Progress in Cancer Prevention
This timeline of advances in cancer prevention was developed by the American Society of Clinical Oncology (ASCO),
which represents nearly 30,000 physicians who treat people with cancer and research new cures. An interactive
version, which includes timelines of advances against a range of common cancers, is available online at
www.CancerProgress.Net.
Overview
The ultimate goal is to avoid cancer altogether. Stopping smoking, eating a healthy diet, and avoiding excess sun
exposure have all been shown to reduce cancer risk. Declining use of tobacco, in particular, is a major factor
behind the falling rate of new cancer cases in the U.S. This rate has decreased by 10 percent since peaking in the
early 1990s.
In addition to lifestyle changes, researchers are discovering a growing number of biomedical tools to prevent
cancer, including preventive drugs and surgery for women at high risk of breast or ovarian cancer; removal of
precancerous polyps for colorectal cancer; and vaccines to prevent the viruses that cause cervical, head and neck
and liver cancers.
Timeline
1950s-1960s Smoking linked to cancer; cessation campaigns begin
In the 1950s, studies begin to show that smoking is a major cause of cancer, particularly lung cancer.
In the early 1960s, both the U.S. Surgeon General and the U.K. Royal College of Physicians issue reports
linking smoking to cancer and other serious health problems. In later years, smoking is also established
as a major cause of pancreatic cancer, and second-hand smoke is declared a threat to the health of
non-smokers. Tobacco control and smoking cessation soon become the most important strategies for
reducing the worldwide toll of lung cancer.
1966 Lung Cancer
Warning labels first appear on cigarette packs
Warnings about cancer and the other health risks associated with smoking begin appearing on
cigarette packs sold in the United States. Starting in 1966, cigarette pack labels are required to state:
“Caution: Cigarette Smoking May Be Hazardous to Your Health.”
1970s Pancreatic Cancer
Tobacco use found to cause pancreatic cancer
Several studies find that tobacco use, especially cigarette smoking, is a major cause of pancreatic
cancer. Smoking cessation becomes the primary tool for reducing the risk of the disease.
Progress ress in Cancer Prevention
2
1970s Use of cancer-causing asbestos declines
As studies confirm long-suspected links between asbestos and certain cancers, use of asbestos begins
to decline. In the 1980s, its use is banned in a growing number of applications, and environmental and
health regulations help to dramatically limit exposure to asbestos in workplaces and homes. Asbestos
exposure has been shown to increase a person’s risk of lung cancer, mesothelioma (an aggressive
cancer in the chest or abdomen), and other serious health problems. Because these problems often
occur decades after exposure, however, the impact of preventive efforts will be felt gradually in the
years ahead.
1981 Liver Cancer
First cancer vaccine prevents cancer-causing hepatitis B infection
The FDA approves the first vaccine against hepatitis B, one of the primary causes of liver cancer. In
1991, the U.S. begins routine vaccination of all children against hepatitis B, and by 2007, the number
of acute hepatitis B cases among children under 15 years declines by 98 percent. Over time, routine
vaccination is expected to reduce rates of liver cancer in the U.S. and globally among adults who were
vaccinated as children.
1981 Ovarian Cancer
Oral contraceptives found to cut ovarian cancer risk
Studies first begin suggesting that oral contraceptive use lowers the risk of developing ovarian cancer.
Evidence continues to accumulate over the coming years, and in 2008, a review of 45 published
studies concludes that “the pill” lowers ovarian cancer risk by 20 percent for every five years it is used.
Authors of the 2008 study estimate that oral contraceptives had prevented some 200,000 ovarian
cancers and 100,000 deaths worldwide in the 50 years since oral contraceptives were introduced, and
may currently prevent 30,000 new cases of ovarian cancer each year.
1970s-1990s Melanoma
Research links sun exposure to melanoma risk
A growing number of studies in this period suggest that sun exposure plays an important role in the
development of some melanomas. Specifically, frequency and duration of exposure, as well as a history
of severe sunburn, are found to be associated with a person’s risk of the disease. In the 1980s, the
public health community and advocacy groups such as the Skin Cancer Foundation begin cautioning
the public about the potential risks of sun exposure.
1986 Second-hand smoke formally declared a carcinogen
The U.S. Surgeon General, and later the International Agency for Research on Cancer, officially state
that second-hand smoke is a carcinogen. A number of cities around the world ban indoor smoking in
the years that follow.
Progress ress in Cancer Prevention
3
Late 1980s Benzene discovered to cause blood cancers
Scientists find that occupational exposure to benzene, a chemical commonly used as a solvent and in
oil-related products, is associated with increased risk of developing non-lymphocytic leukemia, non-
Hodgkin lymphoma, and other diseases. Following this discovery, workers begin taking steps to protect
themselves from benzene exposure and reduce their cancer risk.
1998 Treatment guidelines highlight obesity-cancer link
Major studies linking obesity to an increased risk of common cancers prompt the National Institutes of
Health to publish clinical guidelines on managing obesity in adults. The guidelines point specifically to
the increased risk for endometrial, breast, prostate and colon cancers, in addition to other serious
health problems.
