12-year review of HK Breast Cancer Registry: Neoadjuvant chemo effective in stage ≥II, HER2-positive and triple-negative disease

A 12-year review of Hong Kong Breast Cancer Registry (HKBCR) records of patients diagnosed with breast cancer in 2006–2017 showed that neoadjuvant chemotherapy (NAC) was effective in tumour downstaging, with one-fifth of patients subsequently achieving pathological complete response (pCR) in the breast and axillary lymph nodes. Patients with HER2-positive (nonluminal) and triple-negative disease were most likely to achieve pCR.

“NAC was initially used for locally advanced or inoperable breast cancers to reduce tumour size and facilitate surgery,” wrote the researchers. “Subsequently, use of NAC has been extended to early operable breast cancers, which allows downstaging of disease and potential reduction of the extent of surgery, facilitating breast-conserving surgery [BCS]. We assessed the effectiveness of NAC among Hong Kong breast cancer patients according to rates of pCR and BCS.” [Breast J 2016;22:316-321; Hong Kong Med J 2017;23:251-257; Hong Kong Med J 2023;doi:10.12809/hkmj219333]

HKBCR records of 13,435 patients (13,625 cases) diagnosed with breast cancer in 2006–2017 were included in the study. The NAC group comprised 1,084 patients (1,097 breast cancer cases) and the non-NAC group comprised 12,351 patients (12,528 breast cancer cases).

Among the 13,625 breast cancer cases, 13.6 percent of patients aged <40 years were treated with NAC, compared with 8.0 percent and 1.9 percent of patients aged 40–69 years and ≥70 years, respectively. Administration of NAC was positively associated with cancer stage at diagnosis: the proportion increased from 0.3 percent in patients with stage I disease to 26.9 percent among patients with stage III disease. Furthermore, greater proportions of patients with HER2-positive (luminal B), HER2-positive (nonluminal), or triple-negative disease received NAC.

A fifth (20.1 percent) of 1,097 breast cancer cases treated with NAC achieved pCR in the breast and axillary lymph nodes. Subsequent analysis according to biological subtype revealed optimal outcomes in patients with HER2-positive (oestrogen receptor–negative and progesterone receptor–negative) tumours, with a pCR rate of 46.0 percent. pCR rates in HER2-positive (luminal B) and triple-negative subtypes were 29.4 percent and 29.3 percent, respectively, which were significantly higher than rates in other hormone receptor–positive subtypes (all p<0.05).

Patients with clinical stage IIA disease were most likely to switch from mastectomy to BCS after NAC (53.9 percent vs 38.2 percent of stage IIA patients in the non-NAC group), followed by patients with clinical stage IIB disease (38.3 percent). “Even among patients with clinical stage III disease, 14.1 percent underwent BCS after NAC,” highlighted the researchers.

The proportion of patients treated with NAC in Hong Kong nearly doubled during the 12-year study period, from 5.6 percent in 2006–2011 to 10.3 percent in 2012–2017, which is likely due to increasing acceptance of NAC for treatment of locally advanced and hormone receptor–negative disease, as reflected in updates of various national and international guidelines (eg, National Comprehensive Cancer Network guidelines and European Society for Medical Oncology guidelines). [https://www.nccn.org/professionals/physician_gls/; https://www.esmo.org/guidelines/breast-cancer]

“Quality of life–focused research has shown significantly better body image scores among patients who undergo BCS vs mastectomy, which reinforces the benefits of NAC for breast cancer in terms of downstaging the disease, increasing resectability, and enhancing BCS eligibility among patients who would otherwise require mastectomy. However, a recent meta-analysis showed that, compared with adjuvant chemotherapy, NAC was associated with more frequent local recurrence. Thus, continued follow-up of patients registered in the HKBCR will provide important insights into NAC’s long-term outcomes,” underscored the researchers. [Int J Environ Res Public Health 2019;16:4970; Lancet Oncol 2018;19:27-39]