Adequacy of early-stage breast cancer systemic adjuvant treatment to Saint Gallen-2013 statement: the MCC-Spain study

Inés Gómez‐Acebo ,María Fernández-Ortiz,Claudia Suárez-Calleja ,O Sanz-Guadarrama ,María Sala ,Ana Molina‐Barceló ,A Molina ,Vı́ctor Moreno ,Rafael Marcos‐Gragera ,Núria Aragonés ,Conchi Moreno‐Iribas ,Beatriz Pérez‐Gómez ,Gemma Castaño‐Vinyals ,Manolis Kogevinas,Jéssica Alonso-Molero,Marcela Guevara,Mónica Mirones,Pilar Amiano,Juan Alguacil,Marina Pollán,Leire Gil-Majuelo,Trinidad Dierssen-Sotos,Javier Llorca

doi:10.1038/s41598-021-84825-2

Abstract

The St Gallen Conference endorsed in 2013 a series of recommendations on early breast cancer treatment. The main purpose of this article is to ascertain the clinical factors associated with St Gallen-2013 recommendations accomplishment. A cohort of 1152 breast cancer cases diagnosed with pathological stage < 3 in Spain between 2008 and 2013 was begun and then followed-up until 2017/2018. Data on patient and tumour characteristics were obtained from medical records, as well as their first line treatment. First line treatments were classified in three categories, according on whether they included the main St Gallen-2013 recommendations, more than those recommended or less than those recommended. Multinomial logistic regression models were carried out to identify factors associated with this classification and Weibull regression models were used to find out the relationship between this classification and survival. About half of the patients were treated according to St Gallen recommendations; 21% were treated over what was recommended and 33% received less treatment than recommended. Factors associated with treatment over the recommendations were stage II (relative risk ratio [RRR] = 4.2, 2.9–5.9), cancer positive to either progesterone (RRR = 8.1, 4.4–14.9) or oestrogen receptors (RRR = 5.7, 3.0–11.0). Instead, factors associated with lower probability of treatment over the recommendations were age (RRR = 0.7 each 10 years, 0.6–0.8), poor differentiation (RRR = 0.09, 0.04–0.19), HER2 positive (RRR = 0.46, 0.26–0.81) and triple negative cancer (RRR = 0.03, 0.01–0.11). Patients treated less than what was recommended in St Gallen had cancers in stage 0 (RRR = 21.6, 7.2–64.5), poorly differentiated (RRR = 1.9, 1.2–2.9), HER2 positive (RRR = 3.4, 2.4–4.9) and luminal B-like subtype (RRR = 3.6, 2.6–5.1). Women over 65 years old had a higher probability of being treated less than what was recommended if they had luminal B-like, HER2 or triple negative cancer. Treatment over St Gallen was associated with younger women and less severe cancers, while treatment under St Gallen was associated with older women, more severe cancers and cancers expressing HER2 receptors.

Highlights

The St Gallen Conference endorsed in 2013 a series of recommendations on early breast cancer treatment
We hereby briefly summarize St Gallen-2013 recommendations according to breast cancer (BC) subtypes that are almost identical to those formulated in the previous meeting
Patients with luminal A-like BC should be treated with endocrine therapy, cytotoxics may be added in the case of selected patients

Summary

Introduction

The St Gallen Conference endorsed in 2013 a series of recommendations on early breast cancer treatment. Patients with luminal B-like (HER2 positive) BC should receive cytotoxics, anti-HER2 and endocrine therapy; patients with HER2 positive (non-luminal) BC should receive cytotoxics and anti-HER2 and patients with triple negative (basal-like) BC should be treated with cytotoxics It is noteworthy, that St Gallen panel was not unanimous in most of its decisions and it remarked that its recommendations were not just a blind guide; instead, “detailed decisions on treatment will, as always, involve clinical considerations of disease extent, host factors, patient preferences and social and economic constraints”[5]. Our objectives are: (1) to ascertain the clinical factors associated with St Gallen-2013 recommendations accomplishment, (2) to investigate whether there are differences by age and intrinsic BC subtype regarding St Gallen fulfilment, and (3) to examine the impact St Gallen non-fulfilment may have on survival with breast cancer. As most women in MCC-Spain were recruited before the 13th St Gallen Conference, St Gallen recommendations cannot be interpreted as a gold standard; our purpose is not to perform an audit but to identify patterns in actual clinical practice

Objectives

Methods

Results

Conclusion