Molecular profile of breast cancers in Guinean oncological settings

Breast cancer is a complex disease characterized by the accumulation of multiple molecular alterations giving each tumor phenotype and an own evolutionary potential. This study aimed to describe the distribution of the profile and molecular subtypes of breast cancers followed at Surgical Oncology Unit of Donka National Hospital. This was retrospective and descriptive study on cases of breast cancer in which the hormone receptor status and expression of the Her2 oncogene have been performed from 2007 to 2016. We recorded 58 cases including 56 (96.6%) women and 2 (3.4%) men. The average age was 48.2 ± 10.9. Invasive ductal carcinoma accounted for 50 (86.2%) cases. The SBR grade was II in 31(53.4%) cases, III in 21 (36.2%) cases and I in 6 (10.3%) cases. The tumor was classified as T4 in 36 (62.1%) cases; it was metastatic in 11(19.0%) cases. Estrogen receptors were positive in 29 (50.0%) cases, progesterone receptors positive in 25 (43.1%) cases, the Her2 oncogene was positive in 22 (39.3%) cases. The distribution of molecular sub-types was: 20 (34.5%) luminal A, 15 (25.9%) triple negative, 13 (22.4%) Her2 overexpressed, 8 (13.8%) luminal B and 2 (3.2%) undetermined. This preliminary study showed the poor accessibility of immunohistochemistry for the molecular diagnosis of breast cancer in our country. Luminal A subtypes and triple negatives were more common. The determination of molecular subtypes is a rational basis for hormone therapy and targeted therapy, thus personalizing the treatment of breast cancer.


Introduction
Breast cancer is a major global public health problem. About 1,671,149 cases are diagnosed each year, including 521,907 deaths worldwide [1]. The number of cases reached 53,000 and more than 11,000 deaths in France [2]. In Africa, the incidence is 133,390 new cases with 63,160 deaths [1]. In North and Middle East Africa, breast cancer is the first cancer in women. It accounts for 14 to 42% of all female cancers with an exponential increase [3]. In Guinea, the agestandardized incidence is 14.5 new cases per 100,000 and the mortality rate is 7.9 per 100,000 [1]. It represents the leading cause triple-negative subtypes [8]. Indeed, immunohistochemistry is used to define biological prognostic factors and especially to make a target therapy. This target therapy has been made possible through the use of monoclonal antibodies and hormone therapy. In our country, immunohistochemistry (IHC) is not available and there are very little data on the molecular profile of breast cancer [4,9]. This study aimed to determine the first trends in the molecular profile of breast cancers followed at the surgical oncology unit of Donka National Hospital.

Methods
This was retrospective and descriptive study on cases of breast cancer in which the hormone receptor status and expression of the Her2 oncogene have been reported. These patients were followed at the and SBR I in 6 cases (10.3%). The tumor stage was less than or equal to T2 in 14 cases (24.1%), and greater than T2 in 44 cases (75.9%).

Discussion
This study highlights the dire need for IHC in sub-Saharan Africa. In this retrospective study, IHC was performed for 10.2% of breast cancers diagnosed from 2007 to 2016. Access to IHC remains limited, as it accounts for less than 30% of breast cancers in West African countries [10,11]. It is often during study projects, whether monocentric [12] or multicenter [13], that the molecular profile is better performed in different sub-Saharan Africa countries. On the other hand, there is better access in the Maghreb countries [14]. IHC is not available in our country as in most countries of sub-Saharan  [18] in Uganda reported in their study a high frequency in the 30-39 age groups. Age at diagnosis is an important prognostic factor since tumors diagnosed at younger ages are generally more aggressive and/or less response to treatment. This young age is related to the age of the female population in Guinea, whose under-40s represent 83.1% [19]. The anatomo-clinical characteristics of breast cancer in this study are the same as those of breast cancer reported in a previous study [5]. They are characterized by tumors larger than T2 (75.9%), stage III and IV (70.9%), high grade (SBR II and III) (89.6%), and metastatic (19.0%).
Intensive Care Consortium (ICC) was the common histological type in more than 80% as in several other studies in Africa and elsewhere [14,13,20]. However, many efforts still have to be made by Guinean pathologists as to the description of histological types. In western countries, the majority of breast tumors are less than 2cm, reflecting early detection of the disease [21]. We did not take into account the tumor size in this study but 75.9% were classified T3-T4. HR is different depending on the types of receptors. In our study, ER were positive in 50.0% while PR were positive in 43.1%. This receptor positivity appeared to be higher than in Mali where Ly et al. [26] showed that ER and PR were positive in 39% and 29% respectively.

Conclusion
This preliminary study showed the poor accessibility of immunohistochemistry for the molecular diagnosis of breast cancer in our country. Luminal A subtypes and triple negatives were more common. The determination of molecular subtypes is a rational basis for hormone therapy and targeted therapy, thus personalizing the breast cancer treatment.
What is known about this topic  Breast cancer in sub-Saharan African women is aggressive: triple negatives and high grades.

What this study adds
 We noted a difference in the distribution of molecular subtypes: luminal A more frequent than triple negative, but still high grade.