Therapeutic strategies for treating breast cancer differ according to molecular subtype. We investigated whether dedicated breast PET (DbPET), a high-resolution molecular breast imaging system, could stratify breast cancer by subtype.
We included 390 patients with invasive breast cancer who underwent ring-type DbPET between January 2016 and March 2018. The association between SUVmax and various tumor characteristics such as size, nuclear grade, estrogen receptor (ER) status, human epidermal growth factor receptor 2 (HER2) status, and Ki-67 labeling index, were assessed. Tumor subtypes were classified as luminal A-like, luminal B-like, ER+/HER2+, ER-/HER2+, or triple negative on the basis of the St. Gallen International Expert Consensus.
The median patient age was 57 years, the median tumor size was 1.5 cm, and the median SUVmax on DbPET was 6.9. The number of patients with each subtype was luminal A-like in 113, luminal B-like in 185, ER+/HER2+ in 40, and ER-/HER2+ in 12, and triple negative in 40 patients. SUVmax significantly correlated with tumor size (P < 0.001), nuclear grade (P < 0.001), ER status (P = 0.004), HER2 status (P < 0.001), and Ki-67 labeling index (P < 0.001). The median SUVmax values of the luminal A-like, luminal B-like, ER+/HER2+, ER-/HER2+, and triple negative subtypes were 4.6, 8.2, 9.5, 16.1, and 10.4, respectively (Table, all values of P < 0.001 relative to luminal A-like). Thus, DbPET distinguished luminal A-like tumor subtype from other subtypes.
SUVmax on dedicated breast PET according to molecular subtypes. Subtypes Median SUVmax (IQR) P value reffered to luminal A-like Luminal A-like 4.6 (3.0-6.8) Luminal B-like 8.2 (4.6-12.4) < 0.001 ER+/HER2+ 9.5 (5.5-16.6) < 0.001 ER-/HER2+ 16.1 (7.5-20.2) < 0.001 Triple negative 10.4 (4.2-17.0) < 0.001
DbPET can be used to classify breast cancer into molecular subtypes, which may help determine the necessity of adjuvant chemotherapy. SUVmax, as assessed on DbPET, may thus contribute to the selection of proper therapeutic strategies in invasive breast cancer.
Hiroshima University Hospital.
Has not received any funding.
All authors have declared no conflicts of interest.