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Prostate cancer mortality projections reach a new high

2020; Wiley; Volume: 126; Issue: 17 Linguagem: Inglês

10.1002/cncr.33127

1097-0142

Carrie Printz,

Global Cancer Incidence and Screening

The report projected a total of 1,806,590 new cancer cases and 606,520 deaths in 2020, or approximately 4950 new cases and 1600 deaths each day. According to the findings, incidence and mortality rates are declining for a number of major cancers, including breast and colorectal cancer. However, disease reductions have halted for prostate cancer—the report predicts that in 2020 the disease will have the highest number of diagnoses among male cancers at 21%, compared with the next highest malignancy, lung and bronchus cancer (13%). The findings also indicate that an estimated 1 in 9 men will be diagnosed with prostate cancer compared with 1 in 15 men who will be diagnosed with lung and bronchus cancer. Of those diagnosed with prostate cancer, approximately 10% are expected to die of the disease. The ACS estimates that a total of 33,330 people will die from prostate cancer this year, compared with 31,620 estimated deaths from the disease in 2019. Although many urologists have expressed concern about the projections, Walter M. Stadler, MD, the Fred C. Buffett Professor of Medicine and Surgery, director of the genitourinary oncology program, and deputy director of the Comprehensive Cancer Center at The University of Chicago Medicine, urges taking a “wait-and-see” approach. “We have to recognize that the 2020 deaths are estimates and not actual deaths,” he says. “If we look at some of the more firm data in the report, from 2013 to 2017, there was a decline in prostate cancer deaths.” The ACS report also notes that the prostate cancer death rate declined by 52% from a peak of 39.3 per 100,000 population in 1993 to a low of 18.8 per 100,000 population in 2017, although it appears to have stabilized in recent years. Mortality rates are based on the denominator, which is the number of diagnosed prostate cancer cases. Because incidence rates have declined markedly after peaking with the use of extensive screening for the disease in the 1990s, mortality rates could appear to be on the increase even though people are dying of metastatic disease at the same rate, he says. “We have to be very cautious about interpreting these broad mortality rates from what is labeled as prostate cancer when it is, in reality, 2 different diseases,” he says. The first type of prostate cancer is low-grade, or Gleason score 6, disease, which is the most common. Few men die of it. The second type is what Dr. Stadler refers to as “real prostate cancer,” falling in the range of Gleason scores of 7 to 10. Not only is this grade of disease much more aggressive and lethal, it also is the type that physicians have the most difficulty diagnosing, he says. “Historically, we haven't been able to tell if it's real prostate cancer until the gland can be removed and sliced apart,” says Dr. Stadler. “Biopsy is improving with things like magnetic resonance imaging, but at least 20% to 30% of the time, the biopsy is incorrect—meaning that even though it says the patient has benign, low-grade prostate cancer, he ends up having real prostate cancer. This is what makes everyone nervous.” Some experts attribute the projected rise in prostate cancer mortality rates for 2020 to changes in prostate-specific antigen (PSA) screening guidelines that were meant to prevent overdiagnosis and overtreatment and resulted in decreased testing. After the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial (a large-scale research effort designed by the National Cancer Institute to determine the effects of screening on cancer-related mortality and secondary endpoints) concluded that there were no marked differences in mortality between men who were screened using the PSA test versus men who were not screened, the US Preventive Services Task Force (USPSTF) in 2012 changed its guidance to recommend against annual PSA testing of all men aged 50 to 75 to screen for the disease. However, after reviewing additional studies, the USPSTF changed its guidance again in 2018, noting that the decision to undergo periodic PSA-based screening for prostate cancer should be an individual one that includes a discussion of the potential benefits and harms of screening between patients and their physicians. The guidance also points out that many men will experience potential harms of screening, including false-positive results that require additional testing and possible prostate biopsy as well as overdiagnosis and overtreatment. Dr. Stadler believes in taking a more thoughtful, personalized approach to screening. “I think we need to spend more time thinking about ‘smart screening,’” he says. “If a patient is 89 with multiple comorbidities, for example, will he really benefit from PSA testing compared to a 55-year-old man who runs half marathons, for example?” In particular, he says, physicians would be better equipped to engage in shared decision making with their patients if they could show them a graphical interface with data concerning specific treatments, side effects, and outcomes. “If you can go on a website and compare quality ratings of mattresses based on costs, firmness, and durability, you should be able to do the same thing looking at a patient's mortality risk and risks for developing cancer,” he says. “Yet, our EMR [electronic medical records] and billing systems are not set up that way. We need tools like AI [artificial intelligence] to overcome our inherent bias of wanting concrete, ‘yes or no’ answers when medical decisions are much more of a gradation.” Still, other oncologists have voiced concerns regarding the research that informs the guidelines. Edmund Folefac, MB/CHB, a medical oncologist at The Ohio State University Comprehensive Cancer Center – Arthur G. James Cancer Hospital and Richard J. Solove Research Institute in Columbus is particularly interested in how PSA screening results should be applied to African American men, who are approximately 1.8 times more likely to be diagnosed with prostate cancer and 2.5 times more likely to die of it compared with White men. He is critical of recommendations that were based on the PLCO study, which included only approximately 4% of African American men, although African Americans comprise approximately 13% of the US population. “Because their volume of the disease is twice as high as Caucasians, researchers should have increased the number of African American participants to 25% or 26%,” he says. He notes that the other major screening study that drove recommendations, the European Randomized Study of Screening for Prostate Cancer (ERSPC) trial, was conducted in Scandinavia, where the Black population is quite small. Furthermore, approximately 80% of PLCO participants in the study received PSA testing at least once during the trial, thereby diluting the impact of its findings, he says. Dr. Folefac is a strong advocate for screening “because we now have the imaging and genomic testing to be able to tell whose cancer will hurt them,” he says. He attributes the rising mortality rates to the fact that fewer deadly cancers were detected early enough after the 2012 USPSTF guidance recommended against regular PSA testing. “The lead time before prostate cancer begins manifesting symptoms is about 5 to 10 years, so if we diagnose a patient's cancer while it's still confined to the prostate, his chances of survival at 5 years are nearly 100%. But if we diagnose it after it has spread, the chances of survival are 30%,” Dr. Folefac says. Another benefit to early diagnosis and active surveillance is that patients are regularly seeing their physicians, who can talk to them about lifestyle modifications that can improve their health and reduce their risk of developing advanced disease. Dr. Folefac also supports modeling studies that can contribute toward the development of treatment guidelines for specific subgroups of patients. “We need to go back to the drawing board and do the required studies to come up with better evidence for informing guidelines,” he says, noting that more must be channeled into this type of research. “We need to invest a lot more in prevention studies, so we have the best quality data, and to stop treating prevention as an afterthought, which is what's currently being done.”