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Nuclink: Journal of Current Radiation and Public Health Issues Volume 1, Number 4 THE CURRENT CANCER EPIDEMIC AND THE BABY BOOM GENERATION (continuted) By
Jay M. Gould, Director BABY
BOOMERS
AND CANCER INCIDENCE
IN CONNECTICUT, 1980-2000
(CONTINUED) All age groups shared in the extraordinary increase observed from 1985 to 1992. But thereafter, the youngest group--age 45 to 64--continued to increase. Older men registered declines in diagnoses in the years when the immediate effects of Chernobyl fallout were wearing off. Figure 10 indicates how much higher than expected were the observed number of cases after 1985 associated with Chernobyl fallout arriving in May 1986. By 1992 there would have been only 1300 cases if there had been no change from the 1980 age-specific rates for each age group. This is less than half of the observed number. This is a similar to Figure 4 which shows that in 1992 there had been a peak level of 2600 breast cancers diagnosed, as against the projected number of about 1900 if there had been no change in the incidence rates for each age group. Figure 11, like Figure 5, shows how the gap between the observed and projected overall incidence rate for prostate cancer among men older than 45 widened after 1985. The rise from 1985 and decline after 1992 is much sharper than in the case of breast cancer The other notable difference between Figure 11 and Figure 5 is that the projected prostate cancer rate is seen to rise steadily since 1980, whereas the projected breast cancer overall incidence rate declines steadily. The annual change in the projected rates have nothing to do with Chernobyl fallout but merely reflects the changing age composition as female baby boomers reach the age of 35 in 1980 and male baby boomers reach the age of 45 in 1990. Figure 12 records the annual change since 1980 in the observed prostate cancer incidence rate for young men aged 45 to 60. Despite a sharp rise after 1990, when Connecticut baby boomer men reached the age of 45 in 1990, the incidence rate for older men is seen to be nearly six times greater in 1992, and almost five times greater in 1995. Thus the early emergence of prostate cancer among baby boomer men in the 1990s has little effect on the overall incidence rate, because its incidence rate is so low. In Figure 13, as in Figure 8, we project the annual change in the total number of prostate cancer cases for the period 1996-2000, by assuming that each five year age group would register the same annual percent change achieved in the period 1991-1995 over the preceding five year period. But Figure 13 shows a much sharper rise after 1995 than the projected change in breast cancer incidence shown in Figure 8. This is the same epidemiological puzzle posed by Figure 3. From 1935 to 1990 the breast cancer incidence rate far exceeded the corresponding prostate cancer incidence rate, but this relationship was abruptly reversed in the 1990s. The answer to this epidemiological puzzle is that the latency period for prostate cancer is about 20 years longer than that for breast cancer. While baby boomer women first began to be diagnosed with breast cancer at the early age of 35 in the 1980s, the corresponding increase for baby boomer men will begin in the year 2000 when they reach the age of 55. This age group will then begin to dominate the ranks of prostate cancer victims. In the next century the increase in prostate cancer will continue and surpass the peak levels reached by the AIDS epidemic that began in 1980. The observed trends in the Connecticut breast and prostate cancer incidence in the 15 year period 1980-1995 have enabled us to discern that two different epidemiological anomalies were in operation in these years, which must be analyzed separately if we want to understand what to expect in the future. Here is the logic underlying the hypothesis we have just presented to support our contention that the decline in incidence observed in the years 1990-99 cannot long continue. The first anomaly is the upsurge in incidence among all age groups, old and young, in the decade 1980-1990. We associate much of this upsurge with two (hopefully singular) environmental disasters--- the Three Mile Island accident of 1979 and the arrival of Chernobyl radiation in 1986. We have demonstrated elsewhere that the very young in Connecticut, who are most vulnerable to the adverse effects of low-level radiation, did record extremely significant increases in childhood cancer incidence in the aftermath of the arrival of Chernobyl radiation. It is evident from the evidence above that old people too are extremely vulnerable to the immediate adverse effects of a sudden large-scale environmental insult like Chernobyl. The incidence of both breast and prostate cancer among the old rose more quickly than that of younger adults when exposed to Chernobyl fallout in the period 1986-1990. The incidence then declined quickly in the years 1990-95 when the immediate effects of Chernobyl were wearing off. The other important trend throughout this period was the increasing entry of baby boomers into the pool of adults old enough to be diagnosed with cancer. These baby boomers were diagnosed at an age much earlier than previous generations. We do not know to what degree such early diagnosis may have been accelerated by the Chernobyl radiation, but we do know that the incidence of breast and prostate cancer for younger persons continued to rise after 1990, even when the incidence for older persons declined. For example, for the years 1991 to 1995, young Connecticut women aged 35 to 49 registered annual increases over the previous five years of 1.2 percent in breast cancer incidence as contrasted to an 0.4 percent annual increase for women over 50. Thus, we can expect a continuation of a relative increased incidence among younger women after 1995. Similarly, younger men aged 45 to 64 registered a much higher average annual increase of 19.4 percent each year in the period 1991-1995 over the previous five year period, as compared with a smaller corresponding average annual increase for older men of 11.1 percent. Here too we would expect a continuation after 1995 in the increasing relative incidence of prostate cancer among younger men. In both cases, because by 1995 baby boomers are beginning to reach the age of 50, which represents an early age for contracting either breast or prostate cancer, we may ask what happens when baby boomers reach the ages of 65 and 75 in the next century, the ages at which the bulk of cancers emerge. We can answer such questions by turning to the national U.S. mortality data for breast and prostate cancer available for White and Black men and women since 1950. The Census Bureau has provided population projections to the year 2020 by 10 year age groups. For example, large numbers of persons born in 1945 will survive to 2020 (when they will reach the age of 75). At this age, incidence of cancer is much greater. Thus, the bulk of breast and prostate cancers in baby boomers will occur in the next century when they reach the older age-groups. Radiation-initiated cancer mortality of course works quite differently than incidence because of long latency periods, which could be as long as 35 years for breast cancer and 55 years for prostate cancer. However, large-scale exposure of cancer patients to low-level radiation might act as a promoter and accelerate the process of carcinogenesis: The patient might die sooner rather than later. We shall find when we contrast Black cancer mortality trends below with those of Whites that a greater degree of immune system impairment on the part of Blacks can be likened to accelerating the process of aging. Blacks tend to die much sooner than Whites of cancer. In the next section, we will analyze the currently available U.S. mortality data available for breast and prostate cancer beginning in 1950 for each of four cohorts: White and Black women over the age of 35, and White and Black men over the age of 45. In each case we will be testing our basic hypothesis advanced above that anomalous increases in mortality in the period 1979-90, associated at least in part with radioactive releases from Three Mile Island and Chernobyl, began to dissipate after 1990, permitting deaths among older persons to decline somewhat after 1990. However, deaths among younger persons, especially among baby boomers, increased steadily after 1990 and will continue to increase for many decades as the baby boomers reach the older ages at which the bulk of breast and prostate cancer deaths occur. One of the most interesting findings suggested by the future projections is that after 1995 increasing prostate and breast cancer deaths among baby boomer men and women will first cause a decline in the overall rate, but will turn into a rise in the next century as aging baby boomers reach the peak years in which cancer takes it toll. |
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