['To examine the prevalence of self-reported functional limitations in a breast cancer population, identify whether these reported limitations are attributed to breast cancer versus other coexisting illnesses, and examine how this attribution changes over time from early in treatment to 9 months later.', 'Longitudinal, observational study.', 'Community dwelling adults in Detroit metropolitan area.', '2033 participants (1011 breast cancer patients, 1022 controls) aged 40-84 years.', 'Participants were asked about each of 23 possible coexisting illnesses in addition to breast cancer and whether or not each illness, including breast cancer, caused any activity limitation.', 'Of the 933 cancer patients who completed both baseline and follow-up evaluations, 45% were aged 65 years and older. At baseline, 56% of patients 65 years and older reported functional limitation compared with 50% of patients younger than 65 years (p=0.005). Of those patients who reported limitation at baseline, 59% of older patients and 78% of younger patients attributed their limitation to breast cancer (p<0.001). At follow-up, 53% of older and 37% of younger patients reported functional limitation (p<0.001), with 27% of older patients compared with 57% of younger patients (p<0.001) attributing limitation to breast cancer.'] Does attribution of functional limitation to cancer decrease in the year following breast cancer diagnosis in older patients?