ABSTRACT
Breast cancer is the
commonest site specific, malignancy affecting women and the most common cause
of cancer mortality in women world wide. Our knowledge about breast cancer is
evolving but it is still limited with respect to its etiology and biology and
with respect to its features in individual countries and cultures.
The study was conducted to identify and determine the risk
factors for breast cancer in a Tertiary hospital in Nigeria. A retrospective
case control study was carried out in National Hospital Abuja. A total of
544samples were used in the work comprising of 272 cases and 272 controls . The
data was obtained directly from patients case file. Information obtained were;
Sex, Occupation, Weight, Height, Parity, Age, Religion, Marital Status,
Smoking, Family history of breast cancer, Alcohol consumption, Menarche and
Oral Contraceptive history. The data was entered and analyzed using SPSS 15
version. The P value accepted as significant was set at P < 0 .05 at 95%
confidence level. Test statistics performed were chi-square (x2) and
odds ratio (OR) in order to obtain the association as well as level of risk of
a given risk factor.
Females constituted 521 (95.8%)
of the study population while males were 23(4.2%). Patients age ranged between
25-74 years with age groups 35-44 and 45-54 years constituting the highest
frequencies of 158 (29.4%) and 160 (29.8%) respectively. Those who had early menarche
were 257(51.1%) while normal menarche were 246 (48.9%). Population of women who
used oral contraceptives were 110 (21.8%) while those who did not use were 395
(78.2%). Parity among patients ranged between 0-10
children with those having 1-5 children having the highest frequency of 361
(72.8%). 264 (49.1%) of the patients consumed alcohol while 274 (50.9%) did not
consume alcohol. Mother 60 (40.0%) and Sister 37 (24.7%) had the highest
frequency for patient with family history. Civil servant 229 (43.5%) had the
highest frequency for occupation of patients in the study. This was followed by
those doing business 120 (22.8%). Housewives 96 (18.3%) Retiree 49 (9.3%)
Student 18 (3.4%) and Farmers 14 (2.7%). 25 (4.6) of the patients smoked while
515 (95.4%) did not smoke. 47 (32.2%) of the patient were underweight while 99
(67.8%) were over weight. 459 (84.7%) of patients were Christians while 83
(15.3%) were practicing Islam. Finally 447 (82.9%) were married while 56(10.4%)
were single and widows were 36 (6.7%) in the study.
In conclusion, Gender, Age, Parity, Early menarche,
Use of oral contraceptives, Alcohol consumption, Occupation and family history
of patients with breast cancer were identified as risk factors for breast
cancer as well as had significant association for development of breast cancer.
Smoking, Religion, Marital status and BMI of patients were not identified as
risk factors for developing breast cancer in the study.
CHAPTER ONE
1.0 INTRODUCTION
Breast
Cancer constitutes a major public health issue globally with over 1 million new
cases diagnosed annually, resulting in over 400,000 annual deaths and about 4.4
million women living with the disease. It is the commonest site specific
malignancy affecting women and the most common cause of cancer mortality in
women
worldwide.1,2
In
Africa, Breast Cancer has overtaken cervical cancer as the commonest malignancy affecting women and
the incidence rates appear to be rising. 3,4 In Nigeria for example,
incidence rate has increased from 13.8–15.3 per 100,000 in the 1980s, to 33.6 per 100,000
in 1992 and 116 per 100,000 in 2001.5These
increases in incidence are due to changes in the demography, socio-economic
parameters, epidemiologic risk factors, better reporting and awareness of the
disease.
There is an
international/geographical variation in the incidence of Breast Cancer.
