Several factors influence lung cancer survival rates. The type of cancer, the stage it is at when diagnosed, and the overall condition of the patient all play a role in determining survival. Cancer survival is usually expressed in terms of a five-year survival rate, which is the percentage of patients with cancer who survive at least five years after their cancer is diagnosed.
Studies have shown that five-year survival rates among non-small cell lung cancer patients vary by stage. Stage 0 patients have the best survival, of close to 50 percent at five years. Approximately one-quarter of stage II patients survive to five years, as compared to eight percent of stage III patients and only two percent of stage IV patients. In general, small cell lung cancer tends to proceed more rapidly to terminal disease. Ten to fifteen percent of patients with limited-stage small cell lung cancer, and between one and two percent of those with extensive-stage cancer, survive to five years.
Estimates of cancer survival do not reflect current treatment advances that may lead to better chances of survival, because they are typically calculated for a five-year period that does not include the previous year. Further, each patient responds to treatment in a unique way; aggregate estimates do not account for individual factors that may improve or worsen the likelihood of survival.
The overall number of deaths in the United States from lung cancer rose throughout the 1980s, and began to drop for men in the 1990s. However, a similar decrease has not been observed among women. Over fifty thousand current and former smokers have been enrolled in the National Lung Screening Trial to find out if chest x-rays and CT scans taken before the onset of lung cancer symptoms may improve early diagnosis and therefore survival.