HOW TO AVOID BREAST CANCER

Breast cancer is when cancer
develops from breast tissue. [1]
Signs of breast cancer may include
a lump in the breast, a change in
breast shape, dimpling of the skin,
fluid coming from the nipple, or a
red scaly patch of skin. [2] In those
with distant spread of the disease,
there may be bone pain, swollen
lymph nodes, shortness of breath,
or yellow skin. [3]
Risk factors for developing breast
cancer include obesity , lack of
physical exercise, drinking alcohol ,
hormone replacement therapy
during menopause, ionizing
radiation, early age at first
menstruation, and having children
late or not at all.[2][4] About
5-10% of cases are due to genes
inherited from a person's parents,
including BRCA1 and BRCA2
among others. Breast cancer most
commonly develops in cells from
the lining of milk ducts and the
lobules that supply the ducts with
milk. Cancers developing from the
ducts are known as ductal
carcinomas, while those
developing from lobules are known
as lobular carcinomas.[2] In
addition, there are more than 18
other sub-types of breast cancer.
Some cancers develop from pre-
invasive lesions such as ductal
carcinoma in situ. [4] The diagnosis
of breast cancer is confirmed by
taking a biopsy of the concerning
lump Once the diagnosis is made,
further tests are done to
determine if the cancer has
spread beyond the breast and
which treatments it may respond
to.[2]
The balance of benefits versus
harms of breast cancer screening
is controversial. A 2013 Cochrane
review stated that it is unclear if
mammographic screening does
more good or harm. [5] A 2009
review for the US Preventive
Services Task Force found evidence
of benefit in those 40 to 70 years
of age, [6] and the organization
recommends screening every two
years in women 50 to 74 years old.
[7] The medications tamoxifen or
raloxifene may be used in an
effort to prevent breast cancer in
those who are at high risk of
developing it. [4] Surgical removal
of both breasts is another useful
preventative measure in some
high risk women. [4] In those who
have been diagnosed with cancer,
a number of treatments may be
used, including surgery, radiation
therapy, chemotherapy, and
targeted therapy.[2] Types of
surgery vary from breast-
conserving surgery to mastectomy.
[8][9] Breast reconstruction may
take place at the time or surgery
or at a later date. In those in
whom the cancer has spread to
other parts of the body,
treatments are mostly aimed at
improving quality of life and
comfort.[9]
Outcomes for breast cancer vary
depending on the cancer type,
extent of disease, and person's
age. [9] Survival rates in the
developed world are high, [10] with
between 80% and 90% of those in
England and the United States
alive for at least 5 years , [11][12]
but in developing countries
survival rates are poorer. [4]
Worldwide, breast cancer is the
leading type of cancer in women,
accounting for 25% of all cases.
[13] In 2012 it resulted in 1.68
million cases and 522,000 deaths.
[13] It is more common in
developed countries[4] and is
more than 100 times more
common in women than in men.
[10][14]
Signs and symptoms
Early signs of possible breast
cancer
Breast cancer showing an inverted
nipple, lump and skin dimpling.
The first noticeable symptom of
breast cancer is typically a lump
that feels different from the rest
of the breast tissue. More than
80% of breast cancer cases are
discovered when the woman feels
a lump. [15] The earliest breast
cancers are detected by a
mammogram.[16] Lumps found in
lymph nodes located in the
armpits[15] can also indicate
breast cancer.
Indications of breast cancer other
than a lump may include
thickening different from the
other breast tissue, one breast
becoming larger or lower, a nipple
changing position or shape or
becoming inverted, skin puckering
or dimpling, a rash on or around a
nipple, discharge from nipple/s,
constant pain in part of the breast
or armpit, and swelling beneath
the armpit or around the
collarbone. [17] Pain
(" mastodynia") is an unreliable
tool in determining the presence
or absence of breast cancer, but
may be indicative of other breast
health issues. [15][16][18]
Inflammatory breast cancer is a
particular type of breast cancer
which can pose a substantial
diagnostic challenge. Symptoms
may resemble a breast
inflammation and may include
itching, pain, swelling, nipple
inversion, warmth and redness
throughout the breast, as well as
an orange-peel texture to the skin
referred to as peau d'orange ;[15]
as inflammatory breast cancer
doesn't show as a lump there's
sometimes a delay in diagnosis.
Another reported symptom
complex of breast cancer is Paget's
disease of the breast. This
syndrome presents as skin
changes resembling eczema, such
as redness, discoloration, or mild
flaking of the nipple skin. As
Paget's disease of the breast
advances, symptoms may include
tingling, itching, increased
sensitivity, burning, and pain.
