WEBVTT 1 00:00:00.540 --> 00:00:01.410 Hi, everyone. 2 00:00:01.410 --> 00:00:03.990 In today's lecture, we'll be discussing global trends 3 00:00:03.990 --> 00:00:05.793 in cancer morbidity and mortality. 4 00:00:06.630 --> 00:00:08.700 So the three goals of this lecture, 5 00:00:08.700 --> 00:00:10.560 to summarize global cancer trends, 6 00:00:10.560 --> 00:00:13.515 to draw comparisons between cancer rates in men and women, 7 00:00:13.515 --> 00:00:16.890 and between cancer in high-income countries 8 00:00:16.890 --> 00:00:20.190 and low and middle-income countries, or LMICs, 9 00:00:20.190 --> 00:00:23.160 and discuss the epidemiological transition of cancer 10 00:00:23.160 --> 00:00:26.580 and its implications for future cancer incidents. 11 00:00:26.580 --> 00:00:27.810 So to begin with, 12 00:00:27.810 --> 00:00:30.157 we're looking at figure 2.3 in the textbook 13 00:00:30.157 --> 00:00:32.850 "Global Cancer Trends: Cases and Deaths," 14 00:00:32.850 --> 00:00:34.860 and we see that the number of cases 15 00:00:34.860 --> 00:00:38.550 has increased from approximately 10 million in 2000 16 00:00:38.550 --> 00:00:41.700 to approximately 14 million in 2012. 17 00:00:41.700 --> 00:00:44.400 We also see that the number of deaths from cancer 18 00:00:44.400 --> 00:00:46.770 has increased from about 6 million in 2000 19 00:00:46.770 --> 00:00:51.548 to approximately 8 million in 2012. 20 00:00:51.548 --> 00:00:53.130 It's also important to realize 21 00:00:53.130 --> 00:00:56.160 that even though the raw numbers or the absolute numbers 22 00:00:56.160 --> 00:01:00.540 of cancer cases and deaths have increased, 23 00:01:00.540 --> 00:01:04.740 the cancer rates have actually decreased during that time 24 00:01:04.740 --> 00:01:08.040 because of an increase in population. 25 00:01:08.040 --> 00:01:10.557 So we can attribute a lot of this increase 26 00:01:10.557 --> 00:01:15.557 to the growth in aging of the world's population. 27 00:01:16.680 --> 00:01:18.840 We also see that life expectancy 28 00:01:18.840 --> 00:01:22.710 increased over this period from 68 to 71 years, 29 00:01:22.710 --> 00:01:24.420 and because the majority of cancers 30 00:01:24.420 --> 00:01:25.860 are diagnosed later in life, 31 00:01:25.860 --> 00:01:27.510 elderly populations are expected 32 00:01:27.510 --> 00:01:30.370 to have higher crude, or unadjusted rates, of cancer 33 00:01:31.380 --> 00:01:33.810 than young populations. 34 00:01:33.810 --> 00:01:36.150 Next, when we divide the trends 35 00:01:36.150 --> 00:01:38.790 in cancer mortality between men and women, 36 00:01:38.790 --> 00:01:39.690 as I noted before, 37 00:01:39.690 --> 00:01:43.080 we see that there's a slight decrease in mortality rates. 38 00:01:43.080 --> 00:01:45.430 So that is deaths per a hundred thousand people 39 00:01:46.560 --> 00:01:51.510 decreased for both men and women between 2000 and 2012. 40 00:01:51.510 --> 00:01:54.995 So we see, thus, that the age standardized rates of cancer 41 00:01:54.995 --> 00:01:58.620 show these decreasing rates of cancer mortality 42 00:01:58.620 --> 00:02:01.893 even though cancer incidence is slightly increasing. 43 00:02:03.300 --> 00:02:05.520 When we look at, as the textbook calls, 44 00:02:05.520 --> 00:02:07.020 developing or developed nations, 45 00:02:07.020 --> 00:02:09.840 or is going to refer to them as high-income countries 46 00:02:09.840 --> 00:02:12.103 and low and middle-income countries, 47 00:02:12.103 --> 00:02:16.380 we see that there's very different profiles 48 00:02:16.380 --> 00:02:19.590 of cancer mortality between these groups of countries. 