One hundred years ago, tuberculosis was a major killer in the United States. In the 1950s, polio killed and disabled millions of Americans.
TB is still a threat worldwide, but effective use of antibiotics has reduced infections and deaths in the United States and other developed countries. Thanks to the Salk vaccine, introduced in the mid-1950s, polio has been virtually eliminated in this country and lingers in only two small areas of the world.
When cancer was targeted in the National Cancer Act of 1971, expectations were similarly high. Labeled by then-President Nixon as the War on Cancer, the goal was to find more effective treatments and ultimately a cure. Those hopes have been revived again and again, most recently by research directions spurred by the Human Genome Project. Nevertheless, the question, “Are we there yet?” must be answered in the negative.
Cancer still ranks right behind heart disease as the No. 2 killer in the United States, accounting for nearly 25 percent of deaths. Deaths from stroke declined by 60 percent during the period from 1975 to 2006, and deaths from cardiovascular disease, by 52 percent during the same period.
The cancer death rate for American men has declined since 1975 primarily because of less smoking and fewer lung cancer cases. But the overall cancer death rate, after adjusting for the age and size of the population, has declined by only about five percent since 1950.
Cancer is clearly a much more complex disease than was thought in 1971. In fact, it’s not one disease but many, and the more scientists learn about cancer, it seems, the more there is to learn.
Some Successes, Some Failures
Thanks to ongoing research, treatments have been improved and great strides have been made against some cancers, most notably childhood leukemia, chronic myeloid leukemia, Hodgkin’s and non-Hodgkin’s lymphoma and testicular cancer. For many women, breast-preserving lumpectomy has replaced mastectomy as a treatment option.
On the other hand, pancreatic cancer, lung cancer, brain tumors and metastatic melanoma remain largely incurable. Sixty percent of lung cancer patients die within a year.
Any time cancer has already spread by the time of diagnosis, successful treatment is very difficult. And symptoms rarely appear before that time.
SCREENING: The obvious answer is to detect cancer early, before it has had time to spread. And one major thrust of the War on Cancer has been to increase public awareness about screening programs that are effective in detecting early cancer.
Screening with the Pap test was one of the earliest and most successful efforts, reducing by half the number of deaths from cervical cancer. Other widely publicized screening programs have targeted breast, prostate and colorectal cancers.
From the highly effective public awareness campaigns, it’s easy to get the impression that if enough Americans would take the time to get a mammogram or a colonoscopy, the War on Cancer could be won. Unfortunately, that is not the case.
The PSA (prostate-specific antigen) blood test is a highly effective way of detecting early prostate cancer. Yet the U.S. Preventive Services Task Force recently started advising men not to screen for prostate cancer with either the PSA test or the digital rectal examination. Such screening, the task force concluded, does more harm than good.
Many men and their doctors cried out in alarm at such a recommendation. Why wouldn’t you want to know that you had an early cancer in your prostate gland? Why wouldn’t you get a simple blood test to help detect that cancer?
One reason is that the test produces many false positives that lead to biopsies and other procedures that are costly and carry risks. When cancer is detected, available treatment options frequently result in serious after effects such as erectile dysfunction and urinary incontinence. And, finally, research indicates that many of those early cancers that are “successfully treated” may never have caused harm. At this time, doctors have no certain way of knowing how a cancer that is detected will behave over time.
To a lesser degree, some of the same objections can be made about screening for breast cancer. The claim has been made that mammography has reduced the breast cancer death rate by 15 percent, but some researchers believe that most of this decrease can be attributed to improved treatments rather than screening.
A study of three decades of screening published in The New England Journal of Medicine [November, 2012] concluded that mammography has “only marginally reduced the rate at which women present with advanced cancer,” and that “screening is having, at best, only a small effect on the rate of death from breast cancer.” According to the authors, about a third of newly diagnosed breast cancers represent overdiagnosis and lead to unnecessary treatment. As with prostate cancer, screening is not always effective at stopping the most aggressive, life threatening cancers.
Developing effective treatments–or a cure–involves more than just finding the smallest possible lump.
NEW TREATMENTS: David Nathan, author of The Cancer Treatment Revolution [2007] is optimistic about the potential of new “smart drugs.”
One of these drugs, Avastin, blocks the action of VEGF, a substance that promotes the formation of the new blood vessels needed to nourish the rapidly growing tumor. Another frequently used drug, Gleevec, targets abnormal proteins inside cancer cells that are responsible for the uncontrolled growth.
Many of the new drugs are designed to identify and attack specific molecules of a specific type of cancer, slowing or halting their growth without causing damage to healthy tissue. Even better results can be expected as a result of knowledge gained from the Human Genome Project.
While these new approaches are promising, the drugs developed so far have been costly. According to an update published in the Journal of the American Medical Association [2009], 90 percent of cancer drugs approved since 2005 cost more than $20,000 for 12 weeks of therapy. And the survival they offer is frequently less than two months.
The best news about cancer is that most cases are preventable by making good lifestyle choices: avoiding cigarette smoke and excessive exposure to ultraviolet radiation from the sun and other sources; exercising regularly; and eating a healthy diet.
REFERENCES:
American Cancer Society, “Cancer facts and figures 2013.”
Shira Berman, “Lung cancer 2013: the good, the bad, and the ugly,” Medscape Oncology, December 18, 2013.
Archie Bleyer, M.D., and H. Gilbert Welch, M.D., MPH, “Effect of three decades of screening mammography on breast-cancer incidence,” NEJM, November 22, 2012.
Kim Bielenberg, “Terminal decline: how we’re winning war against cancer,” Dublin Independent, updated May 12, 2014.
“Cancer treatment revolution potential with new drug,” ScienceDaily, March 25, 2014.
Gina Kolata, “Advances elusive in the drive to cure cancer,” New York Times, April 24, 2009.
Denise Mann, “Cancer: the good, the bad, and the ugly,” WebMD Feature, reviewed by Louise Chang, M.D., August 17, 2005.
Peggy Orenstein, “Our feel-good war on breast cancer,” New York Times, April 25, 2013.
Reynold Spector, “The war on cancer: a progress report for skeptics,” Cancer Science Institute, January/February, 2010.
Scott Terranella, “Doctors excited by new cancer treatment,” ABC News, April 4, 2014.
07/21/2014
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