Accuracy of ultrasound elastography for predicting breast cancer response to neoadjuvant chemotherapy: A systematic review and meta-analysis

Table 1 Characteristics of the included studies (n = 14)

No	Ref.	Country	Study design	Sample size	Study participants	Type of ultrasound elastography	Cut-off	Reference standard	Mean age (in years)
1	Evans et al[7], 2018	United Kingdom	Prospective	64	Patients with breast cancer receiving NACT	Shear wave elastography	Mean stiffness = 50 kPA	Assessment of any invasive cancer cells in the tumour bed at surgical resection after 6 cycles of NACT and an assessment of nodal metastases at axillary surgery	52
2	Evans et al[8], 2018	United Kingdom	Prospective	80	Patients with breast cancer receiving NACT	Shear wave elastography	Mean stiffness = 83 kPA	Assessment of any invasive cancer cells in the tumour bed at surgical resection after 6 cycles of NACT and an assessment of nodal metastases at axillary surgery	53
3	Falou et al[9], 2013	Canada	Prospective	15	Locally advanced breast cancer patients receiving NACT	Strain wave elastography	Mean strain ratio = 81	Histopathological examination following mastectomy	45
4	Fang et al[10], 2019	China	Prospective	60	Breast cancer patients with stage IIa-IIIc (T1-T4; N0-N3; M0) and underwent surgery after receiving NACT	Strain wave elastography	Mean strain ratio = 5.4	Pathological examination after surgical resection	39
5	Fernandes et al[11], 2019	Canada	Prospective	92	Patients with biopsy confirmed locally advanced breast cancer receiving NACT	Strain wave elastography	Elastography score = 4	Histopathological examination	55
6	Hayashi et al[12], 2012	Japan	Retrospective	55	Histologically confirmed invasive breast cancer before NACT, and they underwent surgery after completion of NACT	Strain wave elastography	Elastography score = 4	Pathologic response was assessed in surgical specimens of the breast with reference to the standards of the Japanese Breast Cancer Society	52
7	Jing et al[13], 2016	China	Prospective	62	Patients with diagnosis of breast carcinoma by ultrasound-guided core needle biopsy who received neoadjuvant chemotherapy followed by surgical excision	Shear wave elastography	Stiffness threshold-36.1%	Pathologic assessments involved a 2-step process. First, samples from core needle biopsies were examined to record the histologic and biologic characteristics of the tumours. These findings were usually combined with the clinical features of the patients to predict the response to neoadjuvant chemotherapy. Second, pathologic responses to neoadjuvant chemotherapy were evaluated according to the Miller-Payne grading criteria	49
8	Katyan et al[14], 2019	India	Prospective	86	TNM stage III and T3N0 subset of stage IIb breast cancer patients receiving NACT	Strain wave elastography	Strain ratio = 0.1	Histopathological examination	NA
9	Lee et al[15], 2015	Korea	Retrospective	71	Women with stage II-III invasive breast cancers who received NACT	Shear wave elastography	Mean stiffness = 98.1 kPA	Histopathological examination	NA
10	Ma et al[16], 2017	China	Prospective	71	Women confirmed with invasive breast cancer by ultrasound guided core needle biopsy and underwent NACT and subsequent surgical excision	Shear and strain wave eastography	Stiffness threshold-30.4%; Strain ratio = 6.7	Histopathological examination	47.3
11	Ma et al[17], 2020	China	Prospective	43	Breast cancer patients who were confirmed to be HER-2 positive by biopsy and puncture and underwent NACT	Shear wave elastography	Mean stiffness = 30 kPA	Histopathological examination after surgical resection	NA
12	Maier et al[18], 2020	Germany	Prospective	134	Histologically confirmed unilateral or bilateral breast cancer and indication for NACT	Shear wave elastography	Shear wave velocity = 3.35	Pathological examinations and immunohistochemistry from the core-cut biopsy before and from the surgical specimen after NACT	52.1
13	Wang et al[19], 2019	China	Prospective	65	Patients confirmed via biopsy to have breast cancer prior to receiving NACT treatment and they received no other treatment	Strain wave elastography	Strain ratio = 8	Histopathology results of the lesion samples isolated in the surgery were compared with those of the biopsy specimens obtained prior to treatment to determine the response to NACT	48.3
14	Zhang et al[20], 2020	China	Prospective	91	Patients diagnosed with invasive breast cancer by ultrasound-guided core needle biopsy and received NACT and subsequent surgical intervention	Shear wave elastography	Stiffness threshold–41.4%	Histopathological examination	46.9

HER: Human epidermal growth factor receptor; kPA: Kilopascals; NA: Not available; NACT: Neoadjuvant chemotherapy; TNM: Tumour node metastasis.