49 00:02:19.590 --> 00:02:21.690 So among men living in developing nations, 50 00:02:21.690 --> 00:02:22.890 the total number of deaths 51 00:02:22.890 --> 00:02:24.810 due to either liver cancer or stomach cancer 52 00:02:24.810 --> 00:02:27.510 was four times higher than in developed nations, 53 00:02:27.510 --> 00:02:30.600 reflecting high rates of infection by liver viruses 54 00:02:30.600 --> 00:02:33.390 like hepatitis B or hepatitis C virus 55 00:02:33.390 --> 00:02:35.280 and stomach bacteria, 56 00:02:35.280 --> 00:02:37.890 so primarily Helicobacter pyloris. 57 00:02:37.890 --> 00:02:39.330 We also see that there's a contamination 58 00:02:39.330 --> 00:02:40.760 of food supplies by molds 59 00:02:40.760 --> 00:02:44.493 that produce highly-carcinogenic alpha toxins. 60 00:02:45.660 --> 00:02:48.360 Also, reciprocally, we see 61 00:02:48.360 --> 00:02:50.490 that deaths from colorectal cancer or prostate cancer 62 00:02:50.490 --> 00:02:52.830 occurred more frequently in developed nations, 63 00:02:52.830 --> 00:02:54.300 partially due to intakes of diets 64 00:02:54.300 --> 00:02:56.880 high in fat and calories and low in fiber, 65 00:02:56.880 --> 00:02:58.452 fruits and vegetables. 66 00:02:58.452 --> 00:03:00.360 And lung cancer and other cancers 67 00:03:00.360 --> 00:03:01.800 arising from tobacco smoking 68 00:03:01.800 --> 00:03:04.683 caused the most male deaths in all populations. 69 00:03:06.475 --> 00:03:09.780 Among women, breast cancer is the leading cause of death 70 00:03:09.780 --> 00:03:12.480 in both developing and developed nations. 71 00:03:12.480 --> 00:03:15.900 Among women living in low and middle-income countries, 72 00:03:15.900 --> 00:03:18.810 cancer of the uterine cervix, or cervical cancer, 73 00:03:18.810 --> 00:03:20.160 is the second leading cause of death 74 00:03:20.160 --> 00:03:21.780 principally due to a lack of screening 75 00:03:21.780 --> 00:03:25.680 for pre-malignant dysplastic lesions of the cervical mucosa. 76 00:03:25.680 --> 00:03:28.950 Lung cancer causes nearly as many deaths as breast cancer 77 00:03:28.950 --> 00:03:32.220 in high-income countries, and rising rates 78 00:03:32.220 --> 00:03:33.960 of smoking among women worldwide 79 00:03:33.960 --> 00:03:35.700 have resulted in increasing numbers 80 00:03:35.700 --> 00:03:39.300 of female lung cancer deaths in all populations. 81 00:03:39.300 --> 00:03:41.850 Finally, death from stomach cancer or liver cancer 82 00:03:41.850 --> 00:03:43.080 occurs more frequently 83 00:03:43.080 --> 00:03:44.520 in low and middle-income countries, 84 00:03:44.520 --> 00:03:46.290 whereas cancers of the colon, and rectum, 85 00:03:46.290 --> 00:03:49.560 pancreas, and ovaries cause relatively more deaths 86 00:03:49.560 --> 00:03:51.810 in high-income countries. 87 00:03:51.810 --> 00:03:53.760 When we turn to look at the US, 88 00:03:53.760 --> 00:03:57.600 we have these predicted statistics from 2022. 89 00:03:57.600 --> 00:04:01.140 So while the numbers haven't completely been calculated yet, 90 00:04:01.140 --> 00:04:02.130 it's predicted that there'll be 91 00:04:02.130 --> 00:04:05.693 1.9 million new cancer diagnoses in the US, 92 00:04:05.693 --> 00:04:10.018 and breast cancer is the most common cancer diagnosis. 93 00:04:10.018 --> 00:04:13.830 In the same year, 609,360 people 94 00:04:13.830 --> 00:04:15.510 are predicted to die of cancer. 95 00:04:15.510 --> 00:04:18.300 And the leading cause of mortality among cancers 96 00:04:18.300 --> 00:04:21.120 is lung and bronchus cancer. 