Background

Some risk factors (RFs) in the management of ER-positive, HER2-negative metastatic breast cancer (ER+HER2-MBC), such as a shorter disease-free interval (DFI), visceral involvement or high tumor burden, have been identified in prospective clinical trials; however, the utility of those RFs in the real world has not been well discussed.

Methods

We reviewed our medical records from 2002 to present to assess the utility of RFs (DFI≤24 months [DFI≤24M]; visceral metastases [VIS]; prior (neo)adjuvant anthracycline and/or taxane [A/T]; or ≥ 3 metastatic organs [≥3 ORG]) defined in the TURANDOT risk factor analyses (Brodowicz T, Br J Cancer, 2014), a first-line bevacizumab trial of HR+HER2-MBC patients. According to the analysis, patients with ≥2 RFs were classified as “high-risk (HiR)”, and others were classified as “low-risk (LoR)”. Statistical analyses were performed using the Kaplan-Meyer method and a multivariate COX regression analysis.

Results

We identified 311 ER+HER2-MBC (224 recurrent, 87 advanced) patients who underwent chemotherapy (CTx). The most common RF at the initiation of first-line CTx was VIS (N = 186, 59.8%), followed by A/T, ≥3 ORG and DFI≤24M. The distribution of RFs was as follows: 0 in 89 (28.6%), 1 in 93 (29.9%), 2 in 94 (30.2%), 3 in 30 (9.6%), and 4 in 5 (1.7%). The survival from the initiation of CTx (OSCTx) was significantly poorer in HiR patients than LoR ones (median 815.0 vs. 1062.0 days, p < 0.001, log-rank) in all MBC patients, as well as in 87 advanced BC patients (median 825.0 vs. 1160.0 days, P < 0.05, log-rank). There was no significant difference in the OSCTx between patients with 0 and 1 RF (P = 0.90). In addition, in recurrent BC (rBC) patients, there was no significant difference in the OSCTx between patients with 2 and ≥3 RFs (P = 0.10). Multivariate analyses revealed ≥3 ORG and DFI≤24M as significant RFs (P < 0.05) for all rBC patients (hazard ratios 1.61 and 1.49, respectively).

Conclusions

Our review suggests that RFs such as high tumor burden and shorter DFI identified in prospective randomized studies are applicable to patients in the real world, even with heterogeneous backgrounds.

Legal entity responsible for the study

Junichiro Watanabe

Funding

None

Disclosure

J. Watanabe: Honoraria from AstraZeneca Japan, Chugai Pharmaceuticals, Eisai, Novartis Pharma Japan, Taiho pharmaceuticals, and advisory board member of AstraZeneca Japan, Eisai.

All other authors have declared no conflicts of interest.