 | What Your Doctor Is Reading | | |
Update From the Medical Journals: June 2007
June 29, 2007  By Mary Pickett, M.D.
Harvard Medical School What's the latest news in the medical journals this month? Find out what your doctor is reading. Vitamin D May Help Prevent Cancer Doctors are intrigued by a new study published in the June 1 issue of the American Journal of Clinical Nutrition. The article caught the attention of the news media and the public. This study provides evidence that vitamin D may help prevent a variety of cancers. The vitamin D-cancer connection originally came from statistics showing that people in sunny climates appear to have a lower risk for certain cancers. Sunshine helps the body convert vitamin D into its active form. This led scientists to wonder if vitamin D might be protective. To investigate this idea, researchers randomly divided 1,179 women from Nebraska into three groups. They assigned one group to take 1,000 International Units (IU) of vitamin D daily in addition to calcium supplementation. The second group took calcium and a placebo pill and the third group took only a placebo. The study followed the women for four years to see how many cancers were diagnosed during that time. Researchers were especially interested in the number of cancers (breast, lung, colon, lymphoma, leukemia, myeloma, uterine cancers, and others) that were diagnosed in years two through four of the study. They found eight cancers had been diagnosed in the group taking daily vitamin D and two to three times that number of cancers diagnosed in each of the other two groups. The idea that a treatment as benign as vitamin D might reduce cancer rates is very exciting. However, this is a small study and we need to be cautious about any conclusions. A closer look at the data shows that for any individual type of cancer, there were only one or two extra cases of cancer in the groups of women who didn't take vitamin D. For example, there were four cases of breast cancer in the calcium with vitamin D group and six in the calcium with placebo group. There was one case of lung cancer in the vitamin D group and two in the calcium without vitamin D group. These numbers don't prove the value of vitamin D because the differences may have occurred by chance. The study was thoughtfully designed — except for its small size — and provides a good reason to support further study so we can know with more confidence whether vitamin D impacts our cancer risk. Back to top New Guidelines for Antibiotic Use Before Dental Procedures It's been a long tradition to advise people with heart murmurs and heart-valve abnormalities to take antibiotics before having a dental cleaning or other dental procedure. The purpose of antibiotics was to prevent bacteria in the mouth from bursting into the bloodstream, contaminating the blood and putting the heart valves at risk for an infection called endocarditis. However, many experts have doubted whether the antibiotics made a meaningful difference. After all, brushing your teeth causes bursts of bacteria into the bloodstream, just as a dental cleaning can cause. Perhaps we have been overestimating the risk of dental procedures? The May 8 issue of Circulation published new guidelines from the American Heart Association for antibiotic use before dental appointments. It's based on a comprehensive review of studies and evidence and has also been approved by the Infectious Diseases Society of America, the Pediatric Infectious Diseases Society, and the Council on Scientific Affairs of the American Dental Association. According to the new guidelines, most people with heart murmurs from tight or leaky valves are no longer advised to get antibiotics before dental procedures. Many experts are relieved to see this new guideline in place, so that we can cut down on unnecessary antibiotic use. Treatment with antibiotics before dental work should be limited to - people with artificial (prosthetic) heart valves
- people who have already had endocarditis
- people with severe congenital heart disease (CHD) that has not been surgically repaired, people with CHD whose repair surgeries just happened during the last six months, or people with CHD who have artificial patching material in their heart that is known to have not healed over
- people who have had a heart transplant and have also developed abnormal valves.
Back to top More News in Brief - Without Surgery, Some People with Pancreatic Cancer Miss Out on a Cure. A study in the Annals of Surgery was released online on June 14. This study reviewed care provided in the U.S. to people with pancreatic cancer. The journal will formally publish the article in print in its August issue. If pancreatic cancer is diagnosed before it has spread outside of the pancreas, surgery can cure about one third of these cancers. Otherwise, only 5% of people survive more than five years. About 20% of people have early stage cancer at the time of their diagnosis, making them eligible for surgery. The surgery, known as a Whipple procedure, is a major operation. It involves removing most or all of the pancreas, the gallbladder and part of the intestine. After analyzing 9,559 patients with early-stage pancreatic cancer, researchers were surprised to find that 38% of patients who were eligible for surgery were never offered the procedure. Blacks, older adults, and people who had lower incomes or less education were especially at risk for missing this opportunity. Authors speculate that the low- surgery rate may result from doctors who are poorly informed about available surgery, or from a short supply of experienced surgeons.
- Breast Cancer Gene May Be Passed Down Through Dad. Women with a close relative with breast cancer — a mother, sister, or aunt — may find out through genetic testing that they have a mutation of the BRCA1 or BRCA2 gene. These gene types are linked to breast cancer and ovarian cancer risk. The Journal of the American Medical Association (JAMA) published a study on June 20 that looked at the genetic test results of 1,543 breast cancer patients who had no family history of breast cancer. Women who had two or more healthy close female relatives who had already lived past the age of 45 had only a 5% chance of having a BRCA gene. However, among women with few or no aunts and sisters in their family older than age 45, almost 14% had the BRCA gene. According to the researchers, half of genetic breast cancers are inherited from a woman's father, not her mother. But unless there are women with breast cancer on a father's side, the faulty gene could "hide" in male relatives without showing a pattern of cancer in the family. Since one of these genes puts a woman at increased risk for her lifetime, some women who know they have a BRCA gene will choose to have both breasts and both ovaries removed. This study raises the possibility that women without a family history of breast cancer should be offered genetic testing, particularly if their family tree contains few adult women.
- Taking Estrogen Before Age 60 May Improve Artery Health. Millions of women stopped taking estrogen in 2002 when the Women's Health Initiative connected estrogen and progesterone treatment after menopause to serious health problems. This combination hormone treatment was linked to a higher risk for heart attack, stroke, breast cancer, blood clots in the legs or lungs and gallstones. By 2004, treatment with estrogen alone (without progesterone) was also linked to a higher risk for stroke and blood clots. Despite these findings, some experts have suspected that treatment with estrogen earlier in menopause might not be as risky. They wondered if in fact there is a window of time within which estrogen might provide health benefits to the heart. A study published in the June 21 New England Journal of Medicine took a close look at women who started estrogen-alone treatment at a young post-menopause age — before age 60. After seven years of treatment with estrogen, these women appeared to have fewer calcium deposits in their coronary arteries. Since artery calcium deposits are linked to heart disease, the finding suggests that estrogen might provide a benefit to women who start it early. This study is important to the continuing and very complicated discussion that experts are having about estrogen's benefits and risks. The findings should reassure women who take estrogen soon after menopause for relief of severe hot flashes. However, the study does not provide us with enough information to justify using estrogen solely for heart protection, even in young women.
Back to top Mary Pickett, M.D. is a lecturer for Harvard Medical School and an assistant professor of medicine at Oregon Health & Science University. At OHSU, she is a director of student programs and she oversees teaching of students and medical residents. She practices general internal medicine in Portland, Ore.
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