Factors Associated with Lymph Node Involvement in T1 cT1N0 HER2-Positive Breast Cancer

Lymphovascular invasion, higher grade, negative progesterone receptor (PR) status, larger tumor size, and clinically rather than screen-detected cancers were found to be associated with lymph node involvement in T1 clinically node negative (cT1N0) HER2-positive breast cancers, according to a study conducted at Rush University Medical Center in Chicago, Illinois. 

The findings from this study were presented at the 37th Annual Miami Breast Cancer Conference, held in Miami, Florida from March 5-8, 2020. 

“HER2 directed neoadjuvant therapies for locally advanced HER2-positive breast cancer have improved complete pathologic response and event-free survival. For patients with T1 breast cancers, lymph node status often determines whether neoadjuvant or adjuvant treatment would be indicated,” the authors wrote. “The aim of our study was to identify patient and tumor characteristics associated with positive lymph nodes status in T1 HER2-positive breast cancer.”

Researchers conducted a retrospective review of the medical center’s tumor registry and identified adult patients diagnosed with cT1N0 HER2-positive breast cancers who had undergone surgical treatment followed by adjuvant therapy from January 2009 to October 2019. If patients had received neoadjuvant treatment, they were excluded from the study.

The primary outcome for the analysis was lymph node status. Other patient and tumor variables assessed included age, family and personal breast cancer history, gravida and para status, tumor size, method of tumor detection, histology, presence of simultaneous breast cancer, lymphovascular invasion, grade, and estrogen receptor (ER) and progesterone receptor (PR) status. Furthermore, Fischer’s Exact Test and Chi-Square Test were conducted to evaluate the relationship between patient and tumor variables, as well as lymph node positive disease.

Overall, 98 T1 HER2-positive breast cancers were identified that met the inclusion criteria. Further, 17 (17.35%) were found to have positive lymph nodes. Tumor characteristics correlated with lymph node positive disease included clinically rather than screen-detected cancer (P< 0.001), lymphovascular invasion (P= 0.010), higher grade (P= 0.015), and negative PR status (P= 0.036). There was also a significant difference observed in tumor size when comparing lymph node positive disease and lymph node negative disease (12.41 mm vs. 8.85 mm, respectively; P= 0.029). Moreover, though family history trended positive (P= 0.057), no patient characteristics, including age or personal history of breast cancer, were found to be significantly related. 

“These findings may help inform decisions regarding neoadjuvant treatment for this patient population,” the researchers wrote. 

Reference:

DeCesare L, O’Donoghue C, Nimmagadda N, et al. Pathologic Lymph Node Status among Patients with T1 HER2-Positive Breast Cancer who did not Undergo Neoadjuvant Chemotherapy. Presented at the 37th Annual Miami Breast Cancer Conference held from May 5-8, 2020 in Miami, Florida. Poster 29.