Abstract P2-08-41: Biology, metastases pattern and survival of triple negative breast cancer (TNBC) – A comparison between younger (&lt;40 years) and elderly (&gt;74 years) patients
Authors: Tzikas A-K , Nemes S , Linderholm BK 
Published: May 2019

Background: TNBC remains a poorly defined and heterogeneous subset of breast cancer with an adverse prognosis that more often affects younger patients. The biology and outcome of TNBC in elderly patients are less studied.

Aims: To determine the biology, recurrence rate, metastases pattern and survival from diagnosis of primary BC, as well as from diagnose of recurrences in a population based cohort of primary TNBC with focus on the comparison between younger and elderly patients.

Material and Methods: Patients with primary TNBC stage I-IV diagnosed from 2007 through 2015 were identified through the regional cancer registry and detailed information on tumor biology: histological grade, lymphovascular invasion (LVI) and Ki67; stage, type of adjuvant/neoadjuvant treatment, disease-free interval, type of recurrences (involved organs), and survival times were extracted from patients´ charts. The definition of younger (&lt;40 years) and elderly (&gt;74 years) patients was chosen as these patients not participate in mammogram screening programs. For comparisons all factors but Ki67 were run as dichotomous variables.

Results: A total of 525 patients median age 60 years (range: 24-94) were identified. Stage at diagnose were: stage I (24.0%); II (44.6%); III (23.8%) and IV (3.4%). Biology parameters are as follows: Histopathological grade I (1.7%); grade II, (18.5%) and grade III (77.8%) respectively. LVI was present in 24.4%; median Ki67 was 70% (range 1-100%) and median follow-up time is 55.9 months (range: 24-94). In the whole cohort, 396 (75.5%) patients received adjuvant/neoadjuvant chemotherapy and 373 (71%) patients are free from recurrences. The median DFI was 14.9 months (range: 2.0-64.7).

The clinical stage at diagnosis did not differ between younger (n=58) and elderly (n=96) patients; stage I (12% vs 11.5%; stage II (63.8% vs 48.7%; stage III (22.4% vs 30.8%); stage IV (1,7% vs 9,0%) (p=0.17). A statistically significant difference was found concerning histopathologic grade (grade III 77.0% vs 53.0%; p=0.006) and Ki67 (median 74.5% versus 62.7%; p=0.003) but not for LVI (p=0.915) with a higher proportion of poorly differentiated high proliferative tumors among younger patients. A larger proportion of younger patients received (neo-)adjuvant chemotherapy compared with elderly (94.8% versus 11.5%; p&gt;0.001).

Pattern of recurrence was similar concerning lung (p=0.38); liver (p=0.1); distant lymph nodes (p=0.35) but breast cancer brain metastases were statistically significantly more frequently registered among younger patients (p=0.009). Shorter survival times were found among elderly patients; RFS (p=0.011); BCSS (p=0.002); OS (p&lt;0.001), as well as survival following diagnose of recurrence (p=0.034).

Conclusions: We show that primary TNBC is more aggressive in terms of poor differentiation grade and high proliferation rate with more frequently development of brain metastases in younger compared with elderly patients. The majority of elderly patients still have grade III tumors with a Ki67 &gt; 60% and survival following diagnosis of both primary BC and metastatic BC is short. Our results underline the need for novel treatment options suitable also for an elderly patient population.

Citation Format: Tzikas A-K, Nemes S, Linderholm BK. Biology, metastases pattern and survival of triple negative breast cancer (TNBC) – A comparison between younger (&lt;40 years) and elderly (&gt;74 years) patients [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-08-41.