While it is known that smoking increases risk of lung cancer, a new study has found that heaviest smokers face greatest risk of death from the disease.
While studying the relationship between death rates from lung cancer and how much a person smoked, researchers at West Virginia University found that smoking intensity predicts how the disease will progress.
They found that patients who smoked two packs a day had a 58 percent higher risk of their lung cancers returning or spreading compared with nonsmoking patients.
Smoking intensity is one of only two factors found to predict lung-cancer mortality. The other factor is the stage of the cancer when diagnosed.
For the study, researchers examined almost 350 patients with non-small cell lung cancer.
Males older than age 60 were found to be the heaviest smokers at the time of diagnosis.
The researchers found that patients who smoked more than 61 packs a year had the greatest risk of their cancers recurring, and their survival times were shortest. They were 41 percent more likely to die from lung cancer than patients who smoked less.
"This study is important because lung cancer causes more deaths than any other type of cancer," said lead investigator Nancy L. Guo, Ph.D., a researcher with the Mary Babb Randolph Cancer Center.
"Because five-year survival rates of patients with non-small cell lung cancer are only about 15 percent, it's useful to know which patients are most likely to have their tumors come back.
"Our study showed that those who smoked more than 61 packs a year are more likely to develop tumor recurrence and should be considered for more aggressive therapy," she added.
The study is published in the May issue of the journal Lung Cancer.