97 00:04:21.120 --> 00:04:21.953 We see in the US 98 00:04:21.953 --> 00:04:24.210 that cancer mortality and incidence rates vary considerably 99 00:04:24.210 --> 00:04:27.240 by race and by gender for a number of reasons. 100 00:04:27.240 --> 00:04:30.900 Men have about a 30% higher cancer death rate than women. 101 00:04:30.900 --> 00:04:33.180 And African American men have the highest death rates 102 00:04:33.180 --> 00:04:34.710 from cancers of the lung, and bronchus, 103 00:04:34.710 --> 00:04:36.690 prostate, and colon, and rectum 104 00:04:36.690 --> 00:04:39.633 compared to any other racial or ethnic group in the US. 105 00:04:40.980 --> 00:04:42.993 When we look at a graph of, 106 00:04:44.220 --> 00:04:49.220 I believe this is cancer mortality in men, 107 00:04:49.507 --> 00:04:52.380 we see some really stark differences between cancer types. 108 00:04:52.380 --> 00:04:55.140 So to begin with, more than half of cancer deaths in US men 109 00:04:55.140 --> 00:04:57.360 are due to cancers of the lung, and bronchus, 110 00:04:57.360 --> 00:04:59.280 prostate, colon, and rectum, 111 00:04:59.280 --> 00:05:00.420 and we see that represented 112 00:05:00.420 --> 00:05:03.052 by the highest lines on the graph here, 113 00:05:03.052 --> 00:05:08.052 the darker blue solid line and the blue dashed line. 114 00:05:09.600 --> 00:05:10.560 While lung cancer mortality 115 00:05:10.560 --> 00:05:12.630 has declined slightly since about 1990, 116 00:05:12.630 --> 00:05:13.980 the male death rates from lung cancer 117 00:05:13.980 --> 00:05:17.730 are still more than double that of other anatomic sites. 118 00:05:17.730 --> 00:05:19.200 We also see that in 1987, 119 00:05:19.200 --> 00:05:21.240 prostate cancer surpassed colorectal cancer 120 00:05:21.240 --> 00:05:24.660 as the second leading cause of cancer death in men, 121 00:05:24.660 --> 00:05:26.010 and that during the past decade, 122 00:05:26.010 --> 00:05:27.990 the mortality rates from both prostate cancer 123 00:05:27.990 --> 00:05:31.380 and colorectal cancer show evidence of a gradual decline. 124 00:05:31.380 --> 00:05:33.060 Mortality rates from other malignancies 125 00:05:33.060 --> 00:05:34.020 have remained constant, 126 00:05:34.020 --> 00:05:35.910 with the exception of the rates for stomach cancer, 127 00:05:35.910 --> 00:05:38.973 which have declined dramatically, beginning in about 1930. 128 00:05:39.960 --> 00:05:42.660 When we turn to look at cancer mortality rates in women, 129 00:05:42.660 --> 00:05:44.580 we see the cancer of the lung and bronchus, 130 00:05:44.580 --> 00:05:46.470 breast, and colon and rectum 131 00:05:46.470 --> 00:05:49.110 account for more than half of all cancer deaths. 132 00:05:49.110 --> 00:05:52.170 In 1987, lung cancer surpassed breast cancer 133 00:05:52.170 --> 00:05:55.020 as the leading cause of cancer death in women. 134 00:05:55.020 --> 00:05:57.840 And since 1950, lung cancer mortality among women 135 00:05:57.840 --> 00:06:00.450 has increased by more than 600% 136 00:06:00.450 --> 00:06:04.650 and now accounts for about 25% of all female cancer deaths. 137 00:06:04.650 --> 00:06:06.270 We also see that breast cancer mortality 138 00:06:06.270 --> 00:06:09.270 remained remarkably constant throughout the 20th century, 139 00:06:09.270 --> 00:06:12.840 but now appears to be slightly declining. 140 00:06:12.840 --> 00:06:14.370 Mortality rates from cervical cancer 141 00:06:14.370 --> 00:06:16.078 and stomach cancer declined dramatically 142 00:06:16.078 --> 00:06:19.710 from the 1930 to 2011 time period. 