There may also be discharge from
the nipple. Approximately half of
women diagnosed with Paget's
disease of the breast also have a
lump in the breast. [19]
In rare cases, what initially
appears as a fibroadenoma (hard,
movable non-cancerous lump)
could in fact be a phyllodes
tumor. Phyllodes tumors are
formed within the stroma
(connective tissue) of the breast
and contain glandular as well as
stromal tissue. Phyllodes tumors
are not staged in the usual sense;
they are classified on the basis of
their appearance under the
microscope as benign, borderline,
or malignant. [20]
Occasionally, breast cancer
presents as metastatic disease—
that is, cancer that has spread
beyond the original organ. The
symptoms caused by metastatic
breast cancer will depend on the
location of metastasis. Common
sites of metastasis include bone,
liver, lung and brain. [21]
Unexplained weight loss can
occasionally herald an occult
breast cancer, as can symptoms of
fevers or chills. Bone or joint
pains can sometimes be
manifestations of metastatic
breast cancer, as can jaundice or
neurological symptoms. These
symptoms are called non-specific,
meaning they could be
manifestations of many other
illnesses. [22]
Most symptoms of breast
disorders, including most lumps,
do not turn out to represent
underlying breast cancer. Fewer
than 20% of lumps, for example,
are cancerous, [23] and benign
breast diseases such as mastitis
and fibroadenoma of the breast
are more common causes of breast
disorder symptoms. Nevertheless,
the appearance of a new symptom
should be taken seriously by both
patients and their doctors,
because of the possibility of an
underlying breast cancer at almost
any age. [24]
Risk factors
Main article: Risk factors of breast
cancer
The primary risk factors for breast
cancer are female sex and older
age. [25] Other potential risk
factors include: genetics, [26] lack
of childbearing or lack of
breastfeeding, [27] higher levels of
certain hormones, [28][29] certain
dietary patterns, and obesity.
Recent studies have indicated that
exposure to light pollution is a
risk factor for the development of
breast cancer. [30]
Lifestyle
See also: List of breast
carcinogenic substances
Smoking tobacco appears to
increase the risk of breast cancer,
with the greater the amount
smoked and the earlier in life that
smoking began, the higher the
risk. [31] In those who are long-
term smokers, the risk is increased
35% to 50%. [31] A lack of physical
activity has been linked to ~10%
of cases. [32]
There may be an association
between use of oral contraceptives
and the development of
premenopausal breast cancer,[33]
but whether oral contraceptives
use may actually cause
premenopausal breast cancer is a
matter of debate. If there is
indeed a link, the absolute effect
is small. [34][35] In those with
mutations in the breast cancer
susceptibility genes BRCA1 or
BRCA2 , or who have a family
history of breast cancer, use of
modern oral contraceptives does
not appear to affect the risk of
breast cancer. [36][37]
The association between breast
feeding and breast cancer has not
been clearly determined; some
studies have found support for an
association while others have not.
[38] In the 1980s, the abortion–
breast cancer hypothesis posited
that induced abortion increased
the risk of developing breast
cancer. [39] This hypothesis was
the subject of extensive scientific
inquiry, which concluded that
neither miscarriages nor abortions
are associated with a heightened
risk for breast cancer. [40]
There is a relationship between
diet and breast cancer, including
an increased risk with a high fat
diet,[41] alcohol intake, [42] and
obesity, [43] related to higher
cholesterol levels. [44] Dietary
iodine deficiency may also play a
role.[45]
Other risk factors include
radiation,[46] and shift-work . [47] A
number of chemicals have also
been linked including:
polychlorinated biphenyls,
polycyclic aromatic hydrocarbons,
organic solvents [48] and a number
of pesticides .[49] Although the
radiation from mammography is a
low dose, it is estimated that
yearly screening from 40 to 80
years of age will cause
approximately 225 cases of fatal
breast cancer per million women
screened. [50]
Genetics
Some genetic susceptibility may
play a minor role in most cases.
[51] Overall, however, genetics is
believed to be the primary cause
of 5–10% of all cases. [52] In those
with zero, one or two affected
relatives, the risk of breast cancer
before the age of 80 is 7.8%,
13.3%, and 21.1% with a
subsequent mortality from the
disease of 2.3%, 4.2%, and 7.6%
respectively. [53] In those with a
first degree relative with the
disease the risk of breast cancer
between the age of 40 and 50 is
double that of the general
population.[54]
In less than 5% of cases, genetics
plays a more significant role by
causing a hereditary breast–
ovarian cancer syndrome. [51] This
includes those who carry the
BRCA1 and BRCA2 gene mutation.
[51] These mutations account for
up to 90% of the total genetic
influence with a risk of breast
cancer of 60–80% in those
affected. [52] Other significant
mutations include: p53 ( Li–
Fraumeni syndrome ), PTEN
(Cowden syndrome), and STK11
(Peutz–Jeghers syndrome ), CHEK2 ,
ATM, BRIP1 , and PALB2 .[52] In
2012, researchers said that there
are four genetically distinct types
of the breast cancer and that in
each type, hallmark genetic
changes lead to many cancers. [55]
Medical conditions
Breast changes like atypical ductal
hyperplasia[56] and lobular
carcinoma in situ, [57][58][59]
found in benign breast conditions
such as fibrocystic breast changes ,
are correlated with an increased
breast cancer risk. Diabetes
mellitus might also increase the
risk of breast cancer. [60]
Pathophysiology
Main article: Carcinogenesis
Overview of signal transduction
pathways involved in apoptosis.
Mutations leading to loss of
apoptosis can lead to
tumorigenesis.
Breast cancer, like other cancers,
occurs because of an interaction
between an environmental
(external) factor and a genetically
susceptible host. Normal cells
divide as many times as needed
and stop. They attach to other
cells and stay in place in tissues.
Cells become cancerous when they
lose their ability to stop dividing,
to attach to other cells, to stay
where they belong, and to die at the proper time.