Gynaecomastia secondary to transdermal oestradiol used for androgen deprivation therapy: informed reality vs subjective fear.

Abstract

To provide information that can aid patients with prostate cancer (PCa) and their uro-oncologists in shared decision-making discussions about androgen deprivation therapy (ADT), with transdermal oestradiol (tE2) as one option. We do so by summarising recent literature on breast growth in genetic males undergoing treatment with exogenous E2. Based on the amount of breast development observed in this population, we estimate the maximum amount of breast growth that patients with PCa can expect, if they elect tE2 for ADT. We also present data on risks and management of mastalgia associated with tE2. We summarise findings from five studies involving a total of 480 trans women (i.e., genetic males) undergoing gender-affirming hormone treatment with exogenous oestrogen. Exogenous E2 typically induces less than an A-cup size among trans women. The majority of breast growth occurs within the first year of treatment. We present this evidence to illustrate that the degree of gynaecomastia patients with PCa can expect if they elect tE2 for ADT is quite modest. This information can allay the often-heightened concern patients with PCa and their uro-oncologists may have regarding gynaecomastia induced by tE2 when used for ADT. Development of breast tissue in genetic males taking exogenous E2 tends to be mild and typically results in less than A-cup size. Mastalgia in the form of breast and nipple sensitivity is common with E2 treatment in patients with PCa but is transient in most cases, responds to topical anti-inflammatory agents, and can be managed with neurectomy in severe cases. This information can help clinicians provide accurate counselling and mitigate misconceptions that may dissuade patients from considering tE2 for their ADT.