- Posted by jdavis on August 24, 2011
The goal of a screening program is to find cancers at an early stage when there are fewer symptoms and treatment leads to a higher cure rate.
Examples of screening tests for cancer:
- Pap smear for cervical cancer
- Mammography for breast cancer
- Colonoscopy for colon cancer
Early detection of lung cancer is critical to improving survival. Testing people that are known to be at high risk for developing lung cancer can help to find tumors that are small and more easily treated. Those at high risk include men and women:
- 60 years of age who currently smoke or have a history of smoking
- with previous lung tumors
- with chronic obstructive pulmonary disease (COPD)
Currently, there is no approved screening test for lung cancer that has been proven to improve survival or detect localized disease. However, there are many studies under way to find an appropriate screening tool.
Catching Up With Early Detection
By the time most patients are diagnosed with lung cancer, they have passed the curable stages of the disease. In fact, the average prognosis for recovery is among the lowest of any cancer upon diagnosis, only 15 percent of patients survive another five years. One reason for this is a lack of effective methods to detect lung cancer in its earlier and more easily treatable stages. Unlike mammograms for breast cancer and the PSA test for prostate cancer, currently there is no approved screening test for lung cancer.
However, recent advances in medical research are providing hope for lung cancer patients. New tools are being developed to help physicians detect the disease at earlier stages. For more information on the latest developments, please consult your physician.
Early Detection of Lung Cancer- FACTS
- The five-year survival rate for those whose lung cancer is found when it is localized (before it has spread to other organs) is nearly 50%.
- Only 15% of lung cancer cases are found at the localized stage.
- Research indicates that when lung cancer is diagnosed/detected in an early-stage and surgery is possible, the five-year survival rates can reach 85%.
- Survival rates decline dramatically after the cancer has spread to other organs: 16% at regional site, 2.1% at distant site.
- The majority of the people diagnosed with lung cancer are 55-65 years old.
A newer and more controversial diagnostic tool for detecting lung cancer is the spiral, or helical, CT scan. The spiral CT scan is a CT scan that can image the lungs in a single breath hold. Although spiral CT scans can detect tumors in the earliest stages of disease, there is a debate about whether this earlier detection saves lives. Some experts are concerned that screening will lead to over diagnosis, or the detection of cancers that would not have caused symptoms prior to patients dying of other causes. False positives also are common with baseline CT scans (the first time a person has one) because the test can mistake scar tissues from an old infection, or a benign lump, for cancer. In addition to the mental anguish resulting from a false positive, patients may undergo a needle biopsy, which may result in the collapse of the lung. Many medical professionals feel this risk can be managed by monitoring the growth rather than immediately performing a biopsy.
A study published in The Lancet (Henschke, Claudia I et al. Early Lung Cancer Action Project: overall design and finding from baseline screening. 354:99-104) compared the use of spiral CT scans to chest X-rays for the early detection of lung cancer at New York Weill Cornell Medical Center, New York University Medical Center and McGill University. Among the 1,000 patients tested in the study, 27 cancers were found at baseline screening with the CT scan. Eighty-three percent of these were stage I, the earliest stage of disease, as opposed to seven cancers found with X-rays. An additional seven cancers were detected in annual repeat screening, 85 percent of which were stage I. The cancers were confirmed by biopsies. The patients in the study were all 60 years or older with a history of more than 10 pack-years. These findings were similar to the studies in Japan.
“We have evidence that spiral CTs save lives and should be made available to all potential lung cancer patients,” according to Claudia Henschke, MD, Ph.D., professor of radiology, Weill Cornell Medical Center of New York.
Based on her earlier study, Dr. Henschke currently is leading a second spiral CT trial in New York State. This trial, known as the New York Early Lung Cancer Action Program (NY-ELCAP), is seeking to screen 10,000 current or former heavy smokers to determine whether they have early-stage lung cancer and to provide data on participants’ 10-year survival rate. The findings will be supplemented by similar trials that are taking place around the world.
Another trial designed to research the benefits of the spiral CT scan is the National Lung Screening Trial (NLST). This randomized controlled trial, sponsored by the National Cancer Institute, will enroll 50,000 participants at high risk for lung cancer to determine if there is a 20 percent or greater difference in lung cancer mortality between low-dose spiral CT or chest X-ray.
There is debate as to which trial is the most beneficial to patients. The NY-ELCAP study does not compare people who receive the test with those who do not. According to an editorial published in the June 15, 2002 issue of The Lancet, the result is that the study does not determine whether or not detecting the disease in the early stages actually extends the lives of patients. This, along with the previously mentioned higher rate of false positives, may result in unnecessary mental anguish and health risks.
On the other side of the debate, according to an article published in Radiological Society of North America, Inc News in July 2002, Dr. Henschke identifies the major problem with the NLST to be the focus on overall mortality rate rather than on the case-fatality during the time when the screening shows benefit (meaning death rates from lung cancer of the entire population and not just the specific group being screened). This misdirected focus on overall mortality rates has affected already established screening methods, such as mammography screening for breast cancer (The Lancet, February 2002).
Yet, despite all of the controversy, strides are being made in lung cancer screening that will help improve the survival of patients. “The primary goal of all oncologists is to increase the curability of lung cancer patients,” said Dr. Henschke. “Even though mortality rates have been declining, it is still the number one cancer killer in the United States. We need to do everything we can to ensure that we develop safe, effective detection methods to help increase patients’ survival.”