Do you use breast cancer index (BCI) in patients with 1-3 node positive ER+/HER2- IDC?

The only clinical case where I would consider ordering a BCI in a female patient with 1-3 positive lymph nodes would be in a postmenopausal woman who is considering to take adjuvant tamoxifen for 10 years vs 5 years based on the aTTom trial (Bartlett et al., PMID 31504126).

I do not order BCI in other clinical scenarios, such as in premenopausal women or in postmenopausal women taking an aromatase inhibitor. The data on BCI on NSABP-42 has been presented, and in my opinion, BCI did not show a solid predictive value of extended adjuvant endocrine therapy in this clinical trial. Also, I always consider toxicities and compliance with adjuvant endocrine therapy before considering an extended adjuvant endocrine therapy recommendation.