Women who develop breast cancer are no more likely to have aggressive or advanced tumors if they are cigarette smokers than if they do not smoke, researchers said on Sunday.

Whether cigarette smoking raises a woman’s chances of ever developing breast cancer has remained a controversial question, with some research indicating a risk and other studies not.

Researchers at Fox Chase Cancer Center in Philadelphia investigated whether female smokers who got breast cancer were more likely to have a more serious form.

They analyzed data on 6,162 women with breast cancer evaluated at the facility from 1970 to 2006, and found that whether a woman smoked did not affect whether her tumor was more advanced or particularly aggressive at the time of diagnosis.

Nine percent of the breast cancer patients were smokers when they were first seen.

“For patients who developed breast cancer, there did not appear to be a difference in the cancers that they presented with based on whether or not they had ever smoked,” Dr. Matthew Arumowot of Fox Chase Cancer Center, one of the researchers, said in a telephone interview.

“In addition, there did not appear to be a difference in the type of treatment they were offered, whether or not they were smokers,” added Arumowot, whose findings were presented at a meeting of the American Society for Therapeutic Radiology and Oncology in Los Angeles.

Arumowot said the study did not evaluate whether smokers were more likely than nonsmokers to have complications in treatment for breast cancer or die from the disease.

“I was expecting that maybe there would be more advanced stage (tumors) in patients who were smoking,” Arumowot said.

Arumowot said the findings do that mean that smoking is any less hazardous than multitudes of studies have shown.

The National Cancer Institute said cigarette smoking causes 87 percent of lung cancer deaths and is responsible for most cancers of the larynx, mouth, esophagus and bladder. It said tobacco use, particularly cigarette smoking, is the most preventable cause of death in the United States.