Adjuvant chemotherapy could not bring survival benefit to HR-positive, HER2-negative, pT1b-c/N0-1/M0 invasive lobular carcinoma of the breast: a propensity score matching study based on SEER database

Abstract

Background : The benefit of adjuvant chemotherapy in invasive lobular carcinoma (ILC) is still unclear. The objective of the current study was to elucidate the effectiveness of adjuvant chemotherapy in hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative, pT1b-c/N0-1/M0 ILC. Methods: Based on Surveillance, Epidemiology, and End-Results (SEER) database, we identified original 12334 HR-positive, HER2-negative, pT1b-c/N0-1/M0 ILC patients, who were then divided into adjuvant chemotherapy group and control group. End-points were overall survival (OS) and breast cancer-specific mortality (BCSM). Aiming to minimize the selection bias of baseline characteristics, Propensity Score Matching (PSM) method was used. Results : In a total of 12334 patients with HR-positive, HER2-negative, pT1b-c/N0-1/M0 ILC, 1785 patients (14.5%) were allocated into adjuvant chemotherapy group and 10549 (85.5%) into control group. Used PSM, the 1785 patients in adjuvant chemotherapy group matched to the 1785 patients in control group. By Kaplan-Meier survival analyses, we observed no beneficial effect of adjuvant chemotherapy on OS in both original samples ( P =0.639) and matched samples ( P =0.962), however, ineffective or even contrary results of adjuvant chemotherapy on BCSM both in original samples (P =0.001) and in matched samples ( P= 0.002). In both original and matched multivariate Cox models, we observed ineffectiveness of adjuvant chemotherapy on OS (hazard ratio (HR) for overall survival = 0.82, 95% confidence interval (CI) [0.62-1.09]; P =0.172 and HR=0.90, 95%CI [0.65-1.26]; P =0.553, respectively), unexpectedly promoting effect of adjuvant chemotherapy on BCSM (HR=2.33, 95%CI [1.47-3.67]; P =0.001 and HR=2.41, 95%CI [1.32-4.39]; P =0.004, respectively). Standard surgery was beneficial to the survival of patients. Lymph node metastasis was detrimental to survival and radiotherapy brought survival benefit in original samples, but two issues had unobvious effect in matched samples. Conclusion: In this study, adjuvant chemotherapy did not improve survival for patients with HR-positive, HER2-negative pT1b-c/N0-1/M0 ILC.

Current and future diagnostic and treatment strategies for patients with invasive lobular breast cancer

“…127 They did not identify a beneficial role for adjuvant chemotherapy with regard to overall survival (OS), in line with other literature. 37,[128][129][130][131] Most of the studies included in this meta-analysis did, however, not correct for ER, PR and HER2 and had a relatively short follow-up. A more recent US registry study that evaluated 17 789 patients with stage I-III ILC observed a similar OS after 5 years between patients receiving endocrine therapy alone and those receiving the combination of chemotherapy and endocrine therapy, after adjusting for age, stage, lymph node involvement, histology and radiotherapy.…”

Adjuvant chemotherapy in patients with invasive lobular carcinoma and use of the 21‐gene recurrence score: A National Cancer Database analysis

“…It has been demonstrated previously that ILC differs from IDC in its histopathology, genetic makeup, and pathophysiology and also in the characteristics of its patients and the treatment offered by clinicians 1,2,4,24,25 . Multiple studies have demonstrated that patients who have ILC are treated less often with CT compared with those who have similar tumor stage and IDC histology, with further studies questioning whether patients who have ILC derive any benefit from the addition of CT to their treatment 8,9,26,27 . The evolving myriad of genomic assays allows for more accurate and personalized patient care.…”

“…These tendencies may be explained by early trials demonstrating that patients with ILC had no advantage from the addition of CT to their treatment 8,9,26,27 . They may have been further influenced by findings that the RS had no prognostic value in patients with ILC.…”

The prognosis of invasive ductal carcinoma, lobular carcinoma and mixed ductal and lobular carcinoma according to molecular subtypes of the breast

“…Conservative surgery is most appropriate for ILC when adequate preoperative investigations exclude multifocal and contralateral disease, and wider negative margins may not necessary for ILC [17]. Adjuvant chemotherapy may not improve survival for patients with HR(+)HER2(−) T1b-c/ N0-1/M0 ILC [18]. However, ILC patients could derive significant disease-free survival and OS benefits from chemotherapy, especially for high-risk patients [19].…”