Canadian Cancer Society logo

Prostate cancer

You are here: 

What is prostate cancer?

Prostate cancer is a malignant tumour that starts in cells of the prostate. Malignant means that it can spread, or metastasize, to other parts of the body. Prostate cancer is the most common cancer in Canadian men. It usually grows slowly and can often be completely removed or managed successfully.

The prostate is part of a man’s reproductive system. It is a walnut-sized gland just below the bladder and in front of the rectum. It surrounds part of the urethra, which is the tube that carries urine and semen through the penis. The prostate makes part a liquid called seminal fluid, which mixes with sperm from the testicles to make semen. Semen is released from the penis during orgasm.

Cells in the prostate sometimes change and no longer grow or behave normally. These changes may lead to non-cancerous, or benign, conditions such as prostatitis and benign prostatic hyperplasia (BPH).

Changes to cells of the prostate can also cause precancerous conditions. This means that the cells are not yet cancer but there is a higher chance these abnormal changes will become cancer. Precancerous conditions that can develop in the prostate are prostatic intraepithelial neoplasia (PIN), proliferative inflammatory atrophy (PIA) and atypical small acinar proliferation (ASAP).

In some cases, changes to prostate cells can cause prostate cancer. Most often, prostate cancer starts in glandular cells of the prostate. These cells make a part of the seminal fluid. This type of cancer is called adenocarcinoma of the prostate.

Rare types of prostate cancer can also develop. These include transitional cell carcinoma and sarcoma.

Diagram of the male reproductive system


Sophie Lebel My family is proud of the work I’m doing that is making a positive change in people’s lives.

Read Dr Lebel's story

How can you stop cancer before it starts?

It's My Life! icon

Discover how your lifestyle choices can affect cancer risk and how you can take action with our interactive tool – It’s My Life!

Learn more