A cohort study of topical vaginal estrogen therapy in women previously treated for breast cancer.
OBJECTIVE
To estimate the risk of recurrence of breast cancer associated with the use of topical vaginal estrogen therapy in the management of vaginal atrophy in women previously treated for breast cancer.


METHODS
The study group comprised 1472 women with histologically confirmed breast cancer. In 69 of these subjects (4.7%) their only bothersome menopausal problems were vaginal symptoms. In these women, poorly absorbed topical vaginal estrogen cream or tablets were used. The response of these patients was compared with that of the rest of the database. A Cox regression analysis was performed using sex hormone usage after diagnosis as a time-dependent covariate. Disease-free interval was the outcome measured. Results are expressed as a hazard ratio with 95% confidence intervals. The hazard rate is defined as the probability of disease recurrence or of a subject dying from breast cancer over the study period. A second analysis was performed adjusting for factors known to affect breast cancer prognosis.


RESULTS
Hormone usage was entered as a time-dependent covariate with disease-free interval as the outcome. Subjects who used a topical estrogen alone for menopausal symptoms had an uncorrected hazard ratio of 0.30 (95% confidence interval (CI) 0.11-0.80, p = 0.02). The corrected hazard ratio was 0.57 (95% CI 0.20-1.58, p = 0.28). The hazard rate for a subject dying was not analyzed, as there were too few numbers.


CONCLUSIONS
Although the small numbers of this study preclude a definitive result, topical estrogen usage does not appear to be associated with an increased risk of recurrence of breast cancer.
Dew
J E
JE
School of Women's and Children's Health, University of New South Wales, Royal Hospital for Women, Barker Street, Randwick NSW 2031, Australia.
Wren
B G
BG
Eden
J A
JA
D000282:Administration, Intravaginal; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000401:mortality*; D015331:Cohort Studies; D018572:Disease-Free Survival; D004958:Estradiol / Q000008:administration & dosage / Q000627:therapeutic use*; D015914:Estrogen Replacement Therapy; D005260:Female; D006801:Humans; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000401:mortality*; D009517:New South Wales; D016016:Proportional Hazards Models; D014623:Vaginal Diseases / Q000188:drug therapy* / Q000473:pathology
D004958:Estradiol