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Cancer is a varied group of diseases that have in common the uncontrolled proliferation and spread of abnormal cells, which may invade other tissues of the body. The different types of cancer vary not only in their site or tissue of origin, but also in other factors including cell morphology, rate of growth, and method of spread. Through February 7, 2005, the Indiana State Cancer Registry has recorded 144,930 cases of cancer that were newly diagnosed from January 1, 1997 through December 31, 2001. (Note: basal and squamous cell carcinomas of skin are not reported.) The incidence tables include 137,182 cancers, which includes 2,419 cases of in situ bladder cancer. All other in situ cancers (n = 7,748 are excluded from the incidence tables. The exclusion of in situ cases allows comparisons with national data and is based on the major differences in prognosis and treatment between in situ and invasive cancers. Interpreting the pathologist's description of invasion for urinary bladder tumors has proven difficult for coders and, since patients generally receive the same treatment for in situ and microinvasive tumors, in situ bladder tumors have traditionally been included in incidence rates.
During the 5 year period (1997 - 2001) there were 63,265 cancer deaths of Indiana residents. Cancer incidence is a more accurate measure of the occurrence of cancer than cancer mortality because of the increasing survival and even cure for many cancer sites. Cancer incidence also is of greater value in the investigation of external risk factors for cancer, because the date of diagnosis occurs closer in time to the exposure which may have initiated or promoted the development of cancer. Cancer mortality is of greater importance in identifying potential disparities in screening and treatment.
Cancer incidence increases with age, though cancer can occur in infants as well as the elderly. Section 3 presents age-specific incidence rates (Tables 3.1-5 to3.6-5) and age-specific mortality rates (Tables 3.1-6 to 3.6-6) for all invasive cancers (all sites) and for female breast, cervical, colon, lung, and prostate cancers. During 1997 - 2001, there were 689 new cases of invasive cancer in children less than 10 and an additional 697 cases in those ages 10 - 19. Only 1.0% of cancers occurred in children, whereas 58.0% occurred in those ages 65 and over. Those 70-74 years of age had the largest number of new diagnoses (20,944). The lowest incidence rate* for invasive cancer was in children ages 5-9 (10.8 per 100,000). The incidence rates increased steadily with age to a high of 2,364.1 for those 75-79 and then declined slightly for the population 80 and older.
Cancer mortality also increases with age. During the 5-year period from 1997 - 2001, there were 117 deaths from cancer in children under age 10, and 134 cancer deaths in children ages 10 - 19. Only 0.4% of the total cancer deaths were of children (0 - 19 years of age). In contrast, 70.8% of the cancer deaths were of adults age 65 or older. Adults ages 75-79 had the largest number of deaths (10,278) for the 5-year period. The lowest cancer mortality rate was for 10-14 year-old children (2.4 per 100,000). Mortality rates increased with age to 1,858.9 per 100,000 for those ages 85 and above.
Nationwide African-Americans have a higher risk of cancer than does the white population. For 1997 - 2001, the all-sites cancer incidence rate for Indiana's black population was higher than the rate for the white population (503.6 vs. 462.4), a difference that is statistically significant. The lung cancer incidence rate was significantly higher in African-Americans than in whites (90.8 vs. 78.1), and the incidence rate for prostate cancer was 66.6% higher for black males in Indiana than for white males (216.3 vs. 129.9). In addition, blacks are more likely to be diagnosed at a later stage than are whites, leading to a prostate cancer mortality rate for blacks (78.2) that is 147.4% higher than the rate for whites (31.6).
In general, men are more likely to be diagnosed with cancer than are women. The Indiana 1997 - 2001 cancer incidence rate was 30.8% higher for men than for women (546.5 vs. 417.8). Women have a longer lifespan than men, hence there are more elderly women than men in the population. Since cancer incidence increases with age, more women than men may be diagnosed with cancer. This was the case in Indiana for 1995 - 1999 and 1996 - 2000. However, in Indiana male incidence rates have increased to a greater extent than have female incidence rates, so that during 1997 - 2001 there were slightly more men than women diagnosed with cancer (68,679 vs. 68,502). Besides breast cancer, there are a few other cancers that occur more frequently in women. For example, the rate of thyroid cancer in Indiana females is 2.7 times that of males (8.6 vs. 3.2).
