No abstract

581 Background: While neoadjuvant chemotherapy (NACT) has been established as the standard of care for medically fit patients, there has been renewed interest in utilizing neoadjuvant endocrine therapy (NET) for the treatment of women with estrogen-receptor (ER) positive, HER-2 negative breast cancer. Rates of pCR are known to be low in this population, but there is inconsistent data regarding downstaging and long-term outcomes in a non-trial setting with NET vs NACT. Methods: A prospective institutional databaseof breast cancer patients treated with neoadjuvant therapy at the British Columbia Cancer Agency from 2012-2016 was analyzed to identify all medically fit patients with ER positive, HER2 negative breast cancer. Patients were then divided into two groups: those who received NET or NACT. Baseline characteristics were compared between groups. A matched analysis (age, stage and grade) was then performed to compare rates of downstaging, pCR and scores from a validated neoadjuvant therapy outcomes calculator (CPS+EG). Results: A total of 154 patients met eligibility criteria for this study. One hundred and six patients (69%) received NACT and 48 (31%) received NET. Women offered NACT were significantly younger (51 vs 64y, p < 0.001) than those offered endocrine therapy and presented with a higher clinical stage (LR 27.93, p = 0.002). According to multiple linear regression for downstaging, clinical stage followed by NACT were the most important predictors of downstaging. When matched for age, stage and grade, downstaging was significantly higher with NACT (31/48, 65%) as compared to NET (12/48, 25%), p < 0.001. Of these, 12.5% achieved pCR with NACT as compared to 2.1% with NET, LR 4.243, p = 0.039. No significant differences in CPS+EG scores were identified when comparing NACT to NET. Conclusions: Significantly higher rates of downstaging were achieved with NACT as compared to NET when patients were matched for age, stage and grade. Rates of pCR remain low for ER-positive breast cancer patients. Although not validated with the use of NET, CPS+EG scores predicting long-term outcomes were not significantly different with NET compared to NACT.

Background The use of Oncotype dx (Genomic Health, Redwood City, CA, U.S.A.) testing has been shown to change treatment decisions in approximately 30% of breast cancer (bca) cases, but research on how Recurrence Score testing has affected the type of chemotherapy offered is limited. We sought to determine if the availability of Oncotype dx testing resulted in a change to the type and duration of chemotherapy regimens used in the treatment of early-stage hormone receptor–positive bca. Methods In a population-based cohort study, patients treated in the 2 years before the availability of Oncotype dx testing were compared with patients treated in the 2 years after testing availability. Charts were audited and divided into 2 groups: pre-Oncotype dx and post-Oncotype dx. The groups were compared for differences in duration of chemotherapy (12 weeks vs. >12 weeks), types of agents used (anthracycline vs. non-anthracycline), and myelosuppressive potential of the chosen regimen. Results Of 834 patients who fulfilled the enrolment criteria, 360 fell into the pre-Oncotype dx era, and 474, into the post-Oncotype dx era. An increase of 11.2 percentage points, to 69.5% from 58.3%, was observed in the proportion of patients receiving short-course compared with long-course chemotherapy (p = 0.068). The proportion of patients prescribed anthracycline-containing regimens declined in the post-Oncotype dx era (47.7% pre vs. 32.2% post, p = 0.016). The selection of more-myelosuppressive chemotherapy protocols increased in the post-Oncotype dx era (67.4% pre vs. 78.8% post, p = 0.044). Conclusions In the present study, the availability of Oncotype dx testing was observed to influence the choice of chemotherapy type in the setting of early-stage bca.

e12049 Background: The Oncotype DX test has been shown to change treatment plans in ~30% of cases, but it is unclear if it changes the type of chemotherapy offered. We sought to determine if the availability of Oncotype DX testing in BC resulted in a change in the type of chemotherapy regimens used on early stage breast cancer pts. Methods: This was a cohort study in which pts treated in the 2 years prior to the availability of Oncotype Dx testing were compared to pts treated in the 2 years after it became available in BC. Charts were audited and divided into pre- and post- availability of Oncotype DX testing. The groups were compared for differences in length of chemotherapy (12 vs > 12 weeks), type of agents used (anthracycline vs non-anthracycline) and myelosuppressive potential of regimen chosen. Results: A total of 831 pts fulfilled enrollment criteria; 360 were seen in the pre Oncotype era and 471 were seen in the post Oncotype era. A total of 250 (30.1%) pts were treated with chemotherapy in both cohorts with a median age of 59 for both groups (range of 29-80 and 24-80 respectively, p = NS). There was a decrease of 11.5% in pts receiving chemotherapy from 36.6% to 25.1% (p = 0.0003). Of the pts who received chemotherapy, there was a shift away from regimens containing anthracycline (49.2% vs 32.2%, p = 0.0070) and a shift towards more myelosuppressive chemotherapy regimens (p = 0.0344). There was a significant difference in the duration of chemotherapy regimens chosen with post Oncotype era pts receiving short course chemotherapy 69.5% of the time, compared to only 56.8% in the pre Oncotype era (p = 0.0491). Conclusions: The availability of Oncotype DX testing has resulted in a shift towards use of shorter, more myelosuppressive, non-anthracycline containing chemotherapy protocols. Since being publicly available, fewer pts are receiving chemotherapy but our data suggests a 10% change in treatment plan compared to the 30% change seen in other literature. Further study is warranted to ensure long term outcomes are not negatively impacted by the move towards shorter chemotherapy regimens.