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Cancer: The Facts

By Steven Parker | Cancer | Rating:

Introduction

Cancer is the second leading cause of death in the United States behind heart disease. Provisional mortality figures show that in 1984, 452,470 persons died from cancer in the U.S. According to the American Cancer Society, this figure will rise to 472,000 in 1986. This means that 1,293 people die of cancer each day in the U.S., or about one every 67 seconds. An estimated 930,000 persons in the U.S. will be diagnosed as having cancer in 1986. According to present rates, about 30% of Americans eventually will develop cancer.

Cancer is a disease characterized by the unrestricted proliferation of abnormal cells. Unrestrained growth of abnormal cells may result in a mass, or tumor, that compresses, invades and/or destroys neighboring normal tissue. When the proliferating cells invade surrounding tissue the cancer is considered malignant. Cancer cells may be shed into and carried by the blood or lymphatic vessels to distant sites where they can establish secondary colonies called metastases.

The mechanisms through which a normal cell becomes a cancerous cell are only partially understood. Agents such as chemicals, radiation and viruses can initiate cancer; hormonal, environmental, nutritional and genetic factors can also promote cancer. Promoters facilitate the process of carcinogenesis among cells where initiation has already taken place. Another mechanism of cancer transformation involves oncogenes, segments of genetic material that apparently exist in the chromosomes of every human cell. When triggered by point mutation, translocation, other oncogene products or unknown mechanisms, oncogenes can transform normal cells into cancer cells. In 1980 a retrovirus was isolated that appears to cause adult T-cell leukemia.

The virus, human T-cell leukemia/lymphoma virus (HTLV), is detectable in 90%-100% of patients with adult T-cell leukemia.

New technological advances and biochemical techniques allow scientists to investigate the mechanisms of human carcinogenesis and to characterize exposure to carcinogens, susceptibility to cell transformation and molecular responses to carcinogens. This new field of biochemical or molecular epidemiology opens opportunities to identify individuals at high cancer risk prior to the onset of clinically evident cancer.

Incidence and Prevalence

Incidence

[Data on cancer incidence are collected by the National Cancer Institute's Surveillance, Epidemiology and End Results (SEER) program. Since 1973, the SEER program has collected data on cancer incidence and survival from 11 population-based registries representing about 12% of the U.S. population. The latest available data from the SEER program cover the 10-year period from 1974 through 1983. Cancer incidence estimates for 1986 by the American Cancer Society are based on projections from SEER data.]

All Sites

The American Cancer Society estimates that in 1986, 930,000 new cases of cancer will be diagnosed in the U.S. This figure excludes an estimated 400,000 cases of nonmelanoma skin cancer, 45,000 cases of carcinomain-situ of the cervix and 5,000 cases of carcinoma-in-situ of the female breast.

The five major cancer sites by estimated incidence for 1986 are the lung, 149,000 new cases; colon-rectum, 140,000 new cases; breast, 123,900; prostate, 90,000 and bladder, 40,500. In addition, 25,600 new cases of leukemia and 44,500 new cases of other blood and lymphatic cancers are expected to develop in 1986.

From 1974 to 1983 the incidence rates for cancer from all sites combined increased more rapidly for males than for females and more rapidly for Blacks than for whites.

In 1983, the highest specific cancer incidence rate for any race and sex group was for prostate cancer among Black males, at 126.9 cases per 100,000 population. Lung cancer among Black males had the second highest rate, with 125.3 cases per 100,000. Breast cancer among white females ranked third with 92.1 cases per 100,000 population.

Lung Cancer

Lung cancer is the most common cancer in the United States with an estimated 149,000 new cases in 1986.

The incidence rate of lung cancer among white females increased from 19.7 per 100,000 population in 1974 to 33.5 per 100,000 in 1983, representing an average annual increase of 5.7% and a total increase of 60.9%. This was the largest increase in cancer incidence among any race and sex group for any major cancer in that decade.

Black females had the second largest increase in the incidence rate of a major cancer, with lung cancer increasing from 21.3 cases per 100,000 in 1974 to 33.9 cases per 100,000 in 1983, a 5.2% annual average increase and a 54.3% total increase.

Black males have the highest lung cancer incidence rate for any race and sex group, with 125.3 cases per 100,000. From 1974 to 1983, lung cancer incidence rates for Black males increased at an annual average rate of 2.8% for a total increase of 23.6%.

