PRESENTATION, TREATMENT MODALITIES, AND OUTCOMES OF BREAST CANCER IN YOUNG FEMALES: A COMPARISON WITH OLDER AGE GROUP IN LEBANON

Abstract

Background: Breast cancer is the most prevalent cancer in women worldwide. Young breast cancer is not as frequent yet is the most common cancer in females aged 15 to 39 years. To add, young breast cancer is more common in developing countries like Lebanon highlighting the importance of investigating this disease in the region. Nonetheless, studies investigating this entity in Lebanon and the region are scarce.

Objectives: In this study we aim to investigate the differences between young breast cancer patients (<40 years old) and older breast cancer patients (≥40) in terms of tumor characteristics, treatment modalities, and outcomes

Methods: We reviewed charts of female patients with biopsy proven invasive breast cancer who received part of their treatment at AUBMC between 2010 and 2016. Data on patient demographics, tumor characteristics, treatment modalities, and patient outcomes were collected. Follow up was limited to March 2020. Patients were then divided into two age groups: young (<40) and older (≥40) breast cancer patients. The chi-squared test was used to compare categorical variables and the independent t-test was used to compare continuous variables between the two age groups. Univariate and multivariate logistic regression models were conducted to investigate the trends of undergoing complete mastectomy and chemotherapy administration in both age groups. Odds ratios were used to report trends for different variables. A sensitivity analysis was undertaken by recoding the missing values in each categorical variable as an unknown category in that variable. Overall survival and Disease-Free survival curves were computed using the Kaplan Meier method and compared across both age groups using the log rank test. IBM SPSS version 28.0 was used to conduct all statistical analyses. Significance level was set at the 5% level.

Results: We identified 745 patients diagnosed with breast cancer between 2010 and 2016. 126 patients (17%) were younger than 40 years of age. Young breast cancer patients were found to have significantly higher proportion of multiple masses on imagining (38.1% vs 27.2%, P: 0.017), more multifocal and multicentric tumors (39.2% vs 27.3%, P: 0.001), more calcifications on mammography (72.4% vs 51.9%, P:0.001), higher proportion of grade 3 tumors (52% vs 34.2%, P<0.001), higher HER-2 positive disease (30.6% vs 21.6%, P:0.033), and higher lymphovascular invasion (46.7% vs 40.1%, P:0.028). Moreover, the young age group was also found to have higher proportion of stage III cancer (23.8% vs 15.8%, P:0.095), greater tumor size on imaging (2.62 ± 1.63 cm vs 2.29 ± 1.64 cm, P:0.052), and lower Luminal A subtype (30.6% vs 41.8%, P:0.126) but these results did not reach statistical significance. In terms of treatment young breast cancer patients were found to take more chemotherapy (90.2% vs 75.8%: P:0.003), especially neoadjuvant chemotherapy (37.4% vs 24.6%, P:0.028) and anthracycline based chemotherapy (90.2% vs 75.8%, P:0.003). Young patients were also found to take more Trastuzumab (Anti-Her2) treatment (37.3% vs 24.6%; P:0.029). No difference in breast surgery type, axillary surgery, radiotherapy, and hormonal therapy was noted between both groups. Univariate and multivariate logistic regression revealed similar trends in both age groups with positive lymph nodes, multiple tumors on imaging, higher tumor grade, more aggressive molecular subtypes (Luminal B, HER 2, and TN), and higher tumor stage being all associated with greater odds of undergoing complete mastectomy A second model that included in addition to the variables in the first mode the calcification on mammography variable and the sensitivity analysis revealed similar trends with the calcifications on imaging (when present) being associated with higher odds of complete mastectomy. Similarly, the univariate and multivariate analysis for chemotherapy indications revealed that higher tumor size, positive lymph node status, multiple tumors on imaging, higher grade, higher stage, and complete mastectomy were all associated with higher odds of chemotherapy.All patients with HER 2 and Triple negative subtypes were found to take chemotherapy. The second model and the sensitivity analysis revealed similar results with calcifications on mammography (when present) being linked to higher odds of chemotherapy only in the older age group. As for outcomes, young breast cancer patients were found to have a significantly higher proportion of recurrence (16.7% vs 10%, P:0.031) and particularly distant recurrence (14.3% vs 8.2%, P:0.033). Furthermore, there was a statistically significant difference in DFS curves (log rank: 0.012) but not OS curves.

Conclusion: Our results are in line with previous studies on young breast cancer. Our study revealed that young breast cancer patients had more aggressive presentation, more aggressive chemotherapy treatment, similar surgical treatment, and worse recurrence outcomes. We are to our knowledge the first study to investigate all three aspects: tumor characteristics, treatment modalities, and outcomes in Lebanon and the region. There is a need for larger prospective studies, to investigate this disease further to better guide physicians to tailor therapies in the region, avoiding over or under treatment.