The Peter Attia Drive - Qualy #53 - Screening for prostate cancer

00:00:00.000 welcome to the qualies a subscriber exclusive podcast qualies is just a shorthand slang for

00:00:10.640 a qualification round which is something you do prior to the race just a little bit quicker

00:00:14.880 qualies podcast features episodes that are short and we're hoping for less than 10 minutes each

00:00:19.920 which highlight the best questions topics tactics etc discussed on previous episodes of the drive

00:00:26.100 we recognize many of you as new listeners to the podcast may not have the time to go back and

00:00:30.920 listen to every episode and those of you who have already listened may have forgotten so the new

00:00:35.000 episodes of the qualies are going to be released tuesday through friday and they're going to be

00:00:39.000 published exclusively on our private subscriber only podcast feed now occasionally we're going

00:00:43.580 to release quali episodes in the main feed which is what you're about to hear now if you enjoy these

00:00:49.100 episodes and if you're interested in hearing more as well as receiving all of the other subscriber

00:00:53.260 exclusive content which is growing by the month you can visit us at peteratiamd.com forward slash

00:00:59.240 subscribe so without further delay i hope you enjoy today's quali let's talk a little bit about

00:01:06.280 prostate cancer because it's not a cancer that comes without its controversy so let's start with the

00:01:11.800 biggest controversy or certainly one of the biggest controversies or things that would confuse the lay

00:01:15.640 person because about every year the advice changes on this thing called psa so what is the prostate

00:01:24.180 specific antigen psa is a protein it's made by the prostate and its normal function is to liquefy semen

00:01:32.300 so it's highly expressed in the process so the way i explain the prostate to people it's the best analogy i can

00:01:39.740 come up with is if you think about it like a sewer system you have the main sewer leaving the city

00:01:45.760 that's the urethra that's the tube that we normally urinate through but this channel also delivers semen

00:01:52.060 out the tip of the penis off this main sewer are slightly smaller sewers that go to different

00:01:57.860 neighborhoods within the neighborhood there's a sewer that comes out of the individual house

00:02:02.360 and the individual houses in this analogy are prostate epithelial cells they make components

00:02:08.980 of the semen and the semen is used to give nutrients to the sperm while it's trying to fertilize an egg

00:02:15.860 to enable the sperm to penetrate the cervical mucus these different functions psa is a protein that breaks

00:02:23.540 down the semen and liquefies it and people think it's an important for for this whole process of

00:02:29.940 fertilizing an egg so that's what it does and if you look in the semen the psa numbers are 100 million

00:02:36.640 per ml i mean the numbers the amount of this protein in the semen is astronomically high

00:02:42.900 so that's what it is that's what it does so how do we use it as a tool to screen for prostate cancer

00:02:50.220 well we check the values of the psa in the blood so since the prostate is a sexual gland if you check the

00:02:58.100 values of a psa in a eight-year-old boy it would be zero because there's no testosterone in that boy

00:03:04.320 there's no sexual development in that boy and therefore there's you know i mean there's some

00:03:09.840 but effectively no before puberty there's very little levels of testosterone there's no effectively

00:03:16.240 prostate epithelium and there's no psa as a boy goes through puberty to become a young man and then

00:03:22.500 as he goes through the aging process his prostate develops and the then it starts to produce psa as

00:03:29.900 part of the components of the semen now there is a certain amount of leakage of the psa fluid into

00:03:37.780 the bloodstream it's not quote-unquote supposed to leak into the bloodstream but it can and as the

00:03:43.800 prostate gets bigger so think about this concept of this underground sewer system the new york city

00:03:49.500 sewers right they're getting older they're getting leakier and the bigger the prostate gets and the

00:03:55.340 prostate gets larger as we get older some of these pipes get leaky and some of the psa leaks into the

00:04:02.000 blood so it was discovered in the 80s that there's this prostate specific protein that you can pick up in

00:04:10.180 the semen and you can also see in the blood and so it is not cancer specific it's prostate specific

