Ep 153: A 55-Year-Old Here for an Annual Physical

This episode discusses prostate cancer screening and risk-reducing strategies.

Read more on this topic in Harrison's.

Harrison's Principles of Internal Medicine, 22nd Edition

Transcript

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[Ms. Heidhausen] This is Katarina Heidhausen, executive editor of Harrison's Principles of Internal Medicine. Harrison's Podclass is brought to you by McGraw Hill's AccessMedicine, the online medical resource that delivers the latest content from the best minds in medicine. And now, on to the episode. 

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[Dr. Handy] Hi, everyone. Welcome back to Harrison's Podclass. We're your co-hosts. I'm Dr. Cathy Handy. 

[Dr. Wiener] And I'm Dr. Charlie Wiener, and we're joining you from the Johns Hopkins School of Medicine. 

[Dr. Handy] Welcome to today's episode about a 55-year-old here for an annual physical. 

[Dr. Wiener] So Cathy, today's patient is a 55-year-old man who comes to the clinic for his annual physical. His friend was just diagnosed with prostate cancer, and this gentleman is interested in risk reduction and early screening. 

[Dr. Handy] His friend is probably a patient of mine, but let's try and keep him out of the oncology clinic. 

[Dr. Wiener] Yeah, so that's what we're trying to do. And the question which is being asked by the patient says, which of the following regarding prostate cancer is true? And the options are, A. PSA, or prostate-specific antigen, is produced exclusively by prostate cancer cells, so if elevated, means he has prostate cancer. Option B. serum levels of PSA can be increased up to tenfold after a digital rectal exam. Option C. if he has an abnormal digital rectal examination, he almost certainly has prostate cancer. Option D. vitamin E can be taken to reduce the risk of prostate cancer. And option E. is there are no medications currently approved for prostate cancer prevention. 

[Dr. Handy] Just to start more broadly, improved understanding of carcinogenesis has allowed cancer prevention and early detection to expand beyond just the identification and avoidance of carcinogens. Specific interventions to reduce cancer mortality by preventing cancer in those at risk, and effective screening for early detection of cancer are really the goals here. 

[Dr. Wiener] So carcinogenesis is a process that usually extends over years, which provides a window of opportunity where we've been able to intervene. Let's start with PSA, and even what is it? 

[Dr. Handy] PSA stands for prostate-specific antigen. It's a serine protease that causes liquefaction of seminal fluid. It's produced by both non-malignant and malignant epithelial cells of the prostate. So it is prostate-specific, but it's not prostate cancer-specific. 

[Dr. Wiener] Okay, so that rules out option A. We haven't asked it in the question, but tell us a bit about the use of PSA. 

[Dr. Handy] PSA testing was approved by the US Food and Drug Administration in 1994 for early detection of prostate cancer. And the widespread use of the test has played a significant role in the proportion of men diagnosed with early-stage cancers. Over 70 to 80% of newly diagnosed cancers are clinically organ-confined and therefore curable. 

[Dr. Wiener] Option B. talks about the reasons PSA can be increased, including significantly from a digital rectal exam. What do you think about that? 

[Dr. Handy] Serum levels of PSA may increase from a few causes actually. This can include prostatitis or BPH, which stands for benign prostatic hypertrophy, or even prostate cancer. Serum levels are not significantly affected by the DRE. 

[Dr. Wiener] Option C. mentions the digital rectal exam. Does the abnormal one mean prostate cancer? 

[Dr. Handy] The DRE focuses on the prostate size, consistency, and any abnormalities within or beyond the gland. Many cancers occur in the peripheral zone, and they may be palpated on the DRE. Overall, though, only 20 to 25% of men with an abnormal DRE have prostate cancer. 

[Dr. Wiener] What about vitamins in general and vitamin E specifically? 

[Dr. Handy] The selenium and vitamin E cancer prevention trial, or the SELECT trial enrolled African American men aged 50 and over and others aged 55 years and older and showed no difference in cancer incidence in patients receiving vitamin E or selenium alone or in combination relative to placebo. There was a similar lack of benefit for vitamin E, vitamin C, and selenium seen in the Physicians' Health Study II. 

[Dr. Wiener] So I take it that no vitamins really are shown to be preventive for prostate cancer. So that leaves us option E. must be true. There are no medications currently approved for prostate cancer prevention. 

[Dr. Handy] That is correct. No agent is currently approved for the prevention of prostate cancer. The results from several large double-blind randomized chemo prevention trials have established that five alpha reductase inhibitors is a predominant therapy to reduce the future risk of a prostate cancer diagnosis. The prostate cancer prevention trial in which men aged over 55 received placebo or finasteride showed a 25% reduction in prostate cancer incidents from 24% with placebo to 18% with finasteride. There was another trial, the REDUCE trial, and that showed a reduction in incidents from 25% with placebo to 20% with dutasteride. And while both studies met their endpoint, there was concern that most of the cancers that were prevented were low-risk. So neither drug is approved for prostate cancer prevention. 

[Dr. Wiener] So the correct answer for these questions are E. 

[Dr. Handy] Correct. 

[Dr. Wiener] Okay, before we close, what are the things that people can do to decrease their risk of cancer, broadly speaking? 

[Dr. Handy] Avoidance of identified risk factors for cancer and encouraging healthy habits contributes the most to cancer prevention. Biggest one, avoidance of tobacco. Other things, high levels of physical activity are good. Avoidance of the sun. Maintaining a normal weight. Diet is a little bit more complicated. Cohort studies and randomized trials suggest that a reduction of red meat or processed meat consumption has a small, if any, effect on cancer incidence and mortality, although the overall evidence base is weak, but we always recommend having a healthy diet. 

[Dr. Wiener] I'm all about healthy diets. So the teaching points today are that while prostate-specific antigen, or PSA, is produced by the prostate gland, there are many disorders that can cause an elevation, and we should know about them. It is not specific for prostate cancer. There are currently no medications that are approved by the FDA for the prevention of prostate cancer. 

[Dr. Handy] This question and other questions like it can be found on Harrison's Self-Review. And if you'd like to read more about the topic, you can find information on the chapter on benign and malignant diseases of the prostate. Visit the show notes for links to helpful resources, including related chapters and review questions from Harrison's, available exclusively on AccessMedicine. If you enjoyed this episode, please leave us a review, so we can reach more listeners just like you. Thanks so much for listening. 

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