PET Scans Could Identify Patients With Breast Cancer Who May Be Able to Avoid Chemotherapy

Women with one type of human epidermal growth factor receptor 2 (HER2)—positive breast cancer might be able to avoid standard chemotherapy, according to a new study using positron emission tomography (PET) scans. The study, published in Journal of Clinical Oncology, used PET scans to identify a biomarker that predicts which patients might benefit most from standalone agents that the HER2 protein promoting cancer growth.

The researchers evaluated 83 women with stage II or stage III estrogen receptor (ER)-negative, HER2-positive breast cancer. They used PET scans to detect sugar uptake in cancer cells prior to and 15 days after treatment initiation. The patients were given 4 cycles of pertuzumab and trastuzumab and 75 of the patients completed all 4 cycles. The goal was to see if early changes on the PET scan can determine which patients’ tumors will completely disappear after the targeted therapy.

In more than half (56%) of cases, there was a predictive biomarker that could potentially be used as an early response assessment tool, according to the authors. Patients who had high sugar levels in cancer cells 2 weeks after treatment were not likely to fully respond to the targeted treatment alone, and they would need chemotherapy. When sugar uptake is below a certain level after 2 weeks, patients were more likely to have a complete response and be spared chemotherapy.

“Although further studies are needed before the PET scan biomarker can be reliably used on a wide scale, the results of this study have the potential to advance the options for precision medicine in women with breast cancer,” senior author Vered Stearns, MD, professor of oncology, co-director of the Breast and Ovarian Cancer Program at Johns Hopkins, said in a statement.

More attention is being paid to avoiding chemotherapy treatment when possible due to the therapy’s toxic effects. This study follows results from the TAILORx trial, a phase 3 study presented at the 2018 American Society of Clinical Oncology Annual Meeting. TAILORx successfully confirmed that endocrine therapy can be used alone in 70% of women with early-stage breast cancer.

TAILORx used the Oncotype Dx Breast Recurrence Score test to predict which patients had a low risk of distant recurrence and which women will not benefit from chemotherapy. The authors determined that the majority of women with early-stage breast cancer can be spared chemotherapy and avoid its toxic side effects.

In a contributor article for The American Journal of Managed Care®, Molly MacDonald, the founder and chief executive officer of The Pink Fund, which provides 90 days of nonmedical financial aid to patients with breast cancer, explained that the TAILORx results will not only benefit patients by sparing them potential physical side effects, but they may also mitigate financial toxicity for patients. Patients treated with chemotherapy who face physical side effects are also at risk of losing jobs or income due to disability as a result of treatment side effects, she explained.

Reference

Connolly RM, Leal JP, Solnes JP, et al. TBRC026: phase II trial correlating standardized uptake value with pathologic complete response to pertuzumab and trastuzumab in breast cancer [published online February 5, 2019]. J Clin Oncol. doi: 10.1200/JCO.2018.78.7986.