11: Neoadjuvant Chemotherapy and Nodal Response Rates in Luminal Breast Cancer: effects of Age and Tumor ki67

Friday, March 11, 2022

10:31 AM – 10:39 AM CST

Location: Trinity Ballroom

Abstract Presenter(s)

Judy C. Boughey, MD, FACS

Professor of Surgery, W.H. Odell Professor in Individualized Medicine, Chair-Division of Breast and Melanoma Surgical Oncology, Department of Surgery
Mayo Clinic
Rochester, Minnesota, United States

Disclosure: Cairns Surgical (Individual(s) Involved: Self): Data Safety Monitoring Committee work; SymBioSis (Individual(s) Involved: Self): Royalties

Participants should be aware of the following financial/non-financial relationships:

Judy C. Boughey, M.D.: Cairns Surgical (Individual(s) Involved: Self): Data Safety Monitoring Committee work; SymBioSis (Individual(s) Involved: Self): Royalties

Introduction: Neoadjuvant chemotherapy (NAC) is standard for triple negative breast cancer (BC) and HER2+ BC, as response is prognostic and NAC downstages node positive (cN+) disease, thus permitting omission of axillary dissection. However, for HR+/HER2- BC, NAC use is variable and response rates are much lower and thus rates of axillary dissection are higher. Whether Ki-67 is associated with axillary downstaging is unknown.

Methods: With IRB approval, we queried our institutional database to identify all patients (pts) with primary HR+/HER2- biopsy proven cN+ BC (Stage I-III) treated with NAC followed by surgery 01/2012-08/2021. Differences in rate of nodal pCR and breast pCR were evaluated by pre-treatment Ki67.

Results:

326 pts (287 cN1, 11 cN2, 28 cN3) were included. Median age was 50 years (range 22-79). Nodal pCR rate was 26.4% (86/326) and was higher in pts age< 50 than ≥50 (35.8% vs 17.4%, p< 0.001).

Ki67 was available on 233 pts (71%). Ki67 missingness did not vary significantly by clinical factors. Median pre-treatment Ki67 was 30% (range 1-98%). Ki67 did not differ significantly by age category (p=0.18) but did vary by grade (p< 0.001). Those with nodal pCR had significantly higher Ki67 vs those without (median 42% vs 28%, p< 0.001); and this was also true among pts age< 50 and pts age≥50 considered separately. On multivariable analysis, Ki67 and age category were predictive of nodal pCR, while grade was not significant. Nodal pCR was 29.8% in Ki67≥20% group compared to 7.7% with Ki67< 20% (p< 0.001). In age< 50, 40.2% of pts with Ki67≥20% had nodal pCR vs 13.3% nodal pCR with Ki67< 20% (p=0.007). In age≥50, nodal pCR was 19.8% for Ki67≥20% and only 2.9% with Ki67< 20% (p=0.02), Table.

Conclusions:

For pts with HR+/HER2- breast cancer treated with NAC, nodal downstaging is associated with age (< 50) and Ki-67 (≥20%). Rates of nodal pCR in pts≥50 years with Ki67< 20% are very low (< 3%), while for age< 50 and Ki-67≥20%, nodal downstaging occurred in >40% of pts. These data suggest that age and Ki67 should be considered for NAC decision making and can identify pts with high rates of nodal downstaging who may benefit from NAC to enable axillary preservation.

Learning Objectives:

Upon completion, participant will be able to describe how rates of nodal pathologic complete response in patients with luminal breast cancer vary by age
Upon completion, participant will be able to describe how rates of nodal pathologic complete response in patients with luminal breast cancer vary by Ki67
Upon completion, participant will understand how age and Ki67 can help identify patients with highest likelihood of nodal pCR and thus most likely to be considered for axillary preservation