5MO - Subtype-dependent loco-regional recurrence patterns in different subtypes of breast cancer: A retrospective analysis of 16,462 patients over 10 years of follow-up

Background

While numerous studies have consistently reported that the molecular subtypes of breast cancer are associated with different patterns of distant metastasis, few studies have investigated the impact of molecular subtypes on loco-regional recurrence. We retrospectively investigated the patterns of loco-regional recurrence in a large cohort.

Methods

We reviewed the clinical records of all patients who underwent breast cancer surgery between January 2000 and December 2018 in a single institution and investigated the ipsilateral breast cancer recurrence (IBTR), regional recurrence (RR), and contralateral breast cancer (CBC) events. Tumor subtypes were sub-grouped according to hormone receptor (HR) and human epidermal growth factor receptor-2 (HER2) status.

Results

A total of 16,462 patients were included in the analysis. For all patients, the ten-year IBTR-, RR- and CBC survival rate was 4.1%, 3.9% and 3.5%, respectively. On the log-rank test, HR-/HER+ tumors showed the worst IBTR-free survival rate (p<0.001), while HR-/HER2- subtype showed the worst RR- and CBC-free survival rate among all subtypes (p<0.001). Regarding annual recurrence patterns, the IBTR pattern of HR-/HER2+ and HR-/HER- subtypes showed double-peaks, while HR+/HER2- tumors showed a steadily increasing pattern without distinguishable peaks. Additionally, the HR+/HER2- subtype seems to have a steady RR pattern, while other subtypes showed the highest RR incidence at one year following surgery before gradually decreasing. Lastly, the annual recurrence rate of CBC showed gradually increasing tendencies for all subtypes, and the HR-/HER2- subtype showed a highest CBC rate for ten years. Younger patients had more evident difference in IBTR, RR, and CBC pattern between subtypes than elderly.

Conclusions

Loco-regional recurrence occurs with different patterns according to BC subtypes. The guidelines should consider the difference in loco-regional recurrence patterns according to tumor subtypes and recommend tailored surveillance strategies, especially for young patients.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

W. Han, H. Lee: Non-Financial Interests, Personal, Stocks/Shares: DCGen. All other authors have declared no conflicts of interest.