Serum assessment of non-adherence to adjuvant endocrine therapy (ET) among premenopausal patients in the prospective multicenter CANTO cohort

Date 19 October 2018
Event ESMO 2018 Congress
Session Proffered paper session - Breast cancer, early stage
Topics Anticancer Agents
Breast Cancer
Presenter Barbara Pistilli
Authors B. Pistilli1, A. PACI2, S. Michiels3, A. ferreira4, V. poinsignon2, P.H. Cottu5, F. Lerebours6, C. Coutant7, A. Lesur8, O. Tredan9, P. Soulie10, L. Vanlemmens11, C. Jouannaud12, C. Levy13, S. Everhard14, P. Arveux7, A.H. Partridge15, S. Delaloge16, F. André17, I. Vaz-Luis18
  • 1Breast Cancer Group, GUSTAVE ROUSSY, 94800 - Villejuif/FR
  • 2Pharmacologist Unit And Sipam, GUSTAVE ROUSSY, 94800 - Villejuif/FR
  • 3Team Oncostat, Cesp, Gustave Roussy, 94805 - Villejuif/FR
  • 4Medical Oncology, University of Lisbon, lisbon/PT
  • 5Medical Oncology, Institut Curie, 75248 cedex5 - Paris/FR
  • 6Medical Oncology, Institut Curie Saint Cloud, 92210 - Saint Cloud/FR
  • 7Medical Oncology, Centre Georges-François Leclerc (Dijon), 21000 - Dijon/FR
  • 8Medical Oncology, Institut de cancérologie de Lorraine, 54519 - Nancy/FR
  • 9Medical Oncology, Centre Léon Bérard, 69008 - Lyon/FR
  • 10Medical Oncology, Centre Paul Papin, 49055 - Angers/FR
  • 11Medical Oncology, Centre Oscar Lambret, 59020 - Lille/FR
  • 12Medical Oncology, Institut Jean Godinot, 51056 - Reims/FR
  • 13Medical Oncology, Centre Francois Baclesse, 14076 - Caen/FR
  • 14Ucbg, UNICANCER, 75654 - Paris/FR
  • 15Medical Oncology, Dana-Farber Cancer Institute, MA 02215, - Boston/US
  • 16Medical Oncology, Gustave Roussy, 94805 - Villejuif/FR
  • 17Breast Cancer Unit, Department Of Medical Oncology, Gustave Roussy - Cancer Campus, 94805 - Villejuif/FR
  • 18Medical Oncology, Institut Gustave Roussy, 94800 - Villejuif/FR



Previous studies demonstrated that younger patients (pts) with breast cancer (BC) are more likely to be non-adherent to adjuvant ET, leading to impaired prognosis.


The CANTO cohort (NCT01993498) is a French multicenter prospective longitudinal study that will include 12000 pts with recently diagnosed stage I-III BC, to characterize long-term impact of BC treatment toxicities. CANTO COMPLETE, a pre-defined sub study, aims to determine, in premenopausal pts who have been prescribed adjuvant ET, the prevalence and dynamic predictors of non-adherence, at 1 (M12), 3 (M36) and 5 (M60) years, using serum assessment of tamoxifen (TAM) and aromatase-inhibitors (AI) matched with pts’ self-declaration. TAM dosage has been determined by liquid chromatography-tandem mass spectrometry on 200 µL of serum. According to standard definitions, adherence to TAM has been defined as: non-adherent if TAM ≤15 ng/mL (≤40 nM), poorly-adherent if TAM 15-60 ng/mL (40-150 nM) and adherent if > 60 ng/mL (>150 nM).


By December 2017, 11237 pts have been included in CANTO, of whom 1799 (16%) are premenopausal and have been prescribed and agreed to take ET: TAM 1496 (83.2%); TAM + LHRH-analogs (LHRH) 26 (1.4%); AI+LHRH 134 (7.5%); unknown 143 (7.9%).We present here the results of TAM plasma assessment at 1 year on all 1228 pts who reached 1 year of follow-up. Overall, 224 (18.2%) pts appeared not adequately adherent to TAM: 162 (13.2%) non-adherent and 62 (5.0%) poorly-adherent. Matching with pts’ self-declaration and clinical determinants of non-adherence will be presented.


At one year from initiation of TAM, plasma measurements show that a substantial proportion of premenopausal pts are not adequately adherent to this treatment. Poorly-adherent pts could benefit from metabolic and pharmacogenetic investigations. Identification of pts at risk of non-adherence allows early targeted interventions to promote adherence in this unique population.

Clinical trial identification


Editorial Acknowledgement