White and black women in Los Angeles County are the
most likely to be diagnosed with breast cancer, but Asians are slowly catching
up
August 22, 2016--The Los
Angeles Cancer Surveillance Program (CSP), a state-mandated database managed by
the Keck School and the USC Norris Comprehensive Cancer Center, provides
scientists everywhere with essential statistics on cancer.
Newswise — Asian women living in Los
Angeles County are experiencing more breast cancer now than they faced nearly
four decades ago, according to a recently released cancer report card
administered by USC.
When compared to other Asian groups,
Filipino women face the most breast cancer diagnoses in the county, but their
risk is on the decline. The diagnoses went down 6 percent in the seven years
between 2005 and 2012.
In contrast, Korean women are on the
bottom of the list but are experiencing a steep and continuous increase in
breast cancer rates, nearly quadrupling in the 32 years between 1980 and 2012.
The data comes from “Cancer in Los
Angeles County: Trends by Race/Ethnicity 1976-2012.” Released on Aug. 15, the
book is based on all cancers diagnosed among Los Angeles County residents over
the past 37 years — more than 1.3 million cases.
Breast cancer is the most common
cancer in women regardless of race or ethnicity and the most common cause of
cancer death among Hispanic women, according to the Centers for Disease Control
and Prevention. It is the No. 2 cause of cancer death among white, black, Asian
and Pacific Islander women.
An estimated 246,660 women will be
diagnosed with invasive breast cancer in 2016, and about 40,450 women will die
from the disease this year, according to the American Cancer Society.
Christy Russell, director of
the Harold E. and Henrietta C. Lee Breast Center at USC Norris Cancer
Hospital and an associate professor of clinical medicine at the Keck
School of Medicine of USC, has treated breast cancer patients for 30 years.
Russell shares what has she gleaned from all that oncology experience.
Q: Although fewer Korean women develop breast
cancer than any other ethnicity, their breast cancer risk has soared in the
past 37 years. Why are more Korean women developing breast cancer?
CR: Presumably, they have taken on
more “American lifestyle” choices, which would mean earlier puberty, later
menopause, fewer pregnancies, less breastfeeding, perhaps less physical
activity, higher body weight and possibly alcohol. Extensive epidemiologic
studies need to be done to figure out which, if any, of these factors
attributes to the rising rate of breast cancer risk in Korean women.
Q: Why do Filipino women have the highest breast
cancer risk among Asians? What might be causing a decline in this group’s
breast cancer occurrence?
CR: I can’t answer this question.
Epidemiologic studies would need to be done to assess the timing of their
adoption to the “American lifestyle.”
Q: If adopting a more American lifestyle could be
the culprit, why has the rate of breast cancer among white and black women
begun leveling off in the past decade?
CR: The risk of breast cancer in
white and black women is likely leveling off because of their steady use of
screening mammography. Additionally, during the time frame when their risk of
breast cancer is developing, they probably continue to have similar lifestyle
habits as those in years past, such as age at first full-term pregnancy, length
of breastfeeding, use of hormone replacement therapy, exposure to alcohol and
total body weight.
Q: What causes breast cancer?
CR: Breast cancer is related to
lifetime exposure of the breast tissue to uninterrupted estrogen and
progesterone. The ovaries produce these hormones. Anything that prolongs the
exposure to these hormones will increase a woman’s lifetime risk of breast
cancer.
Once a woman begins her ovarian
function during puberty, there are limited things she can do to reduce her risk
of developing breast cancer. Interruptions in the menstrual cycle will reduce
risk. The earlier and the more frequently she interrupts her menstrual cycle,
the greater reduction in risk of breast cancer. This includes full-term
pregnancy, prolonged breast feeding, steady and continuous physical activity,
and maintaining a low and healthy body weight.
Q: What role does alcohol play?
CR: More than 100 epidemiologic
studies have consistently found that alcohol use is related to the risk of
developing breast cancer, and there is no “safe” amount. The more alcohol
consumed, the higher the risk.
After menopause, alcohol, higher
body weight and hormone replacement therapy all increase the risk of breast
cancer. These are all related to continued exposure of the breast to either
estrogen alone or estrogen plus progesterone in the case of hormone replacement
therapy.
Q: Girls are reaching puberty earlier nowadays —
sometimes starting at age 8. What does early puberty mean for breast cancer
risk?
CR: Initiation of puberty is related
to a young woman attaining a specific height and weight. Presumably, the body
knows when it is capable of childbearing and thus puberty begins. Populations
in the world with greater health and nutrition during childhood will decrease
the age at which their girls start puberty.
Reaching puberty earlier increases
the amount of estrogen and progesterone a young woman receives in her lifetime,
so earlier puberty increases her risk of developing breast cancer.
Q: Should menopausal women abstain from hormone
replacement therapy to limit their breast cancer risk?
CR: The use of hormone replacement
therapy is a very personal decision and should be based on the extent of
menopausal symptoms such as hot flashes, sweats and sleep disturbance. The use
should be limited in terms of number of years and should be discontinued as
early as possible to reduce the subsequent increased risk of breast cancer. The
longer a woman is exposed to hormone replacement therapy, the greater her risk
of developing breast cancer.
However, that being said, the
majority of breast cancer risk is related to one’s lifetime exposure to
estrogen and progesterone and is not just related to what happens after
menopause.
Q: When are most women diagnosed with breast
cancer?
CR: Even though the majority of
female breast cancer risk is established during the years between puberty and
menopause, breast cancer generally occurs in older women. The median age for
the appearance of breast cancer in women is mid-sixties.
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