Objective: To detect any significant alteration of basal and TRH stimulated circulating prolactin levels in those with an extremely dense breast composition as compared to ones with a fatty pattern in mammography in climacteric patients with a low risk probability for developing invasive breast cancer within five years according to a validated risk model.
Materials and method: In this matched pairs case-control trial a total of 67 climacteric patients with an extremely dense breast composition were compared to a control group of 71 climacteric patients with an almost entirely fat pattern composition in terms of basal and TRH stimulated circulating prolactin levels. All participants in the study had an estimated 5 years breast cancer risk less than 1.67% according to the validated model of Gail. Subgroup analysis was done according to menopausal status (premenopausal versus postmenopausal) and according to the hormone replacement therapy (HRT) in postmenopausal patients (current users of HRT versus never used HRT).
Results: We did not detect any statistically relevant differences between groups or subgroups in terms of basal, stimulated and Delta levels (stimulated-basal) of prolactin (ng/ml). The differences between groups of extremely dense composition versus almost fatty pattern in terms of DeltaPRL (ng/ml) (+/-S.D.) were not statistically significant (68.1+/-34.5 versus 69.1+/-43.0; unpaired t test, Welch corrected p=0.88, 95% CI -12.1 to 14.0).
Conclusion: Our results do not suggest a contribution of circulating prolactin to increased mammographic density in climacteric patients with low risk probability to develop breast cancer. A study of similar kind is warranted in high risk patients.