New personalized diagnostic and prognostic approaches offer novel strategies to spare some cancer patients unnecessarily harsh and toxic treatments.  Most recently, a study published in the Journal of Clinical Oncology in February reports that PET scans can predict which breast cancer patients will respond successfully to targeted HER2- immunotherapy treatments, without the need for standard chemotherapy.

HER-2 positive breast cancers are a particularly deadly, difficult to treat and likely to recur form of disease. However, recent advances have yielded new targeted immunotherapies that vastly improve prognoses when added to standard chemotherapy regimens. But with these newly effective treatments, is traditional chemotherapy really helping or hurting these patients? 

In this study, researchers set out to identify patients who will respond to targeted therapy alone, without chemotherapy. Drawing from nine different Translational Breast Cancer Research Consortium (TBCRC) medical facilities across the United States, they examined the predictive value of PET scans on HER2 immunotherapy response in 83 breast cancer patients with stage II and stage III HER2-positive tumors. The patients were treated with four cycles of pertuzumab and trastuzumab (without chemotherapy) over a 12-week period, and PET scans were taken prior to and 15 days after treatment.

PET scans are an important tool in oncology, which reveal how aggressive a tumor is by measuring its consumption of sugars. More aggressive tumors gobble up this energy source to fuel their rapid, uncontrolled growth. With this metabolic information, doctors can assess the tumor on a molecular level and even predict its behavior.  “PET has a unique ability to assess the functional and biochemical processes of the body's tissues, which are altered in the earliest stages of disease…often before anatomical or structural changes have occurred,” said Aizhi Zhu of Emory University School of Medicine’s Radiology Department. Thus PET scans provide an early snapshot of what is going on inside a tumor, foretelling how it will progress. Indeed, PET scans are already widely used to assess disease stage and predict treatment responses in other types of breast cancers.

In the HER2-positive breast cancer patients, PET scans predicted successful treatment response without chemotherapy in 44 patients (56%). “Based on our findings, if the sugar uptake shown on the scans is below a certain level at two weeks, antibody therapy may be enough to induce a complete response, and those patients may be spared the toxic e?ects of chemotherapy,” says lead author Roisin Connolly, associate professor of oncology at the Kimmel Cancer Center. “So in the future, we may be able to offer this as a chemo-free approach. Further research is still required… before it can become standard practice in the clinic to make treatment decisions, but it is extremely promising.”

The study follows closely on the heels of a study published last year in the New England Journal of Medicine (June 3, 2018) which reported that approximately 70% of breast cancer patients could forgo chemotherapy after surgery, based on individual genetic testing results. “These findings, showing no benefit from receiving chemotherapy plus hormone therapy…, will go a long way to support oncologists and patients in decisions about the best course of treatment,” says co-author Kathy Albain, MD. “With results of this groundbreaking study, we now can safely avoid chemotherapy in about 70% of patients who are diagnosed with the most common form of breast cancer.”

These studies support a growing trend to pull back on the traditionally heavy-handed approach to cancer treatment, relying instead on tailoring personalized approaches to deliver effective treatment while minimizing exposure to toxic side effects.

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