Every year, the American Cancer Society along with other collaborators (including the Centers for Disease Control and Prevention, the North American Association of Central Cancer Registries, the National Cancer Institute and others) provides an annual report to the nation on the status of our progress in addressing the burden of cancer in our country.
Consider it an accountability report. It provides a considerable amount of information on whether we are—or are not—reducing the incidence and mortality from cancer.
For the past several years, the news has been good. We have seen declines in incidence and deaths from several of the major cancer types in men and women.
Fortunately, this year’s report released today—which covers statistics through 2004—is no exception, and some of the declines in incidence and mortality for cancer overall and certain cancers in particular are striking.
This is probably the key statistic: from 1993 to 2002, the annual decrease in cancer deaths was about 1.1%. From 2002 through 2004, that rate of decline almost doubled to 2.1%.
For men and women, for most of the common cancers, there was a continued decline in death rates.
Among women, there is finally a flattening in the prior increases we have seen in the incidence rate for lung cancer. And, the death rates for lung cancer—which have been declining for many years in men—are finally are starting to show a slowing in women.
As one digs deeper into the report, one of the most stunning declines in cancer incidence was in breast cancer in women. This may not be brand new information, but it certainly confirms what has been reported previously.
Bottom line, breast cancer incidence declined year over year 3.5% from 2001 through 2004.
The authors discuss the various reasons for this decline. Importantly, the trend in decreased breast cancer incidence began prior to the decline in the use of hormone replacement therapy starting in mid-2002.
This trend may be related in part to several factors, they note, including the decline in the use of HRT but it could also be related to the fact that mammograms over the years had picked up a substantial number of very early, non-invasive breast cancers (called ductal carcinoma in situ, or DCIS) preventing them from going on to becoming invasive breast cancers.
The decline could also be due in part to a significant decline in screening mammograms performed during this period of time, meaning that breast cancers that are present are not being diagnosed at an early stage, and will eventually show up later.
The authors make an interesting case for another impact of declining HRT use: because HRT is a risk factor for ovarian cancer as well as breast cancer, that may explain why there has also been a significant decline in the incidence of ovarian cancer as well as breast cancer.
Having declined 1.0% per year from 1995 through 2001, the rates of ovarian cancer incidence declined 3.3% per year from 2001 through 2004. The authors suggest that this rapid decline over the more recent years of analysis may reflect the fact that the prior slower decline was related to oral contraceptive use, while the more recent changes are due to the abrupt decline in HRT use.
Last year we reported on a significant increase in thyroid cancer.
This increase has continued, with the rate tripling from 1995 through 2004. That rate is now 6.1% per year for women. That means the incidence of thyroid cancer in women will double every 12 years at this rate. The comparable rate of increase during the years 1980-1995 was 2.3% per year.
Colorectal cancer incidence rates continue to decline, probably because of increased screening. This includes the fact that screening is leading to an increased prevention of colon cancer, by removal of pre-cancerous polyps.
For men, the decline in colorectal cancer incidence per year from 1998-2004 has been 2.8% per year. For women, the comparable rate decline per year is 2.4%.
Other cancers have increased in incidence. These included melanoma, non-Hodgkin lymphoma, leukemia, and cancers of the bladder and kidney.
Death rates from a number of cancers have continued to decline, and in some that rate of decline has actually accelerated.
Death rates in lung cancer and prostate cancer in men, breast cancer in women and colorectal cancer in both men and women have shown continuing significant declines year over year.
Liver and esophageal cancer deaths, however, increased in men.
In women, death rates have declined for 10 of the 15 most common cancers (breast, colon and rectum, non-Hodgkin lymphoma, leukemia, brain, myeloma, stomach, kidney, cervix and bladder). Death rates were stable for cancers of the pancreas, ovary, and uterus. Liver cancer death rates in women have increased 2.6% annually in women, according to the report.
One of the items noted in the report—but that does not get a lot of press attention—is the significant decline from 1995-2004 in incidence rates of cancers in black men that are related to cigarette consumption.
The examples that I would cite include: lung cancer, down 2.9% per year; oral cavity and pharynx, down 3.1% per year; esophagus, down 5.5% per year; larynx, down 2.8% per year.
Those declines—which are modest from year to year, but substantial over a decade—will help reduce the especially high burden of cancer in this community.
By the same token, there is a significant increase in liver cancer in black men of 3.6% per year for the same time period. The sad commentary here is that some of these cancers can be prevented by adequate immunization against hepatitis B.
Every year’s annual report highlights cancer incidence and mortality rates in a special population. This year, that population was American Indians and Alaska Natives (AI/AN). The report highlights a number of facts that influence the rates of cancer in this population.
For example, the median age of this group is 29 years in 2000, compared to the nationwide median of 35 years.
Poverty in this group is 3 times greater than found in non-Hispanic whites. AI/AN adults were less likely to graduate from high school and more likely to have less than a 9th grade education compared to non-Hispanic white adults.
They have less health coverage, and less often have a usual source of health care. They have a huge number of people age 65 and over who say they have no healthcare coverage.
All of these are factors which contribute to a higher risk of poor outcomes from cancer treatments, and a higher rate of death from cancer.
The list goes on: a greater prevalence of smoking; less leisure time physical activity; more binge and heavy alcohol consumption; lower rates for cancer screening including cervical cancer screening and prostate cancer screening.
On the other hand, cancer incidence rates in this population are less than that found in non-Hispanic whites.
However, when diagnosed, colorectal cancers, breast cancers and cervical cancers were less likely to be diagnosed at localized stages in this population compared to non-Hispanic whites. That translates into poorer outcomes for the treatment of these cancers in this population.
So what does all this mean?
There is certainly some good news in this report.
As the authors report, there has been an accelerated decline in cancer death rates.
In particular, the declines in incidence of colorectal cancer in men and women, the decline in breast cancer incidence rates in women, and a long term leveling in lung cancer rates in women are noteworthy.
The decline in death rates in colorectal cancer is accelerating. Prostate cancer death rates are declining in all racial and ethnic populations.
In melanoma, the increase in incidence trends has slowed, especially among men for whom rates were stable from 2000-2004.
But there is also some not so good news, as reflected in the report of the unequal health status of the AI/AN population.
We continue to make progress, but as I have noted previously, we still have a long way to go.
We hope some of the trends are real and will be longlasting, such as the declines in breast cancer rates. But we must be aware that they may also be due to factors that are not good, such as declining use of screening mammography which means that cancers which are present (and treatable) are not being diagnosed.
As the population in the United States continues to get larger and becomes older (aging is the most important risk factor for breast cancer), we must redouble our vigilance, our medical efforts and our research.
We must continue to do what we already knows works, namely emphasizing our efforts for the prevention and early detection of cancer, as well as being certain that every person diagnosed with cancer has access to the right treatment at the right time.
But, as the American Cancer Society has highlighted over the past month and as the data from the American Indian/Alaska Native data confirms, we must address the access to health care in this country, to assure that everyone has the opportunity to do the best for their health and for themselves.
If we don’t continue all of these efforts, we face the prospect of not maintaining the gains highlighted by this article.
That would be a sad report to deliver to the nation and to the world.