00:04:17.580 and it's actually a very good biomarker for prostate size the bigger the prostate the more leaky it is

00:04:25.400 so to speak and the leakier it is the higher the numbers can go in the bloodstream so there's two

00:04:30.020 variables that can progress over time the size itself which can you could talk about that independent

00:04:36.500 of size so two 30 year olds one guy's got a five gram prostate the other guy's got a hundred gram

00:04:42.340 prostate just to make it extreme you should see a difference but also two guys with the same size

00:04:47.540 prostate that are two decades apart you might see a higher psa you could in the older that's right

00:04:52.360 so and if you do for example like we were always taught you know in you know residency even though

00:04:57.900 i wasn't a urologist you still once in a while have to you know we still did a urology rotation

00:05:01.520 if i recall you wouldn't check a psa on a man right after doing a rectal exam on him because in

00:05:06.820 theory that could artificially have raised the psa presumably by creating more of an insult and

00:05:11.580 increasing that flow pushing some of it into the blood the bloodstream so what can make the psa rise

00:05:17.680 besides just having getting older and having a larger prostate well if you get an infection in

00:05:24.000 your prostate so think about that like you got your city you have your sewer network and there's an

00:05:28.940 earthquake all the pipes are rattled a little bit and they all are extra leaky and that's what an

00:05:35.000 infection is it's not infections in the prostate are either all or none really they're not focal so

00:05:39.580 the whole prostate gets more leaky and the psa number can go way up the other way to think about

00:05:44.480 it is if you have a cancer and the the analogy would be low there's a there's a city block that

00:05:49.600 has the pipes you know the sewer systems clogged there's more back flow into the bloodstream and

00:05:55.140 that's how you pick it up that's not really how it happens but that's a good way for patients to

00:05:58.960 think about it so what is a normal psa well a normal psa is age adjusted so a normal psa for a 40 year

00:06:07.440 old is around 0.5 to 0.6 nanograms per ml for a 50 year old normal meaning this is the median for all

00:06:15.080 the population for a 50 year old it's one and so it kind of goes up stepwise by decade so there are

00:06:21.960 age adjustments that we do for the psa number now what are psa numbers that tell you you don't have

00:06:28.140 a cancer there's no psa number that is a hundred percent no cancer but there is a proportional rise

00:06:36.140 in cancer detection with rising psa numbers so originally the cutoff was set at a psa of four

00:06:43.960 we do you know we think about things more based on the individual scenarios so if you're a younger

00:06:49.480 person if your psa is more than 2.5 that's usually considered to be abnormal and may want you may need

00:06:56.520 further workup you don't need a biopsy right away these days in my opinion but you need further

00:07:00.240 workup so it depends on the age of the patient and depends on how also their prostate size now many

00:07:05.940 guys will go and when they get their psa checked there's another thing that gets checked called the

00:07:10.580 free psa and then a number is reported which is the percentage free which is obviously that

00:07:15.720 you know if their psa is three and their free psa is one then the percent free is reported as 33

00:07:21.040 what does that mean these are different ways for urologists to try to fine tune this prostate specific

00:07:28.820 antigen test to make it more a cancer specific test so again psa just goes up when you have and every

00:07:37.300 man has it's not cancer specific so percent free psa was the first way that urologists began to look at

00:07:44.800 well what's the chance that a psa of four is coming from a cancer versus a psa four coming from just

00:07:53.160 benign overgrowth so remember there's a lot of factors in play one would be if you had a man whose

00:07:58.840 prostate volume was 80 grams that's big and his psa was four well that's a low ratio that's something

00:08:06.640 called psa density how much psa is made per gram of tissue so you'd say well that guy it's very

00:08:14.600 low chance that he has a cancer that guy would also have a high percent free psa so percent free

00:08:22.380 psa is another way to just look at well how much of the psa is produced from benign cells versus