From 1982 to 1983, the incidence rate of lung cancer among white males decreased from 82.7 per 100,000 population to 79.3 per 100,000. This 4.1% decrease was the first significant decrease in the incidence of lung cancer ever observed for any race and sex group in the U.S.

Colorectal Cancer

Among males, colorectal cancer is the third leading cause of cancer behind lung cancer and prostate cancer. In 1983, there were 58.3 colorectal cancers per 100,000 white males and 58.7 per 100,000 for Black males. From 1974 through 1983, the incidence of colorectal cancer has increased a total of 4.8% for white males and 22.8% for Black males.

Among females, colorectal cancer is the second leading cause of cancer, with an incidence rate of 42.6 per 100,000 white females and 46.6 per 100,000 Black females. From 1974 through 1983, colorectal cancer incidence rates have increased 1.1% for white women and 15.2% for Black women.

The American Cancer Society estimates there will be 140,000 new cases of colorectal cancer in 1986 (98,000 colon and 42,000 rectum), making colorectal cancer the second leading type of cancer in the U.S. (behind lung cancer).

Breast Cancer

The 1983 age-adjusted breast cancer incidence rate for white females was 92.1 cases per 100,000, while the rate for Black females was 81.8 per 100,000. The incidence of female breast cancer appears to be slowly increasing, although comparisons to previous years may be misleading due to a dramatic increase in incidence after disclosure of breast cancer among prominent women in 1974, followed by a decrease in incidence in subsequent years.

In 1986, an estimated 123,000 new cases of breast cancer will occur in the U.S. According to the American Cancer Society, 1 out of 11 women will develop breast cancer at some time during her life.

At the time of first diagnosis, 50% of breast cancers are detected as local disease, 40% as regional disease and 10% as distant disease.

Prostate Cancer

In 1986, 90,000 new cases of prostate cancer are expected to occur, ranking prostate cancer as the second leading type of cancer among males behind lung cancer.

About 80% of prostate cancers are diagnosed in men over the age of 65. 8.7% of white males and 9.4% of Black males born in 1985 may be expected to develop prostate cancer.

Since the early 1970s, the incidence of prostate cancer has increased about 2.2% per year for both Black and white men. The 1983 prostate cancer incidence rate for Black men was 126.9 cases per 100,000, over 50% higher than the rate of 80.3 per 100,000 for white men.

Uterine Cancer

Incidence rates of endometrial uterine cancer peaked in 1975 at 33.3 cases per 100,000 for white women and 16.9 for Black women, then decreased to 24.0 and 14.9, respectively, in 1983.

From 1974 to 1983, the incidence of cancer of the cervix declined more than any other type of cancer among women, dropping 30.8% for white women to 7.9 cases per 100,000 and dropping 38.4% to 14.2 cases per 100,000 for Black women.

The American Cancer Society estimates that in 1986, 50,000 new invasive cases of uterine cancer will occur, including 14,000 cases of cancer of the cervix and 36,000 cases of cancer of the endometrium.

Leukemia

In 1986, an estimated 25,600 new cases of leukemia will occur, about half of which will be acute and half chronic. Acute leukemia accounts for 80% of the 2,000 cases in children. The most common leukemias among adults are chronic lymphocytic leukemia, accounting for 40% of leukemia cases, and acute granulocytic leukemia, with 33% of all cases.

Between 1974 and 1983, slight decreases (about 1% per year) occurred in leukemia incidence rates for all race and sex groups. In 1983 leukemia incidence rates (per 100,000 population) were 12.5 for white males, 7.1 for white females, 11.0 for Black males and 6.7 for Black females.

Childhood Cancers

Childhood cancer incidence rates have remained stable from 1974 to 1983. For whites aged 0-14 those incidence rates (per 100,000 population) were reported for 1983 as follows: acute lymphocytic leukemia, 2.8; cancer of the brain and nervous system, 2.3; bone cancer, 0.8; Hodgkins disease, 0.8; non-Hodgkins lymphoma, 0.9; kidney cancer, 1.0 and cancer of the soft tissues, 0.9.

Mortality

[Cancer mortality figures are based on data from the entire United States collected by the National Center for Health Statistics.]