143 00:06:19.710 --> 00:06:21.210 And colorectal cancer mortality 144 00:06:21.210 --> 00:06:23.673 has gradually declined since the 1950s. 145 00:06:25.410 --> 00:06:28.290 Finally, when we look at this figure 2.9 from your textbook 146 00:06:28.290 --> 00:06:30.330 about the epidemiologic transition of cancer 147 00:06:30.330 --> 00:06:32.970 by age and economic region, 148 00:06:32.970 --> 00:06:35.640 we see some key differences between different age groups 149 00:06:35.640 --> 00:06:37.860 and different geographic regions in the world. 150 00:06:37.860 --> 00:06:40.260 So the 2014 World Cancer Report 151 00:06:40.260 --> 00:06:43.290 released by the World Health Organization, or the WHO, 152 00:06:43.290 --> 00:06:45.390 warns of an impending tidal wave of cancer 153 00:06:45.390 --> 00:06:47.700 in many populations of the world. 154 00:06:47.700 --> 00:06:49.350 The reason why this is 155 00:06:49.350 --> 00:06:51.352 is because of the epidemiologic transition 156 00:06:51.352 --> 00:06:54.630 which states that chronic diseases like cancer 157 00:06:54.630 --> 00:06:56.610 are gradually replacing acute diseases 158 00:06:56.610 --> 00:06:58.440 in the aging world population. 159 00:06:58.440 --> 00:07:00.180 So we see an increase of chronic diseases 160 00:07:00.180 --> 00:07:01.830 like cancer and heart disease 161 00:07:01.830 --> 00:07:04.833 and a decrease in infectious diseases, primarily. 162 00:07:06.000 --> 00:07:07.890 This figure shows the increasing proportion 163 00:07:07.890 --> 00:07:10.170 of incident cancers or cancer incidents 164 00:07:10.170 --> 00:07:12.960 in older versus younger adults since 1980, 165 00:07:12.960 --> 00:07:16.923 and the corresponding data for LMICs and HICs. 166 00:07:17.790 --> 00:07:19.740 During the period 1980 to 2010, 167 00:07:19.740 --> 00:07:22.260 the proportion of cancer incidents diagnosed 168 00:07:22.260 --> 00:07:24.750 among people living in economically-developing regions 169 00:07:24.750 --> 00:07:27.358 increased from 50% to 65%, 170 00:07:27.358 --> 00:07:29.670 and the proportion of new cases diagnosed 171 00:07:29.670 --> 00:07:31.830 in people over 65 years of age 172 00:07:31.830 --> 00:07:35.220 increased from 35% to 55%. 173 00:07:35.220 --> 00:07:37.200 Clearly, the greatest increases in cancer rates 174 00:07:37.200 --> 00:07:39.120 have occurred in elderly populations 175 00:07:39.120 --> 00:07:41.550 of low and middle-income nations. 176 00:07:41.550 --> 00:07:44.010 Approximately 60% of new cancer cases 177 00:07:44.010 --> 00:07:45.750 and 70% of all cancer deaths 178 00:07:45.750 --> 00:07:47.970 now occur in Africa, Asia, 179 00:07:47.970 --> 00:07:50.460 Central America, and South America. 180 00:07:50.460 --> 00:07:53.310 Such populations have a virtual perfect storm 181 00:07:53.310 --> 00:07:54.900 of increasing longevity, 182 00:07:54.900 --> 00:07:56.940 coupled with predisposing behavioral factors 183 00:07:56.940 --> 00:07:59.820 and conditions that increase cancer risk. 184 00:07:59.820 --> 00:08:01.710 These conditions or these factors 185 00:08:01.710 --> 00:08:03.624 include addiction to tobacco and alcohol, 186 00:08:03.624 --> 00:08:07.500 unhealthy nutrition, obesity, physical inactivity, 187 00:08:07.500 --> 00:08:08.640 and widespread exposure 188 00:08:08.640 --> 00:08:10.950 to certain sexually transmitted infectious agents 189 00:08:10.950 --> 00:08:13.560 that predispose to malignant transformation 190 00:08:13.560 --> 00:08:18.560 like HPV and other sexually-transmitted infections.