Abstract P4-02-09: Clinical and histopathologic characteristics of breast cancer in very young patients
Authors: Finkelman BS , Blanco LZ , Siziopikou KP 
Published: May 2019

Background: While breast cancer risk increases with age, about 7% of breast cancer cases in the US are diagnosed in women &lt;40 years of age. Evidence suggests that young breast cancer patients tend to have more aggressive disease subtypes, less favorable tumor biomarker profiles, higher risk of relapse, and poorer survival. However, there is no universally accepted definition of "young patients," and most studies have focused on premenopausal women or those &lt;40 years of age, with some studies using age &lt;35. To date, very little is known on the clinical and histopathologic characteristics of breast cancer in very young women, namely those ≤30 years of age. In this study, we describe such features in a cohort of very young women treated for breast cancer at our academic institution.

Methods: Our patient population consisted of all cases of invasive breast carcinoma at Northwestern Memorial Hospital in women &lt;40 years of age at surgery between January 1, 2009, and December 31, 2015. Very young was defined as having an age ≤30. Histopathologic features including tumor size, grade, histologic type, presence of lymphovascular invasion (LVI), lymph node status, tumor markers (ER, PR, HER2) and Ki-67 proliferation rate were recorded. Cases in which specific histopathologic features could not be determined from available materials were excluded from the corresponding analysis. The use of neoadjuvant chemotherapy, type of surgery, and the use of prophylactic surgery on the contralateral side were also recorded and analyzed.

Results: A total of 301 invasive breast carcinoma cases were identified (age range 18-39). 40 cases of very young (age ≤30) women with breast cancer (13%) were identified. Nearly all very young patients were diagnosed with tumors of ductal histology (39/40, 98%). Just under half of these patients (19/40, 48%) had a T1 (&lt;2 cm), 16/40 (40%) had a T2 (2-5 cm), and 2/40 (5%) had a T3 (&gt;5 cm) tumor at the time of surgery. The majority of these carcinomas were grade 3 (25/39, 64%), 14/39 (36%) were grade 2, and none were grade 1 tumors. Over half of the tumors were highly proliferative with a high Ki-67 count of &gt;20% (17/31, 55%). ER was expressed in 34/40 (85%), PR in 25/40 (63%) and HER2 in 9/40 (23%). LVI was present in half of the cases (20/40, 50%), and positive lymph nodes were identified in over a third (15/40, 38%) of the cases. Neoadjuvant chemotherapy was used in 9/40 (23%). Three patients (8%) had no residual carcinoma at the time of surgery post chemotherapy. Most of these very young patients chose a mastectomy (28/40, 70%), and 19/40 (48%) also underwent a prophylactic mastectomy on the contralateral side.

Conclusions: Our study is one of the largest to date to describe the characteristics of breast carcinomas in very young women (age ≤30). Poor pathologic features such as high tumor grade, high proliferation rate, and presence of LVI were seen in half or more of these very young patients. A high rate of positive lymph nodes was also seen. Mastectomy, often with contralateral prophylactic surgery, was the procedure of choice. Further studies evaluating the molecular characteristics of these tumors and the prevalence of underlying genetic mutations are under way in this unique population of very young breast cancer patients.

Citation Format: Finkelman BS, Blanco LZ, Siziopikou KP. Clinical and histopathologic characteristics of breast cancer in very young 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 P4-02-09.