Kenny
http://health.usnews.com/usnews/health/healthday/071207/obesity-diabetes-li
nked-to-cancers.htm
Obesity, Diabetes Linked to Cancers
Studies find effects on breast, prostate and colorectal tumors
By Ed Edelson
Posted 12/7/07
FRIDAY, Dec. 7 (HealthDay News) -- Obesity and diabetes -- risk factors so
often linked to heart disease -- can also affect the incidence and severity
of cancer, a collection of four new studies suggests.
The findings, presented Friday at the American Association for Cancer
Research's Sixth Annual International Conference on the Frontiers of Cancer
Prevention Research in Philadelphia, link weight gain and diabetes to a
number of malignancies, including breast, prostate and colorectal cancer.
"All of these are consistent with what we would expect with the occurrence
of each of these cancers or cancer survival," said Elizabeth Platz,
associate professor of epidemiology at the Johns Hopkins Bloomberg School
of Public Health. "Metabolic perturbations enhance certain cancers. Insulin
and other hormonal factors influence cell growth and make cells multiply."
Women with diabetes have a 50 percent increased risk of developing
colorectal cancer, according to the first study, by researchers at the
University of Minnesota. The group, led by Andrew Flood, assistant
professor of epidemiology and public health, followed more than 45,000
women enrolled originally in a breast cancer detection program for more
than eight years.
The increased incidence of colorectal cancer remained significant after all
possibly confounding factors were taken into account. While the reason for
the increased risk is not known, Flood said it could be due to the elevated
levels of insulin seen with diabetes.
High levels of insulin in diabetic women could explain a threefold higher
risk of death from breast cancer, said the second study, by researchers at
Yale University. They measured blood levels of C-peptide, a marker of
insulin secretion, in women in a long-term study of breast cancer. Over an
eight-year period, the women in the highest third of C-peptide levels had
twice the risk of dying from breast cancer, compared to women in the bottom
third, the researchers said.
Another study, by researchers at the Johns Hopkins Bloomberg School of
Public Health, found that weight gain after a diagnosis of invasive breast
cancer could significantly increase a women's risk of death from the
cancer.
The study of more than 4,000 women with breast cancer classified them by
body mass index, a ratio of weight to height. For obese women, the risk of
dying of breast cancer was 2.4 times greater than for women with a normal
body weight, a relationship that persisted when age, menopausal status and
smoking were taken into account.
Another Johns Hopkins study provided a possible explanation for the lower
risk of prostate cancer seen in men with diabetes. The researchers matched
264 men diagnosed with the cancer with a group of 264 cancer-free men,
measuring C-peptide levels in both groups.
Men with elevated blood levels of C-peptide when the study started were
one-third less likely to develop prostate cancer than those with lower
levels. Men with higher C-peptide levels had half the risk of developing
prostate cancer confined to the prostate.
The protective effect of those high levels could be due to the activity of
insulin in relation to the male hormone testosterone, Plantz said.
C-peptide derives from the same parent molecule as insulin, and insulin is
known to reduce the activity of testosterone, which stimulates the growth
of prostate cancer, she said.
The possible protective effect of insulin against prostate cancer could
offer a mirror image of the negative effect of estrogen -- the female sex
hormone -- in breast cancer, said Dr. Rexford Ahima, professor of medicine
at the University of Pennsylvania.
"We have known for years that women who are obese are at high risk of
breast cancer," Ahima said. "Fat tissue makes estrogen, which promotes
breast cancer. The frightening thing is that the more obese you are, the
greater the risk you have of dying of cancer. For every increase of 10
kilograms, 14 pounds, there is a 14 percent increased risk of breast cancer
death."
So, instead of thinking of obesity just as a risk factor for heart disease,
its effects on cancer must also be taken into account, Platz said. "In
general, it is a good thing to do to avoid obesity," she said. "That is a
message consistent with what we know about good health."
More information
nked-to-cancers.htm
Obesity, Diabetes Linked to Cancers
Studies find effects on breast, prostate and colorectal tumors
By Ed Edelson
Posted 12/7/07
FRIDAY, Dec. 7 (HealthDay News) -- Obesity and diabetes -- risk factors so
often linked to heart disease -- can also affect the incidence and severity
of cancer, a collection of four new studies suggests.
The findings, presented Friday at the American Association for Cancer
Research's Sixth Annual International Conference on the Frontiers of Cancer
Prevention Research in Philadelphia, link weight gain and diabetes to a
number of malignancies, including breast, prostate and colorectal cancer.
"All of these are consistent with what we would expect with the occurrence
of each of these cancers or cancer survival," said Elizabeth Platz,
associate professor of epidemiology at the Johns Hopkins Bloomberg School
of Public Health. "Metabolic perturbations enhance certain cancers. Insulin
and other hormonal factors influence cell growth and make cells multiply."
Women with diabetes have a 50 percent increased risk of developing
colorectal cancer, according to the first study, by researchers at the
University of Minnesota. The group, led by Andrew Flood, assistant
professor of epidemiology and public health, followed more than 45,000
women enrolled originally in a breast cancer detection program for more
than eight years.
The increased incidence of colorectal cancer remained significant after all
possibly confounding factors were taken into account. While the reason for
the increased risk is not known, Flood said it could be due to the elevated
levels of insulin seen with diabetes.
High levels of insulin in diabetic women could explain a threefold higher
risk of death from breast cancer, said the second study, by researchers at
Yale University. They measured blood levels of C-peptide, a marker of
insulin secretion, in women in a long-term study of breast cancer. Over an
eight-year period, the women in the highest third of C-peptide levels had
twice the risk of dying from breast cancer, compared to women in the bottom
third, the researchers said.
Another study, by researchers at the Johns Hopkins Bloomberg School of
Public Health, found that weight gain after a diagnosis of invasive breast
cancer could significantly increase a women's risk of death from the
cancer.
The study of more than 4,000 women with breast cancer classified them by
body mass index, a ratio of weight to height. For obese women, the risk of
dying of breast cancer was 2.4 times greater than for women with a normal
body weight, a relationship that persisted when age, menopausal status and
smoking were taken into account.
Another Johns Hopkins study provided a possible explanation for the lower
risk of prostate cancer seen in men with diabetes. The researchers matched
264 men diagnosed with the cancer with a group of 264 cancer-free men,
measuring C-peptide levels in both groups.
Men with elevated blood levels of C-peptide when the study started were
one-third less likely to develop prostate cancer than those with lower
levels. Men with higher C-peptide levels had half the risk of developing
prostate cancer confined to the prostate.
The protective effect of those high levels could be due to the activity of
insulin in relation to the male hormone testosterone, Plantz said.
C-peptide derives from the same parent molecule as insulin, and insulin is
known to reduce the activity of testosterone, which stimulates the growth
of prostate cancer, she said.
The possible protective effect of insulin against prostate cancer could
offer a mirror image of the negative effect of estrogen -- the female sex
hormone -- in breast cancer, said Dr. Rexford Ahima, professor of medicine
at the University of Pennsylvania.
"We have known for years that women who are obese are at high risk of
breast cancer," Ahima said. "Fat tissue makes estrogen, which promotes
breast cancer. The frightening thing is that the more obese you are, the
greater the risk you have of dying of cancer. For every increase of 10
kilograms, 14 pounds, there is a 14 percent increased risk of breast cancer
death."
So, instead of thinking of obesity just as a risk factor for heart disease,
its effects on cancer must also be taken into account, Platz said. "In
general, it is a good thing to do to avoid obesity," she said. "That is a
message consistent with what we know about good health."
More information
