his week's news is about lung cancer & Computerized Tomography, simply called CT scans. Lung cancer has the highest death rate amongst those with Cancer; more than 164,000 individuals die each year off lung cancer. Even among early Stage 1 lung cancer, the # of patients surviving at 5 years is only 70%. When it reaches Stage 4 lung cancer, the 5 year survival rate drops dramatically to only 5%!
It is unfortunate that we diagnose these early stage patients mostly by accident; often while performing a workup for another reason. Because screening methods of detecting cancers of the Breast, Colon, Prostrate and Cervix have resulted in better survival rates, additional screening studies have been conducted using Chest x-rays. And to try and detect lung cancer at early stages with the hope of achieving similar outcomes. Unfortunately, previous studies have not shown any benefits for screening for lung cancer. However recently, a group of investigators have reported that an annual screening with low dose CT scans may be able to detect early stage lung cancer that could be potentially curable.
A CT imaging system is a form of x-rays that produce cross sectional images of slices of body anatomy like the slices in a loaf of bread. The study conducted internationally with participating institutions from the United States, Europe & Asia generated interesting results. Between 1993 and 2005, investigators screened 31,567 individuals who had a high risk for lung cancer. High risk individuals were defined as those who have a history of cigarette smoking, occupational exposure to Asbestos, Uranium, Brillium or Radon, and those who did not smoke but had significant exposure to 2nd hand smoke. CT screening was then repeated 17 to 18 months after the initial screening for 27,456 of the individuals. Of the initial 31,567 participants who had an intial CT screening, 4146 individuals were found to have at least 1 nodule in the lung, and 405 were found to have lung cancer after a biopsy. For those individuals who had annual CT screening, the lung nodules were found in 1460 individuals with 74 diagnosed with lung cancer. The total # of participants who were diagnosed with lung cancer was 484.
Of those 484 participants who developed cancer, 85% had Stage I lung cancer and their estimated survival rate at 10 years was 88%, significantly better than the current 5 year survival rate of 70% for clinical Stage I lung cancer. While there is talk about the benefit of CT screening of lung cancer, a recent article in the Wall Street Journal raises concern over excessive radiation exposure associated with too many CT scans. The advancement in CT technology has led to improved efficiency and increased indications for its use. As a result, there has been explosive growth in the use of CT scans in recent years. In 2003, there were 57 million CT scans performed with some individuals receiving multiple CT scans exposing them to total radiation doses at levels near those of some survivors of nuclear attacks on Japan in World War II. Those survivors received average doses of 20 Millisiverts, a measurement of radiation exposure. For comparison, a single Chest CT scan has an average radiation of 8 - 10 Millisiverts, 10 Milliesiverts is said to be associated with increased risk of lung cancer.
According to the US Food & Drug Administration, a CT examination with an affective dose of 10 Millisieverts may be associated with an increase in the possibility of Cancer of approximately 1 in 2000. The natural incidence of fatal cancer in the US population is about 1 in 5. In other words, any one person with the risk of individual radiation exposure is much smaller than the natural risk of Cancer. Also, there are certain differences. The bomb survivors received that amount of radiation all at once, while patients under controlled CT scanning are exposed to small doses of Radiation that accumulate over time. We don't know the effects of this kind of exposure. Additionally, the types of radiation being used are different. Currently there are no studies that have analyzed the impact of the CT scan as a cause for cancer. Furthermore it is believed that there is a lag time of about 20 years between the radiation exposure and the development of a detectable cancer.
We feel that the ability to detect early stage lung cancer outweights the risk of radiation exposure from CT screening, in certain individuals. CT screening is beneficial and should be considered for those individuals who are at high risk of developing lung cancer. Invididuals who smoke, who have a history of occupational exposure and who have a history of 2nd hand smoke. Nevertheless, radiation is a radiation! It is always best NOT to get exposed to radiation unless it is necessary. Unfortunately, not all insurance companies will cover the CT screening procedure. We recommend talking with your doctor to determine your level of risk and the potential value of the screening.
It is unfortunate that we diagnose these early stage patients mostly by accident; often while performing a workup for another reason. Because screening methods of detecting cancers of the Breast, Colon, Prostrate and Cervix have resulted in better survival rates, additional screening studies have been conducted using Chest x-rays. And to try and detect lung cancer at early stages with the hope of achieving similar outcomes. Unfortunately, previous studies have not shown any benefits for screening for lung cancer. However recently, a group of investigators have reported that an annual screening with low dose CT scans may be able to detect early stage lung cancer that could be potentially curable.
Of those 484 participants who developed cancer, 85% had Stage I lung cancer and their estimated survival rate at 10 years was 88%, significantly better than the current 5 year survival rate of 70% for clinical Stage I lung cancer. While there is talk about the benefit of CT screening of lung cancer, a recent article in the Wall Street Journal raises concern over excessive radiation exposure associated with too many CT scans. The advancement in CT technology has led to improved efficiency and increased indications for its use. As a result, there has been explosive growth in the use of CT scans in recent years. In 2003, there were 57 million CT scans performed with some individuals receiving multiple CT scans exposing them to total radiation doses at levels near those of some survivors of nuclear attacks on Japan in World War II. Those survivors received average doses of 20 Millisiverts, a measurement of radiation exposure. For comparison, a single Chest CT scan has an average radiation of 8 - 10 Millisiverts, 10 Milliesiverts is said to be associated with increased risk of lung cancer.
According to the US Food & Drug Administration, a CT examination with an affective dose of 10 Millisieverts may be associated with an increase in the possibility of Cancer of approximately 1 in 2000. The natural incidence of fatal cancer in the US population is about 1 in 5. In other words, any one person with the risk of individual radiation exposure is much smaller than the natural risk of Cancer. Also, there are certain differences. The bomb survivors received that amount of radiation all at once, while patients under controlled CT scanning are exposed to small doses of Radiation that accumulate over time. We don't know the effects of this kind of exposure. Additionally, the types of radiation being used are different. Currently there are no studies that have analyzed the impact of the CT scan as a cause for cancer. Furthermore it is believed that there is a lag time of about 20 years between the radiation exposure and the development of a detectable cancer.
We feel that the ability to detect early stage lung cancer outweights the risk of radiation exposure from CT screening, in certain individuals. CT screening is beneficial and should be considered for those individuals who are at high risk of developing lung cancer. Invididuals who smoke, who have a history of occupational exposure and who have a history of 2nd hand smoke. Nevertheless, radiation is a radiation! It is always best NOT to get exposed to radiation unless it is necessary. Unfortunately, not all insurance companies will cover the CT screening procedure. We recommend talking with your doctor to determine your level of risk and the potential value of the screening.
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