Sean Lock first discovered he had cancer in 1990 when a one-night stand spotted symptoms on his back.
A woman named Tina alerted the comedian to a misshapen tag on his skin that he discovered to be a malignant melanoma - as Mirror Online reports.
The 8 Out of 10 Cats team captain died aged 58 this week after a battle with cancer - but he had previously said how this encounter in 1990 saved his life.
READ MORE: Sean Lock's final public video to raise money for food charity before he died aged 58
He said: "She said there was something weird on my back. I asked her what it looked like and she said it was a patch of skin which was black, misshapen, with a crusty texture and about the size of a 10p piece.
"I had no idea how long it had been there. It didn't hurt or itch, so there was nothing that would have drawn my attention to it.
"I never saw Tina again, but if I happen to bump into her, the first thing I'll tell her is that she saved my life."
He attributed his condition to his previous career before comedy, working as a labourer.
Following in his builder father's footsteps, he found a job stripping concrete panels off buildings - which meant that he was outdoors for sometimes 12 hours a day.
The comedian joked how the macho atmosphere of the building site did not account for sun protection.
He told the Daily Mail: "You could hardly ask a big Irish foreman, 'Please could you rub some Ambre Solaire on my back?'
Sean's skin tag was in the small of his back meaning he was unable to see it. But after Tina had alerted Sean to the mark, he consulted a dermatologist who removed the melanoma straight away.
However, Sean claimed he did not take the procedure particularly seriously as he slept in and arrived late to his follow up appointment.
Sean said he felt "invincible" like nothing could ever harm him when he was younger - and he did not even realise the words "malignant melanoma" meant cancer.
But in the following five years, Sean said he heard of an explosion in skin cancer cases, particularly in older people who had moved abroad to warmer climates.
And when a friend of his parents died from cancer, he realised how "lucky" he had been.
Symptoms of skin cancer
The NHS explains what to look out for in malignant melanomas.
It says: "The most common sign of melanoma is the appearance of a new mole or a change in an existing mole.
"This can happen anywhere on the body, but the most commonly affected areas are the back in men and the legs in women.
"Melanomas are uncommon in areas that are protected from sun exposure, such as the buttocks and the scalp.
"In most cases, melanomas have an irregular shape and are more than 1 colour.
"The mole may also be larger than normal and can sometimes be itchy or bleed.
"Look out for a mole that gradually changes shape, size or colour."
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