Overweight and obesity are a growing health problem worldwide and are linked to poor quality of life and BC outcomes. Fewer data are available that describe patterns of weight change or evaluate robust associations with weight gain following BC in a European population.
We used data collected from 4875 women with Stage I-III BC included in an ongoing prospective French multicenter clinical study from 2012-14 (CANTO, NCT01993498). Body Mass Index (BMI) and physical activity (PA) were assessed at diagnosis (dx), 3-6 (T1) and 12 (T2) months after primary treatment. Weight changes ≥ 5% of weight at dx were considered significant. Group based trajectory models (GBTM) described risk of overweight or obesity over time. Multivariate logistic regression assessed factors associated with significant weight gain at T1 and T2.
At dx, mean age was 56 y (range 22-88), median BMI was 24.6 (range 14.7-59.0), 29% pts were overweight and 19% obese. 54% pts received chemo (CT) and 82% endocrine therapy (ET). GBTM found that the majority of overweight and obese pts remained so over time. By T2, weight increased in 24% pts (median gain + 5 Kg [range 2-33]), was stable in 63% pts and decreased in 13% pts in the overall population. Factors associated with higher risk of significant weight gain by T2 included age <50 vs > 65 (adjusted odds ratio 2.1 [95% Confidence Interval 1.3-3.2]), receipt of CT vs no (1.6 [1.3-2.1]), receipt of ET vs no (1.7 [1.1-2.7]), PA < 10 MET-hours/week vs ≥ (1.3 [1.1-1.6]) and having already gained weight by T1 (for each Kg gained, 1.6 [1.5-1.6]) (Table).Table: 1738P
Multivariate logistic regression of factors associated with weight gain after BC in the overall population (N = 4875)
|T1 (3-6 months after treatment)||T2 (12 months after treatment)|
|% pts who gained weight||aOR* (95% CI)||% pts who gained weight||aOR* (95% CI)|
|Age (years) <50 50-65 >65||25 17 8||2.8 (1.8-4.2) 2.2 (1.6-3.0) ref||35 24 11||2.1 (1.3-3.2) 2.0 (1.5-2.7) ref|
|BMI at diagnosis (kg/m2) Underweight (<18.5) Normal (18.5-24.9) Overweight (25.0-29.9) Obese (≥30)||25 18 16 14||1.7 (0.9-3.0) 1.3 (1.1-1.7) 1.4 (1.1-1.9) ref||33 26 24 18||1.9 (1.1-3.4) 1.7 (1.2-2.3) 1.7 (1.3-2.4) ref|
|Level of Physical Activity^ Failing to reach 10 Reach/maintain ≥10||16 17||1.0 (0.8-1.2) ref||26 22||1.3 (1.1-1.6) ref|
|Receipt of chemotherapy Yes No||21 12||1.3 (1.1-1.7) ref||29 18||1.6 (1.3-2.1) ref|
|Receipt of endocrine therapy Yes No||16 19||1.1 (0.7-1.5) ref||24 25||1.7 (1.1-2.7) ref|
|Weight gain at T1 Continuous, for 1 Kg gained||-||-||-||1.6 (1.5-1.6)|
aOR= adjusted odds ratio; CI= confidence interval.*
Adjusted for all variables in the table + menopausal status, education, smoking status, alcohol, tumor stage, subtype, breast and axillary surgery. ^In Metabolic Equivalent of Task (MET)-hours/week, based on World Health Organization recommendations on physical activity and expressed as change in physical activity behavior from diagnosis to T1 and to T2, respectively.
In this large contemporary epidemiology study of French BC survivors, a significant proportion of pts were overweight or obese at dx, and one in four of all pts gained substantial weight after treatment. Weight gain is particularly common in pts who are younger, treated with CT or ET and less physically active. Our data will inform weight loss survivorship programs targeting pts at higher risk of overweight, obesity and weight gain after BC.
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A. Di Meglio: Recipient of the 2017 ESMO Clinical research Fellowship Award. I. Vaz-Luis: Recipient of research grants from Susan Komen for the Cure and the “Association pour la recherche sur le cancer (ARC)”. All other authors have declared no conflicts of interest.