00:08:28.780 cancerous cells so if two guys have a psa of four and one has a free of one so he's 25 free and the

00:08:36.420 other guy has a free of three which is 75 free what's the different physiologically in those situations

00:08:42.420 well there's less bound psa in the lower percent free and that's more often associated with prostate

00:08:49.600 cancer so that's just a correlation so it's not like it means that in other words it's hard we can't

00:08:55.140 infer what because i would i would have assumed that the binding protein is in the periphery it's in the

00:09:00.380 plasma right yeah it's it's bound up when it comes out of the epithelial cell so it's just how it's

00:09:06.760 processed so psa's process is not a full length protein when it's born and and so the other way

00:09:13.040 that we now so just for the listeners so we have absolute cutoffs for psa for an older man 2.5 and

00:09:19.800 younger man but they're all really case specific in my opinion percent free psa was the first way to

00:09:25.160 say let's try to fine tune what the psa means so a high percent free psa is associated with a big

00:09:31.360 prostate less of a chance of prostate cancer a low percent free psa is associated with a higher

00:09:39.420 likelihood that that psa is produced from a gland with prostate cancer in it the other variables that

00:09:46.020 we use are psa density so that's highly predictive of what's going on in the prostate so an easy

00:09:53.020 threshold or cutoff for for you peter we talk on the phone about some of your patients percent free

00:09:58.480 psa density more than 0.1 it raises a little bit of a red flag a psa density of more than 0.15

00:10:05.820 that raises a red flag so think about it and that median prostate volume for a 60 year old guys 40

00:10:12.900 grams so 40 gram prostate psa less than four it's probably it's it's pretty safe a psa of six six that

00:10:23.300 raises red flags and you know this from your own patients that okay that guy probably has something

00:10:27.280 going on so that's how i think about it now think about the 80 gram prostate with the psa of four

00:10:32.980 oh you you have these patients in your practice they don't have cancer on average right a percent

00:10:39.040 free psa helps with that there are two other new tests that yeah so you got me onto the 4k

00:10:45.720 two years ago and i really consider it a game changer for for the guys like me who were in the peanut

00:10:52.020 gallery so i don't you know i make it my job to know as much as is knowable with the time that i

00:10:58.200 have about every possible disease that could afflict my patients but that means i need to spend as much

00:11:03.140 time thinking about colon cancer as i do coronary artery disease as i do prostate cancer so for me the

00:11:09.880 4k which again you didn't i mean you did me a great service not only did you get me interested in

00:11:14.720 but you introduced me to andrew at memorial sloan kettering i'm blanking on andrew's last

00:11:17.780 andrew vickers vickers yeah amazing guy yes and i mean the guy couldn't have been more generous

00:11:22.940 with his time i mean just gave me the schooling tutorial on this topic so good you know we put

00:11:29.100 together a patient handout on this thing and he even edited it for us um i feel like not an i'm

00:11:35.560 worried not enough patients understand that and i'm worried not enough primary care physicians

00:11:39.680 understand the importance of the 4k test can you explain how that has changed the way we do things

00:11:45.320 so this test you're alluding to and there's another test that performs equally well called

00:11:49.600 the prostate health index or phi test these both leverage off this idea that prostate cancer cells

00:11:56.880 make psa differently than benign prostate cells and so the 4k score is the fork calocrine test it takes

00:12:06.700 psa percent free psa intact psa and hk2 it takes those four prostate specific proteins produced and

00:12:17.460 it has a calculator to really just discriminate between a cancerous cell and a benign cell

00:12:23.080 phi uses the similar concept it uses something called minus two pro psa which is psa for all the

00:12:31.380 scientists out there plus two amino acids on the five prime side of it so minus two pro psa right

00:12:36.680 and you you measure those specific psa based proteins in the blood and the 4k score is great

00:12:43.640 because andrew vickers and hans lilia developed it with this other great urologist peter scardino

00:12:49.400 memorial and what they they looked at was well what's the chance that this person is diagnosed

