Relationship between long durations and different regimens of hormone therapy and risk of breast cancer

摘要: ContextWomen using combined estrogen and progestin hormone replacement therapy (CHRT) have an increased risk of breast cancer; however, data on use for long durations associated with patterns are lacking.ObjectiveTo evaluate relationships between durations CHRT use and cancer by histological type receptor status.DesignPopulation-based case-control study.SettingThree counties in western Washington State.ParticipantsNine hundred seventy-five women 65-79 years age diagnosed invasive breast from April 1, 1997, through May 31, 1999 (histology: 196 lobular cases, 656 ductal cases, 114 cases other type, 9 cases with unspecified type; (ER)/progesterone receptor (PR) status: 646 ER+/PR+ 147 ER+/PR− 101 ER−/PR− [6 ER−/PR+ 75 unknown ER/PR status were not included the analyses herein]) 1007 population controls.Main Outcome MeasuresRisks invasive lobular, ductal, ER+/PR+, ER+/PR−, ER−/PR− breast carcinomas.ResultsWomen unopposed therapy (ERT) (exclusive ERT use), even 25 or longer, had no appreciable increase risk of cancer, although odds ratios inconsistent with a possible small effect. Ever users (includes who also used ERT) 1.7-fold (95% confidence interval [CI], 1.3-2.2) increased including 2.7-fold CI, 1.7-4.3) increased risk lobular carcinoma, 1.5-fold 1.1-2.0) 2.0-fold 1.5-2.7) cancers. The was greatest those using longer (users 5-14.9 ≥15 had 1.5-fold [95% 1.0-2.3] 1.6-fold 1.0-2.6] increases respectively, 3.7-fold 2.0-6.6] and 2.6-fold 1.3-5.3] carcinoma, respectively. Associations similar magnitudes seen among of both sequential continuous CHRT. Risks ER−/PR− tumors any form therapy; however, numbers these tumors limited power to detect associations.ConclusionThese suggest that is particularly tumors, whether progestin component taken manner.