Association of vaginal smear cytology with menstrual status in breast cancer.
The relationship of clinically defined menstrual categories and an independent measure of hormonal stimulation, maturation index of vaginal smear cytology, was studied. Analysis of 596 smears obtained at the time of breast cancer diagnosis revealed a statistically significant association between menstrual status and maturation index. However, within each menstrual group varying levels of maturation were noted. Estrogenic effect in the absence of exogenous hormone administration was found in 11% of patients following bilateral oophorectomy and among 24% of women whose natural menopause occurred 20 years or longer prior to diagnosis. Endogenous estrogen production appears to continue for many years among some women. Clinical factors such as obesity, diabetes and/or hypertension may stimulate high squamous maturation in some patients. Others of the same age and with similar clinical histories were found to have atrophic smears. The differences in maturation index may be due to individual variations in: endogenous hormone levels; sensitivity of the vaginal mucosa to similar hormonal stimuli; use of certain medications; or unidentified exogenous factors. The maturation index was found to be significantly associated with the following prognostic factors: weight relative to height, tumor size and estrogen receptor content of the primary tumor. These findings indicate that vaginal smear cytology may define specific subsets within menstrual categories which may be relevant to therapy and prognosis in breast cancer.