All Sites

Provisional figures for 1984 indicate that there were 452,470 deaths from cancer in the U.S., for a cancer mortality rate of 191.6 per 100,000 population. Final statistics for 1983 showed 440,620 cancer deaths and a rate of 188.3 deaths per 100,000 population.

Cancer was the second leading cause of death in the U.S. in 1984, accounting for 22.1% of all deaths, second only to heart disease.

Among white males in 1983, there were 211.7 cancer deaths per 100,000. The leading cause of death from cancer among white males in 1983 was lung cancer with 71.2 deaths per 100,000, accounting for one third of all cancer deaths in white males.

Among Black males in 1983, there were 300.5 cancer deaths per 100,000. Almost one third of those deaths resulted from lung cancer (97.3 deaths per 100,000), with prostate cancer ranking as the second most likely cause of death from cancer (46.1 deaths per 100,000) in this group.

There were 135.4 cancer deaths per 100,000 white females in 1983. Cancer of the breast accounted for 26.8 deaths per 100,000, followed by lung cancer with 24.5 deaths per 100,000. In 1983, Black females had 158.5 cancer deaths per 100,000, with breast cancer causing 27.8 deaths per 100,000, followed closely by lung cancer at 24.8 deaths per 100,000.

From 1974 to 1983, mortality rates for all cancers combined increased a total of 3.9% for white males and 4.2% for white females. The corresponding increase for Black males was 14.1%, and for Black females, 8.1%.

The largest declines in cancer mortality rates among white males from 1974-1983 were for testicular cancer ( 49.7%) and Hodgkin's disease ( 48.5%). The largest increases in cancer mortality rates for white males were for malignant melanoma ( + 23.7%) and multiple myeloma ( + 13.5%).

For white females, the largest declines in cancer mortality rates from 1974-1983 were in Hodgkin's disease ( 36.0%) and cancer of the cervix ( 30.6%); the largest increases were for lung cancer ( + 61.1%) and cancer of the larynx ( + 25.0%).

Among Black males, the largest decline in cancer mortality rates from 1974-1983 was for Hodgkin's disease ( 41.4%), while the largest increases were in multiple myeloma ( + 28.5%), lung cancer ( + 23.8%) and cancer of the mouth and pharynx ( + 23.5%).

The largest decline in cancer mortality rates for Black women from 1974-1983 occurred in uterine cervical cancer ( 29.1%) and Hodgkin's disease ( 21.4%); the largest increases were for lung cancer ( + 64.4%) and multiple myeloma ( + 28.2%).

Lung Cancer Mortality

Lung cancer is the leading cause of cancer deaths in the United States, with 130,100 lung cancer deaths expected in 1986, including 89,000 males and 41,100 females.

In 1983, malignant neoplasms of the respiratory and intrathoracic organs caused 119,962 deaths, or 27.1% of all cancer deaths.

The mortality rate from lung cancer among white males has been stable since 1980, with a rate of 71.2 deaths per 100,000 in 1983.

Black males have the highest lung cancer mortality rate of any race and sex group at 97.3 deaths per 100,000. However, from 1982 to 1983, for the first time, there was a decrease in the lung cancer mortality rate for Black males from 97.5 to 97.3.

Lung cancer mortality rates among both Black and white females are increasing faster than for any other cancer. From 1974 to 1983, lung cancer among white females increased 61.1% to 24.5 deaths per 100,000. Among Black females, the increase was 64.4% to 24.8 deaths per 100,000. Preliminary projections indicate that in 1986 lung cancer became the leading cause of cancer death among women, surpassing breast cancer, which for over 50 years was the leading cause of cancer death among women.

Colorectal Cancer Mortality

Colorectal cancer is the second leading cause of cancer deaths in the U.S., with an estimated 60,000 deaths in 1986 (51,800 colon cancer deaths and 8,200 rectum cancer deaths).

Over the 10-year period from 1974 to 1983, colorectal cancer mortality rates declined for white males 1.8% to 25.4 deaths per 100,000, and for white females, 9.3% to 17.5 deaths per 100,000.

Colorectal cancer mortality rates increased from 1974 to 1983 for Black males by 10.2% to 25.8 deaths per 100,000, and increased for Black females by 4.7% to 202 deaths per 100,000.

