Cancer Facts
(reproduced from American
Cancer Society)
What
Is Cancer?
Cancer is a group of diseases characterized by uncontrolled growth and spread
of abnormal cells. If the spread is not controlled, it can result in death.
What
Causes Cancer?
Cancer is caused by both external (chemicals, radiation, and viruses) and internal
(hormones, immune conditions, and inherited mutations) factors. Causal factors
may act together or in sequence to initiate or promote carcinogenesis. Ten or
more years often pass between exposures or mutations and detectable cancer.
Can
Cancer Be Prevented?
All cancers caused by cigarette smoking and heavy use of alcohol could be prevented
completely. The ACS estimates that in 1998 about 175,000 cancer deaths are expected
to be caused by tobacco use and an additional 19,000 cancer deaths are related
to excessive alcohol use, frequently in combination with tobacco use. Many cancers
that are related to dietary factors could also be prevented. Scientific evidence
suggests that up to one-third of the 564,800 cancer deaths that are expected
to occur in the US this year are related to nutrition. In addition, many of
the one million skin cancers that are expected to be diagnosed in 1998 could
have been prevented by protection from the sun's rays.
Screening examinations, conducted
regularly by a health care professional can result in the detection of cancers
of the breast, colon, rectum, cervix, prostate, testis, tongue, mouth, and skin
at earlier stages, when treatment is more likely to be successful. Self examinations
for cancers of the breast and skin may also result in detection of tumors at
earlier stages. The nine screening-accessible cancers listed above account for
approximately half of all new cancer cases. The 5-year relative survival rate
for these cancers is about 80%. If all Americans participated in regular cancer
screenings, this rate could increase to more than 95%.
How
Is a Person's Cancer Treated?
By surgery, radiation, chemotherapy, hormones, and immunotherapy.
Who
Is at Risk of Developing Cancer?
Anyone. Since the occurrence of cancer increases as individuals age, most cases
affect adults middle-aged or older. Cancer researchers use the word risk in
different ways. Lifetime risk refers to the probability that an individual,
over the course of a lifetime, will develop cancer or die from it. In the US,
men have a 1 in 2 lifetime risk of developing cancer, and for women the risk
is 1 in 3.
Relative risk is a measure of the
strength of the relationship between risk factors and the particular cancer.
It compares the risk of developing cancer in persons with a certain exposure
or trait to the risk in persons who do not have this exposure or trait. For
example, smokers have a 10-fold relative risk of developing lung cancer compared
with nonsmokers. This means that smokers are about 10 times more likely to develop
lung cancer (or have a 900% increased risk) than nonsmokers. Most relative risks
are not this large. For example, women who have a first-degree (mother, sister,
or daughter) family history of breast cancer have about a twofold increased
risk of developing breast cancer compared with women who do not have a family
history. This means that women with a first-degree family history are about
two times or 100% more likely to develop breast cancer than women who do not
have a family history of the disease.
How
Many People Alive Today Have Ever Had Cancer?
The National Cancer Institute estimates that approximately 8 million Americans
alive today have a history of cancer. Some of these individuals can be considered
cured, while others still have evidence of cancer.
How
Many New Cases Are Expected to Occur This Year?
About 1,228,600 new cancer cases are expected to be diagnosed. Since 1990, approximately
11 million new cancer cases have been diagnosed. These estimates do not include
carcinoma in situ (non invasive cancer) except for urinary bladder, or basal
and squamous cell skin cancers. Over 1 million cases of basal and squamous cell
skin cancer are expected to be diagnosed this year.
How
Many People Are Expected to Die of Cancer?
This year about 564,800 Americans are expected to die of cancer—more than 1,500
people a day. Cancer is the second leading cause of death in the US, exceeded
only by heart disease. One of every four deaths in the US is from cancer. Since
1990, there have been approximately 5 million cancer deaths.
What
Is the National Cancer Death Rate?
Between 1991 and 1995, the national cancer death rate fell 2.6%. Most of the
decline can be attributed to decreases in mortality from cancers of the lung,
colon-rectum, and prostate in men, and breast, colon-rectum, and gynecologic
sites in women. The declines in mortality were greater in men than in women,
largely because of changes in lung cancer rates; greater in young patients than
in older patients; and greater in African Americans than in whites although
mortality rates remain higher in African Americans.
How
Many People Are Surviving Cancer?
In the early 1900s, few cancer patients had any hope of long-term survival.
In the 1930s, about one in four was alive five years after treatment. About
491,400 Americans, or 4 of 10 patients who get cancer this year, are expected
to be alive five years after diagnosis.
This 4 in 10, or about 40% is called
the "observed" survival rate. When adjusted for normal life expectancy
(factors such as dying of heart disease, accidents, and diseases of old age),
a "relative" 5-year survival rate of 58% is seen for all cancers.
Five-year relative survival rates, commonly used to monitor progress in early
detection and treatment of cancer, include persons who are living five years
after diagnosis, whether in remission, disease-free, or under treatment. While
these rates provide some indication about the average survival experience of
cancer patients in a given population, they are less informative when used to
predict individual prognosis.
What
Is the Difference Between In Situ and Invasive Cancer?
Carcinoma in situ (non invasive cancer) is the earliest stage of cancer. At
this stage, the cancer cells are only in the layer of cells they developed in,
and have not yet spread to other parts of that organ or elsewhere in the body.
Most in situ cancers are curable if they are treated before they progress to
invasive cancer. For this publication, unless otherwise specified, statistics
are for invasive cancers only. Because most in situ cancers cause no symptoms
and do not always progress to invasive cancers, they cannot be counted as accurately
as invasive cancers.
What
Are the Costs of Cancer?
The financial costs of cancer are great both to the individual and to society
as a whole. The National Cancer Institute estimates overall annual costs for
cancer at $107 billion; $37 billion for direct medical costs, $11 billion for
morbidity costs (cost of lost productivity), and $59 billion for mortality costs.
Treatment of breast, lung and prostate cancers account for over half of the
direct medical costs.
The debate on health care system
reform highlights the cost of treating cancer in a new way. According to 1994
data, about 18% of Americans under age 65 have no health insurance, and about
14% of older persons have only Medicare coverage. The proportion of the population
that is uninsured, moreover, does not take into account the millions of Americans
now living with disease or disability who daily encounter problems with our
health care system, including the 8 million Americans who have had cancer.
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