Atomic Bomb Radiation Exposure Update

As we are all contemplating the implications of North Korea’s self-admitted nuclear weapons program, an interesting paper in the Journal of the National Cancer Institute provides some additional food for thought.  Scientists in Hiroshima, Japan, reviewed tumor registries in the cities of Hiroshima and Nagasaki, looking at the incidence of tumors of the nervous system and pituitary gland that were diagnosed between 1958 and 1995.  The effects of radiation exposure on these areas of the body have not been well understood in the past.  The study revealed that 80,160 atomic bomb survivors developed tumors of the brain, nerves or pituitary gland during the interval between 1958 and 1995.  A rarely occurring tumor of the nerves, referred to as a schwannoma, occurred nearly five times more often following high levels of exposure to atomic bomb radiation when compared with bomb survivors that experienced minimal exposure.  However, even relatively modest radiation exposure doses significantly increased the risk of developing schwannomas, as well as other tumors of the nervous system and the pituitary gland (the so-called “Master Gland,” which resides at the base of the brain).

While an increased risk of thyroid cancer and malignancies of the blood and bone marrow have long been known to occur after exposure to the ionizing radiation released by nuclear explosions, this is the first study to identify a dose-related increase in the incidence rare nervous system and pituitary gland tumors following exposure to a nuclear weapon detonation.

Antiperspirant Use & the Risk of Breast Cancer

A rumor has recently been circulating on the Internet that links antiperspirant use with an increased risk of developing breast cancer.  A study in the Journal of the National Cancer Institute looked at 813 breast cancer patients and 793 randomly selected women volunteers without breast cancer.  All study participants were evaluated for antiperspirant use habits through an in-person interview.  The study determined that the risk of breast cancer did not increase with the usage of antiperspirants or deodorants.  Shaving the underarm areas with a razor, with or without the subsequent use of antiperspirants or deodorants, likewise did not increase the risk of developing breast cancer.  Thus, the study concludes that there is no observable correlation between the use of antiperspirants or deodorants and the risk of developing breast cancer.

CT Scans, C-Reactive Protein & Heart Disease

C-reactive protein (CRP) is a molecule that plays a crucial role in the inflammatory process.  There is ample research linking elevated CRP levels with an increased risk of heart attacks.  The role of CT scans of the heart (looking for calcifications within the coronary arteries) has been less certain.  With the recent proliferation of free-standing radiology centers that advertise CT scans for coronary calcium screening, there has been considerable public interest and debate regarding the indications and prognostic significance of such scans.  A brief perusal of almost any metropolitan newspaper in the United States will reveal advertisements for coronary artery scans, total body CT scans, “virtual colonoscopy,” and the like.  Unfortunately, there is very little data regarding either the safety or the usefulness of such ala carte radiographic scans.  This is an important public health issue, as these “screening examinations” are being performed on largely asymptomatic people without a physician’s recommendation, and by individuals who can afford to pay for the tests out of pocket. 

A study in the current issue of Circulation assessed, for two years, 967 volunteers without known coronary artery disease or diabetes.  All study volunteers underwent coronary artery calcium measurements using a CT scanner, and assessment of CRP levels in their blood.  The study determined that patients with the highest blood levels of CRP and increased coronary artery calcifications were at more than 6 times the risk of developing a fatal heart attack, and were at almost 8 times the risk of experiencing a heart attack, death, stroke, or the necessity of having a surgical procedure performed to open their blocked coronary arteries (when compared to volunteers with the lowest values for these two tests.  Even patients with low blood levels of CRP and moderate amounts of calcium in the coronary arteries had almost twice the risk of experiencing a fatal heart attack, and nearly three times the risk of experiencing any cardiovascular complication, when compared to patients with low CRP and coronary artery calcium levels.  This study suggests that the combination of CRP testing and CT scanning of the coronary arteries may provide a very sensitive measure of cardiovascular disease risk in patients without known coronary artery disease or diabetes.

Motor Vehicle Exhaust Pollution & Mortality

There is growing evidence that the particulate matter in motor vehicle exhaust (and especially from diesel-powered vehicles) can cause cancer and severe respiratory impairment.  A new study from the Netherlands, published in the current issue of the journal The Lancet, takes a careful look at this issue.  A sample of 5,000 randomly chosen volunteers, aged 55 to 69 year, participated in this study from 1986 to 1994.  The proximity of the volunteers’ homes to major roads and highways was then calculated, and the levels of particulate motor vehicle exhaust and nitrogen dioxide in the vicinity of each volunteer’s home was documented by reviewing air quality monitoring data.  

Briefly, the study found that death due to heart and lung disease was almost twice as common among people who lived near a major road or highway when compared to people who lived in rural areas.  Therefore, the study concludes that living adjacent to a major road or highway is associated with a greater risk of death due to heart and lung disease.  These adverse effects of motor vehicle exhaust exposure persisted even when controlling for age, preexisting lung disease, smoking and other potentially confounding factors.

Briefly…

JAMA: Women with low blood levels of the vitamin folic acid were 1.5 times more likely to have a miscarriage than women with higher levels of folate.  Currently, virtually all baked goods, dry pastas and cereals are fortified with folic acid following research showing that folate supplementation during pregnancy  reduces the risk of spine and spinal cord abnormalities in the fetus.  This study also suggests that folate may also help to protect against miscarriage as well.

New England Journal of Medicine:  Two studies, one from the United States and one from Italy, are reporting their 20 year results comparing breast conservation therapy (lumpectomy plus radiation) with modified radical mastectomy.  Both studies confirm earlier research that showed no significant differences in survival rates among women treated with either approach.  In both groups of women, approximately 25% died of breast cancer during the 20 years of follow-up.  In the Italian study, about 9% of the women electing breast conservation therapy experienced a recurrence of breast cancer in the breast that was previously treated, while about 2% of the women who received a mastectomy experienced a recurrence at the operative site.  In the U.S. study, a comparison was made of women who had undergone lumpectomy for invasive breast cancer, with or without subsequent radiation therapy to the affected breast.  Approximately 40% of the women who did not undergo radiation therapy developed a recurrence of cancer in that same breast.  Among the women who underwent lumpectomy followed by radiation, the risk recurrence in the breast was about 14%.  It should be noted that the “lumpectomy”  performed by the Italian surgeons is far more extensive than the surgery performed by most American surgeons.  The lead surgeon in the Italian group, Dr. Umberto Veronesi, performs a considerably more substantial surgical resection than American surgeons, generally involving the removal of one-fourth of the breast, or more.  This factor may explain the slightly smaller incidence of same breast recurrences among the Italian patients receiving breast conserving therapy when compared to their American counterparts.  What is most important to remember, however, is that the survival of patients in both studies was equivalent among patients in the breast conserving (lumpectomy plus radiation) and mastectomy groups.  This is further evidence that breast conserving therapy for breast cancer results in equivalent survival when compared to modified radical mastectomy