America at War: Vaccines for Cancer
While the daily coverage of the war in Iraq demands our attention, America is fighting no less than three other wars, each more than 30 years old. Our longest standing war is with North Korea: war was declared in 1951 and, although the fighting on the ground stopped three years later, we have never signed a peace treaty with the North Koreans. Two subsequent wars have been declared against more elusive foes: the war on poverty, and the war on cancer. President Lyndon Johnson declared war on poverty in his State of the Union address in 1964, and pushed jobs and social welfare bills through congress; unfortunately, his efforts to fight poverty were thwarted by an even more difficult war, the one in Vietnam.
Seven years later, President Richard Nixon opened a second front, declaring war on cancer. Last week, the American Cancer Society released the latest figures on the war against cancer (available at www.cancer.org/docroot/STT/stt_0.asp). This year alone, nearly 600,000 Americans will die from cancer—nearly 150,000 more Americans than were killed in World War II, and ten times the number that died fighting in Korea. Death rates from other leading killers—heart disease, stroke, pneumonia—have dropped sharply over the last half of the 20th century; yet, despite the declaration of war and thirty years of skirmishes, death rates for cancer have hardly budged.
Are we losing the war? Is it time to pull out?
Winning the Battles
Well, not really. There have been some notable successes since the war on cancer was declared in the early 1970s. First and foremost, mortality from cancer in children has been cut in half since 1975—an enormous victory that has saved thousands of young lives. Men with lung, prostate, or colon cancer—the three most dangerous foes—are living longer than ever before with successful treatment. For women, breast and colon cancer victims are also living longer, thanks largely to new drugs—although the battle against lung cancer continues to go badly for women, as a result of increased cigarette smoking by women in the 1960s, ‘70s and ‘80s.
So why the flat cancer rate overall? If we’ve been fighting for 30 years and won some major battles, why aren’t we winning the war? With these notable victories, have there been equally dramatic losses on the battlefield?
Well, no, actually. The biggest defeat we have suffered in the war on cancer isn’t really a defeat at all: the reason as many Americans die of cancer today as they did in 1972 is that we are living longer lives. As we age, we have more time to develop cancer—and cancer is a committed, stealthy and dangerous foe.
So do our victories over other diseases mean that inevitably we’ll lose our war to cancer, and to aging? Only time will tell. But we do have new weapons at our disposal, and the most promising ones are cancer vaccines.
A recent article in the Journal of the American Medical Association reviewed the current status of cancer vaccine development (1). The good news from the frontlines: 13 cancer vaccines are currently in Phase 3 clinical trials, spanning the gamut of cancers from breast cancer to melanoma (for details, see www.cancer.gov/BenchMarks/archives/2003_03/vacc_trials.html.) These vaccines are different than the traditional vaccines, in that they fight cancer, rather than prevent it. Each of these vaccines has gone through extensive testing in animals, and proven effective in fighting cancer, as well as Phase 1 and Phase 2 clinical trials to establish their safety in humans. Unlike many other Phase 3 trials, the cancer vaccines are primarily aimed at the sickest people, with the hardest to treat forms of various cancers. Thus, determining whether the vaccines work is a challenge for researchers.
More recently, some researchers are taking a different approach: rather than saving vaccines for the sickest patients, they are using vaccines in patients who are healthier, in order to stave off a recurrence of cancer. In military terms, it’s the difference between sending new troops into the heat of a dangerous firefight as reinforcements, versus sending them in to a recently stabilized situation, as peacekeepers. The results of ongoing trials will tell us whether one strategy is better, or whether both are effective.
And finally, two vaccines are available to prevent cancer; the hepatitis B vaccine, which is FDA-approved, and the human papillomavirus (HPV) vaccine, which is in Phase 3 clinical trials. Hepatitis B infection is a major risk factor for liver cancer. HPV, a form of genital warts, is the culprit behind most cervical cancers. In the long run, these two vaccines may turn out to be some of our greatest victories in the war on cancer.
So, although you don’t read much about it in the newspapers, like the war with North Korea and the war on poverty, the war against cancer quietly rages on. It will be interesting to see which of our three oldest wars comes to an end sooner. With the promise of new vaccines, don’t bet against major victories in the war on cancer.
1. Mitka, M. Cancer Vaccine Research Inches Forward. Journal of the American Medical Association 291:550-552 (2004).