Maintaining Your Health on Mackinac
New Tools for Diagnosis and Treatment of Lung Cancer
By Yvan Silva, M.D.

Lung cancer continues to be the leading cause of death for men and women. This year, in 2007, it is estimated that 200,000 or more cases of lung cancer will be diagnosed in this country. The mortality is high - six of 10 individuals will die within a year of discovery, mainly because the cancer is diagnosed late, and spread has already occurred. Most lung cancers do not cause symptoms until the cancer has spread. Preventive measures and early detection are important goals.

Screening individuals at high risk for lung cancer might reduce the morbidity and mortality statistics, if indeed routine screening could detect tumors while they're still potentially curable. Prior studies of lung cancer screening with chest X-ray did not support this premise. The evolution of computed tomography (CT) to its present state is promising, in that it is more sensitive for the detection of very small tumors. This hypothesis is currently under study in several research centers, and it is yet a bit early to be definitive as a recommendation for wide screening.

Tobacco smoking is believed to be responsible for 87 percent of cases of lung cancer. The risk increases with the duration of time you've been smoking, and the number of cigarettes smoked each day. Second-hand smoke is also a known risk factor. Exposure to substances such as asbestos, arsenic, radioactive dust, and radon; radiation exposure from medical or environmental sources, and a family history of cancer are also relevant. The risk of developing cancer is increased because tobacco smoke contains a variety of injurious substances, including carcinogens - substances known to cause cancer. In the current state of knowledge, stopping smoking is the only proven method for reducing the risk of developing lung cancer.

In spite of all the facts associating smoking as continuously dangerous to health in several aspects, about one quarter of all women in the United States continue to smoke. In a study of high school seniors in 2000, 30 percent of females reported having smoked in the past 30 days. Most women who currently smoke started smoking as teenagers. It remains paradoxical that these statistics continue in the face of restrictions on cigarette advertising, school programs, prohibition of sales to minors, and increasingly the continuing rise in the cost of and taxes on tobacco products.

Tobacco marketing and promotion, especially of cigarettes produced for women, continues to dominate. Teenagers smoke to express equality with adults, although the risks for addiction are well known. Many women believe that smoking may help to control weight. In a recent study of young women who dieted or were concerned about their weight, current smokers numbered two to one to nonsmokers. In the three years from 1995 to 1998, cigarette advertising and promotion expenditures rose from $4.9 billion to $6.7 billion. Pregnant women continue to smoke at the rate of 13 percent to 22 percent, in spite of knowing of the harmful effects to the fetus. Education plays a role; college graduates are one third less likely to become smokers, compared to women with less than a high school education.

Women are being targeted in tobacco advertising, teenage girls are drawn to smoke under social pressures, and as this continues, lung cancer has become the leading cause of cancer deaths in this country, responsible for as many deaths as breast cancer and all gynecological cancers combined. In 2003, an estimated 80,100 U.S. women were diagnosed with lung cancer, and 68,800 women died from this disease. The Surgeon General reported in 2001 on women and smoking, noting smoking was a fullblown epidemic in women owing to a 600 percent increase in the death rate from lung cancer. This epidemic is spreading throughout the world. Since the 1990s, 20 million women have started smoking in China; from 1986 through 1991, the number of women smokers in Japan increased from nine percent to 18 percent. These increases continue through Asia and Africa and other continents.

Is there a gender difference? Some studies suggest that this might be the case. For example, a study of 1,108 men with lung cancer, 781 women with lung cancer, and 2,070 individuals without the disease, given the same lifelong exposure to smoking, women had 1.5 times the risk compared with men. The risk appeared greater when the combination was included of duration of smoking and number of cigarettes smoked. Other studies, on the other hand, have not shown similar conclusions.

New studies of gene mutations and DNA repair capacity suggest that women may be more susceptible; a new estro- gen receptor "beta" has also been detected in lung tumors, suggesting a role in the formation of tumors. Sex-specific research is currently underway to study these differences. Whether women are more susceptible to lung cancer from smoking than men is debatable; there are important differences. Women smokers are more likely to develop a certain type of lung cancer, adenocarcinoma, than men. Women who have never smoked are more likely to develop lung cancer than men who have never smoked. Estrogen may be one important factor.

Methods for early detection of lung cancer have long been sought by public health authorities, physicians, and concerned patients, especially people who continue to smoke. Indeed, several attempts to intensively screen people for lung cancer, such as chest Xrays and examination of sputum samples for cancer cells, have not resulted in lowering the cancer-specific mortality from this malignancy, raising doubts whether screening regimens can enable early detection.

With the emergence of computer based studies such as CT scans, examination of the lungs has greatly been improved above chest X-rays, which reveal about 80 percent of lung tissue and also, because of overlapping structures, fail to show early or small cancers. The latest technological innovation in computer based testing is helical computed tomography; while the regular CT scan sections the tissues in vertical or horizontal planes, this examination spirally examines all the tissues in the chest and thus provides a detailed look at a greater amount of lung tissue.

Early reports are showing that helical CT scans can detect small lung cancers when surgical removal and theoretical cure is possible. These CT examinations are gaining in popularity; commercial centers are opening up and offering several new types of studies, which have not as yet been proven. Direct-to-consumer advertisements are appearing in many newspapers and periodicals offering these studies to patients with prescriptions from their doctors.

Since they're as yet unproven on a cost-effective basis, third-party insurance payers will not pay for these studies when done for screening purposes, and patients are required to pay directly. The costs are high. There is uncertainty about the benefits in that some lesions may be falsely thought to be malignant, leading to invasive testing and adding new risks. Large, prospective studies of screening, where patients with lung cancer are compared with a normal control group, are underway and will take time.

Dr. Silva is a professor of surgery at Wayne State University and a resident of Woodbluff on Mackinac Island.