WEBVTT 1 00:00:00.480 --> 00:00:01.440 Hi, everyone. 2 00:00:01.440 --> 00:00:04.920 In today's lecture, we'll be discussing cancer prevention. 3 00:00:04.920 --> 00:00:06.270 We have three goals. 4 00:00:06.270 --> 00:00:07.440 We're going to explain the importance 5 00:00:07.440 --> 00:00:10.519 of primary, secondary, and tertiary cancer prevention, 6 00:00:10.519 --> 00:00:12.030 we're going to provide examples 7 00:00:12.030 --> 00:00:14.280 of the three levels of cancer prevention, 8 00:00:14.280 --> 00:00:15.679 and finally, we'll touch upon a summary 9 00:00:15.679 --> 00:00:18.360 of all module one lectures. 10 00:00:18.360 --> 00:00:20.100 So to begin with, primary, secondary, 11 00:00:20.100 --> 00:00:21.930 and tertiary cancer prevention 12 00:00:21.930 --> 00:00:25.380 are the three main categories of cancer prevention. 13 00:00:25.380 --> 00:00:27.912 Primary cancer prevention is avoidance of exposure 14 00:00:27.912 --> 00:00:31.260 to disease-causing risk factors in the first place. 15 00:00:31.260 --> 00:00:33.570 Secondary prevention is screening for the detection 16 00:00:33.570 --> 00:00:37.080 of antecedent conditions that predispose to disease. 17 00:00:37.080 --> 00:00:39.060 When people get screened early 18 00:00:39.060 --> 00:00:41.550 or screened at any point in the disease progress, 19 00:00:41.550 --> 00:00:43.410 they oftentimes have a higher likelihood 20 00:00:43.410 --> 00:00:47.512 of surviving the cancer by being treated early 21 00:00:47.512 --> 00:00:51.084 before the cancer has spread to other parts of the body 22 00:00:51.084 --> 00:00:52.959 or become more significant. 23 00:00:52.959 --> 00:00:56.400 Finally, tertiary prevention is behavioral changes 24 00:00:56.400 --> 00:00:57.900 that limit the progression of disease 25 00:00:57.900 --> 00:01:00.690 and improve the quality of life after diagnosis. 26 00:01:00.690 --> 00:01:03.180 So these could relate to physical activity, 27 00:01:03.180 --> 00:01:05.910 or diet, or other factors. 28 00:01:05.910 --> 00:01:08.670 The rationale for cancer preventions is that, 29 00:01:08.670 --> 00:01:11.190 as we've discussed, cancer is a leading cause 30 00:01:11.190 --> 00:01:12.750 of mortality and morbidity, 31 00:01:12.750 --> 00:01:16.593 especially for people under age 85 years. 32 00:01:17.820 --> 00:01:21.270 We also see that cancer therapies have improved, 33 00:01:21.270 --> 00:01:22.103 but at the same time, 34 00:01:22.103 --> 00:01:26.670 morbidity and mortality have not changed hugely. 35 00:01:26.670 --> 00:01:28.195 We also see that effective cancer prevention 36 00:01:28.195 --> 00:01:30.390 and control initiatives must incorporate 37 00:01:30.390 --> 00:01:32.910 scientific validity, linguistic appropriateness, 38 00:01:32.910 --> 00:01:34.050 and cultural competence. 39 00:01:34.050 --> 00:01:36.270 And I really like this quote 40 00:01:36.270 --> 00:01:37.950 because it really testifies to the importance 41 00:01:37.950 --> 00:01:42.030 of designing prevention strategies for specific communities, 42 00:01:42.030 --> 00:01:44.790 specific individuals, and really taking into account 43 00:01:44.790 --> 00:01:47.700 all aspects of their identity. 44 00:01:47.700 --> 00:01:50.100 So their biologic and genetic makeup, 45 00:01:50.100 --> 00:01:53.790 as well as their practices related to diet, 46 00:01:53.790 --> 00:01:58.560 their daily lives, their work, economic considerations 47 00:01:58.560 --> 00:02:00.930 when designing things or programs 48 00:02:00.930 --> 00:02:03.630 that will work for them to prevent cancer. 49 00:02:03.630 --> 00:02:05.910 So to begin with, primary prevention 50 00:02:05.910 --> 00:02:08.880 is essentially avoiding risk factors for cancer. 51 00:02:08.880 --> 00:02:10.549 Primary prevention implicates 52 00:02:10.549 --> 00:02:13.230 both individuals and structures. 