Epidemology of Breast Cancer:Risk Factors,Treatment Adherenceand Outcome of Breast Cancer Patients Attending Tikur Anbessa Specialized Hospital, Addis Ababa, Ethiopia
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Date
2023-09
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Addis Ababa University
Abstract
Background: Breast cancer is the most common cancer and the leading cause of cancer deaths
among women worldwide. In resource-limited nations, the combination of late presentation, low
survival rates, a poor health care system, and a lack of health care financing resource contribute
to the population's perception that treatments for breast cancer are ineffective or unavailable,
thereby causing more delay in diagnosis and treatment. Adherence has been identified as a
primary determinant of patient outcome and clinical benefit. In Ethiopia, breast cancer is one of
the most commonly diagnosed cancers among women. However, due to constrained health
resources and poor awareness among the population, most patients did not visit health facilities
for early diagnosis and treatment. As a result, most patients did not benefit from treatment since
most Ethiopian women are frequently diagnosed at an advanced stage. Moreover, non-adherence
to chemotherapy is not well investigated in patients attending their treatment in Addis Ababa,
Ethiopia.
Objective: The objective of the study was to assess the epidemiology of breast cancer among
patients treated at the Oncology Department, Tikur Anbessa Specialized Hospital, and Addis
Ababa, Ethiopia.
Methods: The study applied multiple epidemiologic designs. A case-control study was
conducted from May 2018 to June 2019. A total of 230 cases and 230 controls (care givers)
participated in order to assess the sociodemographic and hematologic profiles and risk factors for
breast cancer. The cross-sectional study was conducted among 164 breast cancer patients taking
chemotherapy. In addition, secondary data were also collected to assess the outcome of breast
cancer patients treated from September 2010 to August 2014 at TASH. Data were collected
using face-to-face interviews, chart reviews, and telephone interviews. An independent student t-
test was performed to compare the mean hematological parameters. A chi-square test was done
to see if there was a significant difference in hematologic parameters between cases and controls.
A binary logistic regression analysis was conducted to examine the association between potential
risk factors and breast cancer. A multivariable logistic regression model-based analysis was
conducted to control the effect of potential confounding factors. Median ages at diagnosis and
the interquartile range (IQR) were calculated. Based on life table analysis, one-, three-, five-, and
10-year overall survival rates were calculated. Median survival estimates were obtained using the
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Kaplan-Meier survival analysis method. Survival curves were compared using the log-rank
statistic. Cox's proportional hazards model was used for bivariate and multivariable analyses.
Results: The mean (+ SD) ages of study patients for the case-control study were 42.8 (+12.1)
and 39.3 (+11.1) years for cases and controls (caregivers of cancer patients), respectively. Nearly
half, or 100 (43.5%) of patients and 34 (14.8%) of controls, did not have any formal education.
Moreover, the majority, 175 (76.1%) of cases and 155 (67.4%) of controls, were married. The
mean values of most hematological parameters were significantly lower among cases. Moreover,
the mean platelet count was higher among cases. However, there was no significant difference in
the total white cell count among cases and controls. On the other hand, nearly half, 89 (46.6%)
cases and 96 (41.7%) controls, were blood group O. Blood group AB was the least common,
accounting for 19 (9.9%) and 20 (8.7%) of the cases and controls, respectively. However, a
statistically significant association was not found between breast cancer and the ABO or Rh
blood type.
Based on risk factor analysis, the odds of breast cancer were higher among illiterate women
(AOR: 2.57; 95% CI: 1.38–4.99) and among those who were unemployed (AOR: 3.78; 95% CI:
1.46–9.78; P = 0.006) as compared to educated and employed women. However, the odds of
breast cancer were 0.19 times lower among pre-obese women (AOR. 0.19(95%CI: 0.19; 95% CI:
0.043–0.826) compared to underweight women. Based on factors related to life style,
consumption of oil solid at room temperature was associated with breast cancer (AOR: 3.50,
95% CI: 2.18–5.62, P<0.001). In addition, women who used animal dung or wood as a source of
fuel had higher odds of breast cancer (AOR: 4.91, 95% CI: 2.72–8.86, P<0.001) compared to
women who used electricity as a source of fuel. Moreover, women who had previous benign
surgery, post-menopausal women, and women with early menarche (<12 years) had significantly
higher odds of breast cancer as compared to women who had no previous benign surgery,
premenopausal women, and menarche >15 years, respectively. While women who had moderate
physical activities had significantly lower odds of breast cancer as compared to women who had
no moderate physical activities, In the study that investigates adherence to chemotherapy, among
164 breast cancer patients, 137 (83.5%) were adherent to their chemotherapy. Severe illness was
one of the main reasons for non-adherence. Distance from the referral center and types of
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recommended treatment regimens were significantly associated with non-adherence. For survival
analysis, our retrospective cohort study included a total of 402 patients, with a median [IQR] age
at diagnosis of patients 43[35–50] years. The median follow-up time was 58.3 months. By the
end of follow-up, 233 (58%) of the patients were dead. The five- and ten-year survival rates were
50% and 34%, respectively. Based on multivariable cox regression analysis, advanced stage at
diagnosis (HR = 3.84; 95% CI 2.00–7.35, P< 0.001) and cancer metastasized tumor 1.79 (95%
CI 1.13-2.83, P = 0.012) were significantly associated with a higher risk of death.
Conclusion and recommendations: Based on the findings of the case-control study, illiterate
women had higher odds of breast cancer. As compared to controls, the majority of the
hematological profiles of patients were significantly lower. The study demonstrated there was no
significant association between the ABO/Rh blood group and breast cancer. The result of the risk
factors for breast cancer revealed that occupational status, using wood or animal dung as a source
of fuel, consumption of solid oil, menopausal status, early menarche, and previous benign breast
surgery were linked with breast cancer. While women with a history of moderate physical
exercise had lower odds of breast cancer. Regarding level of adherence, good adherence to
chemotherapy was observed among 137 (83.5%). The most identified factor for non-adherence
was the severity of the illness. The study also indicated a relatively poor survival rate, which was
associated with a late-stage diagnosis and metastasizing cancer. Based on the findings, we
recommend that attention be given to high-risk breast cancer groups and those with designated
hematologic abnormalities. Efforts should be exerted for further study with a large sample size in
order to establish the purpose of the ABO blood group in the prognosis of breast cancer. There is
also a need to design applicable interventions to inform women about lifestyle changes to
decrease breast cancer risk in high-risk groups. Since distance, transportation cost, and access to
health care are the most important factors that determine adherence to chemotherapy, the
extension of cancer screening and treatment centers should be encouraged. Moreover, there is a
need for strengthening public awareness and mass screening to enhance early initiation of
treatment, reduce advanced stages, and improve the survival of patients.
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Keywords
Breast cancer, hematological profiles, risk factors, adherence, survival