[MUSIC] With the 1.1 million cases in 2012, prostate cancer is the second most common cancer among men. Almost 70% of these cases occur in more developed countries. And we observed in the last 20 years a sharp increase of incidence rates in these countries. And there are still a lot of differences between countries. Up to 25 times between the countries with the high rates and the countries with the lower rates. The high rates, we find the high rates in Australia, New Zealand, and North America. In terms of mortality, the rates are lower, and also the rates are decreasing. But the most of mortality we observe in developing countries. Despite the importance of this disease in terms of burden of incidents and mortality. Though, there is still a lot of uncertainty and controversy about the use or not of an early detection test for screening. We have two main screening test to detect prostate cancer. One is the digital rectal examination. Which is when a clinician inserts his lubricated finger in the rectum to feel the presence of lumps or changes, hard or soft spot in the prostate. This test has never been evaluated by randomized control trials as a screening test. But there are studies they evaluated its sensitivity and specificity. Sensitivity is around 53%, specificity of 84%. And the positive predictive value is 18%, which means that around 72% patient positive the digital rectal examination will not have prostate cancer at the biopsy. Then we have the PSA, the Prostate Specific Antigen, which is a protein found in the blood that is produced by normal prostate tissues and cancer and, of course, prostate cancer. This test has been developed mostly to follow the patients with prostate cancer, and to follow and monitor the of these patients. But that has been quickly used as a screening test worldwide. And is one of the reasons why we observe this increase in the incidence rates of prostate cancer during the last 20 years. The overall sensitivity of this test is 21%, which increased to 51% for cancer and more advanced cancers, like cancer with a up to eight. And the specificity is 91% with a positive predictive value of 30%. There have been two big randomized trials that evaluated the effectiveness of PSA test as a screening test to reduce mortality from prostate cancer. One is the Prostate, Lung, Ovarian, Screening trial, that has been done in the United States. And the other one is the European Randomized Study of Screening for Prostate Cancer. There are a lot of differences between the two studies in terms of design and the conduction of the studies. The American study enrolled approximately 77,000 patients. They offered a PSA test every year, plus/minus the digital rectal examination. And the cut-off chosen for the PSA was 4 nanograms over milliliter. And at the end of the study period, they didn't find any difference in mortality between the patients screened and the patients not screened. The European study enrolled approximately 162,000 patients. They offered the PSA test every four years. And the cutoff chosen was 3 nanograms per millimeter. And at the end of the follow up period they actually found a 20% reduction on mortality among the patients that have been screened as compared to those not screened. The two studies though, were criticized a lot because they had a lot of shortcomings. Particularly the American study had a low compliance. I mean, the compliance for the PSA test was relatively high. It was 85%, but it was a low compliance for the biopsy for the patients that were positive at a PSA test. The compliant was 40% in the first round and 30% in the second round. Besides, that was different in the European study, the compliance for the biopsy was actually relatively high, 86%. Another big problem was the contamination of the controls with PSA. So at least the 52% of the controls actually had the PSA test in the American study. And that was very, very low in the European study, it was 6%. And also, 44% of the control and screen patients had a PSA before the study started. Other problems were a short follow-up for both the studies and the power due to very few advance in terms of prostate cancer mortality. What both studies found, though, was that this PSA screening leads to overdiagnosis of cancer cases that maybe could never develop symptoms in a lifetime of a patient, and the patient couldn't have died from this cancer. So the European study estimated that to prevent one prostate cancer death in ten years, we need to screen 1,410 men. And, of course, once we screen these men and they test positive, we have to treat. So the second problem is over treatment. And the estimation is that to prevent one prostate cancer, that we have to treat 48 men. And the side effects, the complications of the treatments, are very frequent and very heavy. The treatments that we use for prostate cancer surgery, radiotherapy and hormonal therapy. And all of them can give very, very heavy side effects, such as urinary incontinence, sexual dysfunctions, and bowel problems. So currently, the PSA test, given these results, has not been recommended as a mass screening in any countries. There are some associations in some countries that suggest, though, that a man should have all the information to take an individual decision to be screened or not. So the idea is to have a shared decision making, with the clinician giving all the information about the uncertainties of the test, the risk associated with the test, and the benefit associated to the test. And is the men that can value of all this information and decide whether to be screened or not. So in conclusion, despite the fact that this is a big and important public health problem, there are not the tests that are effective to be used in population based organized screening. PSA test has been shown to have a small effect in reducing the mortality rate of screened people. And so it is an individual decision to be taken together with the health physician to decide if is the case or not to be screened. Given the little benefit, and the relatively high rate of harms that a screening can bring. [MUSIC]
