低Magee方程式によるT1乳がんの経済的エスカレーション解除：ゲノム検査なしの単一施設からの経験

The Oncotype Dx^® assay is a validated tool for determining prognosis and predicting benefit from adjuvant systemic chemotherapy in patients with node-negative, early-stage hormone receptor (HR)-positive, human epidermal growth factor receptor-2 (HER-2)-negative breast cancer. However, genomic testing could incur additional costs, impacting both the patient and the health system. This study aims to explore a subset of patients with a Magee equation score ≤18 who may safely forgo Oncotype Dx^® testing.

Single institution retrospective analysis of postmenopausal patients with de novo, unifocal breast carcinoma that is node negative, Nottingham grade 1, T1, HR positive (>1%), and HER-2 negative. Magee equation 2 (ME2) (https://path.upmc.edu/onlineTools/mageeequations.html) scores were calculated for each patient. The correlation coefficient between Oncotype Dx^® and ME2 was determined.

Oncotype Dx^® recurrence score, treatment, and outcomes were analyzed in 126 post-menopausal women diagnosed between 2015 and 2020. The mean tumor size was 1.09 cm, and the mean Oncotype DX^® score was 12. The average ME2 score was 13.6. The correlation coefficient between Oncotype and ME2 score was statistically significant (r = 0.3442; p<0.0001). At a median follow-up of 5.03 years, there were no local or distant recurrences or breast cancer-related deaths reported in this patient cohort.

This study suggests that omitting the Oncotype Dx^® assay may be feasible in postmenopausal women with early breast cancer and an ME2 score ≤18. Using comparable tools, such as ME2, may reduce financial toxicity in this population and overall costs to the system. Larger study recommended.