OBJECTIVE: To evaluate if uterine myoma is associated with breast cancer. METHODS: This case-control study used a nationwide database in Taiwan. We identified 24,315 patients with newly diagnosed breast cancer as cases and matched them with 24,281 patients without breast cancer on age, sex, urbanization, income, and initial diagnosis date. Patients with prior mastectomy were excluded. We used logistic regression analysis to assess the association between uterine myoma and breast cancer while adjusting for confounders. We evaluated the impact of surgical removal of uterine myoma on subsequent breast cancer among patients with uterine myoma. RESULTS: We found that 2,892 (11.9%) patients with newly diagnosed breast cancer and 2,541 (10.5%) patients without breast cancer had a history of uterine myoma. The association between breast cancer and uterine myoma was significant (adjusted odds ratio [aOR]=1.14; 95% confidence interval [CI]=1.07–1.21; p<0.001). This association remained in patients who used hormone (aOR=1.20; 95% CI=1.08–1.33; p=0.001) or who did not use hormone (aOR=1.11; 95% CI=1.03–1.19; p=0.005) within 5 years prior to the index date. Surgical removal of uterine myoma was not associated with a decreased risk of breast cancer (aOR=0.99; 95% CI=0.88–1.10; p=0.795). CONCLUSION: A minor increased risk of breast cancer was found in women with a history of uterine myoma. This association remained in patients with recent hormone use. Removal of uterine myoma was not associated with decreased risk of breast cancer.
Breast Neoplasms* ; Breast* ; Case-Control Studies* ; Diagnosis ; Female ; Hormone Replacement Therapy ; Humans ; Leiomyoma* ; Logistic Models ; Mastectomy ; National Health Programs ; Odds Ratio ; Taiwan ; Urbanization ; Uterus

OBJECTIVE: Uterine myoma which results in the magnitude of ovarian cancer remains uncertain. This study aimed to assess the association between women with previous uterine myoma and the risk of ovarian cancer. METHODS: This population-based case-control study was conducted using the Taiwan National Health Insurance Research Database between 2006 and 2010. We identified 4,088 adult women with newly diagnosed ovarian cancer with 16,348 women without ovarian cancer matched for age, urbanization level, income and initial diagnosis date. Logistic regression analyses were used to evaluate the variables associated with ovarian cancer. In addition, the effect of surgical interventions on the risk of ovarian cancer was also evaluated. RESULTS: Women with previous uterine myoma were more likely than those who did not to have ovarian cancer (adjusted odds ratio [aOR]=2.26; 95% confidence interval [CI]=2.06−2.49). Patients with uterine myoma who either received (aOR=1.79; 95% CI=1.51−2.13) or did not receive hormone replacement therapy (aOR=2.51; 95% CI=2.24−2.82) experienced a significantly higher risk of ovarian cancer than those without uterine myoma, respectively. However, patients with uterine myoma who underwent either myomectomy (aOR=0.55; 95% CI=0.39−0.77) or hysterectomy (aOR=0.33; 95% CI=0.26−0.42) had a significantly lower risk of ovarian cancer. CONCLUSION: The results revealed that a significantly higher risk of ovarian cancer in women with previous uterine myoma, through an indirect mechanism. Furthermore, a lower risk of ovarian cancer was observed in women who underwent surgical removal of the uterine myoma.
Adult ; Case-Control Studies ; Diagnosis ; Female ; Hormone Replacement Therapy ; Humans ; Hysterectomy ; Leiomyoma ; Logistic Models ; National Health Programs ; Odds Ratio ; Ovarian Neoplasms ; Taiwan ; Urbanization