53 00:02:13.230 --> 00:02:16.140 Individuals can make healthy choices to prevent cancer, 54 00:02:16.140 --> 00:02:19.320 but societies and communities can also put policies in place 55 00:02:19.320 --> 00:02:20.670 that make it easier for individuals 56 00:02:20.670 --> 00:02:24.750 to choose healthy behaviors or to avoid unhealthy behaviors. 57 00:02:24.750 --> 00:02:27.630 It's also important to note that socioeconomic factors 58 00:02:27.630 --> 00:02:30.630 are implicated throughout all levels of cancer prevention. 59 00:02:30.630 --> 00:02:33.570 For example, if someone cannot afford fruits and vegetables, 60 00:02:33.570 --> 00:02:36.510 they may be at a greater risk for cancer 61 00:02:36.510 --> 00:02:39.903 because they're not able to consume a healthy diet. 62 00:02:42.270 --> 00:02:45.360 Here we see some more examples of primary prevention, 63 00:02:45.360 --> 00:02:47.460 including as we discussed in the last lecture, 64 00:02:47.460 --> 00:02:49.230 the importance of avoiding infections 65 00:02:49.230 --> 00:02:51.630 and limiting environmental risks like sunlight, 66 00:02:51.630 --> 00:02:54.633 sources of radiation, and chemical carcinogens. 67 00:02:55.590 --> 00:02:57.150 This great chart from your textbook 68 00:02:57.150 --> 00:02:59.453 discusses a lot of common cancer risk factors 69 00:02:59.453 --> 00:03:02.370 and the corresponding prevention strategies. 70 00:03:02.370 --> 00:03:05.220 So for example, the hepatitis virus 71 00:03:05.220 --> 00:03:08.460 can cause liver and biliary tract cancer, 72 00:03:08.460 --> 00:03:10.650 and a key way to prevent that is to avoid exposure 73 00:03:10.650 --> 00:03:14.130 to the virus or to be vaccinated against it. 74 00:03:14.130 --> 00:03:16.830 And again we see the importance of socioeconomic factors, 75 00:03:16.830 --> 00:03:18.030 because if you live in a community 76 00:03:18.030 --> 00:03:19.100 where there's not primary care 77 00:03:19.100 --> 00:03:22.920 or where you're unable to obtain the vaccination, 78 00:03:22.920 --> 00:03:24.750 that's gonna limit your ability 79 00:03:24.750 --> 00:03:27.750 to prevent liver and biliary tract cancer. 80 00:03:27.750 --> 00:03:30.060 Similarly, if you do live in a community 81 00:03:30.060 --> 00:03:32.190 where that vaccination is available 82 00:03:32.190 --> 00:03:33.450 but you're not able to afford it, 83 00:03:33.450 --> 00:03:35.970 or you don't have insurance coverage that will pay for it, 84 00:03:35.970 --> 00:03:38.490 that's another barrier to being protected 85 00:03:38.490 --> 00:03:40.503 against liver and biliary tract cancer. 86 00:03:41.970 --> 00:03:43.290 Secondary cancer prevention 87 00:03:43.290 --> 00:03:45.720 is early diagnosis and treatment. 88 00:03:45.720 --> 00:03:46.770 We'll see later in the course 89 00:03:46.770 --> 00:03:47.970 that many epidemiological studies 90 00:03:47.970 --> 00:03:49.860 will analyze the correlation between 91 00:03:49.860 --> 00:03:53.100 cancer outcomes and stage of diagnosis. 92 00:03:53.100 --> 00:03:54.756 Cancer screening is a key area of focus 93 00:03:54.756 --> 00:03:58.410 in cancer epidemiology, and methods vary 94 00:03:58.410 --> 00:04:01.053 depending on country, cancer type, et cetera. 95 00:04:02.340 --> 00:04:05.454 So here we see that any effective cancer control program 96 00:04:05.454 --> 00:04:07.470 includes comprehensive cancer screening 97 00:04:07.470 --> 00:04:08.875 for the timely diagnosis and effective treatment 98 00:04:08.875 --> 00:04:13.743 of cellular lesions that could progress to invasive cancer. 