Cancer death rates are dropping for multiple reasons.
Grand Rapids, Mich. (Aug. 13, 2009) – The number of cancer deaths has declined steadily in the last three decades. Although younger people have experienced the steepest declines, all age groups have shown some improvement, according to a recent report in Cancer Research, a journal of the American Association for Cancer Research.
“Our efforts against cancer, including prevention, early detection and better treatment, have resulted in profound gains, but these gains are often unappreciated by the public due to the way the data are usually reported,” said Eric Kort, M.D., who completed the study while employed as a research scientist at Van Andel Research Institute (VARI) in Grand Rapids, Mich.
Cancer mortality rates are usually reported as composite age-adjusted rates. These rates have been declining modestly since the 1990's. However, these statistics heavily emphasize the experience of the oldest Americans for whom mortality rates are the highest. As a result, trends emerging in younger Americans can be concealed.
The decline in cancer death rates has been sharpest among children.
As an alternative to age-adjustment, Kort examined cancer mortality rates stratified by age and found that for individuals born since 1925, every age group has experienced a decline in cancer mortality. The youngest age groups have experienced the steepest decline at 25.9 percent per decade, but even the oldest groups have experienced a 6.8 percent per decade decline.
We might expect a general decline in cancer death rates due to the decline in the fraction of the population that smokes cigarettes. But that steep decline in child cancer death rates probably isn't due to less exposure to parental cigarette smoke.
We have lots of ways to cut our cancer death risk. Some studies have found a reduced risk of colorectal cancer from aspirin and non-steroidal anti-inflammatory drugs (NSAIDS). Turns out aspirin will help against some colorectal cancers even after diagnosis.
Regular use of aspirin after colorectal cancer diagnosis may reduce the risk of cancer death, report investigators from Massachusetts General Hospital (MGH), Dana-Farber Cancer Institute and Brigham and Women's Hospital. In the August 12 issue of the Journal of the American Medical Association, the study's authors also find that the aspirin-associated survival advantage was seen primarily in patients with tumors expressing the COX-2 enzyme, a characteristic of two-thirds of colorectal cancers.
Intermittent calorie restriction might cut your cancer risk too. Want more ways to cut your cancer risk? Lots of dietary changes will cut your risk of death from cancer.
Results released today from the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial show that six years of aggressive, annual screening for prostate cancer led to more diagnoses of prostate tumors but not to fewer deaths from the disease. The study, led by researchers at Washington University School of Medicine in St. Louis and conducted at 10 sites, will appear online March 18 in the New England Journal of Medicine (and in the journal's print edition on March 26).
"The important message is that for men with a life expectancy of seven to 10 years or less, it is probably not necessary to be screened for prostate cancer," says the study's lead author and principal investigator Gerald Andriole, M.D., chief urologic surgeon at the Siteman Cancer Center at Washington University School of Medicine and Barnes-Jewish Hospital.
Prostate cancer is a slow killer for most men. So this result isn't entirely surprising. Someone getting a diagnosis of prostate cancer when they have 5 years till their heart gives out is probably going to die from heart failure, not prostate cancer. The researchers of this study think that their younger enrollees might eventually show that early detection will help them live longer.
Screening for prostate cancer can reduce deaths by 20%, according to the results of the European Randomized Study of Screening for Prostate Cancer (ERSPC) published online 1700 hours CET, today 18 March (NEJM, Online First*). ERSPC is the world's largest prostate cancer screening study and provides robust, independently audited evidence, for the first time, of the effect of screening on prostate cancer mortality.
The study commenced in the early 1990s involving eight countries – Belgium, Finland, France, Italy, Netherlands, Spain, Sweden and Switzerland - with an overall follow-up of up to 12 years. Participants totalled 182,000 but then narrowed down to 162,000 men in seven countries, aged 55-69; only those who had not been screened could take part. The findings are being unveiled at the 24th Annual Congress of the European Association of Urology (EAU) in Stockholm, Sweden (17 - 21 March 2009).
