This is a prospective, single-center, three-arm Phase 1 safety and feasibility trial evaluating anti-estrogen therapy in men age 50 years and older with symptomatic unilateral inguinal hernias. Participants will be randomized to receive fulvestrant 250 mg intramuscularly, fulvestrant 500 mg intramuscularly, or letrozole 5 mg orally for 6 months. The study will evaluate safety, tolerability, feasibility, hormone changes, hernia size, patient-reported outcomes, bone density, and imaging-based hernia classification.

Inclusion Criteria:

• Male sex
• Age ≥ 50 years at time of enrollment
• Symptomatic unilateral inguinal hernia confirmed on physical examination
• Hernia visible / confirmed on groin ultrasound
• Non-recurrent inguinal hernia (primary hernia only)
• Willing and able to provide written informed consent
• Able and willing to comply with all protocol-required visits, laboratory assessments, imaging, and follow-up
• Willing to use contraception and avoid fathering a child during study participation and for 12 months after last dose
• Willing to be counseled regarding vitamin D and calcium supplementation Bone safety mitigation measure per PIND response.

Exclusion Criteria:

Hernia Characteristics

• Scrotal hernia (any)
• Bilateral inguinal hernia
• Recurrent inguinal hernia (prior repair at same site)

Renal & Hepatic

• Clinically significant renal dysfunction judged by investigator to increase study risk
• Clinically significant hepatic dysfunction at baseline

Hematologic

■ Clinically significant baseline hematologic abnormality (including elevated hematocrit or polycythemia)

Urologic / Prostate

• Symptomatic benign prostatic hyperplasia (BPH) requiring active medical or procedural treatment
• Clinically significant untreated prostate disease

Skeletal / Bone

• Baseline osteoporosis (T-score ≤ -2.5 on DEXA at any site)
• Recent fragility fracture (within prior 12 months or as judged by investigator)
• Other clinically significant skeletal vulnerability judged to increase risk from estrogen suppression

Immunosuppression ■ Active immunosuppression (e.g., systemic corticosteroids, biologic agents, post-transplant regimens)

Psychiatric

■ Unstable or uncontrolled psychiatric illness that, in the investigator's judgment, would interfere with safe study participation

Reproductive / Fertility ■ Actively pursuing fertility or planning conception during study participation

Prior / Concomitant Therapy

• Current use of androgen replacement therapy, exogenous estrogen, or other endocrine-active agents that would confound study interpretation
• Prior or current use of aromatase inhibitor or selective estrogen receptor modulator / degrader within 6 months of enrollment

General

■ Any other clinically significant medical condition, laboratory abnormality, or circumstance that, in the investigator's judgment, would place the participant at unacceptable risk or compromise study integrity

Eligibility is limited to individuals who identify as male, consistent with the biological mechanism under investigation and the study population defined in the protocol.

Individual participant data will not be shared outside the study team. Aggregate study results may be disseminated through presentations and publications.