Relationship between chemotherapy and prognosis in different subtypes of node-negative breast cancer

Low-Frequency Ultrasound Enhances Paclitaxel Efficacy in EMT6 Subcutaneous Tumors in Balb/c Mice

BACKGROUND

The objective of this study was to explore the effects of 30 kHz ultrasound on the efficacy of paclitaxel in subcutaneous breast tumors in Balb/c mice in vivo.

MATERIALS AND METHODS

40 Balb/c female mice were divided into 5 groups: model control group, paclitaxel intraperitoneal (ip) group (20 mg/kg, ip, at 3 day intervals for a total of 3 doses (q3d×3)), paclitaxel intratumoral (it) group (20 mg/kg, it, q3d×3), paclitaxel intraperitoneal (20 mg/kg, ip, q3d×3) combined with low-frequency ultrasound (LFU) group, and paclitaxel intratumoral (20 mg/kg, it, q3d×3) combined with LFU group. Ultrasound parameters were 30 kHz, 200 MW intensity, 15 min, q3d×3. The antitumoral effect was determined by examining the tumor weight in subcutaneously inoculated EMT6 breast carcinoma models in Balb/c mice. All subcutaneous tumors were examined using high performance liquid chromatography (HPLC) upon completion of the experiments. Drug concentrations in the subcutaneous tumors were also analyzed using HPLC. Finally, paraffin sections of the subcutaneous tumors were made, and after hematoxylin and eosin staining, the tumor morphology was examined under a light microscope.

RESULTS

LFU combined with paclitaxel significantly restrained tumor growth in transplanted subcutaneous EMT6 tumors in Balb/c mice, and this effect correlated with increased local concentrations of paclitaxel in the tumors. Body weight measurement did not reveal significant adverse effects on the Balb/c mice during the study.

CONCLUSION

LFU combined with paclitaxel has a significant synergistic effect in the treatment of breast cancer.

Biologic subtype is a more important prognostic factor than nodal involvement in patients with stages I and II breast carcinoma

Purpose

Nodal infiltration has been one of the most important prognostic factors in breast cancer. In recent decades, risk stratification has greatly changed, and is applied in accordance with hormone receptor and human epidermal growth factor receptor 2 (HER2) status. We compared the prognostic power of tumor subtype to nodal involvement in early breast cancer.

Methods

We reviewed the medical records of 505 patients who had curative surgery for stage I or II breast cancer. We analyzed clinicopathologic factors according to tumor subtype and nodal involvement. Tumors were classified into 4 subtypes according to immunohistochemical status of estrogen receptor, progesterone receptor, HER2, and Ki67 labeling index. Disease-free survival (DFS) and overall survival were analyzed.

Results

There were 363 node-negative patients (71.9%) and 142 node-positive patients (28.1%). Luminal A, Luminal B, HER2, and triple-negative breast cancer subtypes were composed of 207 (41.0%), 147 (29.1%), 42 (8.3%), and 109 patients (21.6%), respectively. The median follow-up period was 89.5 months. Node negative-luminal A subtype showed the best prognosis with regard to 5-year DFS, and the pN1-triple negative subtype was associated with the shortest DFS (95.1% vs. 67.8%; hazard ratio, 9.554; P < 0.001). However, the node negative-triple negative subtype was associated with a worse 5-year DFS than the pN1-luminal A subtype ([86.4%; hazard ratio, 2.647; P = 0.048] vs. [93.2%; hazard ratio, 2.061; P = 0.194]).

Conclusion

Node negative-triple negative breast cancer was associated with a poorer prognosis than pN1-luminal A subtype. Tumor subtype has greater prognostic power compared to nodal status in early breast cancer.