The Lynx Group

Adjuvant Chemotherapy May Be Spared in Localized Breast Cancer If pCR Is Attained with Neoadjuvant Chemotherapy

April 2019, Vol 10, No 2

San Antonio, TX—Reaching pathologic complete response (pCR) after neo­adjuvant chemotherapy correlates with significantly improved event-free survival (EFS) and overall survival (OS) in patients with localized breast cancer, according to results of a large comprehensive meta-analysis presented at the 2018 San Antonio Breast Cancer Symposium.

Survival was improved across various types of breast cancer in patients with pCR who received neoadjuvant therapy, with particularly robust results in patients with triple-negative or HER2-­positive breast cancer.

Furthermore, EFS and OS were similar regardless of whether patients received treatment with additional adjuvant chemotherapy, suggesting that adjuvant chemotherapy can be omitted in some patients with early breast cancer who achieve pCR with neoadjuvant chemotherapy.

“Similar outcomes with or without adjuvant chemotherapy in patients who attain pCR on neoadjuvant chemotherapy…suggest that adjuvant chemotherapy could potentially be omitted under certain circumstances,” said Laura M. Spring, MD, Breast Medical Oncologist, Massachusetts General Hospital Cancer Center, Boston.

“These important findings suggest that further research is needed to evaluate the clinical utility of escalation and de-escalation strategies in the adjuvant setting based on neoadjuvant response,” Dr Spring added.

“Additional adjuvant chemotherapy …adds to toxicity and may represent overtreatment for some patients who get to pCR on neoadjuvant therapy. Neoadjuvant chemotherapy offers several additional advantages over adjuvant therapy, including rapid assessment of response using surrogate markers like pCR,” Dr Spring stated.

The meta-analysis included published studies about localized breast cancer with 25 or more patients featuring neoadjuvant chemotherapy that reported pCR results, as well as disease recurrence and/or survival based on pathologic outcome. A PubMed search identified 3209 potential studies, but only 52 met the inclusion criteria; the total number of patients included in these studies was 27,895.

pCR as a Predictive Marker

pCR was achieved in 21.1% of the patients included in the meta-analysis. pCR varied by subtype, with approximately 30% of patients with triple-negative breast cancer or HER2-positive disease reaching pCR with neoadjuvant therapy compared with fewer than 20% of patients with hormone receptor (HR)-positive breast cancer.

The patients who achieved pCR after receiving neoadjuvant chemotherapy had significantly better EFS than the patients with residual disease. The 5-year EFS rate was 88% for patients with pCR versus 67% for those with residual disease.

A similar relationship was observed between pCR and OS. The 5-year OS rate was 94% for patients with pCR versus 75% for those with residual disease.

The relationship between pCR and survival was strongest in patients with triple-negative breast cancer or with HER2-positive disease, although survival was improved to a lesser extent by pCR versus residual disease in HR-positive, HER2-negative breast cancer.

The 5-year EFS was improved in patients with pCR who received treatment with adjuvant chemotherapy as well as in those who did not (86% vs 88%, respectively).

One of the study’s strengths is that pCR was highly predictive of EFS and OS, regardless of the type of neoadjuvant regimen that the patient received.

“This suggests that the path taken to attain pCR may not be critical,” Dr Spring said.

Commenting from the audience, Laura J. Esserman, MD, MBA, Director, Carol Franc Buck Breast Care Center, UCSF Helen Diller Family Comprehensive Cancer Center, San Francisco, CA, stated, “This is a fantastic job of presenting complex data. The data show that however you get to pCR, you have a good outcome. This study supports de-escalation of therapy in localized breast cancer.”

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