LUGANO-COPENHAGEN, 29 September, 2016 Breast cancer patients over 50 years old could be spared invasive procedures by use of stratification based on tumour size and molecular characteristics, including Ki67. The cell proliferation index Ki67 is significantly associated with lymph node metastases in patients aged over 50 years and with smaller tumours, which may help reduce the need for sentinel lymph node biopsies in some women, researchers report at the ESMO 2016 Congress in Copenhagen.
The Ki67 protein is associated with cell proliferation and therefore gives an indication of the aggressiveness of disease, which makes it a useful indicator for treatment decisions in breast cancer. However previous research has not settled the question of the relationship between Ki67 and other tumour features such as size and axillary lymph node metastases.
Analysis of data from 1,785 patients treated for breast cancer (T1-T2, N0-N1) at the National Cancer Institute of Milan showed higher Ki67 values were significantly associated with larger tumour size and increased likelihood of axillary lymph node metastases in patients aged 50 years or older, regardless of hormone receptor or HER2 status.
“We may have found an indirect way of evaluating nodal status in a small subset of patients, thus sparing them some invasive procedures,” said principal investigator Dr Giacomo Bregni, from the IRCCS AOU San Martino and the IST-Istituto Nazionale per la Ricerca sul Cancro in Genova, Italy, previously working at the National Cancer Institute of Milan.
However, no relationship between Ki67 and axillary lymph node metastases was found in patients aged under 50 years or with tumours of 10mm or less in size.
Researchers also noted that the odds of axillary lymph node metastases increased by 42% for each 5mm increase in tumour size (95% CI: 1.33-1.51) in all breast cancers except triple negative cancers.
“Ongoing studies are evaluating axillary surgery and sentinel lymph node biopsy in breast cancer, and it could be worthwhile to consider a stratification based on tumour size and molecular characteristics including Ki67,” Dr Bregni said.
Providing independent comment on the study, Dr Giuseppe Viale from the University of Milan and the European Institute of Oncology, said, “Sentinel lymph node biopsy is the standard of care for the local treatment of patients with clinically node-negative early breast cancer, because it allows us to spare unnecessary completion axillary dissection.”
“However, some 70% of these patients will have a negative biopsy, thus raising the question whether we are able to identify patients for whom sentinel lymph node biopsy might be avoided.”
“The current study suggests that patients with exceptionally good prognosis, according to age, tumour size and tumour proliferative fraction, and those with triple-negative breast carcinoma are at such a low risk of axillary lymph node metastases that they may be spared sentinel lymph node biopsy.”
“This is a mono-institutional and retrospective study, and therefore hypothesis-generating, however a multi-centre clinical trial is currently recruiting more than 1000 patients to verify whether, in presence of a negative preoperative axillary assessment, sentinel lymph node biopsy can be spared and the decision on adjuvant medical treatment be taken according only to the biology of the tumour,” concluded Dr Viale.
-END-
Notes to Editors
References
1 Abstract 163P ‘Breast cancer ki67, tumor size and axillary nodes relationship, it’s complicated,’ will be presented by Dr. Giacomo Bregni during Poster Display Session ‘Breast Cancer, Early Stage’, on 10.10.2016, 13:00 - 14:00, Hall E
Disclaimer
This press release contains information provided by the authors of the highlighted abstracts and reflects the content of those abstracts. The commentators expressed their own independent opinion. It does not necessarily reflect the views or opinions of ESMO and ESMO cannot be held responsible for the accuracy of the data.
About the European Society for Medical Oncology
ESMO is the leading professional organisation for medical oncology. Comprising more than 13,000 oncology professionals from over 130 countries, we are the society of reference for oncology education and information. We are committed to supporting our members to develop and advance in a fast-evolving professional environment.
Founded in 1975, ESMO has European roots and a global reach: we welcome oncology professionals from around the world. We are a home for all oncology stakeholders, connecting professionals with diverse expertise and experience. Our educational and information resources support an integrated, multi-professional approach to cancer treatment. We seek to erase boundaries in cancer care as we pursue our mission across oncology, worldwide.
Abstract: 163P
Breast cancer Ki67, tumor size and axillary nodes relationship: it's complicated
Background
The cell proliferation labeling index Ki67 is a discussed parameter for treatment decisions in breast cancer (BC). Prior works have not settled the question whether Ki67 is independent of other tumor features. Herein, we investigated the relationship between Ki67, tumor size (T-size) and age with axillary lymph node metastases (ALNM) in early BC patients (pts).
Methods
We analyzed 1,785 pts treated for T1-T2 N0-N1 BC from 01/11/2011 to 30/09/2015 at Istituto Nazionale dei Tumori in Milan. Correlation between Ki67 and T-size was calculated by Spearman's coefficient, &rgr;. Associations of ALNM with Ki67 and other tumor characteristics were investigated by logistic regression. Fully adjusted odds ratio (OR) with 95% confidence intervals (CIs) were estimated in all cases, and separately analyzed according to T-size and age.
Results
Higher T-size was associated with higher Ki67 values in pts ≥50 years (ys) (&rgr; 0.343, p < 0.001) with no substantial differences according to hormone receptor (HR) and HER2 status. Such correlation was weaker (&rgr; 0.248, p < 0.001) in pts <50 ys with HER2 negative BC and absent among HER2 positive BCs. Ki67 values ≥20% were associated with increased odds of ALNM in pts aged ≥50 with T-size ≤10 mm (OR 2.87; 95% CI: 1.39-5.92). No relationship was found between Ki67 and ALNM in tumors > 10 mm and in pts aged <50. The odds of ALNM increased according to T-size (OR for each 5 mm increase 1.42; 95% CI: 1.33-1.51) in all BCs except the triple negative (TN). Noteworthy, compared to HR positive HER2 negative tumors, TN cases showed significantly lower odds of ALNM (OR 0.44; 95% CI: 0.21-0.91) in T-size >10 to 20 mm and in T-size >20 to 50 mm (OR 0.32; 95% CI: 0.16-0.67).
Conclusions
Our analysis seems to exclude significant relation between Ki67 and ALNM, while T-size and ALNM were confirmed to be highly related in all BCs but TN. Given these data it is appropriate to discuss if axillary surgery may be redundant in cases with exceptionally good prognosis and in pts with poor prognosis that will be offered systemic therapy and radiotherapy anyway. Hence BC pts aged > 50 with small tumors and low Ki67 and most TN pts represent ideal candidates for current clinical trials evaluating the potential for eliminating axillary surgery and sentinel node biopsy.
Legal entity responsible for the study
Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy
Funding
Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy
Disclosure
All authors have declared no conflicts of interest