Cancer Deaths Drop, But Incidence Rises

Roxanne Nelson

January 05, 2012

January 5, 2012 — The good news is that overall cancer death rates have declined for both men and women. The not so good news is that the incidence rates for some cancer types appear to be increasing.

According to a report issued by the American Cancer Society (ACS), and published online January 4 in 2 parts in CA: A Cancer Journal for Clinicians, cancer-specific mortality rates from 1999 to 2008 have declined in both men and women of every racial/ethnic group, with the exception of American Indians/Alaska Natives, for whom rates have remained stable.

One part of the report notes that the overall reduction in cancer deaths rates since 1990 in men and 1991 in women extrapolates to the prevention of about 1,024,400 deaths from cancer.

Of note, the most rapid decrease in annual mortality rate was observed among black (2.4%) and Hispanic men (2.3%).

Death rates continue to decline for all 4 major cancer sites — lung, colorectum, breast, and prostate. Lung cancer alone accounted for nearly 40% of the total decline in men and breast cancer accounted for 34% of the total decline in women.

For all 4 major cancer sites, incidence rates declined, with the exception of breast cancer in women, which remained relatively stable from 2005 to 2008 after decreasing by 2% per year from 1999 to 2005.

Mortality rates reflect changes in incidence, as well as progress and advances in treatment and diagnosis, explained Elizabeth Ward, PhD, national vice president of intramural research for the ACS.

Incidence trends are more difficult to interpret, she told Medscape Medical News. For example, incidence rates for breast cancer have fluctuated, she noted. The sharp decline of almost 7% from 2002 to 2003 has been attributed to the decrease in use of hormone replacement therapy after the publication of the results of the Women's Health Initiative in 2002.

In addition, the introduction of screening programs might have led to an increased incidence, said Dr. Ward. "Incidence rates went up for prostate cancer when PSA screening was introduced, for instance. But mortality rates are going down for all 4 major cancer sites, even if incidence trends do not correlate."

Rising Rates for 7 Cancers

Unfortunately, incidence rates for other cancers have been rising. In the other part of the report, ACS researchers examined trends in incidence rates from 1999 to 2008 for 7 cancers.

During the past decade, the incidence rates of cancers of the pancreas, liver, thyroid, and kidney, and of melanoma have gone up. In addition, there was a rise in esophageal adenocarcinoma and in certain subtypes of oropharyngeal cancer that are associated with human papillomavirus (HPV) infection. Racial/ethnic differences were observed for some but not all of the cancers with rising incidence rates.

For example, increased incidence rates for HPV-related oropharyngeal cancer and melanoma were seen only among whites; increased rates for esophageal adenocarcinoma were seen among whites and Hispanic men. Rates of hepatic cancer rose in white, black, and Hispanic men and in black women. Conversely, rising incidence rates of thyroid and kidney cancers were observed in all racial/ethnic groups except Native American and Alaska Native men.

The ACS found that people 55 to 64 years of age had the highest increase in incidence rates for liver and HPV-related oropharyngeal cancers; people 65 years and older had an increase in incidence rates for melanoma. For men with HPV-related oropharyngeal cancer and women with thyroid cancer, rising incidence rates were highest among people 55 to 64 years of age.

The reasons for these increasing trends are not entirely clear, said Dr. Ward, adding that there might be a number of underlying reasons. The increased incidence of HPV-related oropharyngeal cancers, for example, might be associated with changes in sexual behaviors that increase the risk for HPV exposure.

"Esophageal adenocarcinoma may be related to rising obesity rates and an increased prevalence of gastroesophageal reflux disease," she said. "This in turn can lead to Barrett's esophagus."

The increased incidence rates of thyroid and kidney cancer are far less clear. "There has been suspicion that part of the reason is an increase in detection as our technology improves," explained Dr. Ward. "That may be part of the explanation, or there may really be a true increase and we just don't know the real causes yet."

