Cancer rates in the United States continue to fall, according to a new government report, with the exception of certain cancers linked to increasingly common health woes facing Americans.
The new report, which tracked U.S. cancer rates from 1975 through 2009, found increases in incidence of cancers related to obesity and those linked to human papillomavirus (HPV).
The "Annual Report to the Nation on the Status of Cancer" is a joint project from researchers at the government's Centers for Disease Control and Prevention and National Cancer Institute, in addition to the American Cancer Society and North American Association of Central Cancer Registries. It was published Jan. 7 online in the Journal of the National Cancer Institute.
Fewer Americans have been dying of cancer since about 1990, and the new report found cancer death rates continued to drop from 2000 to 2009, by about 1.8 percent per year among men and 1.4 percent per year among women over that time period.
Men were less likely to die from 10 of the 17 most common types of cancers, including lung, prostate, colon, stomach cancers and leukemia, while cancer death rates for women fell for 15 of the 18 most common types of cancers, including cancers of the breast, cervix, ovary, bladder and lung.
The researchers said these declines in cancer death rates may be because of reductions in risk factors like smoking and improvements in early detection and treatments.
Cancer death rates among children 14 and under also fell overall by 1.8 percent.
"The continuing drop in cancer mortality over the past two decades is reason to cheer," Dr. John R. Seffrin, chief executive officer of the American Cancer Society, said in a written statement. "The challenge we now face is how to continue those gains in the face of new obstacles, like obesity and HPV infections. We must face these hurdles head on, without distraction, and without delay, by expanding access to proven strategies to prevent and control cancer.
Overall cancer rates decreased by 0.6 percent per year among men between 2000 and 2009, were stable among women, and increased by 0.6 percent per year among kids ages 14 and under.
Among men and women, there were reported increases for cancers tied to obesity, such as those of the kidney, pancreas and uterus (the latter, of course, for women only). There were also increased cases of liver cancer, which previously have been linked to rising rates of the viral liver disease hepatitis C -- especially among baby boomers -- and also rising rates of melanoma of the skin, which the researchers tied to increases in exposure to harmful ultraviolet radiation, such as through tanning.
Thyroid cancer also appears to be on the rise, which may be linked to improved screening tests or other unknown risk factors. Dr. Cari Kitahara of the National Cancer Institute told CBSNews.com in November that said observed increases in both large and small thyroid tumors may be attributable to changes in certain environmental or lifestyle-related exposures, including obesity.
Last year's report on national cancer rates, which tracked cancer in the U.S. through 2008, also found obesity contributed to rising rates of cancers of the esophagus, uterus, pancreas and kidney. Rising rates of melanoma were also reported.
This year's report contained a special feature section that focused on cancers related to HPV. Human papillomavirus is the most common sexually transmitted disease in the United States, according to the CDC. There are more than 40 types of the virus that can infect the genitals of males and females, and most people who become infected don't know they have the virus. The virus can be spread via oral, vaginal and anal sex.
The new report found increases in rates for HPV-associated oropharyngeal cancer (throat cancer) among white men and women, in addition to rises in anal cancer rates among white and black men and women.
Dr. Michael B. Prsytowsky, chairman of the department of pathology at Albert Einstein College of Medicine in the Bronx, New York, explained to CBSNews.com that oropharyngeal cancer affects the area towards the base of the tongue where the tonsils reside. Alcohol and smoking can also lead to these cancers, however, HPV accounts for about 70 percent of the cancers in this area, he said.
Prystowsky, who was not involved in the report, said that cancers driven by HPV are slow-growing, with some research showing HPV may take 12 years before a person develops cancer. That means many of the adults included in the new report may have been infected 20 years ago.
That's why taking all three recommended doses of the HPV vaccine is crucial, he said.
"We need to get adolescent children -- both boys and girls -- vaccinated before they're sexually active," Prsytowsky said. "Parents need to understand the vaccine is safe and effective and prevents disease down the road."
The report found that less than half of girls ages 13 to 17 got at least one dose of the recommended HPV vaccine. The government's Healthy People 2020 campaign aims to have 80 percent of eligible girls vaccinated by the next decade.
Despite increased rates of oropharyngeal cancer, cervical cancer rates declined among all women except American Indian/Alaska Natives, the report showed.
Prystowsky said that may be due in part to women getting screened for cervical cancer with a Pap test, since there's no screening test to catch precancerous cells for oropharyngeal cancer.
Cervical cancer rates were found to be highest among women living in low socioeconomic status (SES) areas compared to women living in high SES areas. The researchers found women with no usual source of medical care or health insurance were far less likely to get a Pap test for screening cervical cancer.
CDC director Dr. Thomas R. Frieden agreed that more needs to be done to prevent cancers driven by HPV in future generations.
"Vaccinating against HPV can prevent cervical cancer, but, tragically, far too many girls are growing into adulthood vulnerable to cervical cancer because they are not vaccinated," he said.
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