Prostate biopsy results: PIN and ASAP

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 that wasn’t picked up on your first 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.

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 treatment 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 (peeing) 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:

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 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.

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?
  • Will I need any other tests?

List of references and reviewers

Updated August 2022 | Due for review August 2023

  • Ben-Shlomo, Y. et al. The risk of prostate cancer amongst black men in the United Kingdom: the PROCESS cohort study. Eur. Urol. 53, 99–105 (2008).
  • Bostwick, D. G. & Cheng, L. Precursors of prostate cancer: Precursors of prostate cancer. Histopathology 60, 4–27 (2012).
  • Clouston, D. & Bolton, D. In situ and intraductal epithelial proliferations of prostate: Definitions and treatment implications Part 1: Prostatic intraepithelial neoplasia. BJU international 109, 22–26 (2012).
  • 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. 110 Suppl 4, 22–24 (2012).
  • Cui, K. et al. Chemoprevention of prostate cancer in men with high-grade prostatic intraepithelial neoplasia (HGPIN): a systematic review and adjusted indirect treatment comparison. Oncotarget 8, 36674–36684 (2017).
  • De Marzo, A. M., Haffner, M. C., Lotan, T. L., Yegnasubramanian, S. & Nelson, W. G. Premalignancy in Prostate Cancer: Rethinking What We Know. Cancer Prevention Research 9, 648–656 (2016).
  • Dickinson, S. I. Premalignant and malignant prostate lesions: pathologic review. Cancer Control 17, 214–222 (2010).
  • Elkoushy, M. A., Elshal, A. M. & Elhilali, M. M. Incidental Prostate Cancer Diagnosis During Holmium Laser Enucleation: Assessment of Predictors, Survival, and Disease Progression. Urology 86, 552–557 (2015).
  • 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 14, 361–365 (2016).
  • Laurila, M. 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 46, 3068–3072 (2010).
  • Leone, A. et al. Atypical small acinar proliferation (ASAP): Is a repeat biopsy necessary ASAP? A multi-institutional review. Prostate Cancer and Prostatic Diseases 19, 68–71 (2016).
  • Lloyd, T. et al. Lifetime risk of being diagnosed with, or dying from, prostate cancer by major ethnic group in England 2008–2010. BMC Medicine 13, (2015).
  • Merrimen, J. L. O., Evans, A. J. & Srigley, J. R. Preneoplasia in the prostate gland with emphasis on high grade prostatic intraepithelial neoplasia: Pathology 45, 251–263 (2013).
  • Montironi, R., Mazzucchelli, R., Lopez-Beltran, A., Scarpelli, M. & Cheng, L. Prostatic intraepithelial neoplasia: its morphological and molecular diagnosis and clinical significance. BJU International 108, 1394–1401 (2011).
  • Morote, J. et al. The current recommendation for the management of isolated high-grade prostatic intraepithelial neoplasia. BJU International 129, 627–633 (2022).
  • Mottet, N., Cornford, P. & van der Bergh, R. C. N. EAU Guidelines on Prostate Cancer. (2022).
  • National Institute for Health and Care Excellence. Prostate cancer: diagnosis and management. (2021).
  • Prostate cancer risk management programme: overview. GOV.UK https://www.gov.uk/guidance/prostate-cancer-risk-management-programme-overview.
  • Wobker, S. E. & Epstein, J. I. Differential Diagnosis of Intraductal Lesions of the Prostate. [Review]. Journal of Surgical Pathology 40, e67-82 (2016).
  • Zynger, D. L. & Yang, X. High-grade prostatic intraepithelial neoplasia of the prostate: the precursor lesion of prostate cancer. International journal of clinical and experimental pathology 2, 327 (2009).

This publication has been reviewed for accuracy and updated by:

  • our Health Information team
  • our Specialist Nurses.