e12608 Background: Complete pathological response (pCR) is a surrogate of successful neoadjuvant treatment of triple-negative breast cancer (TNBC). We extended our study from 2016, where we discussed unusually high pCR employing taxane/platinum (T/P) without the use of adriamycin and cyclophosphamide (AC). Methods: This is a retrospective observational study of an underserved, low income, rural population in Oroville, California over 10 years (2011-2021). Neoadjuvant chemotherapy was offered to eighteen women with ages ranging from 36 to 77 years old (mean age is 56). Minimum requirements for evaluation was three cycles administered within 90 days of starting treatment. The primary end point of this study was pCR. We analyzed the relationship between pCR, chemotherapy regimen, proliferation rate of original tumor by Ki-67 and the ratio of neutrophil and lymphocyte (NLR). The two regimens of chemotherapy included both standard AC+T or the alternative treatment with T/P. We grouped Ki-67 to above and below 50% pre-treatment. NLR was grouped between those above and below 3.2. Results: Our study produced a respectable response rate with 12/18 (67%) achieving pCR. There was no difference with or without exposure to anthracyclines. Out of the twelve who achieved pCR, eight (67%) received T/P and four (33%) got AC+T. Ki-67 in all eighteen patients ranged from 2% to 97% with a median of 75%. Ki-67 was >50% in 10/12 (83%) patients who achieved pCR and 3/6 (50%) in those who did not have a response. NLR was a significant predictor for pCR. 8/12 (67%) of patients who experienced pCR had a NLR of <3.2 compared to the 1/6 ( 17%) with no response. The p-value is .0455. Conclusions: Treatment with the alternative regimen of T/P didn’t affect pCR in our population. We hypothesize that some of the beneficial effects of cytotoxics affected the patient’s immunological milieu on top of the direct effect of the malignant clone.
e12606 Background: Invasive lobular carcinoma (ILC) differs from the more prevalent invasive ductal carcinoma (IDC) in histology, molecular underpinning, and biological responsiveness to cytotoxics. Patients diagnosed with IDC or ILC were evaluated in the clinical setting to determine if they differ in responsiveness to neoadjuvant hormone treatment. Methods: This is a retrospective observational study of an underserved, low income, rural population in Oroville, California. The data for this study was collected over ten years (2011-2021) from 58 estrogen receptor positive (ER+) breast cancer patients. The majority of these patients (48/58) were diagnosed with IDC with ages ranging from 35 to 91 (mean age is 66) and the remaining 10 were diagnosed with ILC with ages ranging from 58 to 85 (mean age is 64). Patients were given neoadjuvant hormone treatment starting after their initial biopsy confirming ER+ status until scheduled surgical removal by lumpectomy or mastectomy. Ki-67 was measured prior to treatment and then measured again after a minimum of 14 days on hormone therapy. The initial Ki-67 range for patients with IDC was 2%-75% (median of 15%). Ki-67 initial range for patients with ILC was 2%-30% (median of 11%). Positive response to treatment was set at > 50% reduction in Ki-67, with no response set at < 50% reduction in Ki-67. We compared the response rates of ILC and IDC patients using a chi-square test. Results: Chi-square analysis found no statistically significant difference between IDC and ILC response to hormone therapy. 34/48 (71%) patients with IDC responded to treatment, and 8/10 (80%) of ILC patients showed response. Incidentally, we noticed a higher prevalence of ILC in our community compared to expected numbers. Conclusions: When evaluating hormone therapy responsiveness in the neoadjuvant setting, there is no observable statistical difference in response rates between IDC and ILC. Neoadjuvant hormone testing employing Ki-67 response identifies subgroups of patients who benefit from the addition of new biologics (-ciclibs, mTOR inhibitors) in addition to hormone treatment. Our experience supports testing in this way to further individualize the care of patients unable to participate in clinical trials.
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