99 00:04:16.530 --> 00:04:19.260 So some examples of cancer screening techniques 100 00:04:19.260 --> 00:04:23.010 are the mammogram, which is going to look for breast cancer, 101 00:04:23.010 --> 00:04:24.810 the Papanicolaou or Pap test, 102 00:04:24.810 --> 00:04:26.520 which is going to look for cervical dysplasia 103 00:04:26.520 --> 00:04:27.900 or cervical cancer, 104 00:04:27.900 --> 00:04:31.380 endoscopy, which can look at symptoms or signs 105 00:04:31.380 --> 00:04:34.950 for Barrett's esophagus and stomach ulcers, 106 00:04:34.950 --> 00:04:36.570 dental examination, 107 00:04:36.570 --> 00:04:39.300 which can give show signs of oral leukoplakia, 108 00:04:39.300 --> 00:04:44.280 colonoscopy, which can detect symptoms of colon cancer, 109 00:04:44.280 --> 00:04:48.540 prostate specific antigen or PSA tests and ultrasound, 110 00:04:48.540 --> 00:04:51.690 which can look at cancers of the prostate gland, 111 00:04:51.690 --> 00:04:52.995 and dermatologic examination, 112 00:04:52.995 --> 00:04:56.523 which can look at certain types of skin cancer. 113 00:04:57.660 --> 00:05:00.657 We also see related to secondary cancer prevention 114 00:05:00.657 --> 00:05:03.450 the importance of population screening programs. 115 00:05:03.450 --> 00:05:05.610 So population screening programs can be used 116 00:05:05.610 --> 00:05:09.390 in conjunction with skilled surgical techniques, 117 00:05:09.390 --> 00:05:13.380 and this has been successful and continues to be successful 118 00:05:13.380 --> 00:05:17.310 in reducing the mortality rates of certain cancers. 119 00:05:17.310 --> 00:05:19.230 Population screening programs 120 00:05:19.230 --> 00:05:22.830 can be difficult to implement on a national level, 121 00:05:22.830 --> 00:05:26.610 but you might hear of a population cancer registry 122 00:05:26.610 --> 00:05:28.950 or a national breast cancer screening campaign 123 00:05:28.950 --> 00:05:30.513 using mammograms. 124 00:05:31.380 --> 00:05:35.070 These can be expensive depending on the size of the country. 125 00:05:35.070 --> 00:05:37.170 And it's important to think about communities 126 00:05:37.170 --> 00:05:39.540 that are either able to access these programs 127 00:05:39.540 --> 00:05:40.830 or unable to access them. 128 00:05:40.830 --> 00:05:44.340 So commonly epidemiological studies might look at 129 00:05:44.340 --> 00:05:47.400 the differences between rural and urban areas. 130 00:05:47.400 --> 00:05:50.640 And a hypothesis might be that people in urban areas 131 00:05:50.640 --> 00:05:53.580 are able to access screening more easily 132 00:05:53.580 --> 00:05:56.250 because they live in close proximity to hospitals, 133 00:05:56.250 --> 00:05:58.743 and health clinics, and primary care centers, 134 00:05:59.580 --> 00:06:02.190 whereas people in rural areas might not be able to access 135 00:06:02.190 --> 00:06:03.570 the same tools and techniques, 136 00:06:03.570 --> 00:06:06.153 and thus might have lower rates of screening. 137 00:06:07.410 --> 00:06:09.150 It's important that screening is accurate, 138 00:06:09.150 --> 00:06:13.050 safe, inexpensive, and acceptable culturally 139 00:06:13.050 --> 00:06:14.313 to the general public. 140 00:06:15.330 --> 00:06:18.450 In high income countries, only about half of cancer patients 141 00:06:18.450 --> 00:06:21.000 eventually die from the diseases. 142 00:06:21.000 --> 00:06:24.600 But one thing that's hindering survival rates 143 00:06:24.600 --> 00:06:26.490 in low and middle income countries 144 00:06:26.490 --> 00:06:28.590 is that 80% of cancer victims 145 00:06:28.590 --> 00:06:31.140 already have late stage, incurable tumors 146 00:06:31.140 --> 00:06:32.313 when they're diagnosed. 147 00:06:33.600 --> 00:06:36.690 Finally, we move to tertiary cancer prevention, 148 00:06:36.690 --> 00:06:38.910 and this is the beneficial behavioral changes 149 00:06:38.910 --> 00:06:40.290 that limit disease progression 150 00:06:40.290 --> 00:06:41.735 and subsequent disability for patients 151 00:06:41.735 --> 00:06:44.580 after they've been diagnosed for cancer. 