Prognostic features of breast cancer differ between women in the Democratic Republic of Congo and Belgium.
OBJECTIVE
Compared to European women, breast cancers in African women present at a younger age, with a higher tumor grade and are more often estrogen receptor (ER)/progesterone receptor (PR) negative. We here investigate the histopathological and immunohistochemical characteristics (ER, PR and human epidermal growth receptor 2 (HER2)) and the proportion of triple negative (Tneg) invasive breast cancers from an unselected series of patients diagnosed in Kinshasa, and compare them to a population of Caucasian women with a palpable breast cancer.


METHODS
From 2010 till 2013, during the first breast cancer awareness campaign, organized in Kinshasa, 87 patients were diagnosed with invasive breast cancer. Diagnose was based on core biopsy. The control group consisted of Caucasian women (University Hospitals of Leuven, Belgium) with a palpable mass, diagnosed between 2000 till 2009, treated with surgery of which the histopathological and immunohistochemical characteristics were collected on excision specimens. Each patient in the Kinshasa group was matched based on age and tumor size to one or more patients of the Leuven database. Differences between both groups with respect to hormone receptors (ER, PR, HER2, Tneg) or grade are presented as relative risks (RR). The analysis is based on a log-binomial model accounting for clustering through matching by a random intercept for cluster. Differences between both groups with respect to hormone receptors correcting for grade is performed by the inclusion of grade as a covariate in the model.


RESULTS
After adjusting for age, tumor volume and tumor grade, ER was more frequently negative (RR = 0.71, p < 0.001), with a trend in the same direction for PR (RR = 0.87, p = 0.057), and HER2 more often positive (RR = 1.60, p = 0.015) compared to the group from the University Hospitals of Leuven. There was no difference in the proportion of breast cancers being triple negative. Sub-analysis showed that the higher HER2 positive rate was only observed in older patients (≥50y: RR = 2.07, p = 0.007) whereas no difference in HER2 positive rate was found in younger patients (<50y: RR = 1.30, p = 0.358). A higher ER negative rate was observed in both age groups, however more pronounced in older patients (≥50y: RR = 0.64, p = 0.001; <50y: RR = 0.79, p = 0.018).


CONCLUSIONS
Breast cancer in women of Kinshasa presents at younger age and is more aggressive (more frequently ER negative and HER2 positive) compared to Caucasian women and this is more pronounced in older women (>50y). Only the ER results were concordant with the results of two similar studies (comparing an African with a European group), but were different when compared to studies on African-American women with breast cancer. This information is very important considering the treatment option: as more tumors are ER negative, endocrine therapy cannot be given while chemotherapy is often too expensive.
General Hospital of Kinshasa, Kasavubu University, University of Lubumbashi, Democratic Republic of Congo; Faculty of Medicine, KU Leuven, Herestraat 49, Leuven, Belgium. Electronic address: gluyeye.gl@gmail.com.
Gertrude
G
Luyeye Mvila
General Hospital of Kinshasa, Avenue Colonel Ebeya, PB 169, Kinshasa, Democratic Republic of Congo. Electronic address: bansido@yahoo.fr.
Donatien
D
Batalansi
Department of Pathology, University Hospital of Ghent & Ghent University, De Pintelaan 185, Ghent, Belgium. Electronic address: marleen.praet@ugent.be.
Marleen
M
Praet
Department of Radiology, UZ Leuven, Herestraat 49, Leuven, Belgium; Department of Imaging and Pathology, KU Leuven, Herestraat 49, Leuven, Belgium. Electronic address: guy.marchal@uzleuven.be.
Guy
G
Marchal
Leuven Biostatistics and Statistical Bioinformatics Centre (L-BioStat), Kapucijnenvoer 35 Building D Box 7001, Leuven, Belgium. Electronic address: annouschka.laenen@med.kuleuven.be.
Annouschka
A
Laenen
Multidisciplinary Breast Center, UZ Leuven, Herestraat 49, Leuven, Belgium. Electronic address: marie-rose.christiaens@uzleuven.be.
Marie-Rose
MR
Christiaens
Department of Obstetrics and Gynaecology, Jan Yperman Hospital, Briekestraat 12, Ypres, Belgium. Electronic address: olivier.brouckaert@yperman.net.
Olivier
O
Brouckaert
Department of Pathology, University Hospital of Ghent & Ghent University, De Pintelaan 185, Ghent, Belgium. Electronic address: cathymulumba@yahoo.fr.
Catherine
C
Ali-Risasi
Department of Obstetrics and Gynaecology, UZ Leuven, Herestraat 49, Leuven, Belgium. Electronic address: patrick.neven@uzleuven.be.
Patrick
P
Neven
Department of Radiology, UZ Leuven, Herestraat 49, Leuven, Belgium; Department of Imaging and Pathology, KU Leuven, Herestraat 49, Leuven, Belgium. Electronic address: chantal.vanongeval@uzleuven.be.
Chantal
C
Van Ongeval
D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001530:Belgium; D044383:Black People; D001943:Breast Neoplasms / Q000737:chemistry* / Q000208:ethnology* / Q000473:pathology; D015023:Democratic Republic of the Congo; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D060787:Neoplasm Grading; D011379:Prognosis; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000032:analysis*; D011960:Receptors, Estrogen / Q000032:analysis*; D011980:Receptors, Progesterone / Q000032:analysis*; D012189:Retrospective Studies; D064726:Triple Negative Breast Neoplasms / Q000208:ethnology / Q000473:pathology; D044465:White People; D001741:Black or African American
D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; C508053:ERBB2 protein, human
African women; Breast cancer; Estrogen receptor; Progesterone receptor; Triple negative