Incidence rates are higher in the developed countries than in the developing
countries and Japan. Incidence rates are also higher in urban areas than in the
rural areas. While mortality rates are declining in the developed world
(Americas, Australia and Western Europe) as a result of early diagnosis,
screening, and improved cancer treatment programs, the converse is true in the
developing world as
well as in eastern and central Europe 6,7
Breast
cancer and its treatment constitute a great physical, psychosocial and economic
challenge in resource limited societies as found in Africa. The hallmark of the
disease in Africa are patients presenting at advanced stage, lack of adequate
mammography screening programs, preponderance of younger pre-menopausal
patients,
and a high morbidity and mortality. 3,6
Pregnancy associated breast
cancer is defined as breast cancer diagnosed during pregnancy or lactation or
one year post partum. Breast cancer and pregnancy can be classified into three
main situations; these are: breast cancer that is detected during the evolution
of pregnancy; breast cancer that is detected during lactation or postpartum,
and pregnancy in patients who have had a previous breast cancer. Cancer
complicates approximately 1 per 1000 pregnancies and accounts for one-third of
maternal deaths during gestation. The prevalence of breast cancer during
pregnancy is increasing due to delayed onset of childbearing. Breast cancer is
diagnosed in approximately 1 in 3000 pregnancies. The incidence ranges from
0.76% to 3.8% of breast cancer cases. The median age of pregnant women affected
with breast cancer is 33 years. In a recent review in Nigeria, 12% of the
patients with Breast Cancer were pregnant or lactating and 74% were
premenopausal, making it the most frequently occurring malignancy during pregnancy,
along with cancer of the uterine cervix.5
1.2.1
Invasive breast cancer
Incidence
rates of invasive female breast cancer for all races combined show three
distinct phases since 1975, when broad surveillance of cancer began:
Between
1975 and 1980, incidence was essentially constant;
Between
1980 and 1987, incidence increased by almost 4% per year;
Between
1987 and 2002, incidence rates increased by 0.3% per year.9
Much of the long-term
underlying increase in incidence is attributed to changes in reproductive
patterns, such as delayed childbearing and having fewer children, which are
recognized risk factors for breast cancer. The rapid increase between 1980 and
1987 is due largely to greater use of mammographic screening and increased
early detection of breast cancers too small to be felt. Detecting these tumors
earlier has the effect of inflating the incidence rate because tumors are being
detected 1-3 years before they would have appeared if they continued to grow
until symptoms developed. During the introduction of mammography, from 1980 to
1987, incidence rates of smaller tumors (<2.0 cm) more than doubled, while rates of larger tumors (3.0 cm or more ) decreased
27%.10 During this time, the trend in diagnosis of smaller (<2.0
cm) tumors continued, increasing by 2.1% per year from 1988 to 1999, and stabilized thereafter.11
A similar time trend was seen with stage at diagnosis, with increases in the
rates limited to cancers diagnosed at a localized stage. The continued, though
slight, increase in overall breast
cancer incidence since 1987 may reflect increase in the prevalencement therapy
(HRT).
1.2.2
Age
From
1980 to 1987, incidence rates of invasive breast cancer increased among women aged 40-49 and 50 and
older (3.5% and 4.2% per year, respectively).11 Since 1987, rates
have continued to increase among women 50 and older, though at a much slower
rate. In contrast, the rates have slightly declined among women aged 40-49.
There has been relatively little change in the incidence rates of invasive
breast cancer in women younger than 40.
1.2.3
Race/ethnicity
During 1992-2002, overall
incidence rates increased in Asian Americans/Pacific Islanders (1.5% per year),
decreased in American India/Alaska Natives (3.5% per year), and did not change
significantly among whites, African Americans, and Hispanics/Latinas.11 This could be attributed to poor prognosis of
aggressive tumor
common in African –American women8.
Incidence rates of breast
cancer by tumor size differed between white and African American women: African
American women were less likely to be diagnosed with smaller tumors (<
2.0 cm) and more likely to be diagnosed with larger tumors
(2.1-5.0 and > 5.0 cm) than white women.11
White women have a higher
incidence of breast cancer than African American women after age 35. In
contrast, African American women have a slightly higher incidence
rate before age 35 and are more likely to die from breast cancer at every age.
Incidence and death rates from breast cancer are lower among women of other
racial and ethnic groups than among white and African women.
1.2.4
In situ breast cancer
Incidence rates of in situ
breast cancer have increased rapidly since 198011 largely because of
increased diagnosis by mammography. Most of this increase represents increased
detection of ductal carcinoma in situ (DCIS), which from 1998 to 2002 accounted
for about 85% of the in situ breast cancers diagnosed.
Incidence rates of DCIS increased more than sevenfold during
1980-2001.12 The increase was observed in all age groups, although
it was greatest in women aged 50
and older.11,12
Most cases of DCIS are detectable only through mammography,
and the large increases in DCIS incidence rates since 1982 are a direct result
of mammography’s ability to detect cancers that cannot be felt. Although
increase in both invasive breast caner and DCIS incidence rates have slowed
since the mid-1980s,13the temporal increase in DCIS since 1982
is larger than the increase in invasive breast cancer.
