Editing Prostate cancer (section)

== Screening ==
{{Main|Prostate cancer screening}}
Most cases of prostate cancer are diagnosed through screening tests, when tumors are too small to cause any symptoms.<ref name=ACS-Signs>{{cite web |title=Prostate Cancer Signs and Symptoms |url=https://www.cancer.org/cancer/prostate-cancer/detection-diagnosis-staging/signs-symptoms.html |access-date=21 May 2023 |publisher=American Cancer Society |date=1 August 2019 |language=en}}</ref> This is done through blood tests to measure levels of the protein [[prostate-specific antigen]] (PSA), which are elevated in those with enlarged prostates, whether due to prostate cancer or [[benign prostatic hyperplasia]].{{sfn|Rebello|Oing|Knudsen|Loeb|2021|loc="Screening and early detection"}}<ref>{{cite web |url=https://www.cdc.gov/cancer/prostate/basic_info/screening.htm |access-date=17 May 2023 |title=What Is Screening for Prostate Cancer? |publisher=U.S. Centers for Disease Control and Prevention |date=25 August 2022 |archive-date=7 September 2017 |archive-url=https://web.archive.org/web/20170907151112/https://www.cdc.gov/cancer/prostate/basic_info/screening.htm |url-status=live }}</ref> The typical man's blood has around 1 [[nanogram]] (ng) of PSA per [[milliliter]] (mL) of blood tested.{{sfn|Carlsson|Vickers|2020|loc="3. Tailor screening frequency based on PSA-level"}} Those with PSA levels below average are very unlikely to develop dangerous prostate cancer over the next 8 to 10 years.{{sfn|Carlsson|Vickers|2020|loc="3. Tailor screening frequency based on PSA-level"}} Men with PSA levels above 4&nbsp;ng/mL are at increased risk – around 1 in 4 will develop prostate cancer – and are often referred for a prostate biopsy.<ref name=ACS-Screen>{{cite web|url=https://www.cancer.org/cancer/types/prostate-cancer/detection-diagnosis-staging/tests.html |accessdate=11 December 2023 |title=Screening Tests for Prostate Cancer |publisher=American Cancer Society |date=4 January 2021}}</ref>{{sfn|Scher|Eastham|2022|loc="Prostate-specific antigen"}} PSA levels over 10&nbsp;ng/mL indicate an even higher risk: over half of men in this group develop prostate cancer.<ref name=ACS-Screen/> <!--Looking for sources to add more here about PSA levels that rise over time-->Men with high PSA levels are often recommended to repeat the blood test four to six weeks later, as PSA levels can fluctuate unrelated to prostate cancer.{{sfn|Carlsson|Vickers|2020|loc="4. For men with elevated PSA (≥3 ng/mL), repeat PSA."}} [[Benign prostatic hyperplasia]], [[prostatitis|prostate infection]], recent [[ejaculation]], and some urological procedures can increase PSA levels; taking [[5α-Reductase inhibitor|5α-reductase inhibitors]] can decrease PSA levels.<ref name=ACS-Screen/>

Those with elevated PSA may undergo secondary screening blood tests that measure subtypes of PSA and other molecules to better predict the likelihood that a person will develop aggressive prostate cancer. Many measure "free PSA" – the fraction of PSA unbound to other blood proteins, usually around 10% to 30%. Men who have a lower percentage of free PSA are more likely to have prostate cancer.{{sfn|Duffy|2020|loc="Percent free PSA"}} Several common tests more accurately detect prostate cancer cases by also measuring subtypes of free PSA, including the Prostate Health Index (measures a fragment called −2proPSA) and 4K score (measures intact free PSA).{{sfn|Duffy|2020|loc="Prostate Health Index (PHI)"}}{{sfn|Duffy|2020|loc="4K score"}} Other tests measure blood levels of additional prostate-related proteins such as [[kallikrein-2]] (also measured by 4K score), or urine levels of [[mRNA]] molecules common to prostate tumors like [[PCA3]] and [[TMPRSS2]] fused to [[ERG (gene)|ERG]].{{sfn|Duffy|2020|loc=Table 2}}

Several large studies have found that men screened for prostate cancer have a reduced risk of dying from the disease;{{sfn|Rebello|Oing|Knudsen|Loeb|2021|loc="Box 1: Screening for prostate cancer in different regions"}} however, detection of cancer cases that would not have otherwise impacted health can cause anxiety, and lead to unneeded biopsies and treatments, both of which can cause unwanted complications.{{sfn|Rebello|Oing|Knudsen|Loeb|2021|loc="Screening and early detection"}} Major national health organizations offer differing recommendations, attempting to balance the benefits of early diagnosis with the potential harms of treating people whose tumors are unlikely to impact health.{{sfn|Rebello|Oing|Knudsen|Loeb|2021|loc="Screening and early detection"}} Most [[medical guidelines]] recommend that men at high risk of prostate cancer (due to age, family history, ethnicity, or prior evidence of high blood PSA levels) be counseled on the risks and benefits of PSA testing, and be offered access to screening tests.{{sfn|Rebello|Oing|Knudsen|Loeb|2021|loc="Screening and early detection"}} Medical guidelines generally recommend against screening for men over age 70, or with a life expectancy of less than 10 years, as a newly diagnosed prostate cancer is unlikely to impact their natural lifespan.{{sfn|Rebello|Oing|Knudsen|Loeb|2021|loc="Screening and early detection"}}{{sfn|Rebello|Oing|Knudsen|Loeb|2021|loc="Box 1: Screening for prostate cancer in different regions"}} Uptake of screening varies by geography – more than 80% of men are screened in the US and Western Europe, 20% of men in Japan, and screening is rare in regions with a low [[Human Development Index]].{{sfn|Rebello|Oing|Knudsen|Loeb|2021|loc="Box 1: Screening for prostate cancer in different regions"}}