title: The impact of overweight and obesity on breast cancer: data from Switzerland, so far a country little affected by the current global obesity epidemic.
abstract: This review presents results from the project "The Impact of Overweight/Obesity on Breast Cancer: data from Switzerland". Swiss data is interesting because the general female population is distinctive in two areas when compared to that of most other industrialized countries: Switzerland has comparatively low rates of overweight (22-23%) and obesity (7-8%) and has rather stable rates of overweight and obesity. The entire project comprised three major issues: (I) etiology of breast cancer (BC). There is a consistently shown association between obesity and postmenopausal BC risk in countries with high obesity prevalence rates in the literature. In our Swiss study group, however, we did not find higher rates of overweight and obesity in postmenopausal BC cases than in the general population. A possible explanation for this observation may be a curvilinear dose-response relationship between BMI and postmenopausal BC risk, so that an increased risk may only be observed in populations with a high prevalence of obese/very obese women; (II) tumor characteristics. BMI was significantly associated with tumor size; this applied not only to the cases where the tumor was found by self-detection, but also to lesions detected by radiological breast examinations. In addition, a higher BMI was positively correlated with advanced TNM stage, unfavorable grading and a higher St. Gallen risk score. No associations were observed between BMI and histological subtype, estrogen receptor status, HER2 status and triple negative BC; (III) patient compliance and persistence towards adjuvant BC therapy. Many studies found that the prognosis of overweight/obese BC patients was significantly lower than that of normal weight patients. However, failure of compliance and persistence towards therapy on the part of the patient is not a contributing factor for this observed unfavorable prognosis. In most therapy modes, patients with increasing BMI demonstrated greater motivation and perseverance towards the recommended treatment.
authors.affiliation: 1 Hospital Grabs, Department of Gynecology & Obstetrics, Breast center, CH-9472 Grabs, Switzerland ; 2 Institute of Social and Preventive Medicine, University of Zürich, CH-8001 Zürich, Switzerland ; 3 University Hospital Basel, Department of Gynecology and Obstetrics, CH-4031 Basel, Switzerland ; 4 Cantonal Hospital Winterthur, Department of Gynecology & Obstetrics, Breast center "SenoSuisse", CH-8401 Winterthur, Switzerland.
authors.forename: Simone
authors.initials: S
authors.lastname: Kann
authors.affiliation: 1 Hospital Grabs, Department of Gynecology & Obstetrics, Breast center, CH-9472 Grabs, Switzerland ; 2 Institute of Social and Preventive Medicine, University of Zürich, CH-8001 Zürich, Switzerland ; 3 University Hospital Basel, Department of Gynecology and Obstetrics, CH-4031 Basel, Switzerland ; 4 Cantonal Hospital Winterthur, Department of Gynecology & Obstetrics, Breast center "SenoSuisse", CH-8401 Winterthur, Switzerland.
authors.forename: Seraina Margaretha
authors.initials: SM
authors.lastname: Schmid
authors.affiliation: 1 Hospital Grabs, Department of Gynecology & Obstetrics, Breast center, CH-9472 Grabs, Switzerland ; 2 Institute of Social and Preventive Medicine, University of Zürich, CH-8001 Zürich, Switzerland ; 3 University Hospital Basel, Department of Gynecology and Obstetrics, CH-4031 Basel, Switzerland ; 4 Cantonal Hospital Winterthur, Department of Gynecology & Obstetrics, Breast center "SenoSuisse", CH-8401 Winterthur, Switzerland.
authors.forename: Monika
authors.initials: M
authors.lastname: Eichholzer
authors.affiliation: 1 Hospital Grabs, Department of Gynecology & Obstetrics, Breast center, CH-9472 Grabs, Switzerland ; 2 Institute of Social and Preventive Medicine, University of Zürich, CH-8001 Zürich, Switzerland ; 3 University Hospital Basel, Department of Gynecology and Obstetrics, CH-4031 Basel, Switzerland ; 4 Cantonal Hospital Winterthur, Department of Gynecology & Obstetrics, Breast center "SenoSuisse", CH-8401 Winterthur, Switzerland.
authors.forename: Dorothy Jane
authors.initials: DJ
authors.lastname: Huang
authors.affiliation: 1 Hospital Grabs, Department of Gynecology & Obstetrics, Breast center, CH-9472 Grabs, Switzerland ; 2 Institute of Social and Preventive Medicine, University of Zürich, CH-8001 Zürich, Switzerland ; 3 University Hospital Basel, Department of Gynecology and Obstetrics, CH-4031 Basel, Switzerland ; 4 Cantonal Hospital Winterthur, Department of Gynecology & Obstetrics, Breast center "SenoSuisse", CH-8401 Winterthur, Switzerland.
authors.forename: Esther
authors.initials: E
authors.lastname: Amann
authors.affiliation: 1 Hospital Grabs, Department of Gynecology & Obstetrics, Breast center, CH-9472 Grabs, Switzerland ; 2 Institute of Social and Preventive Medicine, University of Zürich, CH-8001 Zürich, Switzerland ; 3 University Hospital Basel, Department of Gynecology and Obstetrics, CH-4031 Basel, Switzerland ; 4 Cantonal Hospital Winterthur, Department of Gynecology & Obstetrics, Breast center "SenoSuisse", CH-8401 Winterthur, Switzerland.
authors.forename: Uwe
authors.initials: U
authors.lastname: Güth
keywords: Breast cancer; drug compliance and persistence; overweight; risk factor; tumor characteristics