1998 Breast Cancer
Drug therapy can reduce breast cancer risk in women at high risk
The FDA approves tamoxifen (Novaldex), a hormonal drug already used to prevent recurrence of breast
cancer, to reduce the risk of developing breast cancer in the first place in women who are at high risk
for the disease. The approval is based on a large trial showing that tamoxifen reduced breast cancer
risk by more than 40 percent in women with a strong family history of breast cancer or with mutations
in the BRCA1 and BRCA2 genes. Later research shows that a different drug used to treat osteoporosis,
raloxifene (Evista), is as effective as tamoxifen at preventing invasive breast cancer, but with a lower
risk of certain side effects.
2000 Lung Cancer
Study links household radon exposure to lung cancer
The Iowa Radon Lung Cancer Study demonstrates that ongoing exposure to residential radon – a
naturally-occurring radioactive gas that can emerge through basements and crawl spaces – is
associated with increased risk of lung cancer. The Environmental Protection Agency now estimates that
more than 20,000 lung cancer cases in the U.S. are due to long-term radon exposure in the home.
Since the study, radon inspections have become a routine part of homeownership, promising to reduce
the future burden of the disease.
2003 Colorectal Cancer
Aspirin and similar anti-inflammatory medications help reduce colon cancer risk
Two large studies show that taking daily aspirin prevents the development of precancerous colorectal
polyps, and a later trial involving another anti-inflammatory drug, celecoxib (Celebrex), reports a
similar finding. However, this use of aspirin or similar anti-inflammatory drugs is not yet recommended
for cancer prevention among the general public, due to the risk of potentially serious side effects, such
as stomach bleeding. Large, randomized studies are currently underway to evaluate the benefit of
these drugs in prevention of polyps, second colon cancers and cancer recurrence.
Progress ress in Cancer Prevention
4
2003 Prostate Cancer
First drugs proven effective for reducing prostate cancer risk
Two large trials report that finasteride (Proscar) and dutasteride (Avodart) reduce the risk of developing
prostate cancer by up to 25 percent, compared to placebo. However, debate persists about the
optimal use of these drugs for prostate cancer prevention. Key issues of controversy include whether
these agents increase aggressiveness of tumors that do arise, and whether they only inhibit less
aggressive tumors that would not have been dangerous without treatment in the first place.
2006 Breast Cancer
Tamoxifen and raloxifene equally effective for preventing invasive breast cancer
Findings from one of the largest-ever breast cancer prevention studies show that tamoxifen (Novaldex)
and a newer drug, raloxifene (Evista), are equally effective in reducing the risk of invasive breast cancer
in women at high risk for the disease. (Both drugs lowered the risk by about 50 percent.) The study
found that raloxifene was not as effective, however, at reducing non-invasive breast cancer, such as
ductal carcinoma in situ. Tamoxifen had greater side effects, including a higher risk of blood clots and
uterine cancers.
2006 Cervical Cancer
Preventive cancer vaccine approved for cervical cancer
The FDA approves Gardasil, a vaccine that prevents infection with the two high-risk strains of human
papillomavirus (HPV) known to cause about 70 percent of cervical cancers. The vaccine is approved for
girls and young women aged 9 to 26. The approval is based on data showing the vaccine is 100
percent effective in preventing HPV16- and HPV18-related cervical pre-cancers, as well as genital warts,
for at least 4.5 years following vaccination. Later the same year, the CDC’s Advisory Committee on
Immunization Practices (ACIP) recommends routine HPV vaccination for girls aged 11 and 12; however,
state requirements for HPV vaccinations vary. A second vaccine, Cervarix, was approved in 2009 to
prevent infection against HPV16 and HPV18 in women aged 10 to 25. The cost of the three-dose
regimen remains a persistent challenge to widespread HPV vaccination, with either version of the
vaccine. Also in 2009, the Gardasil vaccine is approved for use in boys for the prevention of genital
warts.
Gardasil is later approved to prevent additional HPV-related diseases in children and young adults aged
9 to 26, including vaginal, vulvar and anal cancers in females, and anal cancer and genital warts in
males.
2007 Breast Cancer
Declining breast cancer incidence linked to lower use of hormone replacement
therapy
Studies link declines in breast cancer incidence in women aged 50 and older to decreased use of
hormone replacement therapy involving estrogen and progestin. One study reports that the rate of
new breast cancer cases declined as much as 13 percent between 2001 and 2003, though researchers
suggest other factors could have also played a role, such as increased use of mammography. Until
2002, when researchers first identified this significantly increased breast cancer risk, hormone
replacement therapy was commonly prescribed to relieve the symptoms of menopause, such as hot
flashes and vaginal dryness.
Progress ress in Cancer Prevention
5
2009 Cervical Cancer
HPV vaccine benefits women over age 26
A large, randomized trial shows that the HPV vaccine Gardasil is more than 90 percent effective in
preventing cervical cancer in women aged 24 to 45 who received all three vaccine doses, and who
were not infected by the virus. While the vaccine is currently approved only for younger women, it is
being considered by the FDA for use in women over age 26.
2010 Melanoma
Indoor tanning declared a carcinogen
After reviewing more than 2,000 patient records, researchers conclude that people who use indoor
tanning beds are 74 percent more likely to develop melanoma than non-users, and that more frequent
tanning bed use further increases the risk. Based on these findings, the International Agency for
Research on Cancer declares that tanning devices are carcinogens. Epidemiologists have proposed that
growing use of tanning beds could partially explain the recent rise in melanoma incidence among
young women. It is hoped that greater regulation and taxation of these services will stem their use.
http://www.cancerprogress.net/downloads/timelines/progress_in_cancer_prevention_timeline.pdf