The former England captain played 79 Tests between 1982 and 1992.
The South-African born batter urged people to get tested after being recently diagnosed himself.
Lamb made his Test debut for England in 1982 and went on to represent the country at three World Cups. He scored 4,656 runs in 79 Tests and enjoyed a 22-year first-class career from 1973 to 1995.
On Twitter, Lamb said: “I urge all men to go and get their PSA levels checked as prostate cancer so often goes undiagnosed.
“Having recently been diagnosed with prostate cancer, I have just completed a month of treatment.
“Put your egos aside-don’t be ignorant about your health.”
He has received support from the sporting world including Gary Lineker who tweeted: “Sorry to read this, Lamby. Wish you a full and speedy recovery. Important message too.”