R. Aguado (Majadahonda, Spain)

Hospital Universitario Puerta de Hierro - (INSALUD)

Author Of 2 Presentations

 On-Demand ePoster Display

149P - Restricted mean survival time (RMST): a new tool for time to event analysis in young breast cancer patients (YBCP)

Abstract

Background

Breast cancer (BC) remains the most common malignancy among young female patients and the leading cause of cancer death in this population. BC in young women is a social problem since it often appears during the period of highest family and professional activity. Very often, YBCP are classified as high risk only by age.

Methods

A retrospective analysis of women with BC diagnosed between 2009-2019 in HUPHM in Madrid and ≤ 45 years old at the moment the diagnosis was made. Survival was analyzed according to histopathological subtypes and stages in this population. The Cox proportional hazards model could not be used because our variables could not meet the proportional hazards (PH) assumption. Instead, the RMST at 60 months has been analyzed as an alternative, which means expected survival time subject to a specific time horizon. Kaplan Meier curves were also estimated.

Results

A total of 537 YBCP were analyzed, 104 events were defined (relapse) with a median follow up of 69 months. The patients were divided by histopathological subtypes and stages, and no significant differences were found between stages according to histological subtypes. RMST was clearly diminished independently stage in triple negative and HR-/HER2+ disease (except for stage III due to a low number of subjects). These differences were greater within stage III between triple-negative disease and the other histologies. These results were compared with a Kaplan Meier analysis at 24 and 60 months showing that the risk of relapse was higher in the HR-negative subtypes regardless of HER2 status.

TN RH+/HER2- RH+/HER2+ RH-/HER2+
n 60 357 58 21
Stage (S): n (%) p=.03
I 12 (20%) 144 (40%) 15 (26%) 7 (33%)
II 33 (55%) 141 (39%) 25 (43%) 10 (47%)
III 15 (25%) 72 (20%) 18 (31%) 4 (19%)
Relapses: n (%) 14 (23%) 52 (15%) 7 (12%) 6 (27%)
RMST Expected average survival time within 60 months
S I: Average time (AT) (95%IC) 50,5 (40-61) 59 (58-60) 60 (60-60) 52,6 (39-66)
S II: AT (95%IC) 51,5 (45-57) 57,3 (55-59) 60 (60-60) 55,3 (49-61)
S III: AT (95%IC) 42,3 (30-55) 51,7 (48,1-55) 54,3 (48-60) 56,6 (51-62)
Relapse Free Survival Rate at 24 // 60 months
S I 91%/61,1 % 99%/94% 100%/100% 83,3%/83%
S II 93%/73,9% 97%/87,5% 100%/100% 100%/75%
S III 69%/56% 91%/72% 94%/ 79,3% 100%/66%
All stages 87%/67% 96%/86% 97,9%/92% 90%/73%

Conclusions

The RMST is a valid tool to analyze the risk of relapse according to the tumor biology and the stage at the time of diagnosis, being comparable to the PH in detecting differences between arms when hazards are proportional, but better when they are not.

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.

Collapse

175P - Tumor biology in Young Breast Cancer Patients (YBCP). A different disease?

Abstract

Background

Breast cancer in Young patients has been related to a more aggressive tumor biology in some studies, due to a more frequent triple negative disease, grade III or vascular/lymphatic invasion. Early age at the time of breast cancer diagnosis has emerged worldwide as an independent factor associated with an increased risk of relapse and death regardless of the treatment administered with some controversies in the cut-off age (40 vs 45).

Methods

We have performed a retrospective analysis of YBCP (≤45 years) treated at the Oncology Department in HUPHM in Madrid-Spain, diagnosed with infiltrating breast cancer between 2009-2019. All data from the pathology and immunohistochemical report were collected and analyzed. We have examined the difference between subtypes and pathological characteristics according to age (<40 and ≥40-45).

Results

From a total of 600 YBCP analyzed, we identified 559 with infiltrating breast carcinoma of which we have a pathological report. The differences according to age are shown below:

<40 ≥40-45 Global population p value
Histology Ductal Lobulillar Other 89% 5% 6% 82% 11% 7% 84% 9% 7% p = 0,1
Grade I II III Unknown 18% 45% 32% 5% 21% 47% 28% 4% 20% 46% 30% 4% p = 0,6
Multicentricity 26% 33% 31% p = 0,09
Histologic Subtypes: Triple Negative HR+ HER2- HR+ HER2+ HR-HER2+ 12% 70% 13% 5% 12% 71% 12% 5% 12% 71% 12% 5% p = 0,9
Ki-67 < 14 ≥ 15 32% 68% 38% 62% 36% 64% p = 0,18
Hormone Receptor ER-/PR- ER+/PR- ER-/PR+ ER+/PR+ 17% 5% 2% 76% 16% 6% 2% 76% 16% 6% 2% 76% p = 0,9
Lymphovascular invasion 35% 35% 35% p = 0,9
Perineural invasion 14% 13% 13% p = 0,8

Conclusions

Most of the tumours were invasive ductal carcinoma, just 20% were grade I, only 12% triple negative tumors, 64% of the tumors had a high ki-67, 83% were hormone receptor positive (76% of them positive for both receptors). Lymphovascular and perineural invasion was present in 35% and 13% respectively. No significant differences were found according to age, with a similar distribution in the different subtypes and prognostic features.

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.

Collapse