PIN and ASAP are changes in the cells in the prostate, which can only be seen under a microscope. PIN stands for prostatic intraepithelial neoplasia. ASAP stands for atypical small acinar proliferation.

If you've been diagnosed with PIN, it's probably high-grade PIN. There is also low-grade PIN, but there's no evidence that this can cause problems in a man's lifetime. You can check with your doctor if you're not sure. When we say PIN, we mean high-grade PIN.

What is PIN?

PIN is not prostate cancer.

PIN stands for prostatic intraepithelial neoplasia. It involves changes to the cells in the prostate. The cells may grow in a different way to normal prostate cells. These changes can only be seen under a microscope.

We don't know what causes PIN, but we do know that the chance of finding it increases as you get older.  

Although PIN is not prostate cancer, many men with prostate cancer do have some PIN as well. But most men with PIN don’t have prostate cancer and won’t go on to develop prostate cancer that needs treating.

What is ASAP?

ASAP stands for atypical small acinar proliferation. ASAP isn’t a medical condition but is a term used to describe changes to prostate cells seen under the microscope, when it isn’t clear whether the cells are cancer. For example, there may not be enough changed cells for the doctor to say whether they are cancer. If you have ASAP your doctor may recommend more tests so that any further cell changes are found early. 

It's possible to have both ASAP and PIN in your prostate.

Am I more likely to get prostate cancer if I have PIN or ASAP?

If you have PIN or ASAP, you are more likely to have prostate cancer found on a second biopsy than a man with no PIN or ASAP.

  • 3 in 10 men with a lot of PIN will be diagnosed with prostate cancer after a second biopsy.
  • Around 8 in 100 men who have ASAP will be diagnosed with prostate cancer after a second biopsy.

If you've been diagnosed with PIN or ASAP and are worried about prostate cancer, speak to your doctor or nurse. Read more about your risk of getting prostate cancer. Or you could speak to one of our Specialist Nurses.

Researchers are looking at whether certain diets or medicines can help to prevent prostate cancer in men with PIN. But we need more evidence for these. Remember, many men with PIN will not get prostate cancer.

What are the symptoms of PIN and ASAP?

PIN doesn’t cause any symptoms. But it’s usually diagnosed when a man has tests or surgery for another prostate problem that does have symptoms. For example, if you have an enlarged prostate as well as PIN, you might have problems urinating (weeing) that are caused by the enlarged prostate, not the PIN.

If you are diagnosed with ASAP, the changed cells may or may not be cancer. If they are cancer, they may cause symptoms, such as urinary problems.

If you do have any symptoms such as problems urinating, speak to your doctor. They can do more tests to find out what's causing them, and suggest treatments that may help.

How are PIN and ASAP found?

PIN and ASAP can only be found by looking at prostate tissue under a microscope. This might happen if:

A doctor who specialises in checking cells under a microscope (a pathologist) will look at the samples. They will send your doctor a report, called a pathology report, with the results. The results will show:

  • whether they found any PIN, ASAP or cancer in your prostate
  • how many samples were affected
  • how much PIN, ASAP or cancer was in each sample.

Ask your doctor or nurse to explain your test results, or you can speak to our Specialist Nurses.

How common are PIN and ASAP?

We don’t know how many men in the UK have PIN or ASAP. But for men who have had their prostate tissue looked at under a microscope (after a biopsy, for example):

  • up to 1 in 20 men (five per cent) have PIN
  • around 1 in 50 men (two per cent) have ASAP.

Black men are more likely to get PIN than white men of the same age. Some research also suggests black men may get a larger amount of PIN at an earlier age than white men. But we don’t fully understand the reasons for this. 

We do know that black men are more likely to get prostate cancer than other men of the same age in the UK. In fact, one in four black men will be diagnosed with prostate cancer. But we still don’t know the reasons why. Read more in our leaflet, Prostate cancer and other prostate problems: Information for black men.

There hasn’t been any research to look at how likely it is for Asian or mixed-race men to get PIN or ASAP.

Will I need treatment for PIN and ASAP?

You won't need any treatment for PIN or ASAP, but you might need regular check-ups every few months. This is to check for any cancer cells that may have been missed by the first biopsy.

You may have:

You might also have an MRI scan to check there's no cancer in parts of the prostate that weren't looked at in your biopsy.

The tests you have will depend on your own situation. Talk to your doctor or nurse if you have any questions . You can also speak to our Specialist Nurses.

If you are diagnosed with cancer, it is more likely to be an early stage because you'll have had these regular check-ups. This means it can be carefully monitored or treated if necessary.

If you do go on to develop prostate cancer, you won't have any more check-ups for PIN or ASAP.

Where can I get support?

There’s still a lot we don’t know about PIN and ASAP. We know this can be frustrating and you might be anxious about getting prostate cancer.

Sometimes, when men are diagnosed with PIN or ASAP they find it helpful to find out more about prostate cancer. Most prostate cancer grows slowly or doesn’t grow at all. It may never cause any problems or shorten a man’s life. It may not need to be treated, and can sometimes be monitored with regular check-ups instead. But some prostate cancer does grow quickly and is more likely to cause problems. This needs treatment to stop it spreading outside the prostate. Read more about the different types of prostate cancer.

