[Impact of pathological complete response to neoadjuvant chemotherapy in invasive breast cancer according to molecular subtype]

Pathological Response in the Breast and Axillary Lymph Nodes after Neoadjuvant Systemic Treatment in Patients with Initially Node-Positive Breast Cancer Correlates with Disease Free Survival: An Exploratory Analysis of the GeparOcto Trial

Simple Summary

The extent of axillary surgery has been reduced in recent years to minimize side effects. However, a negative impact of reduced surgery on outcome must be avoided. We investigated for whom the extent of surgery can be safely reduced by examining early-stage breast cancer patients converting from lymph node (LN)-positive to LN-negative disease after neoadjuvant systemic treatment (NAST). Of 242 initially LN-positive patients treated within the GeparOcto trial, 54.5% were classified as LN-negative after NAST, 31.8% as LN-positive, and for 13.6% data were missing. Overall, 92.1% of patients underwent complete axillary LN dissection, with 6.6% undergoing sentinel LN dissection only. At surgery, 55.4% of patients had no signs of cancer in the LN, 45.0% had no signs of cancer in the breast (of those 8.3% had involved LN), and 41.3% had no signs of cancer at all. Patients with involved LN still had a bad prognosis. Conversion from LN-positive to LN-negative after NAST is of highest prognostic value. Surgical axillary staging after NAST is essential in these patients to offer tailored treatment.

Abstract

Background: The conversion of initially histologically confirmed axillary lymph node-positive (pN+) to ypN0 after neoadjuvant systemic treatment (NAST) is an important prognostic factor in breast cancer (BC) patients and may influence surgical de-escalation strategies. We aimed to determine pCR rates in lymph nodes (pCR-LN), the breast (pCR-B), and both (tpCR) in women who present with pN+ BC, to assess predictors for response and the impact of pCR-LN, pCR-B, and tpCR on invasive disease-free survival (iDFS). Methods: Retrospective, exploratory analysis of 242 patients with pN+ at diagnosis from the multicentric, randomized GeparOcto trial. Results: Of 242 patients with initially pN+ disease, 134 (55.4%) had a pCR-LN, and 109 (45.0%) a pCR-B. Of the 109 pCR-B patients, 9 (8.3%) patients had involved LN, and 100 (41.3%) patients had tpCR. Those with involved LN still had a bad prognosis. As expected, pCR-B and intrinsic subtypes (TNBC and HER2+) were identified as independent predictors of pCR-LN. pCR-LN (ypN0; hazard ratio 0.42; 95%, CI 0.23–0.75; p = 0.0028 for iDFS) was the strongest independent prognostic factor. Conclusions: In initially pN+ patients undergoing NAST, the conversion to ypN0 is of high prognostic value. Surgical axillary staging after NAST is still essential in these patients to offer tailored treatment.

Clinical utility of ABCB1 and ABCG2 genotyping for assessing the clinical and pathological response to FAC therapy in Mexican breast cancer patients

PURPOSE

Resistance to neoadjuvant chemotherapy with 5-fluorouracil, doxorubicin, and cyclophosphamide (FAC) in some patients with locally advanced breast cancer remains one of the main obstacles to first-line treatment. We investigated clinical and pathological responses to FAC neoadjuvant chemotherapy in Mexican women with breast cancer and their possible association with SNPs present in ABC transporters as predictors of chemoresistance.

MATERIALS

A total of 102 patients undergoing FAC neoadjuvant chemotherapy were included in the study. SNP analysis was performed by RT-PCR from genomic DNA. Two SNPs were analyzed: ABCB1 rs1045642 (3435 C > T) and ABCG2 rs2231142 (421 G > T).

RESULTS

In clinical response evaluation, significant associations were found between the ABCB1 C3435T genotype and breast cancer chemoresistant and chemosensitive patients (p < 0.05). In the early clinical response, patients with genotype C/C or C/T were more likely to be chemosensitive to neoadjuvant therapy than patients with genotype T/T (OR = 4.055; p = 0.0064). Association analysis between the ABCB1 gene polymorphism and the pathologic response to FAC chemotherapy showed that the C/C + C/T genotype was a protective factor against chemoresistance (OR = 3.714; p = 0.0104). Polymorphisms in ABCG2 indicated a lack of association with resistance to chemotherapy (p = 0.2586) evaluating the clinical or pathological response rate to FAC neoadjuvant chemotherapy.

CONCLUSION

The early clinical response and its association with SNPs in the ABCB1 transporter are preserved until the pathological response to neoadjuvant chemotherapy; therefore, it could be used as a predictor of chemoresistance in locally advanced breast cancer patients of the Mexican population.

Pathological Response to Neoadjuvant Chemotherapy and the Molecular Classification of Locally Advanced Breast Cancer in a Latin American Cohort

BACKGROUND

The majority of patients with breast cancer in Colombia are admitted into oncological centers at locally advanced stages of the disease (53.9%). The aim of this study was to describe the pathological response obtained with neoadjuvant chemotherapy (NACT) according to the molecular classification of breast cancer in patients with locally advanced tumors treated within the National Cancer Institute (NCI) Functional Breast Cancer Unit (FBCU) in Bogotá, Colombia.

MATERIALS AND METHODS

This was an observational, descriptive, historical cohort study of patients with locally advanced breast cancer treated within the NCI FBCU.

RESULTS

We included 414 patients who received NACT and surgical management. Most patients had luminal B HER2-negative tumors (n = 134, 32.4%). The overall rate of pathological complete response (pCR) ypT0/ypN0 was 15.2% (n = 63). Tumors that presented the highest rate of pCR were pure HER2, at 40.5% (n = 15; odds ratio [OR], 6.7); however, with a follow-up of 60 months, only the triple negative tumors presented a statistically significant difference for event-free survival (EFS; median recurrence time, 18 months; range, 1-46) and overall survival (OS; median follow-up, 31 months; range 10-57). The molecular subtype that most recurrences presented was luminal B HER2 negative, at 38.3% (n = 28). The majority of recurrences (93.2 %; n = 68; OR, 5.9) occurred in patients in whom no pathological response was obtained (Chevallier 3 and 4).

CONCLUSION

Pathological response in locally advanced tumors is related to the molecular subtype of breast cancer, finding higher pCR rates in pure HER2 and triple-negative tumors. A direct relationship was found between disease recurrences and the pathological response, evidencing greater tumor recurrence in patients who did not respond to NACT (Chevallier 3 and 4). EFS and OS were greater in patients with pCR, with statistical significance only in triple-negative tumors.

IMPLICATIONS FOR PRACTICE

This research article is of scientific interest, because it describes the clinical and pathological features and analyzes the correlation between pathological response to neoadjuvant chemotherapy and the molecular classification of locally advanced breast cancer in patients treated in the National Cancer Institute in Bogotá, Colombia. It was found that pathological response is related to the molecular subtype of breast cancer. In addition, there is a direct relationship between disease recurrences and pathological response. The survival results were greater in patients with pathological complete response.