Rare Breast Cancer Types: A Study About Characteristics, Outcomes, and Peculiarities
Nadiye AKDENİZ, Muhammet Ali KAPLAN, Mehmet KÜÇÜKÖNER, Zuhat URAKÇI, Oğur KARHAN, Yasin SEZGİN, Senar EBİNÇ, Erkan BİLEN, Mustafa NACİR, Hüseyin BÜYÜKBAYRAM, Abdurrahman IŞIKDOĞAN
Journal of Oncological Sciences
==Breast cancer (BC) is the most common type of cancer found among women worldwide and has heterogeneity as one of the most important features. 1 BC heterogeneity can be seen in both classic histopathological characterization and molecular classification. BC consists of various conditions characterized by different pathological and biological features, clinical presentation and behavior, treatment responses, and outcomes. According to the World Health Organization (WHO) classification, BC can
... classified in up to 21 different histological types based on varying patterns of morphologic features, growth, and architecture. Invasive ductal carcinomas (IDC) are the most common types of BC and are responsible for approximately 60% to 75% of all breast cancers, whereas 25% of breast cancers are special subtypes. 2 Although clinical, pathological, and epidemiological differences between ductal and lobular carcinomas have been examined in several studies, rarer histologic types of BC like mucinous, tubular, medullary, and papillary carcinomas are poorly known. 3 Our understanding of these subtypes is primarily based on several case reports, small clinical series, and numerous population-based studies. 4 The ABS TRACT Objective: We aimed to explore different features of rarely seen breast cancer (BC) subtypes, including their stage, molecular subtypes, treatment choices, and prognosis. Material and Methods: We retrospectively screened patients who were diagnosed with BC in our hospital between July 2010 and June 2018. A total of 97 patients who had micropapillary, cribriform, mucinous, papillary, tubular, apocrine, metaplastic, medullary, and myoepithelial subtypes of BC were finally included in the current study.Results: Ninety-four (96.9%) patients were females. Patients with cribriform and mucinous subtypes were in the younger median age of 41 and 45 years, respectively, whereas papillary cases were reported in the oldest median age (64.5 years). Lymph node and TNM stages showed a statistical difference between the subtypes (p=0.029 and p=0.008, respectively). Most of the cribriform (60%), metaplastic (66.7%), and papillary (70%) cases were diagnosed without lymph node involvement. Apocrine (79%) and micropapillary (75%) tumors mostly presented with nodal involvement. While medullary (75%), tubular (66.7%), and cribriform (66.7%) carcinomas were more likely to be diagnosed at stage II, micropapillary (70.8%), and apocrine (62.5%) carcinomas were mostly diagnosed at stage III. Mucinous, tubular, and cribriform tumors were noticed in the luminal group. Medullary, metaplastic, apocrine, and papillary tumors included triple-negative subgroups. HER2-enriched tumors included apocrine (62.5%), medullary (50%), and micropapillary (25%) subtypes. Disease-free survival and overall survival of the patients showed marginal statistical significance according to tumor subtypes (p=0.086, p=0.085, respectively). Conclusion: In this study, we investigated important features, clinical behavior, management, and outcomes of several rare BC subtypes. We opine that the current study may prove instrumental and informative for both daily clinical practice and future studies.