By initially screening men 55 to 69 years with the PSA marker and offering regular follow up, this led to an increase in early detection. Deaths due to metastasized disease were then reduced. Exact data showed that on average for every 1,408 men screened, 48 had cancer diagnosed and received treatment, resulting in saving one life. Screening took place on average every four years with a mean follow-up over nine years. The cut-off value was a PSA level of 3.0 ng/ml or more. Men with this reading were then offered a biopsy.
What would extend life expectancy much more assuredly: cures for cancer. In the mean time while we wait for cures eat more mushrooms.
Women who are tested less for breast cancer get diagnosed less with breast cancer.
Breast cancer rates increased significantly in four Norwegian counties after women there began undergoing mammography every two years, according to a report in the November 24 issue of Archives of Internal Medicine, one of the JAMA/Archives journals. Rates among regularly screened women remained higher than rates among women of the same age who were screened only once after six years, suggesting that some of the cancers detected by mammography may have spontaneously regressed had they not been discovered and treated.
The idea here is that if the women who were tested less often really had as much lasting breast cancer as that found in the more frequently tested group then the former group really should have had more breast cancer cases found when they were finally tested . But they did not show those "missing" breast cancer occurrences at the end of the trial.
Throughout Europe, the start of screening mammography programs has been associated with increased incidence of breast cancer, according to background information in the article. "If all of these newly detected cancers were destined to progress and become clinically evident as women age, a fall in incidence among older women should soon follow," the authors write. "The fact that this decrease is not evident raises the question: What is the natural history of these additional screen-detected cancers?"
Per-Henrik Zahl, M.D., Ph.D., of the Norwegian Institute of Public Health, Oslo, and colleagues examined breast cancer rates among 119,472 women age 50 to 64 who were all invited to participate in three rounds of screening mammograms between 1996 and 2001 as part of the Norwegian Breast Cancer Screening Program. They compared these to rates among a control group of 109,784 women age 50 to 64 in 1992, who would have been invited for screening if the program had existed at that time. Cancers were tracked for six years using a national registry, and at the end of that time all participants were invited to undergo a one-time screening to assess breast cancer prevalence.
As anticipated, breast cancer rates were higher among screened women than among the control group before the final prevalence screening. "Even after prevalence screening in controls, however, the cumulative incidence of invasive breast cancer remained 22 percent higher in the screened group," the authors write. Of every 100,000 screened women, 1,909 had breast cancer during the six-year period, compared with 1,564 of every 100,000 in the control group. Screened women were more likely to have breast cancer at every age.
An alternative explanation is that each test for breast cancer has false negatives and some of these women who are tested less often are having their breast cancer getting missed. Is that possible?
Suppose this finding holds up. It has some obvious implications. First off, some of the reported claimed progress in curing breast cancer might be a mirage. More frequent testing is turning up earlier stage breast cancer. Some of that earlier stage breast cancer might disappear naturally (perhaps via an immune response) if left alone. Treatment might even impair the immune system and leave it less able to defeat the breast cancer on its own.
This report suggests some women are going thru surgery, chemo, and radiation who would otherwise recover from breast cancer without ever knowing they even had it. Given the ravages of the treatments this is quite unfortunate. But perhaps scientists can discover characteristics of cancers or of patient immune systems that make regression more likely. Then those conditions could be induced in women with breast cancer in order to cause more regressions.
We can expect great advances in early detection. Microfluidic devices will test blood samples with great sensitivity and detect blood markers for cancer (and other diseases as well). The tests will become so sensitive that we are going to hit a problem: we have lots of very small cancers in our bodies (really) that are stuck at the stage of being unable to grow more blood vessels. These very small cancers are going to contribute to a sort of background noise of cancer signals. I expect as the blood assay tests become more sensitive to very low concentrations of cancer markers we will even find that as we age a gradual slow rise in cancer blood markers will be found.
On the bright side, the ability to detect very early stage cancer will lend itself to immune treatments against cancer. Caught early enough a cancer won't have as many mutations that protect it from an immune response. In particular, I'm hopeful that vaccines and monoclonal antibodies will be developed that will rid of cancers without our even having to know the exact location of each cancer. Perhaps as we age we will periodically go in for an anti-cancer immunotherapy that basically kills any early stage cancer cells that have grown up since a previous treatment.