Basic Facts About Cancer
- 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?
Yes, since some external factors can be controlled. About 90% of the 800,000 skin cancers that will be diagnosed in 1996 could have been prevented by protection from the sun's rays. All cancers caused by cigarette smoking and heavy use of alcohol could be prevented completely. The ACS estimates that in 1996, about 170,000 lives will be lost to cancer because of tobacco use. About 19,000 cancer deaths will be related to excessive alcohol use, frequently in combination with cigarette smoking.
Diets high in fruits, vegetables, and fiber may reduce the incidence of some types of cancers. Regular screening and self-exams can detect cancers of the breast, tongue, mouth, colon, rectum, cervix, prostate, testis, and melanoma at an early stage, when treatment is more likely to be successful. These sites include over half of all new cases. Of these cases, about two-thirds of all patients currently survive five years. With early detection, about 95% would survive. This means that of those persons diagnosed with these cancers in 1996, about 115,000 more would survive if their cancers had been detected in a localized stage and treated promptly.
- How is a person's cancer treated?
By surgery, radiation, radioactive substances, chemicals, hormones, and immunotherapy.
- Who gets cancer?
Anyone. Since incidence rises with age, most cases affect adults in mid-life or older. Among children ages 0-14, cancer causes more deaths in the US than any other disease. In the 1980s, there were over 4.5 million cancer deaths, almost 9 million new cancer cases, and some 12 million people under medical care for cancer.
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. As another example, women who have a first-degree (mother, sister, or daughter) family history of breast cancer have about a 2-fold 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 more likely to develop breast cancer (or have a 100% increased risk) than women who do not have a family history.
- How many people alive today have ever had cancer?
It is estimated that over 10 million Americans alive today have a history of cancer, 7 million diagnosed five or more years ago. Most of these 7 million can be considered cured, while others still have evidence of cancer. "Cured" means that a patient has no evidence of disease and has the same life expectancy as a person who never had cancer.
- How many new cases will there be this year?
About 1,359,150 new cancer cases will be diagnosed. This estimate does not include carcinoma in situ and basal and squamous cell skin cancers. The incidence of these skin cancers is estimated to be over 800,000 cases annually.
- How many people will die?
This year about 554,740 will die of cancer_more than 1,500 people a day. One of every four deaths in the US is from cancer.
- What is the national cancer death rate?
There has been a steady rise in the cancer mortality rate in the US in the past half-century. The age-adjusted rate in 1930 was 143 per 100,000 population. It rose to 157 in 1950, to 163 in 1970, and was 172 in 1992. The major cause of this increase has been lung cancer. Death rates for many major cancer sites have leveled off or declined over the past 60 years (see page 5). When lung cancer deaths were excluded, cancer mortality declined 15% between 1950 and 1991.
- How many people are surviving cancer?
In the early 1900s, few cancer patients had any hope of long-term survival. In the 1930s, less than one in five was alive five years after treatment. In the 1940s, it was one in four, and in the 1960s, it was one in three. About 544,000 Americans, or 4 of 10 patients who get cancer this year, will be alive 5 years after diagnosis. The gain from 1 in 3 in the 1960s to 4 in 10 now represents over 91,000 persons each year.
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 56% is seen for all cancers. Five-year relative survival rates are commonly used to monitor progress in early detection and treatment of cancer and include persons who are living five years after diagnosis, whether in remission, disease-free, or under treatment. While these rates are reasonable indicators of the average survival experience of cancer patients in a given population, they are less informative when used to predict individual prognosis. Survival rates should be interpreted with caution. First, the rates are based on patients whose treatment was state-of-the-art at least 8 years ago. Second, it is often difficult to determine the reason for an increase or decrease in survival because the rates are influenced by several factors, including changes in early detection techniques and in treatment strategies.
- What is the difference between in situ and invasive cancer?
In situ cancers are early localized tumors. Traditionally, in situ cancers are counted separately from invasive cancers because it is not certain they will become invasive. Also, the reporting of in situ cancers is not as reliable as it is for invasive cancers. For example, a physician may remove a patient's in situ skin cancer in his/her office and it won't be reported the same as cancers removed in a hospital.






[E-Mail | Guest Book | Return | More Info]