Are lower rates of surgery amongst older women with breast cancer in the UK explained by co-morbidity?

Background: Around 60% of women greater than or equal to 80 years old, in the UK do not have surgery for their breast cancer (vs<10% of younger age groups). The extent to which this difference can be accounted for by co-morbidity has not been established. Methods: A Cancer Registry/Hospital Episode Statistics-linked data set identified women aged greater than or equal to 65 years diagnosed with invasive breast cancer (between 1 April 1997 and 31 March 2005) in two regions of the UK (n=23 038). Receipt of surgery by age was investigated using logistic regression, adjusting for co-morbidity and other patient, tumour and treatment factors. Results: Overall, 72% of older women received surgery, varying from 86% of 65–69-year olds to 34% of women aged greater than or equal to 85 years. The proportion receiving surgery fell with increasing co-morbidity (Charlson score 0=73%, score 1=66%, score 2+=49%). However, after adjustment for co-morbidity, older age still predicts lack of surgery. Compared with 65–69-year olds, the odds of surgery decreased from 0.74 (95% CI: 0.66–0.83) for 70–74-year olds to 0.13 (95% CI: 0.11–0.14) for women aged greater than or equal to 85 years. Conclusion: Although co-morbidity is associated with a reduced likelihood of surgery, it does not explain the shortfall in surgery amongst older women in the UK. Routine data on co-morbidity enables fairer comparison of treatment across population groups but needs to be more complete.