activity did not reduce plasma prolactin levels in intention-to-treat (Treatment Effect Ratio (TER) 1.00, 95% Confidence Interval (CI) 0.95 – 1.06) or per-protocol analyses (TER 1.02, 95% CI 0.93 – 1.13).

Conclusions

It is unlikely that changes in prolactin levels mediate the reduced risk of breast cancer development in post-menopausal women associated with increased levels of physical activity.

Trial registration

clinicaltrials.gov identifier: NCT01435005.

Race, age, and obesity disparities in adult physical activity levels in breast cancer patients and controls

Physical activity has been shown to be inversely associated with breast cancer recurrence and survival. Although physical activity is known to decline with age, rates of change in physical activity have not been well characterized in breast cancer patients and subgroups with known disparities in breast cancer survival, especially in minorities, the elderly, and the obese. We evaluated moderate and strenuous physical activity from high school through diagnosis in 1,220 breast cancer patients, and from high school to recruitment in 935 controls. We compared the proportion of patients and controls meeting the American Cancer Society (ACS) guidelines for physical activity and differences in declines in level of physical activity by race, age, and obesity. At diagnosis, only 33.2% of breast cancer patients met the ACS physical activity guidelines. Only 13.2, 24.7, and 30.5% of African-American (AA), obese, and older (≥65 years) patients met the guidelines, respectively. Controls showed slightly higher rates, with 36.4% overall, 23.7% of AA, 29.0% of obese, and 32.4% of older women meeting the guidelines. AA patients were less likely to meet guidelines compared to White patients (p < 0.0001). Obese patients were less likely to meet guidelines compared to non-obese (p < 0.0001). We found that both moderate and strenuous physical activity declined after high school in patients and controls. AA patients reported steeper declines in strenuous (p = 0.0027), and total (p = 0.0009) physical activity compared to Whites. Obese patients reported steeper declines in total physical activity compared to non-obese (p = 0.022). Differences in average slopes of declines in physical activity were not observed by age. Our results suggest that strategies and programs to encourage women to maintain recommended levels of physical activity after high school are needed. Furthermore, breast cancer patients, particularly AA and obese patients, should be targeted to help reduce disparities.

Physical activity and its relation to cancer risk: updating the evidence

Scientific evidence for the primary prevention of cancer caused by physical activity of regular moderate-intensity or greater is rapidly accumulating in this field. About 300 epidemiologic studies on the association between physical activity and cancer risk have been conducted worldwide. The objectives of this paper were three-fold: (i) to describe briefly the components of physical activity and its quantification; (ii) to summarize the most important conclusions available from comprehensive reports, and reviews of the epidemiologic individual and intervention studies on a role physical activity in cancer prevention; (iii) to present proposed biological mechanisms accounting for effects of activity on cancer risk. The evidence of causal linked physical activity and cancer risk is found to be strong for colon cancer - convincing; weaker for postmenopausal breast and endometrium cancers - probable; and limited suggestive for premenopausal breast, lung, prostate, ovary, gastric and pancreatic cancers. The average risk reductions were reported to be 20-30%. The protective effects of physical activity on cancer risk are hypothesized to be through multiple interrelated pathways: decrease in adiposity, decrease in sexual and metabolic hormones, changes in biomarkers and insulin resistance, improvement of immune function, and reduction of inflammation. As there are several gaps in the literature for associations between activity and cancer risk, additional studies are needed. Future research should include studies dealing with limitations in precise estimates of physical activity and of a lack of consensus on what defines sedentary behavior of individuals and those linked with the proposed biomarkers to cancer risk and controlled exercise intervention trials.