The disparity between the 1997 - 2001 Indiana male cancer mortality rate (277.6) and the female mortality rate (177.5) was 56.4%. Despite the larger population of elderly women, more men died of cancer (32,953) than did women (30,312). A small portion of this disparity might be explained by men being slightly more likely to be diagnosed at a later stage of cancer than are women (Section 3.1, Table 3.1-7). In addition, men are more likely to be current or former smokers than are women (56% of men vs. 44.2% of women, Indiana Health Behavior Risk Factor Report 2001). The increased risk of cancer for smokers is important in the higher cancer incidence and mortality rates for men.
For 1997 - 2001, the most frequently diagnosed cancer in Indiana was lung cancer. The next most common cancer was breast cancer, followed by prostate, colon (excluding rectum), and urinary bladder cancers. Section 1 (Tables 1-3 to 1-6) lists the most commonly diagnosed cancers by sex. For men, the most frequently diagnosed cancer was prostate, followed by lung, colon, bladder, non-Hodgkin lymphoma , and rectum. For Indiana women, breast cancer was most commonly diagnosed, followed by lung, colon, uterine body, non-Hodgkin lymphoma, and ovarian cancers.
For both men and women, mortality from lung cancer (19,321 deaths, 11,557 for men and 7,762 for women, in Indiana during 1997 - 2001) was greater than that from either prostate (3,522 deaths) or breast cancer (4,677 deaths). Colon cancer (5,818 deaths) was the second leading cause of cancer death for the total Indiana population.
The 1997 - 2001 lung cancer incidence rate for Indiana (78.9) was significantly higher than the national rate (64.8). See Section 1. In particular, the Indiana male lung cancer incidence rate (109.3) was 31.1% higher than that of the US (83.4). The lung cancer mortality rates for Indiana were also higher than the national rates, though not by as high a percentage as the incidence rates. The prostate cancer incidence rate for Indiana for 1997 - 2001 (135.9) was significantly lower than the US rate (175.5). Whereas, the prostate cancer mortality rate for Indiana (34.1) was higher than that of the US (31.5). These differences suggest that there is less screening for prostate cancer in Indiana than in the rest of the US. A similar, though less dramatic, pattern is seen for female breast cancer, where mortality can be reduced by early detection through screening.
Illness and death from cancer are increasingly preventable by decreasing modifiable risk factors, increasing early detection through improved screening, and developing more effective treatments. Current estimates indicate that at least 75% and perhaps more than 90% of cancers are due to factors external to the patient, i.e., factors other than the patient's heredity, endogenous hormones, and immunologic status. More than two-thirds of these external or "environmental" factors are associated with personal lifestyle and behavior. Tobacco use accounts for approximately 30% of US cancer deaths. Numerous scientific studies have shown that involuntary exposure of nonsmokers to environmental tobacco smoke increases their risk of lung cancer and other illnesses. Another estimated 30% of cancer deaths can be attributed to dietary factors, particularly those associated with obesity, such as high dietary saturated fat and low consumption of fruits and vegetables. An estimated 5% of cancer deaths are associated with low physical activity, and an additional 3% - 7% with personal choices in the areas of sexual contacts, and childbearing.
Section 3 compares Indiana State incidence and mortality rates for all sites and for the most common cancers with the rates for ten groups of counties (regions, see maps). Section 5 presents information on both incidence and mortality rates and counts by county. In Indiana with its numerous small counties (especially in the case of less common cancers), there are often many counties with only a few or no cases of a specific cancer type. To avoid compromising the confidentiality of individuals in those counties, the actual number of cases for a county is not reported if it is less than 5, and in cases where the number for any one sex is less than 5, the number for the opposite sex is not reported either. Rates based on less than 20 total cases are very unstable and can be misleading; hence, no comparison with the state should be made when there are fewer than 20 cases in a county, and those rates are flagged in Section 5. Aggregating several years of cancer data, in many cases, provides meaningful information on rates in small counties and/or for less common cancers. Appendix B (Technical Notes) gives information on rates, confidence intervals, and how to interpret them.
* In general, incidence rates are the number of new cases per 100,000 persons in the population per year and, except for age-specific rates, are age-adjusted to the 2000 US standard million population. See Appendix B. Age-specific incidence rates are the number of new cases occurring in persons of a specified age per 100,000 persons of that age in the population.
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