Breast Cancer Mortality

A total of 38,247 people (37,979 females, 268 males) died from breast cancer in 1983 in the U.S. Projected figures for 1986 indicate 40,200 deaths from breast cancer (39,900 females and 300 males).

In 1983, breast cancer was the leading cause of death from cancer for women, with 37,979 deaths compared to 35,797 deaths from respiratory cancers. It is estimated, however, that in 1986 lung cancer will become the leading cause of death from cancer for women, with 41,100 deaths as compared to 39,900 deaths from breast cancer.

Mortality rates for white women with breast cancer have remained stable from 1974 to 1983 at 26.8 deaths per 100,000. For Black women, breast cancer mortality rates increased 0.9% per year to 27.8 deaths per 100,000 in 1983.

Childhood Cancer Mortality

An estimated 2,175 deaths from childhood cancer will occur in 1986 in the U.S. Despite its rarity, cancer is the chief cause of death by disease among children between 3 and 14 years of age.

Childhood cancer mortality rates have dropped from 8.3 per 100,000 in 1950 to 4.1 in 1983. Mortality rates (per 100,000 population) in 1983 for the major childhood cancers (ages 0-14 years) and the percent change over the 10 years up to 1983 are: acute lymphocytic leukemia, 0.9 ( 30.4%); brain and nervous system, 0.9 ( 6.3%); bone, 02 ( 19.6%); Hodgkin's disease, 0.0 ( 66.7%); non-Hodgkin's lymphoma, 0.3 ( 26.9%); kidney, 0.1 ( 25.7%) and soft tissue cancers, 02 ( 62.6%).

Risk Factor Prevalence

Smoking

According to the American Cancer Society, cigarette smoking is responsible for 83% of all lung cancers. Smoking accounts for about 30% of all cancer deaths. Those who smoke two or more packs of cigarettes a day have lung cancer mortality rates 15 to 25 times greater than nonsmokers.

Among males in the U.S., use of tobacco is responsible for about 90% of all lung cancer, 75% of all neoplasms of the mouth, pharynx, larynx, and esophagus, about 50% of bladder cancer and probably 40% of pancreatic cancers.

Among females in the U.S., tobacco use is responsible for about 75% of the lung cancers, 40% of neoplasms of the mouth, pharynx, larynx and esophagus, 30% of bladder cancers and 25% of cancers of the pancreas.

In 1983, 35.4% of all males 20 years and older and 29.9% of all females 20 years and older were current smokers (having smoked at least 100 cigarettes and currently smoking, including occasional smokers). In 1983, 76.5% of male smokers and 61.8% of female smokers smoked 15 or more cigarettes per day.

In a 1985 National Health Interview survey, 95% of respondents knew that smoking increases the risk of lung cancer, 80% knew that smoking increases the risk of cancer of the esophagus and 35% were aware that smoking increases the risk of bladder cancer.

Per capita cigarette consumption among adults (20 years and older) in the U.S. has fallen from 4,141 in 1974 to 3,384 in 1985. This is the lowest per capita cigarette consumption since 1944 and reflects a growing number of nonsmokers.

Adult smokers (20 years and older) consuming 25 or more cigarettes per day increased from 31% to 34.1% between 1976 and 1980, and female smokers from 19.6% to 23.7%.

Diet

Cancer experts have estimated that 35% of cancer risk is related to diet.

Both epidemiological and laboratory studies have shown a correlation between dietary fat intake and the incidence of cancer of the breast, colon, prostate and endometrium.

Epidemiological studies show an inverse correlation between dietary fiber intake and the incidence of cancer of the breast and colon.

Individuals overweight by 40% or more have an increased risk of colon, breast, prostate, gallbladder, ovarian and uterine cancers.

It is estimated that 20% of cancers of the breast and colon/rectum are attributable to diet and amenable to intervention.

The 1976-80 National Health and Nutrition Examination Survey (NHANES II) revealed that 28.4% of Americans age 25-74 years were overweight (having a body mass index greater than the sex-specific 85th percentiles for persons 20-29 years).

According to NHANES II, the percent of persons 25-74 years old who were overweight included 49.5% of Black females, 29.9% of Black males, 27.5% of white females and 26.7% of white males.

Alcohol

Approximately 4% of all male cancer deaths and 2% of all female cancer deaths can be attributed to alcohol use.

