1129 - Implication of PET-CT to improve negative predictive value for axillary lymph node metastasis in early breast cancer

Background

Neoadjuvant chemotherapy in early breast cancer (EBC) could lead to uncertain axillary lymph node (ALN) metastasis evaluation by imaging modalities at diagnosis while this could decrease surgical extent. Specially, the increase of false negative rate of US (ultrasonography), MRI (magnetic resonance imaging), and PET- CT (Positron emission tomography-computed tomography) might be connected to insufficient radiotherapy or chemotherapy. This study aimed to investigate whether PET-CT could enhance negative predictive value (NPV) for ALC metastasis in early breast cancer.

Methods

We analyzed 1180 breast cancer patients (stage I or II: 94%) treated by partial mastectomy or mastectomy including axillary LN evaluation from January 2004 to October 2013. They performed US (906 patients) or MRI (1051 patients) or PET-CT (449 patients) for detection of primary lesion and ALN metastasis before operation. They were divided into three groups including patients with both estrogen receptor (ER) negative and progesterone (PR) receptor negative [hormone receptor (HR) negative: 248 patients], those with both ER positive and histologic grade (HG) 3 or human epidermal growth factor receptor 2 (HER2) positive [luminal B: 283 patients], and those with ER positive, PR positive, HER2 negative, and HG 1 or 2 [luminal A: 515 patients]. NPVs of US, MRI, PET-CT, and their combinations were calculated in all patients and in three groups of patients, respectively.

Results

NPVs of US, MRI, and PET-CT were 81.9%, 81.3%, and 83.7% for all patients, respectively. They were higher in HR negative patients (89.5%, 87.5%, and 90.4%, respectively) than in all patients, and similar in luminal groups (luminal B: 83%, 78.2%, and 82.4%, respectively; luminal A: 78.2%, 79.4%, and 81.4%, respectively). US or MRI combined PET-CT slightly increased NPVs for all patients (MRI+PET-CT: 85.4% and US+PET-CT: 85.5%). This was due to increase of NPVs in HR negative group (MRI+PET-CT: 94.3% and US+PET-CT: 95%).

Conclusions

Adding PET-CT to US or MRI to predict ALN metastasis might improve NPVs in the EBC patients without HR.

Editorial acknowledgement

Clinical trial identification

Legal entity responsible for the study

Oyeon Cho.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.