- New Developments in Lung Cancer
- April 2000
- Dear Friends
The stimulus for this month's letter comes from a meeting that I recently attended at Cornell University in New York, on the early diagnosis and intervention in lung cancer. Things are really starting to change as we face our nation's most rapidly growing fatal malignancy of both men and women.
Unlike screening for breast cancer, prostate cancer, and colon cancer, there is no recommended approach to the early identification of lung cancer. Not screening for lung cancer is absurd, since we know who is at high risk. Lung cancer will affect some 178,000 people in the United States this year. Eighty-five percent, or 151,300 will die from it no matter what treatment is given. Because lung cancer is usually diagnosed on the basis of symptoms of distant spread or local invasion into critical tissues, the likelihood of cure is extremely low by the time symptoms are present. The cure rate is a little better when lung cancer is diagnoses by accident, i.e., when chest x-rays are obtained for other reasons and show a lung tumor. But the chest x-ray diagnosis of lung cancer usually identifies only advanced stages of disease. Today, we have the knowledge and technology to change all of this. Helical CT scanners are highly effective in identifying tiny nodules in the far reaches of the lungs, called the periphery. These are often too small to be seen on standard chest x-rays. When the tiniest lesions are present, a follow-up study is done in three to six months to identify any growth. Biopsy or surgical removal is used only for growing tumors. So far, this approach has resulted in the removal of malignant growths in all cases.
In addition to CT scanning, sputum cytology can identify cancer cells, which most commonly come from the larger airways of the lungs. Many of these tiny cancers cannot be detected by CT scan. So, it takes both the CT scan for small peripheral lesions, and airway cell markers for central tumors, to find the earlier stages of disease. Our studies done in Grand Junction, Colorado have proven that early stage lung cancer has an excellent cure rate. When diagnosed early, lung cancer has an outcome as favorable as early stages of breast cancer, with an 80% survival rate. Newer chemotherapeutic approaches are also available to shrink some larger tumors and to make them more treatable with surgery. Finally, efforts to prevent the evolution from cells that are showing some degree of disturbance, called dysplasia, into cancer precursors and finally early stage lung cancer is under study. The future promises more exciting developments.
The bottom line is: smokers get lung cancer. Smokers with airflow obstruction as measured by spirometry, have a several-fold increase in lung cancer prevalence than those at equal risk without airflow obstruction. Thus, the spirometer can be a useful tool in identifying populations at highest risk. Anyone over age 45 who has smoked for more than 30 pack-years and who has any degree of airflow obstruction is a candidate for lung cancer screening. Early identification and intervention is the new frontier in lung cancer.
I will be in touch next month.
- Thomas Petty, MD