Neoadjuvant systemic therapy is the accepted approach for women with locally advanced breast cancer for whom immediate surgery is not feasible. It is also an option for women with operable breast cancer who desire an attempt at breast conservation but in whom mastectomy is indicated based on tumor size and location [1-4].
Response assessment during and following neoadjuvant therapy, implications for surgical management of the breast and axillary nodes, pathologic evaluation of the surgical specimen, influence of pathologic findings on prognosis, and options for adjuvant therapy following neoadjuvant treatment will be reviewed here. The rationale for neoadjuvant therapy, patient selection, pre-treatment evaluation, and treatment options are discussed separately. (See "Neoadjuvant therapy for breast cancer: Rationale, pretreatment evaluation, and therapeutic options".)
Clinical response assessment during treatment — Patients undergoing neoadjuvant systemic therapy for breast cancer should undergo periodic clinical evaluations during treatment to assess response and ensure that their tumor is not progressing.
There are no formal guidelines regarding the ideal assessment strategy during neoadjuvant treatment. Our approach is as follows:
- For patients on neoadjuvant chemotherapy (NACT), we perform a clinical examination every two to four weeks (ie, prior to each cycle of treatment). This should include evaluation of the affected breast and ipsilateral axilla.
- For patients undergoing neoadjuvant endocrine therapy, we perform clinical evaluations every four to eight weeks. Their response to treatment is expected to take a longer time to become evident.
- Imaging studies (ultrasound [US] or magnetic resonance imaging [MRI]) should only be performed if disease progression is suspected based on clinical exam.
- Limited data suggest that fluoro-2-deoxyglucose positron emission tomography (FDG-PET) may have a sensitivity and specificity as high as 80 percent , but there are insufficient prospective data to evaluate the ability of FDG-PET to accurately predict response to neoadjuvant therapy. Therefore, we do not perform FDG-PET in this setting outside of a clinical trial.