If you are worried about your biopsy results, our Specialist Nurses are here to talk through your concerns and help answer any questions you might have.

Questions to ask your doctor or nurse

  • Have I got high-grade PIN or ASAP?
  • How much high-grade PIN or ASAP do I have?
  • Do I need further tests to find out more?
  • What is my risk of getting prostate cancer?
  • How often will I need to have check-ups?
  • What will my check-ups involve?
  • Will I need to have another biopsy?
  • What kind of biopsy will I need?
  • Will I need any other tests?

List of references and reviewers

Updated October 2023 | Due for review October 2024

  • Bostwick DG, Cheng L. Precursors of prostate cancer: Precursors of prostate cancer. Histopathology. 2012 Jan;60(1):4–27.
  • Clouston D, Bolton D. In situ and intraductal epithelial proliferations of prostate: Definitions and treatment implications Part 1: Prostatic intraepithelial neoplasia. BJU international. 2012;109(s3):22–6.
  • Clouston D, Bolton D. In situ and intraductal epithelial proliferations of prostate: definitions and treatment implications. Part 2: intraductal carcinoma and ductal adenocarcinoma of prostate. BJU Int. 2012 Dec;110 Suppl 4:22–4.
  • Cui K, Li X, Du Y, Tang X, Arai S, Geng Y, et al. Chemoprevention of prostate cancer in men with high-grade prostatic intraepithelial neoplasia (HGPIN): a systematic review and adjusted indirect treatment comparison. Oncotarget. 2017 Mar 15;8(22):36674–84.
  • Dickinson SI. Premalignant and malignant prostate lesions: pathologic review. Cancer Control. 2010;17:214–22.
  • De Marzo AM, Haffner MC, Lotan TL, Yegnasubramanian S, Nelson WG. Premalignancy in Prostate Cancer: Rethinking What We Know. Cancer Prevention Research. 2016 Aug 1;9(8):648–56.
  • Elkoushy MA, Elshal AM, Elhilali MM. Incidental Prostate Cancer Diagnosis During Holmium Laser Enucleation: Assessment of Predictors, Survival, and Disease Progression. Urology. 2015 Sep;86(3):552–7.
  • Kowalewski A, Szylberg Ł, Skórczewska A, Marszałek A. Diagnostic Difficulties With Atrophy, Atypical Adenomatous Hyperplasia, and Atypical Small Acinar Proliferation: A Systematic Review of Current Literature. Clinical Genitourinary Cancer. 2016 Oct 1;14(5):361–5.
  • Laurila M, van der Kwast T, Bubendorf L, di Lollo S, Pihl CG, Ciatto S, et al. Detection rates of cancer, high grade PIN and atypical lesions suspicious for cancer in the European Randomized Study of Screening for Prostate Cancer. European Journal of Cancer. 2010 Nov;46(17):3068–72.
  • Leone A, Gershman B, Rotker K, Butler C, Fantasia J, Miller A, et al. Atypical small acinar proliferation (ASAP): Is a repeat biopsy necessary ASAP? A multi-institutional review. Prostate Cancer and Prostatic Diseases. 2016 Mar;19(1):68–71.
  • Lloyd T, Hounsome L, Mehay A, Mee S, Verne J, Cooper A. Lifetime risk of being diagnosed with, or dying from, prostate cancer by major ethnic group in England 2008–2010. BMC Medicine [Internet]. 2015 Dec [cited 2015 Nov 5];13(1). Available from:
  • Merrimen JLO, Evans AJ, Srigley JR. Preneoplasia in the prostate gland with emphasis on high grade prostatic intraepithelial neoplasia: Pathology. 2013 Apr;45(3):251–63.
  • Montironi R, Mazzucchelli R, Lopez-Beltran A, Scarpelli M, Cheng L. Prostatic intraepithelial neoplasia: its morphological and molecular diagnosis and clinical significance. BJU International. 2011;108(9):1394–401.
  • Morote J, Schwartzmann I, Celma A, Roche S, de Torres IM, Mast R, et al. The current recommendation for the management of isolated high-grade prostatic intraepithelial neoplasia. BJU International. 2022;129(5):627–33.
  • Mottet N, Cornford P, van der Bergh RCN, Briers E, Eberli D, De Meerleer G, et al. EAU - EANM - ESTRO - ESUR - ISUP - SIOG Guidelines on Prostate Cancer [Internet]. European Association of Urology; 2023 [cited 2023 Mar 30]. Available from:
  • Prostate cancer risk management programme: overview [Internet]. GOV.UK. [cited 2022 Jun 13]. Available from:
  • Wobker SE, Epstein JI. Differential Diagnosis of Intraductal Lesions of the Prostate. [Review]. Journal of Surgical Pathology. 2016 Jun;40(6):e67-82.
  • Zynger DL, Yang X. High-grade prostatic intraepithelial neoplasia of the prostate: the precursor lesion of prostate cancer. International journal of clinical and experimental pathology. 2009;2(4):327.

This publication has been reviewed for accuracy and updated by:

  • our Health Information team
  • our Specialist Nurses.