Tamoxifen Initiation After Ductal Carcinoma In Situ

Endocrine therapy initiation after ductal carcinoma in situ (DCIS) is highly variable and largely unexplained. National guidelines recommend considering tamoxifen for women with estrogen receptor-positive (ER+) DCIS or who undergo excision alone. We evaluated endocrine therapy use after DCIS over a 15-year period in an integrated health care setting to identify factors related to initiation

Trends in Estrogen Receptor Testing and Tamoxifen Initiation After Ductal Carcinoma in Situ During 1996–2011

Background/Aims: Ductal carcinoma in situ (DCIS), a stage 0 breast cancer usually detected on mammogram, accounts for 24% of all breast cancer diagnoses. In 2000, tamoxifen was FDA-approved as adjuvant endocrine therapy for DCIS patients. We assessed tamoxifen initiation after DCIS diagnosis according to calendar year, tumor characteristics and concurrent treatment within Group Health Cooperative (GHC). Methods: We identified female GHC enrollees aged 18–89 years with an incident DCIS diagnosis during 1996–2011. Eligibility criteria required 12 months continuous enrollment before and after DCIS diagnosis. Tamoxifen initiation was identified through pharmacy records. Tumor characteristics and treatment information were captured from the virtual data warehouse. Relative risks (RR) and 95% confidence intervals (CI) for tamoxifen initiation were calculated with multivariable generalized linear models adjusted for age, calendar year, estrogen receptor (ER) status, radiation therapy and grade. Results: We identified 727 women with a DCIS diagnosis, including 163 (22%) who initiated endocrine therapy within 12 months. Fourteen women filled aromatase inhibitor prescriptions and were analyzed with tamoxifen users. ER testing increased from 4% of DCIS cases in 2001 to 71% in 2011. Women diagnosed with DCIS during 1996–2000 were 43% less likely to use tamoxifen as those diagnosed in 2001–2005 (RR: 0.6, CI: 0.4–0.9). However, tamoxifen use did not vary significantly across calendar years after 2001. Among ER-positive tumors, 58% (18 of 31) used tamoxifen in 2001–2005 compared to 39% (47 of 122) in 2006–2011. Among women with unknown ER status, 24% (47 of 194) used tamoxifen in 2001–2005 compared to 15% (21 of 140) in 2006–2011. Younger women were more likely to use tamoxifen (RR: 1.7, 95% CI: 1.1–2.6 for age 45–54 compared to 65–74; P-trend=0.0002). Compared to breast conserving surgery (BCS) with radiation, women who had BCS without radiation (RR: 0.5, CI: 0.2–0.9) or mastectomy (RR: 0.6, CI: 0.4–0.8) were less likely to use tamoxifen. Six percent (n=47) of women had a bilateral mastectomy; of these, \u3c 5 used tamoxifen. Discussion: Increasing ER testing since 2001 has not corresponded to parallel increases in tamoxifen use. Tamoxifen use after DCIS was more common among younger women and those who had BCS and radiation therapy

Tamoxifen Initiation After Ductal Carcinoma In Situ

BACKGROUND. Endocrine therapy initiation after ductal carcinoma in situ (DCIS) is highly variable and largely unexplained. National guidelines recommend considering tamoxifen for women with estrogen receptor-positive (ER+) DCIS or who undergo excision alone. We evaluated endocrine therapy use after DCIS over a 15-year period in an integrated health care setting to identify factors related to initiation. METHODS. Female Group Health Cooperative enrollees ages 18–89 years with a DCIS diagnosis during 1996–2011 were eligible for inclusion. Endocrine therapy was identified through pharmacy records. Tumor and treatment information were from tumor registry reports; demographics and other risk factors were from questionnaires and electronic medical records. Relative risks (RRs) and 95% confidence intervals (CIs) for endocrine therapy initiation were calculated using multivariable generalized linear models. RESULTS. We identified 727 women with a DCIS diagnosis, including 163 (22%) who initiated endocrine therapy (149 tamoxifen, 14 aromatase inhibitor). Younger women were more likely to initiate endocrine therapy (RR 1.69; 95% CI 1.16–2.46 for ages 45–54 vs. 65–74 years). Compared with breast-conserving surgery (BCS) with radiation, women who had BCS alone (RR 0.46; 95% CI 0.25–0.84) or mastectomy (RR 0.54; 95% CI 0.39–0.75) were less likely to use endocrine therapy. ER testing increased from 4% of DCIS cases in 2001 to 71% in 2011; however, endocrine therapy initiation decreased from 58% of ER+ DCIS in 2001–2005 to 37% in 2009–2011. CONCLUSION. Increasing ER testing since 2001 has not corresponded to parallel increases in endocrine therapy initiation. Age, surgery, and radiation were the primary factors associated with initiation. IMPLICATIONS FOR PRACTICE: National guidelines recommend considering tamoxifen for women with ductal carcinoma in situ (DCIS) who are estrogen receptor-positive (ER+) or who undergo excision alone. In this study, the rapid increase in ER testing caused by tamoxifen’s approval in 2000 did not lead to increases in endocrine therapy initiation, despite recognition of an increasing number of DCIS tumors as ER+ each year. Contrary to the suggested guidelines, women who had breast-conserving surgery without radiation were less likely to use tamoxifen than those who had radiation. Future Food and Drug Administration approval of new endocrine agents for DCIS (such as aromatase inhibitors) may provide an opportunity to reemphasize benefits by ER and surgery status