Laura van’t Veer, PhD, Director of the Specialized Programs of Research Excellence (SPORE) of the University of California, San Francisco, commented on the meta-analysis. She said the study confirms that a pathologic complete response in the neoadjuvant setting is generally meaningful as it clearly relates to long-term outcomes. “This is even truer when you divide breast cancer into subtypes,” she said.

For patients who are estrogen receptor–negative or estrogen receptor–positive with higher-grade tumors, the correlation between pathologic complete response and long-term outcome is very strong, whereas the correlation is lacking in patients with low-grade estrogen receptor–positive tumors. “This is what my own research has shown in a smaller dataset, though including genomic information such as the 70-gene MammaPrint signature” she said. “And this strikes me as very important for our patients, who become concerned when they do not achieve a [pathologic complete response] with neoadjuvant treatment.”

When the patient has a low-grade, indolent tumor, which has a low likelihood of recurrence, pathologic complete response is “of no relevance,” and clinicians can reassure these patients, she said. On the other hand, when patients have a high risk of recurrence and do not respond to neoadjuvant treatment, “you know you will have to do something extra.”

She said there is no further point to evaluating pathologic complete response by estrogen receptor and HER2 status alone. Future studies should aim for “the next level” by evaluating pathologic complete response in discrete tumor subtypes. ■

Disclosure: Dr. van’t Veer is co-founder of Agendia Inc.