By Marisa Taylor

Cancer ranks number two among the most common causes of death in the United States. And the National Institutes of Health estimates that the price tag for cancer treatments and related productivity losses were more than $206 billion in 2006.

But in the face of improved cancer treatments and earlier detection, the number of cancer deaths in the U.S. has been on decline for two years in a row, according to a study released Wednesday by the journal of the American Cancer Society.

The news comes as sales of pricey cancer drugs are booming. Early detection of cancer has played an important role in the improvement in survival rates, but so have improvements in cancer treatments.

“In general, improvements in treatments definitely have contributed to the decrease in death rates,” said Mr. Ahmedin Jamal, an epidemiologist with the American Cancer Society and the lead author of the study.

The report, called Cancer Statistics, 2007, reveals that there were 3,014 fewer cancer deaths in 2004 than there were in 2003, a significant improvement from the decrease of 369 deaths between 2003 and 2002.

To be sure, analysts say it is hard to quantify how much new drugs have helped. A combination of drug innovations, improved screening processes, and early detection is likely the cause.

“There have been a lot of improvements in cancer treatments, largely because of the amount of research dollars that have gone into it,” said Morningstar senior stock analyst Jill Kiersky. “But knowing exactly how much of the improvement [in cancer survival] is due to cancer drug companies and cancer drug sales is just a shot in the dark to try to quantify.”

“More people are aware of cancer, so there is an increase in screening,” said Dr. Jamal.

Nevertheless, among the cancer innovations of 2006 cited by the American Cancer Society were the FDA approval of ImClone’s Erbitux for the treatment of head and neck cancer, as well as study that showed that GlaxoSmithKline’s experimental drug for breast cancer, Tykerb, seems to slow tumor growth in women whose cancer was resistant to Herceptin.

And during the past few years, Genentech’s Avastin—which brought in $1.7 billion in sales in 2006—has been instrumental for treating colorectal cancer, and looks to be promising in the field of lung cancer.

Among the major victories highlighted in the report were decreased death rates from breast cancer and colorectal cancer, the latter of which has fallen more than two percent per year since 1998. And while mortality from breast cancer has gradually increased since the ‘70s, rates started leveling off in 2001, according to the report.

Lung cancer deaths have also been decreasing because of a general decline in smoking in the U.S. over the past few years.

Of course, the news isn’t all positive. According to Mr. Jamal, death rates in liver cancer are actually on the rise, along with esophageal cancer in men, which can probably be attributed to smoking and drinking, he said.

Curbing the risks of those two illnesses, however, doesn’t require pricey drugs. Just a little common sense.

“We have to do what we know, which is a reduction in smoking. We have to also practice a healthy diet,” advised Mr. Jamal. “I think if we pay attention to [these factors], we can keep the momentum going.”