Primary fallopian tube carcinoma risk in users of postmenopausal hormone therapy in Finland

Objective: Primary fallopian tube carcinoma (PFTC) is a rare malignancy and only sparse data exist on its possible association with postmenopausal hormone therapy (HT). We therefore studied this association in a nationwide cohort of Finnish HT users.

Methods: All women> 50 years using systemic estradiol-only therapy (ET) (n=117,820 hysterectomized women) or estradiol-progestin therapy (EPT) (n=247,781 nonhysterectomized women) for ≥ 6 months during 1994-2008 were identified from the national medical reimbursement register. The incidence of PFTC in HT users was compared to that in the comparable background population (standardized incidence ratio, SIR, with 95% confidence interval, CI).

Results: A total of 160 cases of PFTC were encountered in users of ET (n=34) or EPT (n=126). The use of EPT ≥ 5 years was accompanied by an increased risk for PFTC (SIR 2.15; 95% CI 1.66-2.72). The SIR increased further to 3.36 (95% CI 2.02-5.24) when EPT use lasted ≥ 10 years. The EPT-related risk for PFTC was restricted to the sequential EPT and it was not seen for continuous EPT. Two leading progestins in EPT, norethisterone acetate and medroxyprogesterone acetate, associated with comparable risk elevations. ET use was not associated with the risk for PFTC.

Conclusions: The long-term, sequential use of EPT associates with an increased risk for PFTC. In absolute terms, 4 additional cases of PFTC would be detected in 10-year follow-up of 10,000 women who have used EPT for at least 5 years.