title: Body mass index, PAM50 subtype, recurrence, and survival among patients with nonmetastatic breast cancer.
abstract: BACKGROUND
  Studies of obesity and survival among patients with breast cancer produce conflicting results, possibly because of heterogeneity by molecular subtype.
  
  
  METHODS
  This study examined whether the association of body mass index (BMI) at diagnosis with breast cancer recurrence and survival varied across subtypes defined by PAM50 (Prediction Analysis of Microarray 50) gene expression. Included were 1559 Kaiser Permanente Northern California members ages 18 to 79 years who had PAM50 assays and were diagnosed with American Joint Committee on Cancer stage I through III breast cancer from 1996 to 2013. Patients reported weight and height. Cox regression models were adjusted for age, menopause, race/ethnicity, stage, and chemotherapy.
  
  
  RESULTS
  Over a median of 9 years (maximum, 19 years), 378 women developed recurrent disease, and 312 died from breast cancer. Overall, BMI was not associated with breast cancer recurrence or survival when controlling for subtype (eg, the hazard ratio per 5 kg/m2of BMI was 1.05 [95% confidence interval, 0.95-1.15] for breast cancer-specific death). However, associations varied by subtype. Among women with luminal A cancers, those who had class II/III obesity, but not class I obesity or overweight, had worse outcomes. When women who had a BMI ≥35 kg/m2were compared with those who had a BMI from 18.5 to <25 kg/m2, the hazard ratio was 2.24 (95% confidence interval,1.22-4.11) for breast cancer-specific death and 1.24 (95% confidence interval, 1.00-1.54) for recurrence. There was no association within luminal B, basal-like or human epidermal growth factor over-expressing subtypes.
  
  
  CONCLUSIONS
  Among patients who had accurately classified breast cancer subtypes based on gene expression, a BMI ≥35 kg/m2was adversely associated with outcomes only among those who had luminal A cancers. Research is needed into whether tailoring recommendations for weight management to tumor characteristics will improve outcomes. Cancer 2017;123:2535-42. © 2017 American Cancer Society.
authors.affiliation: Division of Research, Kaiser Permanente Northern California, Oakland, California.
authors.forename: Elizabeth M
authors.identifier: http://orcid.org/0000-0003-1192-4017
authors.initials: EM
authors.lastname: Cespedes Feliciano
authors.affiliation: Division of Research, Kaiser Permanente Northern California, Oakland, California.
authors.forename: Marilyn L
authors.initials: ML
authors.lastname: Kwan
authors.affiliation: Division of Research, Kaiser Permanente Northern California, Oakland, California.
authors.forename: Lawrence H
authors.initials: LH
authors.lastname: Kushi
authors.affiliation: Channing Division of Network Medicine, Brigham and Women's Hospital, Boston, Massachusetts.|Department of Medical Oncology, Dana Farber Cancer Institute, Boston, Massachusetts.
authors.forename: Wendy Y
authors.initials: WY
authors.lastname: Chen
authors.affiliation: Division of Research, Kaiser Permanente Northern California, Oakland, California.
authors.forename: Erin K
authors.initials: EK
authors.lastname: Weltzien
authors.affiliation: Division of Research, Kaiser Permanente Northern California, Oakland, California.
authors.forename: Adrienne L
authors.initials: AL
authors.lastname: Castillo
authors.affiliation: Utah Cancer Registry, Department of Internal Medicine and Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah.
authors.forename: Carol
authors.initials: C
authors.lastname: Sweeney
authors.affiliation: School of Medicine, Department of Pathology and Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah.
authors.forename: Philip S
authors.initials: PS
authors.lastname: Bernard
authors.affiliation: Division of Research, Kaiser Permanente Northern California, Oakland, California.
authors.forename: Bette J
authors.initials: BJ
authors.lastname: Caan
mesh_terms: D000328:Adult; D000368:Aged; D015992:Body Mass Index; D001943:Breast Neoplasms / Q000235:genetics / Q000401:mortality* / Q000473:pathology / Q000628:therapy; D002140:California / Q000453:epidemiology; D015897:Comorbidity; D005260:Female; D006801:Humans; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000453:epidemiology*; D009367:Neoplasm Staging; D009765:Obesity / Q000453:epidemiology*; D050177:Overweight / Q000453:epidemiology; D011379:Prognosis; D016016:Proportional Hazards Models; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D011960:Receptors, Estrogen / Q000378:metabolism; D011980:Receptors, Progesterone / Q000378:metabolism; D012189:Retrospective Studies; D012307:Risk Factors; D015996:Survival Rate; D059467:Transcriptome
chemical_list: D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; C508053:ERBB2 protein, human
keywords: Prediction Analysis of Microarray 50 (PAM50) gene expression assay; body mass index; breast cancer subtype; molecular classification; mortality; obesity; recurrence; survival