Impact of invasive lobular carcinoma on long-term outcomes in Mexican breast cancer patients.

PURPOSE

The aim of this study was to compare the difference in disease-free survival (DFS) and overall survival (OS) between invasive lobular carcinoma (ILC) and invasive ductal carcinoma (IDC) in our Hispanic population with breast cancer (BC).

METHODS

We retrospectively analyzed a database of 4533 non-metastatic BC patients treated for BC at the National Cancer Institute in Mexico (INCan) between 2006 and 2016. We compared clinical characteristics, treatment and survival between women with invasive ductal and invasive lobular BC. We evaluated differences between survival curves with the log-rank test and used Cox's proportional hazards model for the multivariate analysis.

RESULTS

Median follow-up time was 42.13 months (IQ 25.2-IQ 72.06). The median age was 50.9 years (IQ 43.5-IQ 59.8). DFS at 5 years was 80.8% for IDC versus 76.2% for ILC. 5 years OS was 88.7% for IDC versus 84.3% for ILC. Multivariate analysis showed that factors that negatively affected the 5-year DFS include: clinical stage III [hazard ratio (HR) 4.2, 95% CI 3.36-5.35; p < 0.001], triple negative phenotype (HR 1.4, 95% CI 1.08-1.81; p = 0.009), Ki67 ≥ 18 (HR 1.6, 95% CI 1.28-2.11; p < 0.001), and lobular histological type (HR 1.6, 95% CI 1.09-2.49; p = 0.017). Factors associated with a negative impact on OS were: clinical stage III (HR 4.5, 95% CI 3.15-6.54; p < 0.001), triple negative phenotype (HR 2.4, 95% CI 1.69-3.48; p < 0.001), and Ki67 ≥ 18% (HR 1.9, 95% CI 1.27-2.92; p = 0.02).

CONCLUSION

Our results highlight the different biology of ILC and show that long-term prognosis in terms of DFS is not as favorable as previously reported.