Cancer and Its Impact on Texas: Basic Facts and Questions
What is cancer?Cancer is a group of more than 100 different diseases. The common characteristics of all cancers are abnormal and rapid cell growth and the ability to spread to different areas of the body.
What causes cancer?
Cancer is caused by 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?
Many cases of cancer can be prevented because some external factors which cause cancer can be controlled. About 90 percent of the 800,000 skin cancers in the United States that will be diagnosed in 1995 could have been prevented by protection of the skin from the sun's rays. All cancers caused by cigarette smoking and heavy use of alcohol can be prevented completely. The American Cancer Society estimates that in 1995 about 170,000 lives will be lost to cancer because of tobacco use. About 18,000 cancer deaths will be related to excessive alcohol use that frequently occurs in combination with cigarette smoking.
Diets high in fruit, vegetables, and fiber may reduce the incidence of some types of cancer. Regular screening and self-exams can detect cancers of the breast, tongue, mouth, colon, rectum, cervix, prostate, testis, and skin at an early stage, when treatment is more likely to be successful. These sites include more than half of all new cases. Of these cases, about two thirds of all patients currently survive five years. With early detection, about 92 percent would survive. This means that of those persons in the United States diagnosed with these cancers in 1995, about 100,000 more would survive if their cancers had been detected in a localized state and treated promptly.
Have Texans changed their smoking behaviors?
Yes, smoking prevalence in adults has decreased from 31 percent to 21 percent; yet, this pattern is not reflected in the youngest age groups.
Are cancer detection resources being used by all Texans?
No. In Texas, 16 percent of Hispanic and African-American women have never had a Pap smear, a simple, painless test that can detect cervical cancer at an early stage; only two percent of White women have never had Pap smears. Accordingly, the cervical cancer mortality rate is highest in African-American and Hispanic women.
What do the terms incidence rates and mortality rates mean? Do they ever differ?
An incidence rate is calculated by dividing the number of new cases of a particular cancer during a given period of time by the number of people known to be at risk.
A mortality rate is calculated by dividing the number of people who have died of a particular cancer during a given period of time by the total population at risk.
Mortality rates and incidence rates are not necessarily predictive of each other. Comparison of mortality data in population groups or regions can suggest needs for improved screening, treatment accessibility, or education. Incidence rates reflect all cases that have occurred, not just those resulting in death, and help focus on early detection and prevention issues.
How is a person's cancer treated?
Cancer is treated with surgery, radiation therapy, chemotherapy, hormone therapy, or biological therapy. The doctor may use one method or a combination of methods. The choice of treatment depends on the type and location of the cancer, whether the disease has spread, the patient's age and general health, and other factors.
Who gets cancer?
Anyone. Because incidence rises with age, most cases affect adults in mid-life or older. Among children between the ages of one and 14, cancer causes more deaths in the United States than any other disease. In the 1980s, there were over 4.5 million cancer deaths, almost nine million new cancer cases, and some 12 million people under medical care for cancer.
How many people alive today have ever had cancer?
Over eight million Americans alive today have a history of cancer, five million diagnosed five or more years ago. Most of these five 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. One of every three Texans now living will develop cancer in his or her lifetime.
How many new cases will there be this year?
About 1,252,000 new cancer cases will be diagnosed, with 74,600 of those being from Texas. These estimates do not include carcinoma in situ and basal and squamous cell skin cancers. The incidence of these skin cancers in the United States is estimated to be more than 800,000 cases annually.
How many people will die?
This year about 547,000 Americans will die of cancer. Of the nearly 1,500 people who die each day in the United States, 300 deaths will be caused by cancer. In Texas, 33,100 people will die of cancer this year, more than 90 people each day. Cancer is the second leading cause of death among Texans, responsible for approximately one in four deaths.
What is the national cancer death rate?
There has been a steady rise in the cancer mortality rate in the United States in the last 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 to 174 in 1990. 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 50 years. If lung cancer deaths were excluded, cancer mortality would have declined 14 percent between 1950 and 1990.
What is the Texas mortality rate?
The average annual age-adjusted mortality rate for 1987-1993, was 166 per 100,000, with approximately one in every three deaths attributed to lung cancer. Between 1987 and 1993, age-specific mortality due to cancer was highest among African-Americans and lowest among Hispanic females, overall.
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 patients was alive five years after treatment. In the 1940s, it was one in three. About 500,000 Americans, or four of 10 patients who get cancer this year, will be alive five years after diagnosis. The gain from one in three in the 1960s to four in 10 now represents over 88,000 persons each year.
This four in 10, or about 40 percent is called the "observed " survival rate. When adjusted for normal life expectancy (taking into account other causes of death such as heart disease, accidents, and diseases of old age), a "relative" five-year survival rate of 54 percent is seen for all cancers. The relative survival rate is commonly used to measure progress in the early detection and treatment of cancer.
What is the difference between in situ and invasive cancer?
In situ cancers are small tumors restricted to one area of the body. Traditionally, in situ cancers are counted separately from invasive cancer because it is not certain they will become invasive. Also, the reporting of in situ cancer is not as reliable as it is for invasive cancers. For example, a physician may remove a patient's in situ skin cancer during an office visit, and the procedure will not be reported the same way a larger tumor would be if removed in a hospital.
and Cancer Net, National Cancer Institute, March , 1993
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