Among U.S. males, alcohol consumption contributes to nearly 50% of deaths due to oral and laryngeal cancer, 75% of esophageal cancer deaths and 30% of fatal liver cancers.

In 1983, 37% of Americans 18 years of age and over abstained from alcohol, 31% were light drinkers (.01-.21 ounces of ethanol per day), 22% were moderate drinkers (.22-.99 ounces and 10% were heavy drinkers (1.00 ounce or more per day).

Other Risk Factors

The relationship between exogenous estrogens and uterine cancer was understood in the late 1960s and early 1970s. Partly as a result of the decline in the use of exogenous estrogens, the incidence rates of uterine cancer fell 25.6% for white women and 3.3% for Black women over the 10 years from 1974 to 1983.

About 5% of cancers may be attributable to known occupational exposures to carcinogens.

Approximately 1% of cancers can be attributed to exposure to ionizing radiation besides natural background radiation. Most of the nonbackground radiation exposure comes from medical diagnostic and therapeutic X-rays.

Both DNA and RNA viruses have been shown to cause a variety of neoplasms in animals. In humans, the Epstein-Barr virus is thought to be causally associated with Burkitts' lymphoma, the human T-cell lymphoma virus (HTLV) with adult T-cell lymphoma (ATL) and the papilloma virus with anogenital neoplasms particularly cervical carcinoma.

There is evidence that sexual behavior influences one's risk of developing cervical cancer: onset of coitus prior to age 17 results in a 2.50 increased relative risk of cervical cancer; two or more sexual partners results in a 2.76 increased relative risk and a study of 13,000 nuns over a 20-year period revealed a complete absence of cancer of the cervix.

Intervention Data

Cancer Survival Rates

Notable increases in five-year survival rates for cancer occurred from 1973-76 to 1977-82 for cancers of the testis, prostate, urinary bladder and colon, and for Hodgkin's disease and leukemia. There was no change in the survival rate for female breast cancer from 1973-1982, and there was a slight increase in survival for lung cancer.

Lung Cancer Survival

13% of lung cancer patients (all stages, whites and Blacks) live five or more years after diagnosis. The survival rate at five years is 41% for those whose lung cancer is detected in a localized stage, but just 20% of lung cancers are discovered that early.

Colorectal Cancer Survival

When detected and treated in an early localized state, the five-year survival rate is 90% for colon cancer and 80% for rectal cancer, compared to 51% and 38%, respectively, after distant spread of the cancer.

Breast Cancer Survival

The five-year survival rate for localized breast cancer has risen from 78% in the 1940s to 91% currently. If the breast cancer has already spread beyond local disease at the time of diagnosis, the five-year survival rate drops to 59%.

Cancer Screening

It is estimated that 30% of breast cancer deaths and 10% of cervical cancer deaths might be averted by appropriate screening.

In a 1985 National Health Interview Survey (NHIS), 62% of American women 18 years and older stated they had had a Pap smear test within one year or less. However, 20% of American women aged 30-44 had not had a Pap smear test for three or more years.

67% of American women 18 years and older stated that they had had a breast examination by a doctor or other health professional within the past one year or less in the 1985 NHIS study. However, 12% of women 18 years and older stated that they do not know how to examine their breasts, and an additional 14% stated they have never examined their breasts.

The effect of mass publicity on cancer awareness and subsequent detection was shown in 1974 following the public disclosures of the cancer diagnoses of Mrs. Ford and Mrs. Rockefeller, the wives of the President and Vice-President of the U.S. The incidence of female breast cancer increased by 14% from 1973 to 1974. Preliminary analyses indicate that those with breast cancer diagnosed in late 1974 had a survival rate about 3% higher than those diagnosed in early 1974, probably as a result of earlier detection.

Cancer Expenditures

The estimated total funding of cancer-related activities in the U.S. for 1984 included $1.08 billion from the National Cancer Institute (NCI), $165.9 million from the National Institutes of Health (other than NCI), $113.0 million from other Federal agencies, $189.3 million from state governments, $220.8 million from nonprofit organizations, $3.0 million from labor and $300.0 million from industry for a total of $2,073,587,000.

The budget of the National Cancer Institute for 1984 was over $1 billion ($1,081,581,000), including $896.2 million for research programs, $66.0 million for cancer control and $119.5 million for resource development. The NCI budget for 1986 was projected at $1.46 billion.





Steven Parker

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