Breast Cancer Recurrence According to Molecular Subtype


Background: To evaluate the location of tumor relapse and imaging modality for detection according to thebreast cancer subtype: luminal A, luminal B, HER2 positive luminal B, nonluminal HER2 positive, and triplenegative. Materials and
Methods: A total of 1244 patients with breast cancer with known estrogen receptor (ER),progesterone receptor (PR), Ki-67 and human epidermal growth factor receptor 2 (HER2), who underwentbreast surgery from 2009 to 2012 were analyzed. Patients were classified into the following categories: luminalA (n=458), luminal B (n=241), HER2 positive luminal B (n=227), nonluminal HER2 positive (n=145) and triplenegative (n=173). A total of 105 cases of relapse were detected in 102 patients: locoregional recurrence (n=46),recurrence in the contralateral breast (n=28) and distant metastasis (n=31). Comparison of proportions wasused to determine the difference between subtypes.
Results: Relapse rates by subtypes are as follows: luminal A23 of 458 (5.02%), luminal B 19 of 241(7.88%), HER2 positive luminal B 15 of 227 (6.61%), nonluminal HER2postive 19 of 145 (13.10%) and triple negative 29 of 173(16.76%). Luminal A tumors had the lowest rate ofrecurrence and had significantly lower recurrence rate in comparison with nonluminal HER2 postive (p=0.0017)and triple negative subtypes (p<0.0001). Compared with all other subtypes except nonluminal HER2 positive,triple negative tumors had the highest rate of tumor recurrence (p<0.01). Triple negatives were most likely todevelop contralateral recurrence against all subtypes (p<0.05). Detection rate of locoregional and contralateraltumor recurrence were 28.3% on mammography (n=17/60).
Conclusions: Luminal A tumors are associatedwith a low risk of recurrence while triple negative lesions have a high risk. In case of triple negative tumors, thecontralateral breast has much more recurrence as compared with all other subtype. In terms of detection rates,breast USG was the best modality for detecting tumor recurrence, compared with other modalities (p<0.05).Subtyping of breast tumors using a molecular gene expression panel can identify patients who have increasedrisk of recurrence and allow prediction of locations of tumor recurrence for each subtype.