71P - Is St Gallen 2013 intrinsic subtype classification valid in routine practice?

Date 18 December 2016
Event ESMO Asia 2016 Congress
Session Poster lunch
Topics Breast Cancer, Early Stage
Pathology/Molecular Biology
Presenter Chanyoot Bandidwattanawong
Citation Annals of Oncology (2016) 27 (suppl_9): ix19-ix29. 10.1093/annonc/mdw575
Authors C. Bandidwattanawong1, N. Chalermsuksant2
  • 1Medical Oncology Unit, Department Of Internal Medicine, Bangkok Metropolitan Administration Medical School and Vajira Hospital, 10300 - Bangkok/TH
  • 2Department Of Internal Medicine, Bangkok Metropolitan Administration Medical School and Vajira Hospital, 10300 - Bangkok/TH

Abstract

Background

Breast cancer is the most common cancer among female Thais. Molecular intrinsic subtyping is the best method to classify patients into groups of different prognosis and probably guidance of proper treatment. Intrinsic subtyping based on St Gallen 2013 Expert Concensus using IHC for ER, PR, HEr-2 and Ki-67 is more practical way, however validation in Thai early breast cancer patients was never done.

Methods

We collected data of early breast cancer patients treated in Vajira Hospital from January 1, 2006 to December 31, 2011. There were 171 patients eligible. Baseline characteristics including age, staging, treatments, patterns of recurrence were recorded. No central review for IHC for ER, PR and HER-2 were done. Ki-67 was determined by our institute's pathologists. Primary aim was to calculate the prevalence of breast cancer patients of different subtypes stratified by St Gallen 2013 Concensus. Secondary ones were to determine patterns of recurrences and survival among patients with different subtypes.

Results

We stratified our patients based on only IHC results according to St Gallen 2013 Expert Consensus criteria. There were 32.7% LuA, 30.4% LuB, 18.7% HER-2-enriched and 18.1% triple negative. OS (95%CI) of patients with LuA was 103.17(93.54-112.80), LuB 105.63 (95.46-115.80), HER-2-enriched 87.5 (66.76-108.24) and triple negative 95 (72.72-103.48) months. More patients with LuB subtype had bone and soft tissue metastases. Visceral metastases were found more in patients with HER-2-enriched and triple negative subtypes. Lu A subtype was the only prognostic factor survival regardless of nodal status. Prevalences and survival patterns imitated the data from studies using multi-gene assay.

Conclusions

Stratification of ealy breast cancer patients into subtypes based on 2013 St Gallen Expert Consensus is robust in routine practice. It is the cheaper and more practical tool compared to costly molecular techniques.

Clinical trial indentification

COA 26/2559

Legal entity responsible for the study

Research Facilitation Division, Faculty of Medicine Vajira Hospital

Funding

Research Facilitation Division, Faculty of Medicine Vajira Hospital

Disclosure

All authors have declared no conflicts of interest.