Lobular carcinoma in-situ (LCIS) is less common than DCIS,
accounting for approximately 12% of female in situ breast cancers diagnosed
from 1998 to 2002.11
Similar to DCIS, the overall incidence rate of LCIS has increased more rapidly
than the incidence of invasive breast cancer.11 This increase has been limited
to women older than 40 and largely to postmenopausal women.,12.14
The
death rate from breast cancer in women has decreased since 1990:
Between
1975 and 1990, the death rate for all races combined increased by 0.4%annually; Between
1990 and 2002, the rate decrease by 2.3% annually.15
The percentage of decline was
larger among younger age groups. From 1990 to 2002, death rates decreased by
3.3% per year among women younger than 50, and by 2.0% per year among women 50
and older.15 The decline in breast cancer mortality since 1990 has
been attributed to both improvements in breast cancer treatment
and to early detection.16,17
African American women and
women of other racial and ethnic groups, however, have benefited less than
white women from these advances. From 1990 to 2002, female breast cancer death
rates declined by 2.4% per year in whites, 1.8% in Hispanics/Latinas, 1.0% in
African Americans and Asian Americans/Pacific Islanders, and did not decline
in American Indian/Alaska Natives.18 A striking divergence in
long-term mortality trends is seen between African American and white females.
The disparity in breast cancer death rates between African American and white
women appeared in the early 1980s; by 2002, death rates were
37% higher in African Americans than in white women.15
1.4
Incidence and mortality trends –men
Although
breast cancer in men is a rare disease, accounting for less than 1% of breast
cancer case in the US, between 1975 and 2002, the incidence rate among males increased 1.1% annually. 11 The reasons for
the increase are unknown and are not attributable to increased detection.
Similar to female breast cancer, the incidence of male breast cancer increases with age.19
Men however are more likely than women to be diagnosed with advanced disease
and thus have poorer survival.19
Death rates from male breast cancer have remained essentially constant since
1975. 15
Male breast cancer is an uncommon disease although the
incidence has increased over the past 25 years. Less than 1% of all breast
cancer patients are male. Rates of male breast cancer vary widely between
countries: in Uganda and Zambia the annual incidence rates are 5% and 15%,
respectively of all breast cancer cases. These relatively high rates have been
attributed to endemic infectious diseases causing liver damage, leading to
hyperestrogenism. By contrast, the annual incidence of male breast cancer in
Japan is less than five per million, in parallel with the lower than average
incidence of female breast cancer in that country. Jewish men are the only
racial group with a higher than average incidence (2•3/100 000 per year),
irrespective of living in Israel or the USA.
Risk factors for Breast Cancer
include; Genetic (BRCA2, Klinefelter’s syndrome), Lifestyle (Obesity, Alcohol,
Estrogen intake) , Work (High ambient temperature, Exhaust emissions) and
Disease (Testicular damage, Liver damage, Radiotherapy to chest. The
predominant histological type of disease is invasive ductal,
which forms more than 90% of all male breast tumors.29
Breast cancer unlike cervical cancer
has no precise etiological agent. It therefore constitutes a major
public health issue globally. Our knowledge about breast cancer is evolving,
but it is still limited with respect to its etiology and biology and with
respect to its features in individual countries and cultures.
All efforts are geared towards early diagnosis, prompt and
standardized treatment to reduce the disease burden of advanced disease in
African women, majority who are worse hit in the most productive part of their life time20.
Therefore there is the need to elicit possible risk factors for breast cancer
in Nigeria.
1.6 JUSTIFICATION FOR THE STUDY
The breast is very important in
the life of a woman. It is the essential part of the body which nourishes a new
born. It is one of the part of the body which attracts the opposite sex amongst
adults. In Africa, a woman without breast is regarded as incomplete.
Breast cancer starts with some of the cells in the breast
growing abnormally and in most cases, it isn’t clear what causes normal breast
cells to become cancerous.60 Doctors know that only 5-10% breast
cancers are inherited yet genetic mutations related to breast cancer aren’t
inherited.
The study
was designed to identify, determine as well as establish risk factors that
predispose one to breast cancer in Nigeria. Results obtained will contribute to
public health consciousness to risk factors for breast cancer in Nigeria
1.7 OBJECTIVES
General
Objective:
To
identify the major risk factors for Breast cancer in Nigeria
Specific
Objectives:
1.
To identify the risk factors for
breast cancer
2.
To determine the association of risk
factors contributing to Breast cancer.
3.
To establish major risk factors
contributing to Breast Cancer in Nigeria.
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Item Type: Project Material | Size: 68 pages | Chapters: 1-5
Format: MS Word | Delivery: Within 30Mins.
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