Obesity and the outcome of young breast cancer patients in the UK: The POSH study
Session type: Poster / e-Poster / Silent Theatre session
Obese patients with early breast cancer have a poorer prognosis than non-obese patients. Host factors, tumour pathology and treatment issues have been suggested as possible factors. We examined data from the multi-centre Prospective Outcomes of Sporadic and Hereditary breast cancer study to investigate this in pre-menopausal women.
2956 patients aged ≤40 at breast cancer diagnosis were recruited from 126 UK hospitals between 2001 and 2007. Details of body mass index (BMI), tumour pathology and treatment were collected. Follow-up data were collected at 6 months, 12 months and then annually. Adjuvant chemotherapy prescriptions were reviewed for 85 patients treated locally.
BMI data were available for 2842 (96.1%) patients: 36 (1.3%) were underweight (BMI<18.5), 1489 (52.4%) were healthy weight (18.5≤BMI<25), 784 (27.6%) were overweight (25≤BMI<30) and 533 (18.8%) were obese (BMI≥30). There was a significant difference in 8-year overall survival between BMI categories (p<0.001), with survival of obese patients (58.6%) almost 15% lower than healthy weight patients (73.3%). Median tumour size was significantly higher in obese patients than normal weight patients (26mm vs. 20mm, p<0.001). Obese patients had significantly more grade 3 tumours (63.9% vs. 58.8%, p=0.042) and node positive tumours (54.6% vs. 49.4%, p=0.040) than normal weight patients. ER negative tumours were more frequent in obese patients than normal weight patients (68.0% vs. 59.9%, p=0.001) whereas the incidence of HER 2 positive tumours was similar (28.2% vs. 27.3%, p=NS). Obese patients were significantly more likely to experience a chemotherapy dose delay than healthy weight patients (33.3% vs. 5.9%, p=0.007).
Obesity at diagnosis is associated with inferior survival in young breast cancer patients. Our data confirms that obesity is associated with biologically adverse tumours. Furthermore, more obese patients receive sub-optimal chemotherapy than healthy weight patients. Further studies will explore the effect of body composition on chemotherapy tolerance.