Abstract:

Objective To analyze the clinical value of 21-gene recurrence score（RS） in invasive lobular breast cancer （ILC）.Methods We retrospectively enrolled ILC patients who underwent breast cancer surgery and 21-gene RS testing in the Comprehensive Breast Health Center at Rujin Hospital，Shanghai Jiaotong University School of Medicine between January 2011 and November 2017. Relationships of 21-gene RS with clinicopathological factors and choice of adjuvant chemotherapy were further analyzed in terms of odds ratio （OR） and confidence interval （CI）. Results A total of 59 ILC patients who underwent 21-gene RS testing were enrolled，of whom 10 （16.95%） were classified as low risk；30 （50.85%），as intermediate risk；and 19 （32.20%），as high risk. Both univariate and multivariate analysis demonstrated that molecular subtype status was independently associated with high risk based on 21-gene RS （OR=19.90，95%CI：2.42-163.63，P=0.005）. Multivariate analysis showed that molecular ILC subtype independently influenced use of adjuvant chemotherapy （OR=14.70，95%CI：1.59-136.23，P=0.018），whereas 21-gene RS did not （P=0.527）. Conclusion The 21-gene RS was associated with molecular ILC subtype. Use of adjuvant chemotherapy was related to molecular ILC subtype but not to 21-gene RS，which deserves further clinical study.

Key words: Breast neoplasms, Invasive lobular carcinoma, 21-gene recurrence score, Adjuvant chemotherapy, Molecular subtype