00:12:54.700 with and has high grade aggressive lethal prostate cancer and it gives you a percentile chance so when

00:13:01.300 you get the 4k report it's actually a really nice report it'll say two percent chance twenty percent

00:13:06.280 chance and so forth and so now as you start using this in your practice they they now also give you

00:13:11.280 the psa so you can see the psa and you can say wait a second this guy's psa six but his 4k score is two

00:13:17.340 it's safe what i really like about it is and and so when we do our usually with our patients in their

00:13:23.980 second year sometimes in the first year but usually in their second year we do a cancer screening

00:13:28.120 program where we kind of walk them through every single cancer that you could possibly die of

00:13:33.000 and then we go cancer by cancer risk by risk and we it's a it's a very lengthy process on the back

00:13:39.760 end for the patient we simplified it takes about 90 minutes to go through it but for the males when

00:13:45.500 we come to this i always view this as one of the better i said i wish every cancer had a test like

00:13:51.240 this because as we'll come back to you know pretty much every guy is going to die with prostate cancer

00:13:57.180 but fortunately most men will not die from prostate cancer but our job is to figure out

00:14:02.200 when a guy has prostate cancer as you alluded to earlier is this the bad one yeah or is this the

00:14:07.080 one that if you muck around with it too much and so what i guess vickers and his team have been able

00:14:11.800 to do is figure out that there's now enough data that you can basically turn this into a binary test

00:14:17.220 you know which so that so psa would be a continuous variable right and when you want to test the

00:14:23.480 sensitivity and specificity of a continuous variable you have to use something called a

00:14:26.640 receiver operating characteristic curve and it becomes quite complicated because the question

00:14:31.240 becomes what cut off and as you alluded to it's very difficult with psa because it has to be age and

00:14:37.720 volume adjusted so now it's a three-dimensional receiver operating characteristic curve where you would

00:14:43.300 have a different auc area under the curve for each point in time and volume i mean that becomes

00:14:50.080 almost inconceivable right and yet the the 4k has basically allowed us to say the following

00:14:56.040 if your 4k score is less than 7.5 percent and i might butcher the numbers a little bit but that's

00:15:02.180 right number but if it's less than 1.5 percent the probability that you will be alive the probability

00:15:08.420 that you will die of metastatic prostate cancer is 1.6 percent in the next 20 years yeah it's almost

00:15:13.800 the lifetime of the patient and that's based on this data from andrew's partner a co-developer

00:15:19.960 hans lilya where they had this incredible database from malmo sweden so they could track it and then

00:15:26.100 the reverse is if you're greater than 7.5 percent i think it's like 16 or 17 chance in 20 years they

00:15:32.920 that's the the binary cutoff is 7.5 percent but it's a continuous variable but above that it's

00:15:38.480 continuous it's not like if you're above that you know it's up 50 so it varies based on the number

00:15:43.160 i hope you enjoyed today's quali now sit tight for that legal disclaimer this podcast is for general

00:15:50.260 informational purposes only and does not constitute the practice of medicine nursing or other professional

00:15:55.380 health care services including the giving of medical advice and note no doctor patient relationship

00:16:01.020 is formed the use of this information and the materials linked to the podcast is at the user's

00:16:06.400 own risk the content of this podcast is not intended to be a substitute for professional

00:16:10.560 medical advice diagnoses or treatment users should not disregard or delay in obtaining medical advice

00:16:16.400 for any medical condition they have and should seek the assistance of their health care professionals

00:16:20.760 for any such conditions lastly and perhaps most importantly i take conflicts of interest very

00:16:26.680 seriously for all of my disclosures the companies i invest in and or advise please visit

00:16:32.000 peter atia md.com forward slash about

The Peter Attia Drive - November 05, 2019

Qualy #53 - Screening for prostate cancer

Episode Stats

Length

Words per Minute

Word Count

Sentence Count

Misogynist Sentences

Hate Speech Sentences

Summary

Transcript