Cancer and Its Impact on Texas: Basic Facts and Questions
Updated March, 1998

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?

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 tat 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 survival rate for these cancers is about 80%. If all Americans participated in regular cancer screenings, this rate could increase to more than 95%.

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, and immunotherapy. 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. 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 as 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?

Over eight million Americans alive today have a history of cancer. Some 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 1,228,600 new cancer cases will be diagnosed, with 77,500 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 over 1 million cases this year.

How many people will die?

This year about 564,800 Americans will die of cancer, more than 1,500 a day. In Texas, 35,600 people will die of cancer this year, more than 97 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?

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.

What is the Texas mortality rate?

The average annual age-adjusted mortality rate for 1984-1996, was 169.09 per 100,000, with approximately one in every three deaths attributed to lung cancer. Between 1984 and 1996, 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. About 491,400 Americans, or four of 10 patients who get cancer this year, are expected to be alive five years after diagnosis.

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 58 percent is seen for all cancers. The relative survival rate is commonly used to measure progress in the early detection and treatment of cancer and include persons who are living five years after diagnosis, whether in remission, disease free, or under treatment.

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.

Source: American Cancer Society, Cancer Facts & Figures 1998
and Cancer Net, National Cancer Institute, March, 1993