Comparison of clinical characteristics and pathologic complete response rate after neoadjuvant chemotherapy in women under 35 years and older women with breast cancer.

Background: Age has been confirmed as a very aggressive biological factor associated with the poor prognosis of breast cancer (BC) patients. However, the understanding of young women with breast cancer (YWBC) is scarce. This study compares and evaluates the clinical characteristics and pathologic complete response (pCR) rate after neoadjuvant chemotherapy (NAC) in YWBC and older women with BC.

Methods: We retrospectively analyzed the clinicopathological data and pCR rates of 1,419 non-metastatic BC patients from the Harbin Medical University Cancer Hospital from 1 January 2012 to 31 December 2019. Patients were classified according to age (≤35 vs. >35 years old) with the clinical parameters. The chi-squared or Fisher's exact test was used to evaluate the correlation between clinicopathological variables and pCR. Any predictor variables with P<0.05 in the univariate analysis were included in the multivariate regression analysis to study the relationship between different age groups and pCR.

Results: A total of 879 patients in this study were eligible for analysis, and 71 (8.1%) female patients were ≤35 years old. Compared with elderly patients, YWBC were more likely to achieve pCR (25.4% vs. 15.6%, P=0.03) and undergo breast-conserving surgery (BCS). There was a higher proportion of clinically higher stage in the YWBC group. Patients with YWBC, clinical stage I+II, positive human epidermal growth factor receptor 2 (HER-2) expression, negative progesterone receptor (PR) expression, and KI67 >15% were more likely to achieve pCR (P<0.05).

Conclusions: Our study found that age is the main factor affecting the achievement of pCR in patients with BC. Chemotherapy is more effective in patients with YWBC. We need to pay more attention to this group and achieve individualized treatment, which will facilitate improved treatment of BC and provide new targets and blueprints for clinical therapy.