"Thyroid cancer is really a puzzle," she said. "It is increasing fast, and research is now being conducted to determine the reasons for this increase. For other cancers, we may have a better handle on the reasons they are increasing and there are some public-health measures that can be taken."

Variations by Ethnic/Racial Groups

There were a total of 565,469 recorded cancer deaths in the United States in 2008, which is the most recent year for which data are available. Cancer accounted for 23% of all deaths recorded in the United States, which makes it the second leading cause of death, right behind cardiovascular disease. From 2007 to 2008, there was a decline in the age-standardized cancer death rate of 1.5%, from 178.4 to 175.8 per 100,000.

There are considerable regional/geographic variations in cancer incidence and mortality, the report notes. Lung cancer, for example, has the greatest variation in rates, which reflects smoking prevalence. In Kentucky, which has the highest prevalence of smoking, lung cancer is almost 4 times as high as it is in Utah, which has the lowest prevalence of smoking.

Cancer incidence and mortality rates continue to show considerable variation by racial and ethnic groups. As previously reported by Medscape Medical News, racial and ethnic disparities continue to exist in cancer care, even after factors such as insurance and socioeconomic status are controlled for, and a disproportionate number of cancer-related deaths occur in racial/ethnic minorities.

Most striking is the fact that for all cancer sites combined, black men have a 15% higher incidence rate and a 33% higher death rate than white men in the United States. Black women have an incidence rate that is 6% lower than white women, but a 16% higher death rate.

In the United States, incidence and death rates are consistently higher in blacks than in whites, with the exception of women with breast (incidence) and lung (incidence and mortality) cancer, and of men and women with kidney (mortality) cancer. However, both incidence and death rates are lower in other ethnic/racial groups than in whites and blacks in the United States for all cancer subtypes and the 4 most common sites.

The exception is incidence and mortality of cancers associated with infectious agents, such as stomach, liver, and cervix, which tend to be higher in minority groups than in whites. As an example, incidence and mortality rates are twice as high in Asian Americans and Pacific Islanders as in whites, which reflects a higher degree of chronic infection with Helicobacter pylori and hepatitis B and C.

Projections for 2012

These current statistics give a bit of mixed message, said Richard Schilsky, MD, past president of the American Society of Clinical Oncology (ASCO) and current executive editor of the ASCO Web site CancerProgress.Net. "The big news is that cancer mortality rates continue to go down, and have been for quite some time," he told Medscape Medical News. "This is true for cancer in general, and especially for the most common cancers."

However, it is clear that other cancers are on the rise, said Dr. Schilsky, who is professor of medicine, chief of hematology/oncology, and deputy director of the Comprehensive Cancer Center, University of Chicago, Illinois. "We also haven't seen these declines in some segments of the population, especially African Americans."

Identifying the rising incidence of some cancers can be helpful. "At least in some cases, there may be an underlying explanation that we can work with and hopefully resolve," he said.

Dr. Schilsky added that some of the best news is that more than 1 million deaths attributable to cancer have been averted over the past decade. "That is very encouraging."

For 2012, the ACS estimates that there will be 1.6 million new cases of invasive cancers, and 577,190 cancer-related deaths — corresponding to more than 1500 deaths per day.

For men, prostate, lung and bronchus, and colorectum cancers will be the most common cancers diagnosed, and will account for approximately 50% of all newly diagnosed cases. Prostate cancer alone will account for 29% (241,740) of incident cases.

For women, breast, lung and bronchus, and colorectum cancers will be the 3 most commonly diagnosed types of cancer, and will also account for approximately half of all new cases. Breast cancer alone is expected to account for 29% (226,870) of all newly diagnosed cancers.

"The importance of trends is that they point us in the right direction," said Dr. Ward. "If a cancer type is increasing, it is important to know the causes. This will encourage more studies to investigate these findings."

The authors have disclosed no relevant financial relationships.

CA Cancer J Clin. Published online January 4, 2012. Abstract, Abstract

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