Questions that I addressed include the challenge of “where is prevention delivered" and “how long will we wait to accrue the benefits of prevention”. We have previously documented many barriers to preventing cancer by acting on what we already know (1). In this presentation, I focused more on the global cancer prevention challenges since lifestyle interventions will pay off at a lower cost and greater return than building health services to diagnose and treat the ever-increasing burden of cancer (2).
Tobacco control remains the highest priority in high-income countries and in low and middle-income countries to prevent the 30% or more of cancer that is caused by smoking cigarettes (3). Data from the prospective Nurses’ Health Study demonstrate that cessation from smoking provides greater benefits through reduction of lung cancer mortality than does CT screening (4). More importantly, smoking cessation reduces total mortality by 50% overall, and within 15 years of stopping smoking (4). On the other hand, screening for lung cancer reduces lung cancer mortality, but obviously does not reduce mortality from heart disease and stroke, or the many cancers at other sites (such as bladder and kidney) that are caused by smoking but are not detected by lung cancer screening.
Infections are a major cause of cancer in all countries (5). In high-income countries around 7% of cancers are caused by infections. However in low and middle-income countries the contribution of infections increases to approximately 25%. Vaccines clearly reduce cancer risk. Hepatitis B vaccine, now widespread, reduces liver cancer (6).
Beyond smoking cessation (7) and vaccination programs what should our prevention priorities be? Recent evidence following women prospectively after they were classified according to how closely they adhere to the American Cancer Society nutrition and physical activity guidelines (8) shows that those who are normal weight, eat mainly a plant-based diet, limit their alcohol intake, and are physically active, have significantly reduced incidence of cancer (9). During 12 years of follow-up within this cohort, women adhering to the ACS guidelines had a 22% reduction in diagnosis of new cases of breast cancer and 52% reduction in colon cancer (after adjusting for all other risk factors). Importantly, following the ACS guidelines also significantly reduced mortality (9).
In our research published last year, we also showed that avoiding a known breast carcinogen leads to lower risk of cancer (10). Following the women in the Nurses’ Health Study II, those who avoided alcohol in their adolescent years and before their first pregnancy, had significantly lower risk both of premalignant or precursor breast lesions (proliferative benign breast disease) and of invasive breast cancer through the premenopausal years. Avoiding carcinogens keeps risk low.
Valuing the payoff from prevention
This is complex. One such estimated for childhood vaccination uses the example of South Africa. Benefit gains include healthcare cost savings, productivity of parents attending to the care of sick children, productivity of the children as they grow to attend school and then enter the workforce (11). Externalities in the community are achieved even by the unvaccinated community members. This is due to the overall increases in wellness. These benefits have to be added to the reduction in incidence and mortality of disease as a direct consequence of vaccination. The same range of benefits accrue for hepatitis vaccination where data from Asian countries clearly show that vaccination reduces sickness, time lost from work and associated productivity, mortality, etc. Vaccination reduces the cost of health services and increases life expectancy (12, 13).
This same approach applies to the benefits of quitting smoking and is summarized in the Surgeon General’s Report released earlier in 2014(3). When smokers quit smoking their quality of life improves significantly. For the employer, absenteeism is lower in never smokers than in current smokers, and health care costs are reduced with smoking cessation, as is the subsequent risk of many chronic conditions. These benefits accrued over decades.
Alcohol a known carcinogen
While prevention messages support strategies to reduce alcohol consumption, the risks and benefits of consumption vary disproportionately by age. The societal hazards of alcohol intake include motor vehicle accidents, risky sexual behavior, violence and injuries. The adverse effects accrue in adolescent and early adult years. The risks of cancer and benefits of cardiovascular protection are observed decades later, after the consequences and toll on society due to motor vehicle accidents and alcohol related deaths.
Some question whether weight loss prevents cancer
A recent meta-analysis shows significant benefits for weight loss after bariatric surgery (14). The reduction in cancer is significant in women but not men. The limited number of cancer cases precludes an analysis of risk reduction according to cancer site. In a previous analysis, we showed that bariatric surgery and the subsequent associated weight loss is cost-effective and can be cost saving (15).
In contrast with the benefits of prevention, we currently spend billions of dollars on cancer care in the United States. Hassett and Elkin estimate we spent 125 billion on cancer care in 2010 (16). Furthermore, 13% of all cancer expenditures were for breast cancer. Given the increasing burden of cancer at a system or societal level, these costs are not sustainable for the US or, in fact, for low and middle-income countries (2, 16). In a detailed analysis of the cost-effectives of cancer care, Greenberg et al estimated that the incremental cost for treatment and improved outcomes generating an additional year of life is $27,000 for breast cancer and more for an additional year of life for treatment of patients with other cancer diagnoses (17). With the number of new cases of cancer in the US continuing to increase each year as our population ages (18), the growth in health-care costs for cancer is viewed as unsustainable (16). Cost related decisions are therefore inevitable. At the global level, even greater emphasis on effective low-cost treatment and broad access to this treatment becomes a top priority (2).
Cancer prevention works
Garnering greater resources and priority to implement effective cancer prevention must be our highest priority.
1. G. A. Colditz, K. Y. Wolin, S. Gehlert, Applying what we know to accelerate cancer prevention. Sci Transl Med 4, 127rv124 (2012); published online EpubMar 28 (10.1126/scitranslmed.3003218).
2. K. Chalkidou, P. Marquez, P. K. Dhillon, Y. Teerawattananon, T. Anothaisintawee, C. A. Gadelha, R. Sullivan, Evidence-informed frameworks for cost-effective cancer care and prevention in low, middle, and high-income countries. Lancet Oncol 15, e119-e131 (2014); published online EpubMar (10.1016/S1470-2045(13)70547-3).
