Targeted PET/CT Predicts Early Treatment Response in HER2-Positive Breast Cancer

HER2-positive breast cancer is an aggressive subtype that accounts for a substantial proportion of breast cancer cases. Patients often receive neoadjuvant therapy before surgery to shrink tumors, but assessing response early during treatment remains challenging. Existing methods can be limited by operator dependence, anatomic uncertainty, or insufficient accuracy. New findings now suggest that molecular imaging may help identify treatment response earlier during presurgical therapy.

Researchers at The Fourth Hospital of Hebei Medical University and Hebei Provincial Tumor Hospital evaluated ⁶⁸Ga-HER2 PET/CT as a targeted imaging approach for HER2-positive breast cancer. The technology provides noninvasive, whole-body visualization of HER2 expression and can track changes in HER2-targeted tracer uptake in primary breast tumors and lymph nodes during treatment.

The prospective study included 44 patients with biopsy-confirmed HER2-positive breast cancer. All patients received at least four cycles of neoadjuvant therapy, although treatment regimens varied, followed by surgery. ⁶⁸Ga-HER2 PET/CT was performed at baseline, after the second treatment cycle, and before surgery to determine whether changes in tracer uptake were associated with pathologic complete response.

Baseline imaging did not distinguish patients who would achieve a pathologic complete response from those who would not. After two treatment cycles, however, a greater decrease in tracer uptake in the primary tumor was associated with response at surgery. Patients with at least a 61% reduction in primary tumor uptake had an 85% pathologic complete response rate, compared with 38% among those whose uptake decreased by less than 61%.

The findings were published in the October issue of The Journal of Nuclear Medicine. The authors noted that the study was limited by its small sample size, single-center design, and variation in neoadjuvant treatment regimens. The study evaluated diagnostic performance and did not test whether changing treatment based on PET/CT findings improves outcomes.

“These findings provide preliminary prospective evidence that changes in HER2-targeted tracer uptake can predict treatment response at a very early stage. For patients, the potential importance is that treatment response may be assessed much earlier. If future studies confirm our findings, imaging could provide earlier information to support discussions about alternative treatment strategies or surgical timing,” said Xinming Zhao, M.D., Ph.D., director of the Department of Nuclear Medicine at the Fourth Hospital of Hebei Medical University and Hebei Provincial Tumor Hospital.