Less-common cancers rising ... why?

NEW YORK – There’s been an unexpected rise in seven types of less-common cancers in the United States, in some cases linked to growing obesity rates, says an American Cancer Society report urging more study to determine the underlying causes.

The warning comes as overall cancer death rates dropped between 2004 and 2008, by 1.8 percent per year in men and 1.6 percent in women, according to the study. Better prevention – including anti-smoking campaigns, added screening and improved nutrition – helped decrease mortality from the most-prevalent malignancies, in lungs, breasts and colons.

While higher incidences of pancreatic, liver and esophageal cancers may be the result of added testing or rising obesity, it’s not clear why other less-common cancers are growing in prevalence, the report said.

People are living longer, so lifestyle choices at earlier ages and viruses they were exposed to, such as hepatitis or the human papillomavirus, may spur tumors as people get older, the report suggested.

“All of the viruses we’ve ever been exposed to are viruses that we may see again later in life,” said Diana Contreras, director of Gynecological Oncology at Long Island Jewish Medical Center in New Hyde Park, New York, who was not involved in the report, in a telephone interview.

Other cancers with increasing prevalence rates include kidney cancer, melanoma and different types of oropharyngeal tumors, according to the report in the journal CA: A Cancer Journal for Clinicians.

The rising rates of less-common tumors may exacerbate the growing health-care burden linked to an aging population, the Cancer Society said in a statement that called for added research into their cause.

There was also good news in the report. A decline in lung cancer accounted for 40 percent of the drop in the cancer death rates in men, while a decrease in breast cancer cut women’s death rates by a third. The data, the most-recent available, reflected a trend seen since the early 1990s, according to the society, which said that fewer people smoking, better treatments and technology, and more regular cancer screenings probably contributed.

The report shows that a little more than a million cancer deaths have been averted since the 1990s when the mortality rates for the disease were higher, Elizabeth Ward, national vice president for Intramural Research at the American Cancer Society in Atlanta, in a telephone interview.

“It’s hugely important to know you can do a lot to reduce your own risk by avoiding tobacco, by good nutrition and physical activity and by getting the recommended screening tests for cancer,” Ward said.

The most rapid declines in death rates occurred among black and Hispanic men, according to the report. Still, black men have a 15 percent higher incidence rate and a 33 percent higher death risk than white men, the study found.

“You have to have a doctor that you’re working with annually to give you the proper screening, and you have to report symptoms that might be indicative of problems,” said Len Horovitz of Lenox Hill Hospital in New York. “That’s where most people fall down. They don’t have an annual physical. That’s where much can be found.”

Cancer remains the second-most common cause of death in the United States behind heart disease, accounting for about one of every four deaths in the country, the report.