Environmental factors should be taken seriously when referring to causes for cancer, according to a U.S. President's Cancer Panel report.

The panel charges in the report that grievous harm from carcinogens in the environment has been "grossly underestimated" by the U.S. National Cancer Program.

The 240-page report includes an open letter to U.S. President Obama signed by the two-member panel's chair LaSalle D. Leffall Jr., MD, of Howard University; and panelist Margaret L. Kripke, PhD, of the University of Texas M.D. Anderson Cancer Center.

The two distinguished cancer doctors believed that many avoidable cancers were caused by pollution, radon gas from the soil and medical imaging scans besides lifestyle choices like smoking, poor diet and lack of exercise.

The report, available at pcp.cancer.gov, also offers some of its own advice to consumers.

"The panel urges you most strongly to use the power of your office to remove the carcinogens and other toxins from our food, water, and air that needlessly increase healthcare costs, cripple our nation's productivity, and devastate American lives," it says.

However, American Cancer Society differs on the assessment. "The report is most provocative when it restates hypotheses as if they were established facts," the society's Dr. Michael Thun said in a statement.

He pointed out that this opinion "does not reflect scientific consensus" but "reflects one side of a scientific debate that has continued for almost 30 years."

Cancer is the No. 2 killer of Americans, after heart disease. The two members of the Panel were both appointed to three-year term by former U.S. President George W Bush.