3. U.S. Department of Health and Human Services, "The Health Consequences of Smoking—50 Years of Progress: A Report of the Surgeon General. ," (U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health,, Atlanta, GA, 2014.).
4. S. A. Kenfield, M. J. Stampfer, B. A. Rosner, G. A. Colditz, Smoking and smoking cessation in relation to mortality in women. JAMA 299, 2037-2047 (2008); published online EpubMay 7 (10.1001/jama.299.17.2037).
5. C. de Martel, J. Ferlay, S. Franceschi, J. Vignat, F. Bray, D. Forman, M. Plummer, Global burden of cancers attributable to infections in 2008: a review and synthetic analysis. Lancet Oncol 13, 607-615 (2012); published online EpubJun (10.1016/S1470-2045(12)70137-7).
6. M. H. Chang, S. L. You, C. J. Chen, C. J. Liu, C. M. Lee, S. M. Lin, H. C. Chu, T. C. Wu, S. S. Yang, H. S. Kuo, D. S. Chen, Decreased incidence of hepatocellular carcinoma in hepatitis B vaccinees: a 20-year follow-up study. Journal of the National Cancer Institute 101, 1348-1355 (2009); published online EpubOct 7 (10.1093/jnci/djp288).
7. J. M. Lightwood, A. Dinno, S. A. Glantz, Effect of the California tobacco control program on personal health care expenditures. PLoS Med 5, e178 (2008); published online EpubAug 26 (10.1371/journal.pmed.0050178).
8. L. H. Kushi, C. Doyle, M. McCullough, C. L. Rock, W. Demark-Wahnefried, E. V. Bandera, S. Gapstur, A. V. Patel, K. Andrews, T. Gansler, N. American Cancer Society, C. Physical Activity Guidelines Advisory, American Cancer Society Guidelines on nutrition and physical activity for cancer prevention: reducing the risk of cancer with healthy food choices and physical activity. CA Cancer J Clin 62, 30-67 (2012); published online EpubJan-Feb (10.3322/caac.20140).
9. C. A. Thomson, M. L. McCullough, B. C. Wertheim, R. T. Chlebowski, M. E. Martinez, M. L. Stefanick, T. E. Rohan, J. E. Manson, H. A. Tindle, J. Ockene, M. Z. Vitolins, J. Wactawski-Wende, G. E. Sarto, D. S. Lane, M. L. Neuhouser, Nutrition and Physical Activity Cancer Prevention Guidelines, Cancer Risk, and Mortality in the Women's Health Initiative. Cancer Prev Res (Phila) 7, 42-53 (2014); published online EpubJan (10.1158/1940-6207.CAPR-13-0258).
10. Y. Liu, G. A. Colditz, B. Rosner, C. S. Berkey, L. C. Collins, S. J. Schnitt, J. L. Connolly, W. Y. Chen, W. C. Willett, R. M. Tamimi, Alcohol intake between menarche and first pregnancy: a prospective study of breast cancer risk. Journal of the National Cancer Institute 105, 1571-1578 (2013); published online EpubOct 16 (10.1093/jnci/djt213).
11. T. Barnighausen, D. E. Bloom, D. Canning, J. O'Brien, Accounting for the full benefits of childhood vaccination in South Africa. S Afr Med J 98, 842, 844-846 (2008)
12. H. F. Hung, T. H. Chen, Probabilistic cost-effectiveness analysis of the long-term effect of universal hepatitis B vaccination: an experience from Taiwan with high hepatitis B virus infection and Hepatitis B e Antigen positive prevalence. Vaccine 27, 6770-6776 (2009); published online EpubNov 12 (10.1016/j.vaccine.2009.08.082).
13. S. Q. Lu, S. M. McGhee, X. Xie, J. Cheng, R. Fielding, Economic evaluation of universal newborn hepatitis B vaccination in China. Vaccine 31, 1864-1869 (2013); published online EpubApr 3 (10.1016/j.vaccine.2013.01.020).
14. M. C. Tee, Y. Cao, G. L. Warnock, F. B. Hu, J. E. Chavarro, Effect of bariatric surgery on oncologic outcomes: a systematic review and meta-analysis. Surgical endoscopy 27, 4449-4456 (2013); published online EpubDec (10.1007/s00464-013-3127-9).
15. S. H. Chang, C. R. Stoll, G. A. Colditz, Cost-effectiveness of bariatric surgery: should it be universally available? Maturitas 69, 230-238 (2011); published online EpubJul (10.1016/j.maturitas.2011.04.007).
16. M. J. Hassett, E. B. Elkin, What does breast cancer treatment cost and what is it worth? Hematology/oncology clinics of North America 27, 829-841, ix (2013); published online EpubAug (10.1016/j.hoc.2013.05.011).
17. D. Greenberg, C. Earle, C. H. Fang, A. Eldar-Lissai, P. J. Neumann, When is cancer care cost-effective? A systematic overview of cost-utility analyses in oncology. J Natl Cancer Inst 102, 82-88 (2010); published online EpubJan 20 (10.1093/jnci/djp472).
18. B. Edwards, H. L. Howe, L. Ries, M. J. Thun, H. M. Rosenberg, R. Yancik, P. A. Wingo, A. Jemal, E. G. Feigal, Annual report to the Nation on the State of Cancer, 1973-1999, Featuring implications of age and aging on the U.S. cancer burden. Cancer 94, 2766-2792 (2002).