It’s common knowledge that smoking raises risks of lung cancer. And yet researchers haven’t known whether continued smoking by lung cancer patients would increase the risk of the cancer’s spread.

Researchers at West Virginia University – studying the relationship between death rates from lung cancer and how much a person smoked – have found that smoking intensity in fact predicts how the disease will progress.

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, according to the study published in the May issue of the journal Lung Cancer. The other factor is the stage of the cancer when diagnosed. Almost 350 patients with non-small cell lung cancer were studied.

Males older than age 60 were found to be the heaviest smokers at the time of diagnosis. 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,” she said. “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.”

Chemotherapy drugs could be offered to prevent recurrence and spread of tumors, the authors said. And the heaviest smokers might also be targeted for measures to help them quit smoking.

Patients older than age 60 smoked, on average, 164 packs a year. Males smoked 189 packs a year compared with females’ average of 112.

Patients with stage 3 tumors smoked an average of 198 packs a year.

The study is titled “Impact and interactions between smoking and traditional prognostic factors in lung cancer progression.”

In addition to the Mary Babb Randolph Cancer Center, the study also involved researchers from the WVU Department of Community Medicine.

Source: West Virginia University Health Sciences Center