152 00:06:44.580 --> 00:06:46.950 So some examples of this are smoking cessation, 153 00:06:46.950 --> 00:06:50.670 limiting alcohol intake, regular exercise, improved diet, 154 00:06:50.670 --> 00:06:52.050 maintenance of optimum weight, 155 00:06:52.050 --> 00:06:55.290 and compliance with prescribed treatment regimens. 156 00:06:55.290 --> 00:06:58.530 This is also related to pain control and palliative care. 157 00:06:58.530 --> 00:07:00.390 The goal of tertiary cancer prevention 158 00:07:00.390 --> 00:07:01.680 is to increase survival rates 159 00:07:01.680 --> 00:07:02.700 and improve the quality of life 160 00:07:02.700 --> 00:07:04.830 among cancer survivors and their families. 161 00:07:04.830 --> 00:07:08.160 And it's interesting because there's quite a few overlaps 162 00:07:08.160 --> 00:07:09.750 between tertiary cancer prevention 163 00:07:09.750 --> 00:07:11.070 and primary cancer prevention. 164 00:07:11.070 --> 00:07:16.020 So for example, a lot of these unhealthy behavioral factors 165 00:07:16.020 --> 00:07:19.740 like smoking and alcohol consumption 166 00:07:19.740 --> 00:07:24.450 double as both primary and tertiary prevention strategies. 167 00:07:24.450 --> 00:07:27.450 Finally, to touch upon cancer education, 168 00:07:27.450 --> 00:07:31.020 the importance of educational programs cannot be overstated. 169 00:07:31.020 --> 00:07:33.480 In different countries have implemented 170 00:07:33.480 --> 00:07:37.170 cancer education programs for people at all stages of life. 171 00:07:37.170 --> 00:07:41.760 So a push to incorporate cancer education 172 00:07:41.760 --> 00:07:44.110 into elementary, middle, and high schools 173 00:07:45.060 --> 00:07:49.440 can help people to understand the signs and symptoms 174 00:07:49.440 --> 00:07:52.110 of common cancers that might afflict adolescents. 175 00:07:52.110 --> 00:07:55.560 At the same time, when people at early ages 176 00:07:55.560 --> 00:07:57.570 learn about different kinds of cancers, 177 00:07:57.570 --> 00:08:01.500 they then can go home and speak with their family members 178 00:08:01.500 --> 00:08:05.070 or other community members about the importance 179 00:08:05.070 --> 00:08:06.870 of being aware of those types of cancers, 180 00:08:06.870 --> 00:08:10.590 which in turn can lead to higher rates of elective screening 181 00:08:10.590 --> 00:08:14.819 or higher general awareness of different cancers. 182 00:08:14.819 --> 00:08:18.120 So as the slide says, these programs can promote awareness 183 00:08:18.120 --> 00:08:20.730 of the risk factors and early symptoms of cancer 184 00:08:20.730 --> 00:08:23.040 and provide accurate information on the cost, safety, 185 00:08:23.040 --> 00:08:25.173 and accuracy of cancer screening tests. 186 00:08:26.490 --> 00:08:28.881 These education programs are a big focus 187 00:08:28.881 --> 00:08:31.170 in low and middle income countries 188 00:08:31.170 --> 00:08:35.013 where access to highly-trained clinical staff, 189 00:08:35.013 --> 00:08:40.013 or expensive treatments, or screening machines 190 00:08:40.230 --> 00:08:44.220 might be, the expense of those techniques 191 00:08:44.220 --> 00:08:47.040 and of that personnel might make it difficult 192 00:08:47.040 --> 00:08:52.040 or might be a challenge to implementing programs 193 00:08:52.530 --> 00:08:53.880 on a countrywide level. 194 00:08:53.880 --> 00:08:56.730 And oftentimes, education programs can be implemented 195 00:08:56.730 --> 00:08:59.370 at a lower cost and more widespread 196 00:08:59.370 --> 00:09:01.560 if they're integrated into curriculums 197 00:09:01.560 --> 00:09:05.223 in disparate regions of the country.