Validity of Adjuvant! Online program in older patients with breast cancer: a population-based study

Adjuvant! Online is a prediction tool that can be used to aid clinical decision making in patients with breast cancer. It was developed in a patient population aged 69 years or younger, and subsequent validation studies included small numbers of older patients. Since older patients with breast cancer differ from younger patients in many aspects, the aim of this study was to investigate the validity of Adjuvant! Online in a large cohort of unselected older patients.

We included patients from the population-based FOCUS cohort, which included all consecutive patients aged 65 years or older who were diagnosed with invasive or in-situ breast cancer between Jan 1, 1997, and Dec 31, 2004, in the southwestern part of the Netherlands. We included all patients who fulfilled the criteria as stated by Adjuvant! Online: patients with unilateral, unicentric, invasive adenocarcinoma; no evidence of metastatic or residual disease; no evidence of T4 features; and no evidence of inflammatory breast cancer. We entered data from all patients with the "average for age" comorbidity status (model 1) and with an individualised comorbidity status (model 2).

We included 2012 patients. Median age of patients in the cohort was 74·0 years (IQR 69·0-79·0). 904 (45%) of 2012 patients died during follow-up, whereas 326 (16%) patients had recurrence. Median follow-up for overall survival was 9·0 years (IQR 7·4-10·7), and 6·6 years (4·4-6·6) for patients without recurrence. Using model 1, Adjuvant! Online overestimated 10-year overall survival by 9·8% ([95% CI 5·9-13·7], p<0·0001) and 10-year cumulative recurrence survival by 8·7% ([6·7-10·7], p<0·0001). By contrast, when using model 2, Adjuvant! Online underestimated the 10-year overall survival by -17·1% ([95% CI -21·0 to -13·2], p<0·0001). However, when using model 2, Adjuvant! Online predicted cumulative recurrence accurately in all patients (-0·7% [95% CI -2·7-1·3], p=0·48).

Adjuvant! Online does not accurately predict overall survival and recurrence in older patients with early breast cancer.

Dutch Cancer Foundation.