大夜班也许增加乳腺癌的危险
NEW YORK, Oct 16 (Reuters Health) - There is mounting evidence that women who are persistently exposed to light at night--such as women who work the graveyard shift--may be at an increased risk of breast cancer.
Two new studies that investigated the relationship between nighttime light exposure and breast cancer are published in the October 17th issue of the Journal of the National Cancer Institute.
In the first study, Dr. Scott Davis of the Fred Hutchinson Cancer Research Center in Seattle, Washington, and colleagues interviewed 813 breast cancer patients aged 20 to 74 about their exposure to light at night.
, http://www.100md.com
Nighttime light exposure can come from a variety of sources, including working the night shift, having insomnia or even being exposed to light in the bedroom during sleep.
Breast cancer risk was higher among women who often did not sleep during the period of the night when levels of the sleep-regulating hormone melatonin are typically at their highest, the study indicates. Their breast cancer risk increased 14% for each night of the week that they reported not sleeping during this period.
, http://www.100md.com
Working the graveyard shift upped a woman's risk of developing breast cancer by 60%, Davis and colleagues report.
"The results of this study provide evidence that indicators of exposure to light at night may be associated with the risk of developing breast cancer," the authors conclude.
In the second study, Dr. Eva S. Schernhammer of Harvard Medical School in Boston, Massachusetts, and colleagues examined the relationship between breast cancer and working the night shift in more than 78,000 nurses.
, http://www.100md.com
Women who worked between 1 and 29 years on a rotating night-shift schedule had an 8% increase in breast cancer risk, while women who worked 30 or more years on the night shift showed a 36% increase in their risk of developing breast cancer.
"Women who work on rotating night shifts with at least 3 nights per month, in addition to days and evenings in that month, appear to have a moderately increased risk of breast cancer after extended periods of working rotating night shifts," Schernhammer and colleagues conclude.
, 百拇医药
In an accompanying editorial, Johnni Hansen of the Danish Cancer Society in Copenhagen, Denmark, writes, "Evidence is accumulating for an association between exposure to light at night and breast cancer risk."
One possible explanation for this relationship has to do with melatonin production, she suggests. Melatonin is produced by the brain's pineal gland. Because it is released into the bloodstream at night, the hormone is thought to play a role in regulating sleep.
, 百拇医药
Hansen notes that when normal melatonin cycles are interrupted in women, the production of estrogen from the ovaries is higher and this may contribute to their breast cancer risk.
"There is urgent need for further exploration of the relationship between exposure to light at night, shift work, including timing during the night, and cancers that may be influenced by melatonin," Hansen concludes., 百拇医药
Two new studies that investigated the relationship between nighttime light exposure and breast cancer are published in the October 17th issue of the Journal of the National Cancer Institute.
In the first study, Dr. Scott Davis of the Fred Hutchinson Cancer Research Center in Seattle, Washington, and colleagues interviewed 813 breast cancer patients aged 20 to 74 about their exposure to light at night.
, http://www.100md.com
Nighttime light exposure can come from a variety of sources, including working the night shift, having insomnia or even being exposed to light in the bedroom during sleep.
Breast cancer risk was higher among women who often did not sleep during the period of the night when levels of the sleep-regulating hormone melatonin are typically at their highest, the study indicates. Their breast cancer risk increased 14% for each night of the week that they reported not sleeping during this period.
, http://www.100md.com
Working the graveyard shift upped a woman's risk of developing breast cancer by 60%, Davis and colleagues report.
"The results of this study provide evidence that indicators of exposure to light at night may be associated with the risk of developing breast cancer," the authors conclude.
In the second study, Dr. Eva S. Schernhammer of Harvard Medical School in Boston, Massachusetts, and colleagues examined the relationship between breast cancer and working the night shift in more than 78,000 nurses.
, http://www.100md.com
Women who worked between 1 and 29 years on a rotating night-shift schedule had an 8% increase in breast cancer risk, while women who worked 30 or more years on the night shift showed a 36% increase in their risk of developing breast cancer.
"Women who work on rotating night shifts with at least 3 nights per month, in addition to days and evenings in that month, appear to have a moderately increased risk of breast cancer after extended periods of working rotating night shifts," Schernhammer and colleagues conclude.
, 百拇医药
In an accompanying editorial, Johnni Hansen of the Danish Cancer Society in Copenhagen, Denmark, writes, "Evidence is accumulating for an association between exposure to light at night and breast cancer risk."
One possible explanation for this relationship has to do with melatonin production, she suggests. Melatonin is produced by the brain's pineal gland. Because it is released into the bloodstream at night, the hormone is thought to play a role in regulating sleep.
, 百拇医药
Hansen notes that when normal melatonin cycles are interrupted in women, the production of estrogen from the ovaries is higher and this may contribute to their breast cancer risk.
"There is urgent need for further exploration of the relationship between exposure to light at night, shift work, including timing during the night, and cancers that may be influenced by melatonin," Hansen concludes., 百拇医药