Breast cancer is a commonly
diagnosed cancer in women after non-melanoma skin cancer, and it is the second
leading cause of cancer deaths after lung cancer.
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| heredity and cancer, breast cancer, inherited factors vs. other factors (Photo credit: Wikipedia) |
It has
been seen in studies in adult populations, 5% to 10% of women have a mother or
sister with breast cancer, and about twice as many have either a first-degree relative (FDR) or a second-degree relative with breast cancer.
Risk
increases with the number of affected relatives, age at diagnosis, and the
number of affected male relatives
Genetically
predisposed/Inheritance
Autosomal
dominant inheritance of breast cancer is characterized by transmission of
cancer predisposition
from generation to generation, through either the mother’s or the father’s side
of the family, with the following characteristics:
- Multiple cancers within a family.
- Cancers typically occur at an earlier age than in sporadic cases (defined as cases not associated with genetic risk).
- Two or more primary cancers in a single individual. These could be multiple primary cancers of the same type (e.g., bilateral breast cancer) or primary cancer of different types (e.g., breast cancer and ovarian cancer in the same individual).
- Cases of male breast cancer.
Other Risk Factors for Breast Cancer
include age, reproductive and
menstrual history, hormone therapy, radiation exposure, mammographic breast
density, alcohol intake, physical activity, anthropometric variables, and a
history of benign breast disease
- Age
·
Risk of breast cancer increases with
age, with most breast cancers occurring after age 50 years. In women with a genetic susceptibility, breast cancer, tends to occur at an earlier age than in
sporadic cases.
- Use of Oral Contraceptives
·
Oral contraceptives use are not
entirely consistent, however, use of OCs formulated before 1975 was associated
with an increased risk of breast cancer.
·
Oral contraceptives (OCs) may
produce a slight increase in breast cancer risk among long-term users, but this
appears to be a short-term effect.
- Hormone replacement therapy (HRT)
·
Data exist from both observational
and randomized clinical trials regarding the association between postmenopausal
HRT and breast cancer.
·
Short-term use of hormones for
treatment of menopausal symptoms appears to confer little or no breast cancer
risk.
·
Local use of hormone cream is safer
than oral preparations.
- Age at Menarche, Parity and Menopause.
·
In general, breast cancer risk increases
with early menarche, late menopause; and is reduced by early first full-term
pregnancy.
·
In contrast to ER-positive breast cancers,
parity has been positively associated with triple-negative disease, with no
association with ages at menarche and menopause.
- Radiation exposure
·
Observations in survivors of the
atomic bombings of Hiroshima and Nagasaki and in women who have received
therapeutic radiation treatments to the chest and upper body document increased
breast cancer risk as a result of radiation exposure.
·
The significance of this risk factor
in women with a genetic susceptibility to breast cancer is unclear.
·
Frequent mammograms are also not
recommended.
- Alcohol intake
·
The risk of breast cancer increases
by approximately 10% for each 10 g of daily alcohol intake (approximately one
drink or less) in the general population. Prior studies of BRCA1/BRCA2
mutation carriers have found no increased risk associated with alcohol
consumption.
- Physical activity and anthropometry
·
Weight gain and being overweight are
commonly recognized risk factors for breast cancer. In general, overweight
women are most commonly observed to be at increased risk of postmenopausal
breast cancer and at reduced risk of premenopausal breast cancer. Sedentary
lifestyle may also be a risk factor. One study suggested a reduced risk of
cancer associated with exercise among BRCA1 and BRCA2 mutation
carriers.
- Benign breast disease (BBD) and mammographic density
·
Benign breast disease (BBD) is a
risk factor for breast cancer, independent of the effects of other major risk
factors for breast cancer (age, age at menarche, age at first live birth, and
family history of breast cancer). There may also be an association between BBD
and family history of breast cancer.
·
An increased risk of breast cancer
has also been demonstrated for women who have increased density of breast
tissue as assessed by mammogram, and breast density is likely to have a genetic
component in its etiology.
With a normal active lifestyle, balanced
diet; and breast self examination can beat the dreaded cancer to a larger
extent.
